The brain is capable of carrying out multiple information processes simultaneously, but the capacity of our consciousness is limited and therefore must concentrate on part of the information process. This selection mechanism is called attention. How attention is allocated determines the efficiency of our mental processes; it is probably a central issue of the brain function. Specifically, our action is controlled in parallel by both conscious and unconscious processes. Unconscious processes include many kinds of reflexes and learned actions. Learned actions are particularly interesting because they initially (be fore practice) require consciousness and attention but become automatic after repeated practice (characterized as procedural learning). Therefore, we eventually acquire a large repertoire of learned actions that can be performed automatically and simultaneously. This allows us to perform a complex action, such as keyboard typing, because elementary movements that constitute the complex action can be performed automatically.
We examined spatial attention using a new visual illusion of motion called “line motion effect”. A line, which is presented physically at once, is perceived to be drawn from one side when attention is captured to that side of the line by a preceding visual cue stimulus. This effect is due to acceleration of visual information processing at the locus of attention. The motion illusion is produced by both stimulus-induced (bottom-up) and voluntary (top-down) attention, suggesting that the two kinds of attention act on relatively early stages of visual processing. Using the induction of illusory line motion as a measure we identified how various modes of spatial attention may be represented and reorganized in the brain. Based on these findings, we proposed a model that allows multiple functional modules in the brain to operate simultaneously but as an integrated system.

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Introduction
The visual suppression test reported by Takemori and her colleagues, was already widely known as a test for detecting disturbance of the cerebellar flocculus. Thereafter, this method was also available for detection of central disturbances of the paramedian pontine reticular formation (PPRF) and inferior parietal lobule.
In this report, we adopted this test to examine each disease causing spinocerebellar degeneration, Parkinson disease and Parkinson syndrome.
Subjects
Subjects were 34 patients with spinocerebellar degeneration. The cerebellar type comprised 12 cases, and spinocerebellar type 22 cases. Furthermore we studied 7 cases of Parkinson disease with disturbance of the basal nuclei and 24 cases of Parkinson syndrome.
All cases were in the early or middle stage of the clinical course. We rejected cases that did not show any response to caloric nystagmus, since this was recognized as indicating the progressive stage.
Results
As a result of the visual suppression test, we recognized that there was no enhancement of reaction in LCCA cases and no abnormalities in the visual suppression test in Parkinson disease cases. Some patients with spinocerebellar type degeneration and Parkinson syndrome showed enhanced reaction. Eight PSP patients showed enhanced reaction and their percentages were the highest of all disease groups.
Visual suppression test was considered a useful supplementary diagnostic technique for the differential diagnosis of degenerative disease.

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This study investigated the characteristics of postural sway in cases of Parkinson' s disease (PK). We examined 16 patients diagnosed with PK, of whom 2 were classified as positive symptoms (PK-P), while 6 (PK-Na) and 8 (PK-Nb) were found to exhibit negative symptoms. The subjects stood on a stabilometer with their eyes open or closed with both foot closed together, and the sway of the center of gravity of the body was recorded for one minute. This paper presents 20 measurements of stabilometry in PK, comparing the mean ±2 SD classified by gender and age of healthy subjects, mean ±1 SD, and with observation of factor analysis.
1) There were only a few cases demonstrating data exceeded the mean ±2 SD, considering each parameter. All cases of PK-Na and 6 of 8 PK-Nb cases exceeded the mean ±2 SD, considering every parameter.
2) Four of 8 PK-Nb cases exceeded the mean ± 1 SD, for area, locus length, Romberg's coefficient, vector of velocity in the forward-backward and right-left and standard deviation of amplitude probability density distribution in X- and Y- axes considering each parameter. The proportion of patients exceeding the mean was higher in PK-Nb than in PK-Na.
3) Factor 1 showed centripetal and forward-backward sway type with high factor loading as to locus length, high frequency band in X and Y, vector of velocity in the forward-backward and kurtosis of amplitude probability density distribution in Y. Factor 2 showed right-left and diffuse sway type with high factor loading as to area, vector of velocity in the right-left and standard deviation of amplitude probability density distribution in X and Y. Factor 3 showed displacement and multiple center type with high factor loading as to deviation of the center of sway in X and skewness of amplitude probability density distribution in X and Y.

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Brain infarction on magnetic resonance imaging was defined with high signal on T2-weighted image and low signal on T1-weighted image. However, high signal on T2-weighted image and normal signal on T1-weighted image were frequently observed at the pons. Therefore, we investigated 10 cases of pontine high signal by neuro otological study. Four cases were regarded as pontine ischemia, but 5 cases were considered peripheral vestibular disorder and 1 case remained idiopathic because there were no abnormalities on neuro otological study.
In conclusion, neuro otological study was indispensable for the diagnosis of vertigo even when pontine signal was high.

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Patients with vertigo complain about various degrees of vertiginous sensation. In the present study, vertiginous sensations were induced by caloric and optokinetic stimuli in normal volunteers. A questionnaire survey concerning daily life, including susceptibility to motion sickness, was also conducted.
The subjects consisted of 63 volunteers (24 males and 39 females) ranging in age from 17 to 72 years old, with a mean of 49.5 years of age. None of the subjects had any central nervous disorders or peripheral vestibular dysfunction, as assessed by equilibrium test.
Vertiginous sensation was induced by bilateral caloric stimuli at 30°C. Vertiginous sensation was also induced by optokinetic stimuli at 0-150°/sec with constant bilateral acceleration. A questionnaire containing 26 items concerning daily life was answered by all subjects.
Subjects were classified according to their ability to recognize rotational sensation during caloric and optokinetic stimuli. Nineteen subjects recognized rotational sensation during caloric stimuli but not during optokinetic stimuli. Only three subjects recognized rotational sensation during optokinetic stimuli but not during caloric stimuli. Nine subjects did not recognize rotational sensation during either caloric or optokinetic stimuli. Rotational sensation tended to be recognized during caloric stimuli rather than during optokinetic stimuli.
The twenty-six items on the questionnaire concerning daily life were related to constitutional, physical and psychological factors and susceptibility to motion sickness. The results of the questionnaire were compared among groups classified by the presence or absence of rotational sensation during caloric and optokinetic stimuli.
There were no significant relationships between constitutional, physical and psychological factors and/or susceptibility to motion sickness among the other three groups of subjects. The majority of subjects in all groups replied that they tended to experience motion sickness while traveling by ship or by car, especially when driven by other persons.

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This study evaluated illumination and spatial disorientation under multisensory stimulation (visual, vestibular, tactile and proprioceptive receptor). In this paper, we investigated spatial disorientation in view of postural control and self-motion sensation.
The flight simulator in National Aerospace Laboratory (NAL) was used. The subjects were 20 healthy young persons. The subject stood on the motionbase in front of a big screen. The image of a virtual room of JEM or a random dot pattern were projected on the screen. The image and the motionbase were tilted under computer control. Posture and perceived self-motion were affected by visual stimulation when the virtual image was used, especially when both the motionbase and image were tilted, but when the random dot pattern was projected, these effects were slight. We suppose that these effects were due to differences in the visual information that provided position cues. There was great individual variation in these postural responses. We suggest that this variation is due to individual differences in dependence on visual cues.

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Although the interrelations among dizziness and various psychological factors have been well reported, this is not the case for various therapies. Group psychotherapy was attempted in twenty-six patients who consulted the Department of Otolaryngology, Aichi Medical University between April and September 1997. In addition, questionnaires and the locus length measured by stabilometry with opened eyes and closed eyes were studied before and after the therapy to evaluate the effect. Eight doctors and nurses were studied with the patients as a control group.
Twenty-one of the twenty-six (81%) patients answered that therapy was effective in improving their dizziness. The locus length did not change after therapy on either opened-eye or closed-eye testing in the control group. A similar result to that in the control group was noted on opened eye testing, however, significant improvement (p < 0.05) was observed after therapy on closed-eye testing in the patient group. Furthermore, patients above 55 years old showed less improvement than patients under 55.
Group psychotherapy was effective for dizzy patients, however, it was more effective for patients under 55 years old than for those above 55.

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We often encounter patients with isolated vertigo in which the origin cannot be determined. MR testing for this condition has gained widespread use because of the ease with which it detects ischemia in comparison to that on CT. However, it has remained uncertain whether abnormal imaging findings do indeed reflect clinical morbidity. This study investigated the usefulness of MR imaging and ENG for vertebrobasilar circulation disorder and brainstem dyscirculation.
Of 157 cases of vertigo, OKP (ENG) findings were abnormal in 59 cases (38%) and ETT (ENG) was abnormal in 79 cases (50%). Abnormal MRI findings were observed in 45 cases (29%) and abnormal MRA findings were seen in 111 cases (71%). x² test demonstrated a significant relationship between the MRI and OKP or ETT findings and also between the MRA and OKP or ETT findings.
We conclude that an infarction and high intensity signal in thee, pons and cerebellum were definite morbid findings ; we also recognize a side-to-side difference in the vertebral artery to indicate ischemia or infarction of the lower pons. We confirmed the utility of MR testing in diagnosis and follow up of head and neck ischemic disease as well as the importance of equilibrium examination.

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Sensations of vertigo or disequilibrium in children are usually simplified to the ambiguous complaints 'feel giddy' or 'vertigo'. However, these complaints are rare and there are few clinical reports of such cases in clinical pediatrics.
We examined 41 patients under 18 years old. Twenty-four were female and 17 were male. These patients were brought to our clinic at Saitama Children's Medical Center with complaints of vertigo or disequilibrium between 1992 and 1996. The mean age on initial examination was 6.9 years. The frequency of orthostatic dysregulation (OD) was higher (11 cases; 27%), and 9 of the 11 patients were above 10 years old. The frequencies of acute cerebellar ataxia (9 cases) and multiple sclerosis (4 cases) followed that of OD. In the lower onset-age group (under 5 years old), gait instability due to palsy of the lower limbs was frequently seen. Cases of sensory disturbance were seen more frequently in the higher onset-age group.
To differentiate symptoms due to disturbances of the central or peripheral nerve system, we should consider the age-related characteristic of the diseases and developmental level.

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Recently, because of the development of MRI, it is becoming apparent that there are some cases of cerebellar vascular disorder in the posterior cranial fossa among cases of sudden onset of rotatory vertigo. We reported two cases of sudden onset of rotatory vertigo caused by cerebellar infarction in the territory of the posterior inferior cerebellar artery (PICA) due to cervical occlusive injuries.
Case 1. A 48-year-old male sustained a slight whip lash injury and after ten hours, experienced rotatory vertigo and hoarseness. When he came to our hospital, we could only detect hoarseness. However, vascular disorder in the posterior cranial fossa was suggested by the interview. MRI revealed left cerebellar and medulla oblongata infarction.
Case 2. A 29-year-old male felt rotatory vertigo and vomited after clicking his neck. Upon closer examination, pure rotatory spontaneous nystagmus, sensory disorder accompanied by sensory dissociation in his face and disability in standing and walking were found, suggesting vascular disorder in the posterior cranial fossa. MRI showed infarction in the left inferior cerebellar region, vermis and left lateral-dorsal medulla oblongata. A dissecting aneurysm in the vertebral artery was found on subsequent angiography.
In the Japanese literature, we could find only nine reported cases of cerebellar vascular disorder in the posterior cranial fossa due to the cervical occlusive injuries, in addition to our two cases.
The severity of injuries and the period until onset of diagnostic symptoms varied. Therefore, tracing cerebellar vascular disorders due to cervical occlusive injury required not only neurological and neuro-otological findings, but also attention to the history of the original injury and the development of subsequent symptoms. Without a careful interview, it is very difficult to correctly establish the cause of the disorder.

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