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Biomedical subjects

Motoichiro Kato

Publications and source records attributed to Motoichiro Kato.

At least 19 recordsLinked to original sources
PubMed2007

Unilateral amygdala lesions hamper attentional orienting triggered by gaze direction.

The newly discovered deficit in a bilateral amygdala-damaged case, of not being able to allocate attention to the critical feature of a face (Adolphs R, Gosselin F, Buchanan TW, Tranel D, Schyns P, Damasio AR. 2005. A mechanism for impaired fear recognition after amygdala damage. Nature. 433:68--72.), has opened a new window into the function of the amygdala. This case implies that the amygdala might be essential in detecting potentially relevant social stimuli, and directing attention accordingly. In this study, we have sought to test this implication by investigating the behavioral performance of 5 unilateral amygdala-damaged subjects on spatial cueing tasks. The tasks employed central gaze and arrow direction as cues to trigger attentional orienting in peripheral target detection. Although age-matched normal controls demonstrated a significant congruency effect such that targets presented congruently to cue direction elicited faster detection, amygdala subjects demonstrated no such congruency effect for gaze cues in the face of a significant congruency effect for arrow cues. The results suggest that the social valence of a stimulus is critical for amygdala involvement in visual processing. The results also support the implicated role of the amygdala in detecting and analyzing relevant social stimuli, and orienting attention accordingly.

Adult↗
PubMed2006

Memory and frontal lobe functions; possible relations with dopamine D2 receptors in the hippocampus.

Cerebral cortical regions are thought to be important for cognitive functions such as memory and executive function. Although the functional associations between dopamine D2 receptors and motor and cognitive functions have been extensively examined in the striatum using positron emission tomography (PET), the role of dopamine D2 receptors in extrastriatal regions has been unexplored. We aimed to investigate the relationship between dopamine D2 receptors in extrastriatal regions and the performance of a broad spectrum of cognitive functions including memory, language, attention, and executive function in healthy subjects. Extrastriatal dopamine D2 receptors were measured in 25 male subjects using PET with [(11)C]FLB457. After the PET scans, a battery of neuropsychological tests was administered to all subjects. We found that the binding potential (BP) of [(11)C]FLB457 in the hippocampus was positively correlated with memory function. Furthermore, BP of [(11)C]FLB457 in the hippocampus, but not in the prefrontal cortex, was associated with frontal lobe functions such as executive function and verbal fluency. Our findings suggest that dopamine D2 receptors in the hippocampus might affect the local hippocampal function, but also brain functions outside the hippocampus such as the prefrontal cortex.

Adult↗
PubMed2006

Cerebral cortical dysfunction in patients with temporomandibular disorders in association with jaw movement observation.

Temporomandibular disorders (TMD) represent a group of chronic painful conditions in the masticatory musculature and temporomandibular joint. To examine possible changes in cortical machinery in TMD patients, we compared neuromagnetic signals evoked by cortical neurons between healthy subjects and TMD patients while they were carefully observing the video frames of jaw-opening movements performed by another person. During the movement observation task in the healthy subjects, we found cortical activation in the following sequence with left hemisphere dominance: (1) the occipitotemporal region near the inferior temporal sulcus (human homologue of MT/V5 in monkeys), (2) the inferior parietal cortex (IPC), and (3) the anterior part of the inferior-lateral precentral gyrus (PrCG). In the TMD patients, however, we found deficit or marked attenuation of the neuromagnetic responses in the PrCG and IPC, while the activity of the MT/V5 showed no differences from that in the healthy subjects. In addition, we could not find any differences in cortical magnetic responses between healthy subjects and TMD patients when they were observing palm-opening movements, indicating that cortical dysfunction associated with jaw-movement observation is specific phenomena in the patients of TMD. Thus the present study provides new neuropathological evidence that TMD patients exhibit dysfunction of recognition mechanisms in cerebral cortex during motor observation, and suggests that disturbance of cortical functions regulating visuomotor integration would play a crucial role in development as well as aggravation of TMD.

Adult↗
PubMed2006

Gaze but not arrows: a dissociative impairment after right superior temporal gyrus damage.

Superior temporal sulcus (STS) activation has consistently been demonstrated in the normal brain when viewing eyes, and thus this area is implicated as a gaze processing region in humans. In a recent report, we have presented a case, M.J., with a well-circumscribed lesion to the right superior temporal gyrus (STG), who demonstrated impaired discrimination of gaze direction. In the aim to make distinct whether this impairment is unique to gaze, we have applied a spatial cueing paradigm established by Kingstone and colleagues. In our experiment, pictorial gaze and symmetrical arrows were centrally presented as non-predictive, spatial cues in detecting peripheral targets. Fifteen normal subjects and M.J. participated in the experiment. In concordance with previous reports, controls demonstrated a significant facilitation of reaction times in detecting targets cued by congruent gaze/arrows, compared with incongruent cues. In striking contrast, M.J. showed no such congruency advantage for gaze, in the face of a normal congruency advantage for arrows. We have demonstrated that a circumscribed lesion to the right STG impairs the ability to utilize biological directional information such as gaze, but leaves the non-biological counterpart (arrows) intact. This dissociation implies that indeed, the STS specializes in processing gaze.

Analysis of Variance↗
PubMed2006

Cortical reorganization and somatic delusional psychosis: a magnetoencephalographic study.

A woman complained of feeling a "metal-like thing" in her oral cavity 4 years after a stroke. She was convinced of the physical nature of her complaint despite intact dental and neurological findings. Somatosensory evoked magnetic fields suggested that her decreased right SII function was compensated for by the right SI region, probably contributing to the delusional symptom.

Cerebral Cortex↗
PubMed2006

Family history of alcoholism and cognitive recovery in subacute withdrawal.

A family history of alcoholism has been demonstrated to be an important factor affecting cognitive function. However, no studies have yet been conducted to compare cognitive recovery of family history-positive (FH+) and family history-negative (FH-) alcoholics in the subacute withdrawal period. To tackle this problem, a neuropsychological test battery consisting of six computerized tests was administered to 19 FH+ and 20 FH- alcoholics at 2 and 7 weeks after abstinence. At 2 weeks after abstinence, overall performance of both FH+ and FH- groups was significantly poorer than that of healthy controls. At 7 weeks, these performances tended to recover, but in Trail Making A and Figure Position, performances of FH+ alcoholics remained worse than those of controls, while those of FH- alcoholics did not. Thus cognitive recovery during the subacute withdrawal period was worse among FH+ alcoholics than FH- alcoholics, and this finding should be considered when planning alcohol rehabilitation programs.

Adult↗
PubMed2006

Pathway to psychiatric care in Bali.

The aim of the present study was to trace the help-seeking pathway of mental patients and to elucidate the role of traditional healing in Bali. The source of care before attending Bangli Mental Hospital (Bali) of 54 consecutive patients with no prior psychiatric treatment was investigated. Subjects who had sought help from traditional healers were asked to evaluate treatment effect retrospectively according to a 5-point scale. The pathway to psychiatric care was dominated by traditional healers. Of the patients, 47 (87.0%) consulted a healer (mean number 2.9) before visiting the mental hospital. Consultation with the healers was associated with treatment delay. However, of the 137 traditional healers on the pathway, 11 (8.0%) recommended that the subjects to go to a mental hospital, and all 11 subjects immediately followed the advice. Of the 47 subjects, 14 (29.8%) evaluated the treatment effect as much improved by at least one traditional healer on the pathway, although they ultimately attended the mental hospital. Subjects without psychotic symptoms tended to evaluate the treatment effect as much improved more often than psychotic subjects. Traditional healers function not only as a barrier to reaching psychiatric care, but as either an effective provider of care or a decision-making support for seeking help from psychiatric care for some mental patients in Bali. The knowledge and recognition of psychological disorders by the traditional healers are crucial for early treatment intervention for psychiatric patients.

Adult↗
PubMed2006

Beliefs about causes of schizophrenia among family members: a community-based survey in Bali.

OBJECTIVE: This community-based study investigated causal beliefs regarding schizophrenia among families of individuals in Bali who screened positive for schizophrenia and examined how their beliefs were related to the individual's psychiatric treatment status. METHODS: Causal beliefs of 39 key relatives were examined: 19 of the individuals with schizophrenia had received psychiatric medical treatment and 20 had never received such treatment. A questionnaire developed by the authors that listed 15 possible causes of schizophrenia was used to examine the respondents' beliefs. RESULTS: Key relatives attributed supernatural causes to schizophrenia more often than natural causes. Compared with relatives who listed a natural cause as most important (14 relatives, or 36 percent), relatives who considered a supernatural cause as being the most important (25 relatives, or 64 percent) had a significantly higher mean age and less education and were more likely to have family members with schizophrenia who had never received psychiatric medical treatment. CONCLUSIONS: Families' attribution of supernatural causes was strongly related to no receipt of psychiatric medical treatment by the individual with schizophrenia.

Adult↗
PubMed2006

Dissociative contributions of medial temporal and frontal regions to prospective remembering.

Prospective memory is memory of future intentions or plans in everyday life. Although some previous neuropsychological studies have stated that the prefrontal cortex and the medial temporal lobe are essential for successful prospective remembering, how the two regions contribute to prospective remembering remains unclear. We therefore used prospective memory training in the present study to investigate the neural mechanism of two components of prospective remembering: remembering to remember and remembering content. Two brain-damaged patients participated in this study: patient Y.O., who had lesions in the medial temporal lobe bilaterally, and patient T.K., who had a lesion in the basal forebrain and right medial frontal lobe. Both participants exhibited a severe anterograde amnesic syndrome and had normal IQ scores. Before the prospective memory training the participants underwent several index memory tests to examine their general memory and prospective memory performance. The training consisted of requesting the participants to perform an original mini-day task, in which they were first asked to memorize five simple daily actions with their times for execution, and then to recall the content of the actions when shown a drawing of a clock showing the proper time for execution. A training session was carried out once a week for 3 months. After completing training, the participants were again requested to take the same index memory tests. The results of the training task showed that Y.O.'s memory performance had gradually improved across all sessions of training, but T.K.'s improvement was not as marked. A more detailed analysis revealed that Y.O.'s memory performance was better for recalling time than for recalling content, whereas T.K.'s memory performance was better for recalling content than for recalling time. Furthermore, the results of the final index memory tests showed that the only improvement in Y.O.'s prospective memory was in remembering to remember, and that the only improvement in T.K.'s prospective memory was in remembering content. These results provide strong evidence that these two remembering components of prospective memory have independent neural bases, with the basal forebrain and right medial frontal lobe being required for remembering to remember, and the medial temporal lobe being required for remembering content. The results also suggest that memory training is an effective, means of improving everyday memory.

Adult↗
PubMed2006

Time course of cerebral blood flow changes following electroconvulsive therapy in depressive patients--measured at 3 time points using single photon emission computed tomography.

Although electroconvulsive therapy (ECT) has been employed for treating depression for more than 60 years, its mechanisms of action are yet unknown. To clarify the ECT effects on brain function, we examined cerebral blood flow (CBF) using single photon emission computed tomography at 3 time points--few days before an ECT course (Pre) and approximately 5 days (Post 1) and 1 month (Post 2) after the last ECT session. Eight depressive patients completed the study. In all the patients, the depressive symptoms improved after the ECT course, and major cognitive impairment was not observed at any time point. At Pre, the regional CBF (rCBF) in the widespread areas in the frontal lobe and limbic regions including cingulate cortex and parahippocampal gyrus was lower in the patients than in the normal controls. At Post 1 and Post 2, the rCBF in the frontal and limbic regions continued to be lower in the patients than in the controls although the successive recovery of decreased rCBF in the frontal region was observed. Regarding the time course among the patients, the rCBF in the right medial frontal region significantly increased (toward normal) at Post 2, not at Post 1. These findings suggest that depressive patients have decreased CBF in the frontal and limbic regions, and the medial frontal region plays a crucial role in ECT and recovery from depression. Further, patients who have undergone ECT treatment for depression should be carefully observed because brain functions continue to change even after a successful ECT course.

Adult↗
PubMed2005

Never-treated patients with schizophrenia in the developing country of Bali.

BACKGROUND: A considerable number of individuals with schizophrenia go undiagnosed and untreated in developing countries. In the current study, we investigated the prevalence of schizophrenia, the treatment status of individuals with schizophrenia, and factors associated with never-treated status in a Balinese rural community. METHOD: A door-to-door survey was conducted on 8546 people from the general population to detect individuals with schizophrenia using standardized screening instruments in Bali. RESULTS: Thirty-nine individuals with schizophrenia were identified, giving a point prevalence of 4.2 per 1000 population. Never-treated group subjects (n = 20: 51.3%) had a significantly higher total score on the Positive and Negative Syndrome Scale (p < 0.05) and were less likely to have a history of violent behavior (p < 0.01) than Treated group subjects (n = 19: 48.7%). All 9 subjects who had never shown violent behavior remained untreated. CONCLUSION: The clinical condition of the never-treated individuals with schizophrenia was poor. Individuals with schizophrenia without violent behavior had no opportunity to undergo medical treatment in this developing country setting.

Adult↗
PubMed2005

A deficit in discriminating gaze direction in a case with right superior temporal gyrus lesion.

The superior temporal sulcus (STS) region is well recognized as being heavily involved in detecting and discriminating gaze. Lesions confined to this area are quite rare in humans, and so the research has mainly depended on animal studies and functional neuroimaging in normal human subjects. We report one such rare case, a 54-year-old Japanese female with a possible congenital s anomaly who, after a cerebral hemorrhage, demonstrated a lesion almost completely confined to the entire right superior temporal gyrus (STG). In the subacute phase, the patient showed evidence of left hemispatial neglect, from which she gradually recovered. In the chronic phase, she showed a puzzling difficulty in obtaining eye-contact. We have conducted, in conjunction with conventional neuropsychological evaluations, experimental assessment of her ability in gaze cognition. Her performance on neuropsychological testing demonstrated no compromise in intellect, memory, or language skills, and a close-to-full recovery from neglect. On gaze cognition experiments, she was repeatedly shown to perceive left gaze as straight, and to a lesser degree, straight gaze as right. We suggest that the function of the STG in detecting gaze, together with the directional information it receives from earlier visual areas, may be associated, when damaged, with this deficit in detecting contra-directional gaze. We have demonstrated for the first time that a single circumscribed lesion to the STG results in both gaze processing deficit and concurrent aberrant gaze behavior of the victim herself, implicating a mechanism within the STG as an interface between gaze of others and gaze of self.

Brain Damage, Chronic↗
PubMed2005

Functional network in the prefrontal cortex during episodic memory retrieval.

A recent consistent finding in neuroimaging studies of human memory is that the prefrontal cortex (PFC) is activated during episodic memory retrieval. To date, however, there has been no direct evidence to explain how activity in the right and left PFC and in the anterior and posterior PFC are functionally interconnected. The goal of the present study was to obtain such evidence by event-related functional magnetic resonance imaging (MRI) and the functional connectivity method. Subjects were first asked to try to remember a series of associate-word lists outside the MRI scanner in preparation for a later recognition test. In the MRI scanning phase, they were asked to make recognition judgments in regard to old words, semantically related lure words, and unrelated new words. The analysis of functional connectivity revealed that the posterior PFC in each hemisphere had strong functional interconnections with the contralateral posterior PFC, whereas the anterior PFC in each hemisphere had only weak functional interconnections with the contralateral anterior PFC. No strong functional interconnections were found between the anterior and posterior PFC in either hemisphere. These findings support the hypothesis of an associative contribution of the bilateral posterior PFC to episodic memory retrieval and a dissociative contribution of the bilateral anterior PFC.

Adult↗
PubMed2005

Further evidence for a comparable memory advantage of self-performed tasks in Korsakoff's syndrome and nonamnesic control subjects.

Two experiments were carried out to examine memory in persons with amnesia using self-performed tasks. In Experiment 1, persons with Korsakoff's syndrome and nonamnesic participants with alcoholism learned action phrases not involving real objects by either self-performed tasks or verbal tasks. As indexed by free recall and recognition tests, a memory advantage favoring self-performed tasks was confirmed in both participant groups. In Experiment 2, persons with Korsakoff's syndrome, nonamnesic alcoholic participants, and young control participants learned object names under three different study conditions that differed from one another as to whether actions for each name were verbally generated and whether actions actually were performed. Verbal generation with or without performing the action facilitated recognition, whereas recall advantage was found only in the verbal generation-plus performance condition. These findings confirm a comparable memory advantage of self-performed tasks for a group with Korsakoff's syndrome and a group of nonamnesic comparison participants. Action memory therefore has potential therapeutic implications for memory rehabilitation.

Adult↗
PubMed2005

Selective memory impairment for personally familiar colors following encephalitis.

A 19-year-old man presented with a peculiar memory impairment following non-herpetic viral encephalitis. He was exclusively impaired in generating images for colors of possessions previously well known to him, and consequently these seemed less familiar. He appeared unable to access personally familiar and autobiographical color attributes. Single-photon emission computed tomography and electroencephalogram findings suggest that the right-sided functional abnormalities, specifically in the frontal and temporal regions, were implicated as the functional locus for the patient's unique problem.

Adult↗
PubMed2005

Cognitive dysfunction in systemic lupus erythematosus.

Systemic lupus erythematosus (SLE) is an autoimmune-mediated collagen disease that results in multiorgan failure. It is the collagen disease most frequently associated with neuropsychiatric symptoms, which have been hypothesized to stem from certain types of cognitive dysfunction. Subjects were 21 patients with SLE (one man, 20 women; aged 16-55 years; mean age, 35.1+/-10.7 years) who were undergoing treatment in the rheumatology unit of a general hospital, and 17 healthy control subjects matched to the patient group with respect to age and gender (two men, 15 women; mean age, 35.9+/-6.3 years). They were administered various tests of cognitive function including verbal reasoning, non-verbal reasoning, verbal memory, non-verbal memory, attention and mental flexibility, psychomotor speed and frontal lobe function. In addition, the SLE patients were tested for antiphospholipid antibodies. The SLE patients performed worse than the control group on immediate, delayed and interference of the Rey verbal test and paired associate tests of Wechsler Memory Scale, and their reaction time was slower in Trail A and Trail B tests. Moreover, these findings were more pronounced in the group with major neuropsychiatric symptoms. However, no relationship was apparent between these deficits in cognitive function and the presence or absence of antiphospholipid antibodies. The results suggest that verbal memory and psychomotor speed underlie the neuropsychiatric symptoms seen in SLE patients.

Adolescent↗
PubMed2005

Magnetoencephalographic analysis in children with Panayiotopoulos syndrome.

The aims of this study were to identify the generator of the paroxysmal partial discharges in Panayiotopoulos syndrome by means of magnetoencephalography and to determine the significance of these formations in the epileptogenesis of the developing nervous system. We report magnetoencephalographic data for two cases of Panayiotopoulos syndrome showing the rapid generalization of the source of interictal spikes that explains extraoccipital manifestations such as ictal vomiting and consciousness disturbance.

Cerebral Cortex↗