We aimed to clarify the overall distribution of glycinergic neurons in the brainstem and cerebellum in rats, using in situ hybridization for mRNA encoding glycine transporter 2 (GLYT2). We combined this method with in situ hybridization for mRNA encoding glutamic acid decarboxylase isoform 67 (GAD67), and have presented global and detailed views of the distribution of glycinergic neurons in relation to GABAergic neurons. In addition to this single-detection study, we performed double-detection of GLYT2 mRNA and GAD67 mRNA to determine the distribution of neurons co-expressing these mRNAs. A number of previous studies have shown immunohistochemically that many areas involve neurons in which glycine and GABA (or GAD) colocalize, and the present study has confirmed that such areas certainly involve double-labeled neurons with GLYT2 and GAD67 mRNAs. In addition, the present results have shown that many other areas of the brainstem and cerebellum involve double-labeled neurons. In particular, when lightly labeled GLYT2 mRNA-positive neurons were distributed within the area of GAD67 mRNA-positive neurons, almost all such GLYT2 mRNA-positive neurons were also GAD67 mRNA-positive. Areas or neuron groups expressing exclusively GLYT2 mRNA or GAD67 mRNA were rather limited, such as the superior and inferior colliculi, nucleus of the trapezoid body, raphe pallidus, area postrema, and Purkinje cells. The present study suggests that the colocalization of GLYT2 and GAD67 mRNAs, which may represent the corelease of glycine and GABA from single neurons, is more widespread than has been reported. [Jpn J Physiol 54 Suppl:S183 (2004)]

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In the rat, some findings have been taken to suggest the existence of monosynaptic cortico-motoneuronal (CM) connections. Since this connection is believed to be largely responsible for the ability to make independent digit movements in primates and man, it has been inferred that the monosynaptic CM connection in the rat is likewise important for skilled prehension. We compared intra- and extracellular recordings from forelimb motoneurones in the rats anaesthetized with intravenous injection of α-chloralose and immobilized with gallamine triethidide and artificially ventilated rats. No monosynaptic CM EPSPs were recorded. Instead, we found that the fastest descending excitation in forelimb motoneurones was disynaptically mediated via a cortico-reticulospinal pathway and slowly conducted excitation via corticospinal fibres and segmental interneurones. The findings stress the importance of di- and trisynaptic excitatory corticofugal pathways to forelimb motoneurones in the control of skilful digit movements. [Jpn J Physiol 54 Suppl:S183 (2004)]

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Some studies with extracellular recordings from the brain of awake and unrestrained rats show that psychomotor stimulants such as amphetamine activate most of motor-related striatal neurons at low doses that elicit nonfocused motor activation, while at high doses that induce focused stereotyped behaviour individual motor-related units are further activated or suppressed depending on their behavioural response characteristics. We studied the modulation by methamphetamine on synaptic inputs derived from the pyramidal tract by intracellular recordings, and morphological features of their receptive neurons with intracellular staining in the rat striatum. The excitatory synaptic potentials on the medium spiny neurons evoked by electrical stimulation of the pyramid were enhanced by the administration of methamphetamine, and the neurons projected to the both of the globus pallidus and entopeduncular nucleus. These findings suggest the convergence of glutamatergic excitatory inputs from the pyramidal tract, the final output of motor commands, and dopaminergic excitatory inputs from the substantia nigra pars compact on the medium spiny projection neurons that are involved in the both of the direct and indirect pathways in the rat striatum. [Jpn J Physiol 54 Suppl:S183 (2004)]

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We reported that when rats with the vermis ablated partially were dropped from the supine position, body turning of air righting were either too less (undershooting) or too much (overshooting). Reduction of vermal inhibition by ablation could facilitate fastigial neurons. Present study investigated if fastigial nucleus stimulation could provide similar effects on air righting movements as the vermal ablation. Under Nembutal anesthesia, wire electrodes were inserted into the fastigial nuclei on both sides and fixed on the skull with dental resin in male, adult Wistar rats. After recovery from the operation the rats were dropped from the supine position, while electrical stimulation was applied. Stimuli, currents 200-400mA, pulse widths 200-300msec., repetition frequencies 33-100Hz, duration 2 seconds were started just prior to and ended after falling. When the animals stood still on the four limbs, the stimulation with such parameters induced tilt of the whole body toward the stimulated side. Effects on the air righting were as follows; righting movements began earlier, the head and the body turned toward the stimulated side, and the ventriflexion of the body preceding the body turning in normal righting occurred simultaneously with the turning, and the body turnings varied in degree from under- to overshooting. Further, the landing posture of normal righting, in which the four limbs were extended and the head was raised, was abolished; the four limbs were rather flexed after the body turning. These results were similar to those of vermal ablation. [Jpn J Physiol 54 Suppl:S183 (2004)]

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There are two specific areas identified as supraspinal locomotion-inducing sites in cats: the mesencephalic locomotor region (MLR) in the midbrain and the cerebellar locomotor region (CLR) in the cerebellum. This study aimed to identify supraspinal sites which are involved in evoking hindlimb hopping movements in decerebrate rabbits. Under halothane anesthesia, rabbits (JW, 2-3 kg, ♂) were surgically decerebrated at the precollicular-postmammillary level. The head was then fixed in a stereotaxic apparatus, and the abdominal part was hung up by rubber belts. Pairs of insulated copper wires were inserted into the left and right hindlimb extensors and flexors for EMG recording. Wood's-metal-filled glass microelectrodes were inserted systematically into the midbrain (left side, L1-5) and cerebellum (L3-R3), and electrical stimuli (50 Hz, 10-100 μA, 0.2 ms duration) were applied for 5-10 sec at every 0.5 mm vertically and horizontally. Effective stimulus sites for evoking hindlimb hopping were found in the lateral portion of the midbrain and the midline region of the cerebellar white matter. Histologically, these two sites corresponded to the MLR and CLR identified in cats, respectively. During stimulation to these sites, the left and right hindlimbs exhibited rhythmic hopping movements in phase, not alternately as usually seen in cats' locomotion. These findings suggest that although cats and rabbits have similar locomotion-inducing sites at the supraspinal level, the neural systems for generating their specific locomotor patterns are organized in a different manner in the spinal cord. [Jpn J Physiol 54 Suppl:S184 (2004)]

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We have suggested that lamina VII interneurons receiving inhibition from flexor reflex afferents (FRA) mediate muscle tone suppression in cats. Here we examined whether interneurons having above characteristics contributed to the suppression and restoration of muscle tone, which were respectively induced by injections of carbachol and serotonin into the PRF. Activity of interneurons was extracellularly recorded from the lower lumbar segments (L6-7) of acute decerebrate cats. Lamina VII cells (n=19), which satisfied the characteristics, had a firing rates of 2.1 + 1.3 Hz. Their firing rate was increased (34.6 + 8.7 Hz) after carbachol injections, while it was reduced (4.3 + 2.7 Hz) after serotonin injections. However, cells receiving excitatory FRA inputs (n=15), including those mediating reciprocal Ia inhibition and non-reciprocal group I inhibition reduced their firing rate by carbachol and was re-established after serotonin. Changes in firing rate of 157 cells were also examined with respect to their location. Before carbachol, cells in the intermediate region and dorsal horn had higher firing rates than those in the ventral horn (lamina VII). However the latter had higher firing rates after carbachol.
These results suggest lamina VII interneurons that receive inhibition from volleys in FRAs are possibly involved in the carbachol-induced motor inhibition. Organization of spinal interneurons can be under the control of cholinergic-serotonergic reciprocity in the PRF. [Jpn J Physiol 54 Suppl:S184 (2004)]

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In the Japanese monkey, our recent PET study has shown that the primary motor cortex (M1) and the supplementary motor area were co-activated during bipedal (Bp) locomotion on the treadmill. To elucidate M1 mechanisms related to the control of Bp locomotion, we injected muscimol unilaterally into the digit/ankle, knee, hip and trunk representations within M1. Local injections of muscimol (5μg/μl, 1μl/site) were used to partially inactivate the M1 region identified with MRI and intracortical microstimulation. We found that unilateral M1 injections impaired movements of hindlimb joints, resulting in claudication on the side contralateral to the injection. The most pronounced effect was the foot-drop-like impairment following injection into the digit/ankle region. These impairments were due to a flaccid paresis predominantly observed in the counterpart of inactivated cortical region. Following injections into the trunk region, the monkey slightly dragged contralateral hindlimb with tilting the trunk forward. Despite the asymmetrical gait due to claudication, the cyclic movement of each hindlimb joint was replicable to some extent, however, in the manner different from that observed before muscimol injections. Our results suggest that M1 contributes to the elaboration and step-by-step control of ongoing Bp locomotion with selective adjustments of moment-to-moment movements of the trunk and hindlimbs. [Jpn J Physiol 54 Suppl:S184 (2004)]

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Our PET study has shown that the neural activity of the supplementary motor area (SMA) during bipedal (Bp) locomotion on the treadmill belt was significantly higher than during quadrupedal locomotion in the same monkey (M. fuscata). To elucidate the functional role of the SMA in the control of upright posture and Bp locomotion, we injected muscimol (10μg/l, 1μl/site) into the trunk/hindlimb representations of the SMA. Local injections along a penetration track were made to partially inactivate the SMA regions identified using MRI and intracortical microstimulation. We found that the unilateral SMA injections did not produce any Bp walking defects, whereas bilateral injections impaired the ability of the monkey to maintain upright posture resulting in locomotor defects. During Bp walking on the treadmill belt, step-by-step movements of single limb joints were not replicable and those of neighboring joints (hip-knee and knee-ankle) were no more coordinated, yielding a tottering gait pattern. These postural and locomotor impairments were due to a general reduction of postural muscle tone in the trunk and limbs. Our results suggest that the SMA is involved in the adjustments of posture accompanying Bp walking, and contribute to the elaboration and refinement of ongoing Bp locomotion together with the primary motor cortex. [Jpn J Physiol 54 Suppl:S184 (2004)]

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The STN provides glutamatergic projections to both pallidal segments and the substantia nigra pars reticulata (SNr). In these experiments we explored the effect of STN stimulation on the neuronal activity in SNc. Two monkeys received chronic recording chambers directed at STN and SNc. One chamber was used to carry out electrical stimulation of the STN with a microelectrode (monophasic stimulation at 1/s, pulse width 50 μs, amplitude < 300 μA), and the other to simultaneously record the neuronal activity in SNc, using standard extracellular single-unit recording techniques. Peristimulus histograms were used to calculate the latency and duration of responses.
The experiments showed two response patterns in the SNc. The first was an inhibition of activity, which typically started immediately after the stimulation and lasted 41.4 ± 23.7 ms (n = 122). The second pattern consisted of brief excitatory responses after the stimulation, occurring at a latency of 4.5 ± 2.5 ms (n = 72). Neurons with the two types of responses were not found in a specific topographic organization.
The results suggest that electrical stimulation of the STN has prominent effects on SNc activity. The inhibitory responses are likely due to activation of SNr neurons which then would inhibit SNc neurons. Short-latency excitatory responses are likely mediated via the monosynaptic projection from STN to SNc, or via the pedunculopontine nucleus. [Jpn J Physiol 54 Suppl:S185 (2004)]

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Monkeys were trained to lift a lever (self-paced hand movement); to open the mouth (self-paced mouth movement); and to protrude the abdomen (self-paced trunk movement), all at self-pace. Cortical field potentials were recorded by electrodes implanted on the surface and at a 2.0-3.0 mm depth in various cerebral cortices in the monkey during self-paced movements. A surface-negative, depth-positive potential (readiness potential) appeared about 1.0 s before onset of every self-paced movement in the premotor, motor, somatosensory and posterior parietal cortices. The readiness potential in the premotor cortex did not show so marked a somatotopical distribution and laterality related to a moving hand as those in the motor, somatosensory and posterior parietal cortices. Monkeys were also tasked to rotate both the neck and trunk to the right or left at self-pace (compound movement), after they were trained for self-paced rotation movement of the neck or trunk (simple movement). Cortical field potential recording was performed during the process of learning the compound movement. At an early learning stage when mainly simple movements were performed, readiness potential was smaller in amplitude in the premotor cortex. As the amplitude of the potential in the cortex became bigger, the compound movements gradually increased in number and skill. Electrical stimulation of the premotor cortex through the recording electrodes induced movements similar to the compound movements. This suggests that the premotor cortex is related to the generation of compound movements. [Jpn J Physiol 54 Suppl:S185 (2004)]

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To investigate the role of the supplementary motor area (SMA) in bimanual coordination, single neuron activity was recorded from the SMA during the performance of a bilateral hand movement task in combination with symmetric and asymmetric movements. This task enabled us to separately examine neuronal activity related to unimanual vs bimanual or symmetric vs asymmetric movement process. In the present study, two Japanese monkeys were trained to perform the task. Depending on the locations of motor instruction cues, the monkeys had to execute extension and/or flexion wrist movements with either or both hands. All eight combinations were classified into unimanual vs bimanual or symmetric vs asymmetric movements. About half of the SMA neurons recorded were active in response to contralateral movements, while more than 1/3 of them responded to bilateral movements. The activity specific to unimanual or bimanual movements was observed in 12% of SMA neurons. Of these three types of SMA neurons (contralateral, bilateral, movement-specific), 57% exhibited differential activities between the symmetric and asymmetric movements. [Jpn J Physiol 54 Suppl:S185 (2004)]

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Anticipatory postural adjustments (APAs) can be seen in postural muscles prior to self-triggered or self-inflicted postural perturbations. Their assumed role is to counteract the expected mechanical effects of the perturbation in a feedfoward manner. Timmann and Horak (2001) addressed the role of cerebellum on APAs to compare patients of spinocerebellar degeneration (SCD) with normal subjects. They suggest that the cerebellum may be less influential in APAs. However, this suggestion is still controversial because the cerebellum is well known to use the feedfoward mechanisms to regulate movements. Stepping tasks used in the previous study could not separate focal voluntary movements and postural activity adequately. It is consider that APAs was contaminated with focal movement in this case.In the present study, we investigated the change of APAs in the SCD patients by using the upper limb elevation task in that focal movement and postural activity are separated sufficiently. As the results, the SCD patients showed significantly smaller APAs amplitudes. These data suggest the important role of the cerebellum on generation of APAs. [Jpn J Physiol 54 Suppl:S185 (2004)]

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Reflex activities (M1, M2) of wrist flexor muscles (FCR, FCU) followed by intended movements while catching a falling iron ball were studied. Subjects performed the catching movement following four types of voluntary movement modes; "let go", "holding", "grasping" and "fingering". To eliminate the progressive influence of one mode of experience on reflex activity, a series of trials was set randomly. Surface EMGs were recorded on a data recorder and later those of sixty trials were averaged. The iron ball was released electromagnetically from 45 cm height. Kinetic energy of the falling ball caused the same level of muscle stretch in all four modes. Amplitudes of M1and M2 during "let go" were lower than those during the other three modes. Both FCR and FCU, amplitudes of M1 and M2 showed differences among individuals. It is suggested that the intended conditions or some cortical activations might affect the neural mechanisms with respect to modulation of M1, M2 amplitudes. However, in the present study it was not possible to show a clear difference of M1or M2 between FCR and FCU. Furthermore, we report the influence of the sense of vision on M1and M2 amplitudes. [Jpn J Physiol 54 Suppl:S186 (2004)]

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Horizontal oscillation of the center of pressure is useful for clinical diagnoses.But the vertical oscillation of the center of gravity is left unclear. The vertical oscillation was studied in physiological condition. METHOD: The vertical oscillation was measured from 8 healthy volunteers, aged from 36 to 55 years, with a force plate (G-5500, ANIMA Corp. Japan). Summed signals from 3 load cells were measured in a standing posture with eyes open for 1 min, and in a posture with knee flexion at 45 degree with eyes open for 1 min. The signal was sampled at 100Hz, and digitalized as 16 bits. Every 5 s-signal was analyzed with a Hanning window with the fast Fourier transform and the mean of the power spectra were used for discussion. RESULTS: An oscillation was noted for the knee flexed posture around 2-7 Hz. CONCLUSION: The vertical oscillation was reported to be responsive to the heart pulsations. However, the oscillation was suspected to be increased in physiological tremor. [Jpn J Physiol 54 Suppl:S186 (2004)]

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The purpose of this study is to find an easy way to prevent the hardening of the artery which is the typical results of bad life style. We measured the effects of easy stretch exercise for about 20-30 minutes in the morning and evening on average pulse pressure wave velocity (average PWV) and heart rate of young healthy women students (20-22yaers old), because, PWV is known to be a good indicator of the elasticity of artery, and heart rate to be an indicator of cardiac output. We measured the average PWV by recording ECG (first lead) simultaneously with extra-red pulse wave transducer attached to forefinger of the hand and second toe of the foot. We also measured BMI, maximum and minimum blood pressures.During three weeks after beginning of the every day stretch exercise, the average PWV gradually decreased about 2.6% along with the decrease of heart rate about 8%, of maximum blood pressure about 10%, of minimum blood pressure about 9%. BMI did not change by the stretch exercise.These results suggest that the stretch exercise easy to do is effective to prevent the hardening of the artery even in young healthy women. [Jpn J Physiol 54 Suppl:S186 (2004)]

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[Background] Prolongation of intestinal paralytic state after abdominal operation is a severe problem in the field of surgery. It may cause bacterial flora disorder which lead to bacterial translocation and may trigger complications. In order to prevent this, early recovery from this state is required. [Aim] The aim of this study is to evaluate the effects of epidurally infused Morphine to the recovery of postoperative ileus. [Subjects and Methods] 10 mature hound dogs (10-12kg)were separated to 2 groups. Catheters were inserted into the epidural space. Under general anesthesia laparotomy was done. Strain gauge force transducers (SGT) were sutured to the surface serosa of the body and antrum of stomach, duodenum, jejunum and ileum. Drug infusion started at the time of operation.(a)Natural saline (n=5), b)Morphine sulfate 0.08mg/ml in saline (n=5)).Motility recording started immediately after the operation. [Results] The appearance of first phase 3 was as below. (Hrs after operation(SD)): Body,antrum,duodenum,jejunum,ileum. SALINE:115.0(23.6),72.8(14.1),59.0(16.1),45.7(4.2),34.3(5.8).MORPHINE:50.7(11.3),49.0(11.4),20.8(9.7),12.8(7.7),2.7(1.6).The contractile force of the first phase 3 did not show significant difference between the two groups. [Conclusion] Morphine is often considered to disturb gut motility. In this study morphine suppressed intestinal motility after laparotomy with enough contractile power. We suspect that epidural use of morphine after abdominal surgery is a successful method for early recovery. [Jpn J Physiol 54 Suppl:S186 (2004)]

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The weakly electric fish, Gnathonemus petersii, generates a biphasic electric field from it's own pulse-type electric organ discharges (EOD) in the electric organ located at the base of tail. In the electrosensory systems, variations in the discharge rate and amplitude of own EOD enable the fish to detect local distortions of the electric field as 'electrolocation', and broad distortions evoked by other fish as 'electrocommunication'. In the present work, we examined how sensory stimuli changed the frequency of EOD in electrolocation and communication. In the behavioral experiments, each fish had it's own specific frequency, which was discharged during free swimming. When a metal rod was placed near the side of the fish, the frequency of EOD transiently increased from 5-10 Hz to c.20 Hz, while with the broad stimuli applied between the head and tail, the fish responded with a interval of EOD tuned to the stimulus frequency, with a minimum latency of c.10 ms. In the presence of propofol, that was activator of GABA-A receptor, EOD frequency decreased, but with a sharp tuning. The minimum latency of EOD for stimulus did not change. With a local injection of d-TC near the electric organ, neither responded to EOD frequency tuning nor fixed latency. This evidence suggests that sensory inputs are necessary for frequency tuning of EOD, and that the inhibitory GABAeargic neurons modulate the EOD frequency. [Jpn J Physiol 54 Suppl:S187 (2004)]

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Neuronal activity in the parabrachial nucleus (PBN) of rats was examined using Fos-like immunoreactivity (FLI) in retention and after extinction of conditioned taste aversion (CTA) to NaCl. In experiment 1, intraorally infused NaCl induced significantly greater FLI in the external lateral (els) and central medial subnuclei (cms) in the CTA group that had acquired CTA than in the sham-conditioned control group. Addition of the epithelial sodium channel blocker, amiloride, to NaCl solution severely reduced FLI in the cms but not in the els in both groups. In experiment 2, effects of decerebration after the acquisition of CTA on FLI in the PBN were examined. Decerebration completely eliminated the elevated FLI in the els and cms in the CTA group that was observed in experiment 1. In experiment 3, FLI in the PBN of rats in which CTA had been behaviorally extinguished (EXT group) was examined. FLI in the cms in the EXT group was significantly smaller than in the CTA group, and greater than in the control group. These results suggest that the els and cms are functionally different and that forebrain structures critically contribute to gustatory information processing in the PBN. [Jpn J Physiol 54 Suppl:S187 (2004)]

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To evaluate the role of visceral vagal afferent fibers and glucocorticoid in lipopolysaccaride (LPS)-induced feed-suppression, we observed the food intake and body weight in intact or vagotomized rats starting 2 days before, and continuing 6 days after an administration of 100 μg/kg LPS via the intraperitoneal (ip) route with or without methylpredonisolone succinate (MPDN, artificial glucocorticoid). Vagotomy was performed by one of three ways: (a) selective vagotomy in hepatic (HVX), gastric (GVX), or celiac (CVX) branches; (b) combined vagotomy (HVX+CVX, CVX+GVX, or GVX+HVX); (c) total subdiaphragmatic vagotomy (TVX). Feed-suppression induced by LPS was attenuated in the following order of rats with HVX, GVX, and CVX. Attenuation of LPS-induced anorexia in rats with HVX+GVX was greater than that in any animals with the single or combined vagotomy. However, not only GVX+HVX but also TVX failed to restore the complete food intake impaired by LPS. The anorexia and weight-reducing evoked by LPS was prevented markedly in rats given 150 μg/kg MPDN into the third cerebral ventricle. When 150 μg/kg MPDN, however, was given via the ip route, such preventions were not observed. We conclude 1) that both afferent signals via the hepatic and gastric vagus branches play an important role in the feed-suppression induced by LPS, and 2) that another factors other than vagal afferent signal may be involved in the LPS-induced feed suppression. Furthermore, MPDN ameliorates the LPS-evoked anorexia within the central nervous system. [Jpn J Physiol 54 Suppl:S187 (2004)]

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A sugar acid, 2-B4O has been found to increase from 3.5 to 13 in rat serum μM at 36 h after food deprivation. Injections of 2-B4O (2.5 μM) into rat III cerebral ventricle suppress food intake and single neuronal activity in the lateral hypothalamic area (LHA, feeding center) . 2-B4O hyperpolarizes glucose-sensitive neurons in the LHA via Na-K pump activation, while depolarizes the glucoreceptor neurons in the ventromedial nucleus, satiety center, via closure of ATP-sensitive K channels. The plasma levels of glucose, corticosterone, and catecholamines, and firing rate in both parvocellular neurons in the paraventricular nucleus and sympathetic efferent nerves all increase 2-B4O intravenous injection, indicating activation of the hypothalamo-pituitary-adrenal axis. A 2-B4O (iv) facilitates emotional and spatial learning and memory, and pretreatment of anti-acidic fibroblast growth factor (aFGF) antibody icv eliminates these effects. aFGF is released from ependymal cells in the III ventricle in response to the glucose increase in CSF induced by 2-B4O (iv). 2-B4O suppresses the clinical symptoms of experimental allergic encephalomyelitis (EAE) in Lewis rats ,a model for human multiple sclerosis. These results indicate that 2-B4O is not only a powerful satiety substance, but also effective as an activator of the hypothalamo-pituitary-adrenal axis and sympathetic efferent outflow, and as a memory facilitation and a suppressant of autoimmune function. [Jpn J Physiol 54 Suppl:S188 (2004)]

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The brain dopaminergic system is involved in reward, movement, and goal-directed behaviors. The nucleus accumbens (NAc) receives converging corticolimbic inputs and mesolimbic dopamine inputs. There are 5 subtypes (D1-D5) in dopamine receptors. The specific role of each dopamine receptor subtype in the learning behavior and its neural correlates in the NAc has been known little, because of a paucity of specific drugs capable of discriminating each family member. However, recent advance in gene targeting technique allows us to address this problem. In the present study, we investigate the effects of dopamine D1 or D2 receptor knockout (D1R-KO or D2R-KO) in reward, locomotor activity and spatial learning. To test the neural correlates with these functions, we recorded NAc neural activity while the mouse performed spatial tasks. For behavioral performance, both D1R-KO and D2R-KO mice displayed reduced locomotor activity and slower acquisition of the spatial tasks. D1R-KO did, and D2R-KO did not, change the sensitivity to intracranial self-stimulation. For neural activity, D1R-KO and D2R-KO eliminated excitatory and inhibitory prereward responses, respectively, of NAc neurons. These results provide evidence for the specific role of D1R and D2R in NAc neural response to prediction of reward, locomotor activity and spatial learning. [Jpn J Physiol 54 Suppl:S188 (2004)]

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We have reported that reward-driven discrimination learning of sound order is dependent on D2-like dopamine receptors in the rat. In the present study, we investigated the responsible targets of dopaminergic inputs in the brain and their roles in the discrimination learning of sound order. Water-deprived rats were trained to discriminate order of two sounds, and licking a spout during presentation of a particular sequence (S+) was rewarded with water while the opposite sequence (S-) was not. Either S+ or S- was presented randomly in a trial, which was repeated every one minute for 12 hours in 4 days. Percentage of trials in which rats licked the spout was calculated separately for S+ and S-, and test performance was estimated as the difference. 6-hydroxydopamine (6-OHDA) was locally injected into the brain one week before the test sessions. 6-OHDA injections into the bilateral nucleus accumbens suppressed sound discrimination in a nonspecific manner, so that discrimination of two sounds was impaired as that of sound order was. However, 6-OHDA injections into the bilateral auditory cortex specifically suppressed the test performance of sound order discrimination, while it has no clear effect on discrimination of two sounds. Licking itself was not impaired in both groups of rats. These findings suggest that dopaminergic inputs to the auditory cortex are critical for acquisition of sound order discrimination, while those to the nucleus accumbens are required for association between sensory stimuli and reward. [Jpn J Physiol 54 Suppl:S188 (2004)]

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It has been reported that the neurons in the posterior insular cortex are responsive to taste, visceral, and nociceptive stimuli. In the present study, we recorded extracellular unit activity from the neurons in the posterior insular cortex in anesthetized rats. Of the 20 neurons, 3 showed fluctuations in the spontaneous discharge (INSsp) during single unit recordings without stimulation. At the same time, we also observed spontaneous fluctuations of arterial blood pressure (BP) and heart rate (HR) in simultaneous recording. To analyze the relationships between the BP, HR, and INSsp, the correlation coefficient (r) between these factors were evaluated. The first neuron (unit-0408002) showed 2 times fluctuations in the INSsp during 9 minutes recording. The INSsp was positively correlated with the HR (r = 0.67). The r between the INSsp and the BP was relatively low (r = -0.26). The second neuron (unit-0621002) showed 5 times fluctuations in the INSsp during 46 minutes recording. Increase in the INSsp was associated with spontaneous increase of the BP (r = 0.31) and HR (r = 0.36). The third neuron (unit-0614002) showed 18 times fluctuations in the INSsp during 21 minutes recording. The INSsp was negatively correlated with the BP (r = -0.30). The r between the INSsp and the HR was 0.02. These results indicate that activity of some neurons in the posterior insular cortex associate with spontaneous fluctuations of the cardiovascular system. [Jpn J Physiol 54 Suppl:S188 (2004)]

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Last year, we presented that single neurons in anterior insular cortex of rhesus monkey responded during multi-trial reward schedule task. In the task monkeys were required to complete 1, 2, 3 or 4 red-green visual discriminations to obtain a juice reward. These schedules were randomly picked. In cued condition, a visual cue was presented in each trial, with the brightness of the cue indicating how many trials remaining before the rewarded trial. In shuffled condition, the order of cue brightness was shuffled within each schedule, making the relation between the cue and reward probabilistic.344/510 (67%) anterior insular neurons responded during the task. 166 were tested in both conditions. Anterior insular neurons tended to respond near the end of schedules (63/166 responded only during the rewarded trial in cued condition), and near the end of those trials. 72/166 responses preceded the rewarding event, suggesting reward expectancy signals. In shuffled condition, 6/166 showed graded modulation, which might have the relation with the reward predictability in the task schedule.These results suggest that the single neuronal responses in insular cortex are related to impending reward, and some responses are involved in estimation of reward availability when the rewarding sequence is not indicated to monkeys. [Jpn J Physiol 54 Suppl:S189 (2004)]

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The amygdala has been implicated in both social cognition to infer emotional states of other individuals (which processes are independent of autonomic activity) and own emotional expression based on biological evaluation (which processes are correlated to autonomic activity). Previously we reported that activity of some amygdalar neurons was correlated to biological significance of the objects. In the present study more than 500 monkey amygdalar neurons were recorded during discrimination of various facial expressions. Some neurons were further tested with approaching of the experimenter or various objects toward the monkey, and with various experimenter's actions. Autonomic activity (pupil radius) of the monkey, which reflected emotional expression, were simultaneously recorded. Results indicated that activity of some neurons increased when the experimenter, the hand of the experimenter, and novel objects approached toward the monkey. Pupil radius also increased during this approaching. These neurons did not respond to the photos of various facial expressions. Activity of other neurons increased when the experimenter moved his arm or leg. We are now analyzing correlation between pupil radius and activity of these neurons to determine whether the neurons were involved in emotional expression/biological evaluation or social cognition. Based on these findings, we will discuss about neural mechanisms of social cognition and biological evaluation in the monkey amygdala. [Jpn J Physiol 54 Suppl:S189 (2004)]

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Recent studies have shown that D-serine is abundant in the brain area enriched in N-methyl-D-aspartate (NMDA) receptors and that exogenously applied D-serine potentiates NMDA receptor-mediated neurotransmission. Therefore, D-serine is thought to modulate endogenously NMDA receptor functions. Since NMDA receptors play an important role in the learning, we thought that D-serine could have some effect on the behavior based on the memory and learning. The normal mice and mutant mice lacking D-amino-acid oxidase (DAO), an enzyme which metabolizes D-serine, were used for the behavior study. In the mutant mice, the brain concentration of D-serine thought to be higher than normal mice. We examined the difference in learning ability between the mutant mice and normal mice to characterize the learning behavior of the mutant mice. The learning ability was examined using Morris water maze: the swimming time for the mice to reach the hidden platform was recorded every day for a week. We observed that the swim time was longer in the mutant mice than in the normal mice, and that the decline of the swim time by training in the mutant mice was slower than that in the normal mice. These results suggest that high concentration of D-serine in brain of the mutant mice lacking DAO might have negative effect on the learning behavior. [Jpn J Physiol 54 Suppl:S189 (2004)]

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Neurons in the supramammillary nucleus (SuM) of hypothalamus project densely to the dentate gyrus and the CA2/CA3a regions of the hippocampus. Although the SuM has been considered to modulate the hippocampal function, the interaction between the SuM and the hippocampus is still unclear in freely moving rats. We monitored the neuronal activity in both the SuM and the hippocampus in freely moving rats using c-Fos immunohistochemistry. We compared the numbers of c-Fos positive neurons in the SuM and the hippocampus of rats sacrificed after exploring in an open field for two hours (OF group) with those of rats sacrificed soon after leaving their home cages (HC group). In the SuM, the dentate gyrus, CA1 and CA3 of the OF group, a large number of c-Fos positive neurons were observed, although only few c-Fos positive neurons could be found in those of the HC group. The distribution maps of c-Fos positive neurons in the SuM revealed that most of c-Fos positive neurons were found in the medial part of the SuM. We compared the number of c-Fos positive neurons in the hippocampus of SuM lesioned rats (SuM group) with that of sham operated rats (Sham group) after exploring in an open field. In the dentate gyrus and CA3, the number of c-Fos positive neurons were significantly decreased in the SuM group compared with the Sham group. These results suggest that the neuronal activity in the hippocampus is enhanced by the neuronal activity in the SuM when rats are exploring. [Jpn J Physiol 54 Suppl:S189 (2004)]

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NK3 receptor (neurokinin B receptor)-expressing neurons in the basal forebrain region of rats were characterized histochemically by combining immunocytochemistry, in situ hybridization and retrograde labeling, and electrophysiologically by whole-cell clamp recording. NK3 receptor-immunoreactive neurons were found in the basal forebrain region including the substantia innominata where axon terminals immunoreactive for preprotachykinin B, the precursor peptide of neurokinin B, were densely distributed. More than 90% of NK3 receptor-expressing neurons in the basal forebrain region showed signals for GAD mRNA, GABAergic neuron marker. In retrograde labeling study, NK3 receptor immunoreactivity was detected in about 25% of cortically projecting basal forebrain neurons. In the whole-cell clamp recording study, a selective NK3 receptor agonist evoked membrane depolarization or inward currents with decrease of input impedance in 10 of 100 cortically projecting basal forebrain neurons. Since neurokinin B-producing striatal neurons send axons selectively to the basal forebrain region (Furuta et al., 2000), the present results suggest that the release of neurokinin B by those striatal neurons induces inhibitory effect on cortical neurons via facilitation of GABAergic basal forebrain neurons expressing NK3 receptor. [Jpn J Physiol 54 Suppl:S190 (2004)]

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The medial prefrontal cortex (mPFC) receives monosynaptic ascending projections from both the hippocampus (HP) and the amygdala (AM, mainly the posterior basolateral nucleus) in rats. We have observed that HP- and AM-PFC pathways express long-term potentiation and depression (LTP and LTD), and that the HP-PFC consists of two kinds of electrophysiological properties in posterior dorsal and ventral CA1s (i.e., pdCA1- and vCA1-PFC pathways) in urethane-anesthetized rats. We examined here the synaptic interaction between the pdCA1 (or vCA1)- and the AM-PFC in an evoked potential level, and the effect of tetanization of AM on synaptic plasticity of the HP-PFC. Under conditions where both the pdCA1 and the AM evoked mPFC field potential at one recording site, semi-LTP of pdCA1-PFC increased as a result of in-phase high-frequency burst tetanization of AM-PFC but decreased when it was out-of-phase. We also observed the in- and out-of-phase effects of high or low frequent burst tetanization of AM on the semi-LTP of vCA1-PFC or the semi-LTD of pdCA1-PFC, respectively. Our results suggest that the synaptic interaction between HP- and AM-PFC pathways is controlled in both timing-dependent and -independent manners. [Jpn J Physiol 54 Suppl:S190 (2004)]

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The locomotor activity of rats in the open field is an essential index of the standardized animal test for several neurotoxicity studies. To investigate the influences on activity of learning, memory and emotion, we studied the effect of repetitive measurement at a 1- or 24-h interval and tested the application of footshock (below 0.3 mA, reportedly insufficient to condition fear) at the first measurement. In an open-field cage (45 cm square) equipped with shock grids, the non-shocked control group gradually decreased their activity to 30% during the first measurement for 1 h. During the second measurement with a 1-h interval, the activity curve was consistently lower than the initial version, whereas the curve partially recovered in the 24-h interval group. Footshock presentation at the first measurement amplified this curve-lowering effect at the second measurement, and changes in applied timing varied the amplified magnitude. These observed dependencies on interval length and timing suggest that learning and memory, respectively, underlie the first gradual decrease and the second curve lowering. We report our analysis of locomotor activity as influenced by emotion and the effect of hippocampal and prefrontal lesions caused by ibotenic acid. This work has been supported as LRI by JCIA. [Jpn J Physiol 54 Suppl:S190 (2004)]

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To investigate the prefrontal neuronal mechanism for mnemonic process of multiple objects and their order of presentation, we recorded neuronal activity from lateral prefrontal cortex while two monkeys performed a serial probe reproduction task, in which two sequentially presented objects (C1 and C2) were memorized and then select one target object from two memorized objects based on the color stimulus. Of 611 recorded neurons, 131 neurons showed object-selective delay-period activity during first delay after C1 (D1) and/or second delay after C2 (D2) periods. Forty-seven neurons showed the C1-coding delay-period activity, which was found during D1 and/or D2 periods when preferred object was presented during the C1 period, but not found when the preferred object was presented during the C2 period. Forty-three neurons showed the C2-coding delay-period activity, which was found during D2 period when preferred object was presented during the C2 period, but not found when the preferred object was presented during the C1 period. During the error trials, the C1-coding and C2-coding delay-period activities were decreased. The neurons with the C1-coding and C2-coding delay-period activities did not exhibit object selective activity during the delayed matching to sample task. The C1-coding and C2-coding delay-period activities were recorded from the ventral portion of the lateral prefrontal cortex (VLPFC). These results suggest that the VLPFC plays a role in holding information of both the object and the temporal order of presentation. [Jpn J Physiol 54 Suppl:S190 (2004)]

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"Feeling-of-Knowing (FOK)" is a sense of knowing a word before recalling it, and the FOK provides us clues to understanding the mechanisms of human metamemory systems. We investigated neural correlates of the FOK induced by face-name associations using the Recall-Judgment-Recognition paradigm with event-related functional magnetic resonance imaging (fMRI). Written informed consent was obtained from all the fifteen subjects in accordance with the Declaration of Helsinki, and the experimental procedure was approved by the institutional review board of the University of Tokyo School of Medicine. A 1.5 Tesla scanner system was used for the functional imaging. A T2*-weighted gradient echo echo-planar imaging was used to measure the blood-oxygen level dependent contrast (TR, 3.0 sec; TE, 40 msec) in 22 horizontal slices (voxel size, 4x4x5 mm; inter-slice gap, 1 mm). We analyzed the fMRI data with parametric analyses of six FOK ratings. The regions showing a significant linear relationships with the FOK ratings (FOK regions) were: the bilateral ventral, dorsal, and anterior prefrontal regions; the medial frontal regions; the medial surface regions; the left parietal regions; the bilateral superior temporal and nearby regions; the right anterior temporal region; and the bilateral thalami/basal ganglia. The activations in the temporal regions may reflect higher order information processing of face images as well as semantic information processing of the person to-be-recalled, and the information extracted by these processes may contribute to the FOK. [Jpn J Physiol 54 Suppl:S191 (2004)]

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We have examined how strategies for task performance change during the course of training in the memory-guided saccade task. The monkey was trained to make saccades to a target position (TP) which was determined by the color of the fixation point (FP). The task consisted of two kinds of trials; one representing those in early stages of learning [FP: green, TP: changed with experimental block: G trial] and the other representing those in well-learned stages [FP: white, TP: fixed through blocks: W trial]. After the monkey became abele to perform W trials with high success rate, saccades in G trials tended to direct to the TP for the W trial. In the present study, in order to further examine how the memory of the TP used in trials representing well-learned stages of learning affect the selection of the TP for saccades in the G trial, we introduced a new combination of the color and TP [FP: blue, TP: fixed through blocks: B trial] and examined the relationship between stages of learning in the B trial and the direction of saccades made in G trials. Saccades in G trials tended to direct to the TP for the B trial rather than the W trial while the success rate of the B trial was low. However, this tendency declined as this success rate reached a high level. These results suggest that the memory of the TP used in trials at stages where learning of the TP is in progress can be transferred to other similar types of trials, but that used in trials at well-learned stages can not be transferred. [Jpn J Physiol 54 Suppl:S191 (2004)]

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[Introduction] The aim of the present study is to compare the brain activation maps using fMRI between normal controls and schizophrenic patients during saccade and antisaccade tasks for detecting the neural network dysfunction in schizophrenia. [Subjects and Methods] Right-handed nine schizophrenic patients who showed good performance, nine schizophrenic patients with poor performance and nine healthy volunteers participated in this study. All the subjects were given written informed consent.During the saccade and antisaccade task, fixation point offset occurred after 500-1500 ms before a peripheral target appeared for a duration of 1000 ms. While subjects performed either the saccade or antisaccade task and baseline control tasks, fMRI scans were obtained. [Results and Conclusion] Cortical activations in the front-parietal network depended on the antisaccade task performance in schizophrenic patients. On the other hand, sub-cortical activations in the strieto-thlamic circuit were found only in the control group.Dysfunction of the striato-thalamo-cortical dopaminergic circuitry may reduce inhibition and thus facilitate saccades in schizophrenia. [Jpn J Physiol 54 Suppl:S191 (2004)]

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[Introduction] It has been suggested that abnormal exploratory eye movements are a behavioral marker for schizophrenia. We measured the brain activation maps using fMRI of healthy and schizophrenic subjects to explain the neural networks dysfunction in schizophrenia during exploratory eye movement task. [Subjects & Methods] Twelve healthy and thirteen schizophrenic subjects participated in this study. The subjects were asked to remember a series of presented figure of Benton Visual Retention Test and to compare subsequent figure. The subjects were required to indicate whether the two figures were the same or not by pushing a button. [Results & Conclusion] The result of reaction time and correct answer in schizophrenic patients to be compared with healthy subjects are not significant. Schizophrenic patients showed the more widely activations than normal subjects in the cortical regions including the parietal, frontal and supplementary eye fields. On the other hand, schizophrenic subjects showed reduced activity in the lentiform nucleus and the thalamus compared to healthy subjects. Our results indicate that the dysfunction of striato-thalamic network is intrinsic in schizophrenia and induced fronto-parietal cortical dysfunction. [Jpn J Physiol 54 Suppl:S191 (2004)]

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We evoked neural activity in the cerebral cortex with either electrical or mechanical stimulation of the whisker area in the face. Changes of local blood flow associated with neural activity were analyzed in the rat cerebral cortex on the ipsilateral side. Neural activities were confirmed by measuring fluorescence with voltage-sensitive dye (RH795) or recording electric field potentials. On the ipsilateral side neural resposes were relatively weaker and had a longer delay than those on the contralateral side. Using 605, 585 or 577nm light we focused on dynamic changes in total amount of Hb(HbT), deoxy-Hb(HbR) or oxy-Hb(HbO) concentration. When observed with 605nm light, the response showed a biphasic time course; an initial decrease of reflection light (initial dip: ID) and following its increase on both sides. Compared with the contralateral side, changes of HbR or HbO concentration in the ipsilateral side were smaller both in area and in magnitude of their response, and showed longer delay. Also there are some other differences of their time course between contra- and ipsi-lateral cerebral cortex. [Jpn J Physiol 54 Suppl:S192 (2004)]

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In the previous study we reported that detection of color is dominant in the right hemisphere. Here we examined cerebral lateralization of color discrimination using reaction time (RT) task. Eighteen undergraduate students with normal vision (21-27 years old) were asked to press a key to a target color stimulus which was presented on a CRT. Two discriminative RT tasks were performed. In the first task, one of three color stimuli (2 deg in size, red 635 mm, green 535 mm and blue 445 mm) was presented either right or left visual field at 4 deg holizontally from a fixation point. Subjects were required to press a key with their ipsilateral hand to a target color, which was instructed previously. In the second one, a pair of color stimuli was presented either right or left visual field and subjects were required to press a key when the two stimuli were different. In the first experiment, the left hemisphere was found to be faster than the right hemisphere (367.2±21.0 ms vs. 385.6±21.2 ms). Similar results were obtained in the second experiment. Discrimination time, which was obtained by subtracting simple RT from discriminative RT was faster in the left hemisphere than the right hemisphere (121.4±10.3 ms vs. 150.3±20.0 ms). On the other hand, there was no significant difference between right and left hemisphere in the RT to achromatic targets. These findings seem to suggest that color discrimination is processed in the left hemisphere. [Jpn J Physiol 54 Suppl:S192 (2004)]

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To elucidate the mode of interhemispheric neural connection and cooperation of the two neurons of bilateral somatosensory cortices, cross-correlation analysis were executed for approximately 300 neurons at the forelimb projection areas of 3a of the cats. Neuron data were collected during the spontaneous activity. Cat were anesthetized with Ketamine hydrochloride and sometimes immobilized by Gallamine triethiodide. Neuron pairs were selected having the following properties. 1) responsive to the same electric stimuli with the short latency(less than 10msec) of the same pair stimulation electrodes inserted in the corpus callosum. 2) selected at the optimal recording site of the evoked potentials to the radial nerve stimulation. Neurons pair could be categorized into three groups. 1) Most numerously recorded pairs having the common input neuron. 2)Second numerous pairs with inhibitory feature in cross correlation histogram(CCH). Probably their connection was composed of transcallosal excitatory neuron and local inhibitory neuron.3) Neuron pairs with excitatory feature in CCH were very rarely observed (less than 5%). Although we could not deny a possibility of the anesthetic effect or sampling bias of the selected neurons, these results might indicate that callosal neurons act rather suppressive than excitatory to neurons at the symmetrical position in the contra lateral somatosensory cortex on the spontaneous condition. [Jpn J Physiol 54 Suppl:S192 (2004)]

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On the stereotaxic thalamotomy for Parkinson's disease (PD), excess beta-band (13-27 Hz) rhythmic activities are observed in the thalamic ventroanterior/ventrolateral nuclei (VA/VL). To test the hypothesis that these activities were relevant to muscle rigidity, we analyzed their correlates in the surface electromyograms (EMGs) from limb muscles. The VA/VL beta-band activities were recorded with a bipolar concentric semi-microelectrode and observed as filtered local field potentials (beta-waves). In five PD patients who gave their informed consent to undergo the surgery with the electrophysiological examinations, we found that the VA/VL beta-waves were synchronized with limb muscle EMGs. Analysis revealed their properties as follows. 1) The beta-waves occurred when the patients became alert in a condition with increased or even rigid muscle tone spontaneously or in response to passive stretch maneuver. 2) In this condition, the beta-waves became transiently synchronized with the complex spikes in individual limb muscle EMGs. 3) During this particular period of synchronism the negative-going deflection of beta-waves with concurrent multiple unit spikes preceded the spike EMGs. 4) Active muscle contraction rarely abolished the preexistent beta-waves but rather less affected on their quantity. The results suggest that the excess VA/VL beta-band activities are contingently involved in parkinsonian rigidity by driving individual or presumably a population of muscles to contraction through the thalamocortical pathways. [Jpn J Physiol 54 Suppl:S192 (2004)]

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EEGs of twelve normal subjects were recorded during pleasant (β-Phenyl ethyl alcohol: odor A) and unpleasant (Iso-valeric acid: odor C) odor stimulations using Olfactometer <Takasuna, Co. LTD). Each odor was tested and divided into individual threshold and recognition levels. Respiratory volume and flow, and EEG were simultaneously recorded to determine the onset of inspirations for averaging EEG. Respiratory frequency decreased significantly in odor A recognition (A-R) (P<0.01) and increased in odor C threshold (C-T) and odor C recognition (C-R)(P<0.001, respectively). There were no changes in O2 consumption and CO2 production in all tests. Averaged potentials triggered by onset of inspiration found that there were three positive waves observed during 500ms after inspiring. According to power spectra of these waves, there were significant increases of alpha power on the electrodes except in parietal-occipital areas in A-R and C-R compared with others. The dipole tracing method estimated that dipoles were located in the entorhinal (ENT), centro posterior orbitofrontal (OFC) in A threshold (A-T), and also in the amygdala in C-T. In odor recognition, dipoles were estimated in the ENT and rostmedial OFC, and in the hippocampus in C-R. In general, alpha waves generate from the thalamus. We suggest that there is a link between alpha rhythm generator and brain areas related to odor perception. [Jpn J Physiol 54 Suppl:S193 (2004)]

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To evaluate human mind or feeling electrophysiologically, we examined electroencephalogram (EEG), electrocardiogram ECG and pneumogram. Amusing VTRs (Japanese comedians, Down-town) were shown to healthy male subjects (S.T. 21 yr, M.K. 19 yr, Y.K. 19 yr, Y.K. 19 yr and N.K. 19 yr). EEG was recorded almost 30 m (5 m control, 10 m watching VTR and 15 m recovery) by Neurofax EEG-1100 (Nihonkohden, Tokyo) and analyzed by data analysis software, Focus/QP-211A (Nihonkohden) in the present study. Electrode configuration of 25 points on scalp of subjects was based on the 10-10 electrode method by the IEF, International Encephalogram Federation. EEG was analyzed by FFT (Fast Fourier transform). We detected that amplitudes of beta and gamma on electrodes positions, T7 and T8 in temporal and parietal regions were greatly enhanced during watching the amusing VTR. The amplitude of an enhancement was larger when watching more amusing VTR. If the quantity of amusing level on VTR was small, the amplitude of beta and gamma amplitudes on FFT was small. On the other hand, intervals of respiratory ventilation were decreased during watching the amusing VTR. Even If subject felt that the VTR was funny, the heart rate did not changed during watching the VTR. Present results suggested that EEG and pneumogram were changed specifically in accompanying with emotional changes in response to amusing VTRs. However, ECG were little changed in spite of amusing or non-amusing VTRs. [Jpn J Physiol 54 Suppl:S193 (2004)]

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Bisphenol A (BPA), one of the environmental endocrine disrupter, is released from polycarbonate plastics and may influence the sexual differentiation of brain function. In this study, BPA was exposed to the pregnant wister rats at a dose of 0.1ppm during the last week of prenatal period. This dosage is below the tolerable daily intake level (TDI; 50μg/kg/day). At a age of 6weeks, behavioral tests were started. The offspring were tested using an open field test, an elevated plus maze test, a passive avoidance test, and a forced swimming test. In the BPA treated group, sex differences of the number of rearing and the duration of struggling behavior were disappeared. The duration of immobility, an indication of deppressive behavior, in the forced swimming test was elongated, and the duration of staying in the open arm in the elevated plus maze test were decreased. These findings suggest that the low dose of bisphenol A during the fetal periods impair sexual differentiation of the exploratory behavior, and enhance the depressive behavior and anxiety. [Jpn J Physiol 54 Suppl:S193 (2004)]

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We investigated the influence by chronic exposure to a low concentration of formaldehyde on emotional and learning behaviors in female C3H/HeN mice. Formaldehyde is well known as the main chemical substance inducing sick building syndrome. In this study, we exposed female C3H/HeN mice to 2000ppb formaldehyde for 12 weeks. After exposure, we evaluated the behavioral effects of the chemical using the elevated plus maze test, open field test, Lashley III maze learning test, passive avoidance learning test and hot plate test. A significant difference was observed between exposure mice and control in elevated plus maze test and passive avoidance learning test.The results demonstrated that chronic exposure to a low concentration of formaldehyde increased anxiety and facilitated avoidance learning without affecting influence general activity, exploratory behavior, spatial learning and nociceptive. [Jpn J Physiol 54 Suppl:S193 (2004)]

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We conducted the reading span test (RST) on 10 young student volunteers in order to investigate effects of different loads of exercise on the working memory. Subjects exercised 10 min ergometer cycling with loads in such a way that their heart rate attained to 10, 30, or 60% of predicted maximal heart rate (HRmax). Before and immediately after the exercise they sat on the chair and answered 2-, 3-, 4-, and 5-sentenses RST tasks serially. Mean RST result after each exercise was compared with that before exercise with using a dually tailed t test. Although after 10% exercise RST did not change significantly, after 30 as well as after 60% exercise RST were augmented significantly (p=0.007 and 0.0006, respectively). Present results suggest that relatively mild exercise could have activating influences on the cognitive power in young normal human. [Jpn J Physiol 54 Suppl:S194 (2004)]

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Amber is one of the first substances used by human as decoration and medicine for various disease. In the present study, we measured EEG, ECG, breathing and blood flow to investigate physiological effects of amber. We used foot-bath as stimulation from the body surface and incense as stimulation of the odor from the olfactory system. In the experiment of foot-bath, subjects (N.F., 33 years old and T.Y., 22 years old) put their feet for 20 min in the warm water (40±0.5°C) with and without the amber powder. The EEG was analyzed by meanFFT in 5 frequency bands (δ, θ, α, β, γ). The ECG were recorded by the first bipolar limb lead. Expiration and inspiration were recorded by using a thermister pick-up transducer. The blood flow in forehead was measured with laser flowmeter. The amplitude of δ wave decreased for 10 min after the stimulation of foot-bath, and this change was clearly observed on O1, O2. The decrease in the amplitude of δ wave continued for a longer time with amber, compared to the water without amber. The amplitude of α wave increased after foot-bath without amber on P7, P8 on both sides. The increase in the amplitude of α wave appeared on P8 with amber. On T7, the amplitude of β wave increased in foot-bath without amber. An increase in the amplitude of β wave appeared with amber on P8. No obvious changes were observed in heart rate, respiratory interval and blood flow. The present study showed that the amber induced stimulation influenced EEG and that α and β waves increased in the specific regions of the brain by amber. [Jpn J Physiol 54 Suppl:S194 (2004)]

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We have previously demonstrated that the intravenous administration of apomorphine induced increase in intragastric pressure via dopamine 2-like receptors situated in the area postrema. Since the microinjection of neurokinin-1 antagonist into the vicinity of the nucleus ambiguus (NA) diminished the increase in intragastric pressure, substance P responsive neurons in this area may mediate these gastric responses. To demonstrate this hypothesis, in the present study, we examined the response of neurons adjacent to the NA to the administration of apomorphine and the electrical stimulation of the efferent fibers from the nucleus tractus solitarii (NTS). Intravenous administration of apomorphine (0.1mg/kg) induced excitatory responses of neurons adjacent to the NA in anaesthetized rats. We further determined the effects of the electrical stimulation of the efferent fibers from the NTS and the bath-application of substance P on neurons adjacent to the NA by using whole-cell recording method in a slice preparation of 4-20 days old rats. Some of these neurons during pulse-train stimulation (50-Hz, 50-pulse, 10-sec interval) produced a "wind-up" response. These results suggest that gastric motor responses induced by the apomorphine administration are mediated by substance P responsive neurons adjacent to the NA. [Jpn J Physiol 54 Suppl:S194 (2004)]

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Recent study demonstrated PGE₂ receptors in various sites of micturition reflex. The purpose of this study was determination of the role of PGE₂ on micturition reflex in conscious rats. Methods: Continuous measurements of micturition were performed in SD male rats (300-450g) using the metabolic cage. Number of micturition (N) and urine volume (V) was calculated. 0.5ml or 4 ml the loxprofen solution (Lox) or distilled water (DW, for control) was given orally. Results: In control (0.5ml P.O.) averaged N in first 4 hours was 3.4 and V was 2.1g. At the same time of following day, Lox (1mg/kg, 0.5ml P.O.) was given. Average N in first 4 hours was 2.6 (75%, P<0.01), and V was 1.4g (63.1%, P<0.01). Averaged N and V of after Lox administration in 24 hours did not change from the control (P=0.77 and P=0.56, respectably). V increased from the control at 8-20 hours after the drug administration. For producing the extra-urination, 4ml of water drinking was performed. In control N in first 4 hours was 4.5 and V was 4.2g after 4ml-distilled water drinking. Lox (1mg/kg, 4 ml P.O.) reduced N in 4 hours to 2.8 (61.1%, P<0.02) and V to 2.6g (61.2%, P<0.01). Averaged N and V in 24 hours did not change from the control (P=0.83 and P=0.98, respectably). Conclusion: Loxonin reduced number of micturition and voiding volume in first 4 hours. PGE₂ might be important for the micturition reflex. [Jpn J Physiol 54 Suppl:S195 (2004)]

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Previously we reported effects of Cedrol inhalation on autonomic functions; Cedrol increased parasympathetic activity and decreased sympathetic activity in healthy young human subjects. In the present study, to investigate sites of action of Cedrol effects, we analyzed autonomic functions during inhalation of Cedrol fumes using healthy young and anosmic subjects, and patients with total laryngectomy. Vaporized crystalline Cedrol and blank air were presented to the subjects via a face mask. The results indicated similar effects of Cedrol in young healthy and anosmic subjects; Cedrol significantly decreased heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressure compared to blank air exposure. Spectral analysis of HR variability showed that Cedrol increased a high frequency (HF) component (index of parasympathetic activity), and decreased a ratio of low frequency (LF) to HF component (index of sympathetic activity). Furthermore, LF components of SBP and DBP decreased, suggesting sympathetic decrement. In the totally laryngectomized patients, Cedrol was directly inhaled into the lung through the trachea. In 6 of the 7 patients Cedrol increased HF and in 5 of those it decreased LF of SBP. The results suggested that Cedrol activated the central nervous system partly through the peripheral nerves innervating the lower airway and pulmonary system, which resulted in autonomic changes. [Jpn J Physiol 54 Suppl:S195 (2004)]

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We have shown in anesthetized rats that electro-acupuncture (EA) stimulation of the hindlimb, with an intensity sufficient to excite group III and IV afferents, increases hepatic glucose output(HGO). Since EA stimulation increases, almost in parallel, both HGO and plasma concentration of glucose, it appears likely that the increases of HGO result in elevation of plasma glucose. In the present study, responses of HGO and plasma glucose to EA stimulation of the hindlimb, with an intensity sufficient to excite group II afferents, were investigated in anaesthetised rats. HGO was measured with a microdialysis probe implanted into the left lateral lobe of the liver. Stainless steel needles with a diameter of 0.25 mm were inserted into the right tibialis anterior muscle and connected to an electrical stimulator. The EA stimulation was delivered for 10 min at 0.5 mA, 20 Hz. The EA stimulation with 0.5 mA had no significant changes in HGO. On the other hand, the same EA stimulation elicited increases in plasma glucose. The present results demonstrate that EA stimulation of the hindlimb with low intensity can increase plasma glucose level without increases of HGO, suggesting that the stimulation inhibits glucose uptake in peripheral tissues. [Jpn J Physiol 54 Suppl:S195 (2004)]

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The central baroreceptive neurons in the medulla oblongata express specific basic-leucine zipper (bZIP) transcription factors after baroreceptor stimulation. Here we studied the effects of baroreceptor stimulation on MafG induction in the rat medulla oblongata. MafG is a member of the small Maf protein family that functions as dimeric partners for various bZIP transcription factors by forming transcription-regulating complexes. To determine whether gene expression of MafG is induced in the medulla oblongata after stimulation of arterial baroreceptors by phenylephrine (PE), we examined the expression of the mRNA by the RT-PCR method and that of gene product MafG by immunohistochemistry. The number of MafG transcripts increased significantly in the medulla oblongata after the baroreceptor stimulation. In the PE pressor experiments, MafG-immunoreactive (IR) neurons were distributed in cardiovascular control sites: the NTS, DMX, AMB, CVLM and RVLM. The numbers of MafG-IR neurons in these nuclei were significantly greater in the PE-injected rats than in control rats. The temporal expression pattern of MafG was found to coincide with that of immediate early genes such as Fos. Our results suggest that MafG may play critical roles as an immediate early gene in the signal transduction of cardiovascular regulation mediated by baroreceptive signals in the medulla oblongata. [Jpn J Physiol 54 Suppl:S195 (2004)]

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