The neural mechanism involved in the analysis of complex sounds was studied. By using a given cat's voice, the responses of the neurons at various levels of the auditory pathway to a cat's voice were analyzed with regard to the time patterns and the probability of firing by using a band-pass or band-rejection filter at particular center frequencies. In the cochlear nerve fibers, the responses to a cat's voice were a simple sum of the responses to the filtered components of the cat's voice. No mutual inhibitory interaction due to the coexisting frequency components in the vocalization was found at this level. However, the mutual inhibitory interaction was clearly found in the cochlear nucleus and became more evident at higher auditory centers reaching up to the medial geniculate body. The degree of this inhibitory interaction was different from neuron to neuron. Several collicular auditory neurons did not respond to a cat's voice, but did to filtered components. In an extraordinary case, a similar neuron was also found in the cochlear nucleus.
The neural process of the feature extraction from complex sounds is attributed to the synaptic mechanism of mutual inhibitory interactions. On the other hand, the majority of neurons in AI of the cortex showed an integrative action.

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1) Uptake and localization of ⁴⁵Ca were investigated in the isolated rat neurohypophysis by means of electron microscope autoradiography. The gland was incubated in ⁴⁵Ca-Locke's solution in which 1/10-1/20 of CaCl₂ was replaced by ⁴⁵CaCl₂. The emulsion film was developed by a special method to obtain extremely fine silver grains and the number of grains struck by β-particles from ⁴⁵Ca was counted in photographs of various parts of the tissue.
2) In the gland incubated in 56 mM K-⁴⁵Ca-Locke's solution or stimulated by electrical pulses at 20Hz for 5min, 20-40 grains/mm² were found in the fibers, whereas only 4-6 grains/mm² were found in the control.
3) In 23 fibers depolarized by excess K (678 grains) and 18 fibers stimulated electrically, 50-60% of the grains were found on the granule membrane or within it. Less than 5% of the grains were found on the nerve membrane and in the mitochondria.
4) The conclusion is that ⁴⁵Ca uptake of neurosecretory nerve fibers is increased by depolarization and that more than half the ⁴⁵Ca entering a fiber moves to the membrane of the neurosecretory granules or into the granules themselves.

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Myosin B was extracted at low ionic strength in the presence of ATP from the intestinal smooth muscle of pig. It exhibited a typical Ca⁺⁺-sensitivity like that of skeletal myosin B. The results obtained were as follows:
1) By lowering the temperature from 25°to 15°C, the Mg⁺⁺-activated ATPase activity and the rate of superprecipitation were more greatly decreased than those in the case of skeletal myosin B. On the other hand, for the change from 37° to 25°C, the amounts were the same as those of skeletal myosin B.
2) Temperature changes between 10°and 42°C had no significant effect on the Ca⁺⁺-sensitivity. Viz., it was more stable than that of skeletal myosin B.
3) Without Mg⁺⁺, the ATPase activity of intestinal myosin B was activated tenfold with the increase of KCl concentration from 0.2 to 0.5 M. With 4 mm Mg⁺⁺, the ATPase activity at 0.5M KCl without Mg⁺⁺ was much higher than that at 0.08 M KCl.
4) The ATPase activity at 0.5M KCl without Mg⁺⁺ was activated maximally with an increase of Ca⁺⁺ concentration from pCa 5.5 to pCa 4.0. Its Ca⁺⁺ dependence was very different from that of skeletal myosin B.
The above results may indicate that the differences in the properties of smooth and skeletal myosin B may be due mainly to differences in the properties of myosin.

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Single cell discharges were recorded in vitro from thin sections of cerebellum of the guinea-pig prepared vertical to the cortical surface and incubated in artificial media. White matter stimulation induced antidromic, mossy and climbing fiber responses in neurons in the Purkinje cell layer. Spontaneous discharges were observed in both Purkinje cell and granular layers. In the Purkinje cell layer, most neurons repeated a regular cycle of firing and silent periods. Response of each neuron to white matter stimulation increased and decreased synchronously with this. At the transition from the firing to silent period, many cells generated a sequence of spike bursts. Application of glutamate also caused a similar burst sequence. A train of stimuli to the white matter was followed by a sustained suppression of the spontaneous discharge for several seconds. A single stimulation did not induce a long and profound suppression of spontaneous discharge. These findings were discussed in comparison with those obtained in vivo.

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An attempt was made to identify the electrical property of the circular smooth muscle of the pregnant mouse uterus and to find out the functional interaction between the longitudinal and circular muscle layers.
1. In contrast to the spike potentials which dominate the electrical activity of the longitudinal muscle, slow potential was predominant in the circular muscle. Resting potential, length constant and conduction velocity of circular muscles were-55 mV, 1.2-1.5 mm and 0.5-1 cm/sec, respectively. Length constant and conduction velocity was 3 mm and 20 cm/sec, respectively, for the longitudinal muscle.
2. Coincidental discharge occurred in the circular muscle when the longitudinal muscle contracted spontaneously and vice versa, the feature being unaffected by the treatment with tetrodotoxin. Taking the contraction as representative of the generation of excitation, the result may suggest a myogenic conduction of the excitation between the longitudinal and circular muscles.

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Studies were made on the relation between the skin potential response (SPR) and sweat output of cat foot pads. With weak stimulation of the lateral planter nerve, both the SPR and sweat output increased with increase in the stimulus, but in supra-maximal stimulation, the SPR remained constant and only the sweat output increased. When blood circulation was withheld by ligation of the femoral vessels, sweat output decreased to zero within an hour, whereas the SPR was affected only slightly.
During perfusion of the foot with modified Ringer solution of various compositions, it was observed that the SPR was very susceptible to increase in the K⁺ ion concentration in the perfusate in contrast to slight effects produced by replacement of NaCl with sucrose or by replacement of Cl^- with SO₄^--.
From these results, it seems that the SPR of cat foot pads is caused by change in the membrane permeability of the sweat gland to potassium ion.

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Effects of caffeine on the electrical and mechanical properties of the smooth muscle of various regions of the guinea pig alimentary canal were investigated.
1) Caffeine (5mM) produced contracture (caffeine contracture) in the circular muscle of the stomach and the longitudinal muscle of the ileum, jejunum, caecum (taenia coli), and rectum. In the presence of caffeine, regular phasic contraction ceased in the stomach and taenia coli, but increased in the ileum, jejunum, and rectum.
2) Caffeine (5mM) eliminated the generation of the tonic response completely and suppressed the phasic response of K-induced contracture recorded from all regions of the alimentary canal.
3)Caffeine (5mM) suppressed the spike and slow wave which were generated in the stomach, without any change of the membrane potential and membrane resistance.
4) In Na-free (tris), Ca-free, and Cl-deficient (NO₃) solutions, generation of the slow wave recorded from the stomach was suppressed and in Cl-deficient (Br) solution, the frequency of the slow wave was increased. However, caffeine (5mM) produced contracture in all the above solutions without any marked change of the membrane potential and resistance.
5) Caffeine (5mM) depolarized the membrane in the ileum, taenia, and rectum and enhanced the spike amplitude and frequency in the ileum and rectum. However, it decreased the membrane resistance in the taenia coli and rectum, but increased or did not change the membrane resistance in the ileum.
6) ATP (5mM) and theophylline (5mM) suppressed the generation of the slow wave recorded from the stomach. Theophylline induced contracture, but the amplitude was smaller than that induced by caffeine (5mM). ATP did not induce contracture.
7) From the above results, the effects of caffeine are discussed in relation to the topical differences of the membrane properties in the alimentary canal. The roles of Ca in relation to actions of caffeine on the electrical and mechanical properties are also discussed.

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Influences of ions and temperature on the excitatory action of prostaglandin E2 (PGE) in the pregnant mouse myometrium were studied. In the normal Locke solution (35°C), low concentrations of PGE (10^-9-10^-8g/ml) did not depolarize the membrane, but increased the frequency of the burst spike discharges. High concentrations (10^-6-10^-5) caused depolarization by about 15-25 mV, and the muscle underwent contracture. The effects of low doses of PGE were potentiated to produce a measurable depolarization in low Ca media or at lower temperature, whereas the depolarizing action of PGE of high doses was depressed in excess Ca or in low Na media. Depolarization by PGE was restored in low Na solution when the external Ca concentration was reduced or when the tissue was exposed to lower temperature, suggesting that a possible shift of E_Na alone was not the limiting factor in determining the amount of depolarization. It is argued from the above results that the excitatory effect of PGE varies, depending on the ratio of [Ca] ₀/[Na] ₀, in such a way that the relative dominance of [Ca] ₀ tends to depress the drug action and vice versa. The effect of low temperatures on PGE action appears to resemble that of low Ca.

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