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Kiyoto Kasai

Publications and source records attributed to Kiyoto Kasai.

18 recordsLinked to original sources
PubMed2003

Neuromagnetic correlates of impaired automatic categorical perception of speech sounds in schizophrenia.

Schizophrenia is associated with dysfunction in language processing. At the earliest stage of language processing, dysfunction of categorical perception of speech sounds in schizophrenia has been demonstrated in a behavioral task. The aim of this study was to assess automatic categorical perception of speech sounds as reflected by event-related changes in magnetic field power in schizophrenia. Using a whole-head magnetoencephalographic recording, the magnetic counterpart of mismatch negativity (MMNm) elicited by a phonetic change was evaluated in 16 right-handed patients with chronic schizophrenia and in 19 age-, sex-, and parental socioeconomic status-matched normal control subjects. Three types of MMNm (MMNm in response to a duration decrement of pure-tone stimuli; a vowel within-category change [duration decrement of Japanese vowel /a/]; vowel across-category change [Japanese vowel /a/ versus /o/]) were recorded. While the schizophrenia group showed an overall reduction in magnetic field power of MMNm, a trend was found toward more distinct abnormalities under the condition of vowel across-category change than under that of duration decrement of a vowel or tone. The patient group did not show abnormal asymmetries of MMNm power under any of the conditions. This study provides physiological evidence for impaired categorical perception of speech sounds in the bilateral auditory cortex in schizophrenia. The language-related dysfunction in schizophrenic patients may be present at the early stage of auditory processing of relatively simple stimuli such as phonemes, and not just at stages involving higher order semantic processes.

Adult↗
PubMed2003

Fusiform gyrus volume reduction and facial recognition in chronic schizophrenia.

BACKGROUND: The fusiform gyrus (FG), or occipitotemporal gyrus, is thought to subserve the processing and encoding of faces. Of note, several studies have reported that patients with schizophrenia show deficits in facial processing. It is thus hypothesized that the FG might be one brain region underlying abnormal facial recognition in schizophrenia. The objectives of this study were to determine whether there are abnormalities in gray matter volumes for the anterior and the posterior FG in patients with chronic schizophrenia and to investigate relationships between FG subregions and immediate and delayed memory for faces. METHODS: Patients were recruited from the Boston VA Healthcare System, Brockton Division, and control subjects were recruited through newspaper advertisement. Study participants included 21 male patients diagnosed as having chronic schizophrenia and 28 male controls. Participants underwent high-spatial-resolution magnetic resonance imaging, and facial recognition memory was evaluated. Main outcome measures included anterior and posterior FG gray matter volumes based on high-spatial-resolution magnetic resonance imaging, a detailed and reliable manual delineation using 3-dimensional information, and correlation coefficients between FG subregions and raw scores on immediate and delayed facial memory derived from the Wechsler Memory Scale III. RESULTS: Patients with chronic schizophrenia had overall smaller FG gray matter volumes (10%) than normal controls. Additionally, patients with schizophrenia performed more poorly than normal controls in both immediate and delayed facial memory tests. Moreover, the degree of poor performance on delayed memory for faces was significantly correlated with the degree of bilateral anterior FG reduction in patients with schizophrenia. CONCLUSION: These results suggest that neuroanatomic FG abnormalities underlie at least some of the deficits associated with facial recognition in schizophrenia.

Adult↗
PubMed2003

Progressive decrease of left Heschl gyrus and planum temporale gray matter volume in first-episode schizophrenia: a longitudinal magnetic resonance imaging study.

BACKGROUND: The Heschl gyrus and planum temporale have crucial roles in auditory perception and language processing. Our previous investigation using magnetic resonance imaging (MRI) indicated smaller gray matter volumes bilaterally in the Heschl gyrus and in left planum temporale in patients with first-episode schizophrenia but not in patients with first-episode affective psychosis. We sought to determine whether there are progressive decreases in anatomically defined MRI gray matter volumes of the Heschl gyrus and planum temporale in patients with first-episode schizophrenia and also in patients with first-episode affective psychosis. METHODS: At a private psychiatric hospital, we conducted a prospective high spatial resolution MRI study that included initial scans of 28 patients at their first hospitalization (13 with schizophrenia and 15 with affective psychosis, 13 of whom had a manic psychosis) and 22 healthy control subjects. Follow-up scans occurred, on average, 1.5 years after the initial scan. RESULTS: Patients with first-episode schizophrenia showed significant decreases in gray matter volume over time in the left Heschl gyrus (6.9%) and left planum temporale (7.2%) compared with patients with first-episode affective psychosis or control subjects. CONCLUSIONS: These findings demonstrate a left-biased progressive volume reduction in the Heschl gyrus and planum temporale gray matter in patients with first-episode schizophrenia in contrast to patients with first-episode affective psychosis and control subjects. Schizophrenia but not affective psychosis seems to be characterized by a postonset progression of neocortical gray matter volume loss in the left superior temporal gyrus and thus may not be developmentally fixed.

Adolescent↗
PubMed2003

Progressive decrease of left superior temporal gyrus gray matter volume in patients with first-episode schizophrenia.

OBJECTIVE: Smaller temporal lobe cortical gray matter volumes, including the left superior temporal gyrus, have been reported in magnetic resonance imaging (MRI) studies of patients with chronic schizophrenia and, more recently, in patients with first-episode schizophrenia. However, it remains unknown whether there are progressive decreases in temporal lobe cortical gray matter volumes in patients with first-episode schizophrenia and whether similarly progressive volume decreases are present in patients with affective psychosis. METHOD: High-spatial-resolution MRI scans at initial hospitalization and 1.5 years later were obtained from 13 patients with first-episode schizophrenia, 15 patients with first-episode affective psychosis (mainly manic), and 14 healthy comparison subjects. MRI volumes were calculated for gray matter of superior temporal gyrus and for the amygdala-hippocampal complex. RESULTS: Patients with first-episode schizophrenia showed significant decreases in gray matter volume over time in the left superior temporal gyrus compared with patients with first-episode affective psychosis or healthy comparison subjects. This progressive decrease was more pronounced in the posterior portion of the left superior temporal gyrus (mean=9.6%) than in the anterior portions (mean=8.4%). No group differences in the rate of change over time were present in other regions. CONCLUSIONS: These findings demonstrate a progressive volume reduction of the left posterior superior temporal gyrus gray matter in patients with first-episode schizophrenia but not in patients with first-episode affective psychosis.

Adolescent↗
PubMed2002

An MRI study of temporal lobe abnormalities and negative symptoms in chronic schizophrenia.

Previous magnetic resonance imaging (MRI) studies have reported various subtle brain abnormalities in schizophrenic patients, including temporal lobe abnormalities, which are of particular interest given the role of this brain region in auditory and language processing, and the characteristic deficits in these processes in schizophrenia. Subjects in this study were 16 male patients diagnosed with chronic schizophrenia and 15 healthy male comparison subjects. These patients were characterized by negative symptoms. High spatial resolution coronal MRI 1.5-mm-thick slices were used to measure the gray matter volume of the superior temporal gyrus, anterior and posterior amygdala/hippocampal complex, and parahippocampal gyrus. Patients, relative to normal comparison subjects, evinced a reduction of gray matter volume in bilateral superior temporal gyri and anterior amygdala/hippocampal complex. The reduction in gray matter of the superior temporal gyrus in patients with schizophrenia is consistent with previous findings, and is noteworthy in that it was found in this group of patients with predominantly negative symptoms. The reduction in the anterior amygdala/hippocampal complex was an additional temporal lobe finding. These results underscore the role of temporal lobe structures in the pathophysiology of schizophrenia.

Adult↗
PubMed2002

Fusiform gyrus volume reduction in first-episode schizophrenia: a magnetic resonance imaging study.

BACKGROUND: The fusiform gyrus (occipitotemporal gyrus) is thought to be critical for face recognition and may possibly be associated with impaired facial recognition and interpretation of facial expression in schizophrenia. of postmortem studies have suggested that fusiform gyrus volume is reduced in schizophrenia, but there have been no in vivo structural studies of the fusiform gyrus in schizophrenia using magnetic resonance imaging. METHODS: High-spatial resolution magnetic resonance images were used to measure the gray matter volume of the fusiform gyrus in 22 patients with first-episode schizophrenia (first hospitalization), 20 with first-episode affective psychosis (mainly manic), and 24 control subjects. RESULTS: Patients with first-episode schizophrenia had overall smaller relative volumes (absolute volume/intracranial contents) of fusiform gyrus gray matter compared with controls (9%) and patients with affective psychosis (7%). For the left fusiform gyrus, patients with schizophrenia showed an 11% reduction compared with controls and patients with affective psychosis. Right fusiform gyrus volume differed in patients with schizophrenia only compared with controls (8%). CONCLUSION: Schizophrenia is associated with a bilateral reduction in fusiform gyrus gray matter volume that is evident at the time of first hospitalization and is different from the presentation of affective psychosis.

Adolescent↗
PubMed2002

P300 amplitude over temporal regions in schizophrenia.

To examine the left temporal scalp area reductions of P300 amplitude, event-related potentials (ERPs) during a standard oddball task were recorded in 57 schizophrenic patients and 33 normal controls. The P300 amplitude at T3 was not significantly smaller than that at T4 in schizophrenic patients. In the ANOVA analysis of the P300 peak amplitude and PCA factor scores, significant lateral topographical differences in P300 were not present between patients and controls. However, in schizophrenia, patients in the low T3 P300 group were older and consuming higher doses of antipsychotic medicine than those in the high T3 P300 group, and they had relatively low P300 amplitudes and significantly delayed P300 latency, compared with those in the high T3 P300 group. These findings suggested that although the reduction in the left temporal P300 amplitude did not necessarily exist in schizophrenic patients, it may be associated with the severity of the disease process and/or impairment of cognitive function.

Adult↗
PubMed2002

Psychophysiological index during auditory selective attention correlates with visual continuous performance test sensitivity in normal adults.

The continuous performance test (CPT) provides a reliable index of cognitive function, but it is still unclear what aspects of processing this test measures. This study aimed to investigate the contribution of different aspects of cognitive function to the performance on degraded stimulus CPT (DSCPT), which requires a higher level of mental effort than the conventional CPT. Event-related potential (ERP) components, MMN, N2b, and early and late Nds were measured at 16 electrode sites in 19 right-handed normal volunteers using an auditory selective attention task. The association between CPT sensitivity ratings (sensitivity A') and amplitudes of each component was examined for each electrode site. The CPT sensitivity A' showed a significant positive correlation with the N2b amplitude in the fronto-central and temporal regions, predominantly in the right hemisphere and specifically to the right ear of stimulation. This finding suggests that the controlled deviance detection process was related to DSCPT performance.

Acoustic Stimulation↗
PubMed2002

Neuroanatomy and neurophysiology in schizophrenia.

Schizophrenia is a major mental disorder, characterized by their set of symptoms, including hallucinatory-delusional symptoms, thought disorder, emotional flattening, and social withdrawal. Since 1980s, advances in neuroimaging and neurophysiological techniques have provided tremendous merits for investigations into schizophrenia as a brain disorder. In this article, we first overviewed neuroanatomical studies using structural magnetic resonance imaging (s-MRI), MR spectroscopy (MRS), and postmortem brains, followed by neurophysiological studies using event-related potentials (ERPs) and magnetoencephalography (MEG), in patients with schizophrenia. Evidences from these studies suggest that schizophrenia is a chronic brain disorder, structurally and functionally affecting various cortical and subcortical regions involved in cognitive, emotional, and motivational aspects of human behavior. Second, we reviewed recent investigations into neurobiological basis for schizophrenic symptoms (auditory hallucinations and thought disorder) using these indices as well as hemodynamic assessments such as positron emission tomography (PET) and functional MRI (f-MRI). Finally, we addressed the issue of the heterogeneity of schizophrenia from the neurobiological perspective, in relation to the neuroanatomical and neurophysiological measures.

Brain↗
PubMed2002

The effects of benzodiazepines on event-related potential indices of automatic and controlled processing in schizophrenia: a preliminary report.

The effects of benzodiazepines on cognitive function in schizophrenic patients were investigated using event-related potential (ERP) measurement during an auditory selective attention task. In this study, the authors compared the mismatch negativity (MMN) and N2b components between two subgroups of schizophrenic patients: one is comprised of patients who received no benzodiazepines (NT group, n = 7) and the other is comprised of those administered benzodiazepines in the daytime (T group, n = 7). There were no significant differences in MMN and N2b amplitudes between the two subgroups, whereas the N2b latency was significantly prolonged in the T group relative to the NT group. This suggested that benzodiazepines induce delayed stimulus classification processing in schizophrenic patients.

Adolescent↗
PubMed2002

No effect of gender on tonal and phonetic mismatch negativity in normal adults assessed by a high-resolution EEG recording.

The auditory mismatch negativity (MMN) of event-related potential components has been widely used to assess the ability of auditory automatic change discrimination of verbal and nonverbal stimuli in healthy individuals and patients with various illnesses. To clarify the role of gender differences in the MMN, we compared the amplitude, latency, and topography of tonal and phonetic MMN between healthy males and females, using a high-density (128 channel) electroencephalography montage. The MMN was evaluated in 18 right-handed male and ten age-matched female adults. The MMN in response to a duration change of pure tone and that in response to a phonetic change (Japanese vowel /a/ versus /o/ with 150-ms duration) were recorded. There were no significant differences in amplitude, latency, or laterality for either tonal or phonetic MMN between male and female subjects. This lack of evidence for effects of gender on MMN in response to duration change of tones or that in response to changes of phonemes with a short duration in normal adults may be of relevance to a growing number of researchers who are studying the MMN in healthy individuals and various clinical groups.

Acoustic Stimulation↗
PubMed2002

Do high or low doses of anxiolytics and hypnotics affect mismatch negativity in schizophrenic subjects? An EEG and MEG study.

OBJECTIVE: Many studies have demonstrated mismatch negativity (MMN) attenuation in schizophrenia. Recently, investigators have shown that GABAergic inhibitory neurons may regulate MMN generation. Considering that a substantial proportion of schizophrenic patients receive anxiolytics and hypnotics that have affinity to GABA(A) receptors to reduce their comorbid symptoms of anxiety and sleep disturbances, we need to assess whether anxiolytics/hypnotics might affect their MMN generation. The aim of this study is to assess the possibility that high or low doses of anxiolytics/hypnotics received by schizophrenic subjects affect their mismatch negativity (MMN), using event-related potentials (ERPs) and magnetoencephalography (MEG). METHODS: Twenty-three and 16 patients with schizophrenia participated in the ERP and MEG studies, respectively. Three types of MMN (MMN in response to a duration change of pure-tone stimuli, within-category vowel change (Japanese vowel /a/ with short versus long duration), and across-category vowel change (vowel /a/ versus /o/)) were recorded. RESULTS: High or low doses of benzodiazepine had no significant effects on MMN amplitude/magnetic MMN power, topography/laterality, or latency under any conditions of the ERP or MEG study. CONCLUSIONS: These results suggest that chronic administration of anxiolytics/hypnotics does not significantly affect MMN in schizophrenia.

Acoustic Stimulation↗
PubMed2002

Smaller hippocampal volume predicts pathologic vulnerability to psychological trauma.

In animals, exposure to severe stress can damage the hippocampus. Recent human studies show smaller hippocampal volume in individuals with the stress-related psychiatric condition posttraumatic stress disorder (PTSD). Does this represent the neurotoxic effect of trauma, or is smaller hippocampal volume a pre-existing condition that renders the brain more vulnerable to the development of pathological stress responses? In monozygotic twins discordant for trauma exposure, we found evidence that smaller hippocampi indeed constitute a risk factor for the development of stress-related psychopathology. Disorder severity in PTSD patients who were exposed to trauma was negatively correlated with the hippocampal volume of both the patients and the patients' trauma-unexposed identical co-twin. Furthermore, severe PTSD twin pairs-both the trauma-exposed and unexposed members-had significantly smaller hippocampi than non-PTSD pairs.

Alcoholism↗
PubMed2002

Impaired cortical network for preattentive detection of change in speech sounds in schizophrenia: a high-resolution event-related potential study.

OBJECTIVE: Schizophrenia is associated with language-related dysfunction. At the most basic level, the dysfunction of schizophrenic patients in perceiving phoneme boundaries has been demonstrated in a behavioral task. The goal in this study was to obtain an electrophysiological index of preattentive detection of change in speech sounds by schizophrenic patients. METHOD: A high-density recording system was used to measure mismatch negativity, i.e., difference in electrophysiological responses between standard and deviant auditory stimuli. The amplitude of mismatch negativity was measured in 23 right-handed schizophrenic patients and in 28 healthy comparison subjects. Three types of mismatch negativity were recorded: change in duration of pure-tone stimuli, change in duration of the Japanese vowel /a/, and difference between vowels /a/ and /o/ (across-phoneme change). RESULTS: The schizophrenic patients had a lower amplitude of mismatch negativity for across-phoneme change than for change in duration of tone or vowel. For across-phoneme change, the schizophrenia group showed significantly lower bilateral amplitude of mismatch negativity than the comparison subjects. These findings coincide with those from the analysis of scalp current density, indicating that the schizophrenic patients had a significantly weaker left temporal combination of current sink (perpendicularly sinking into the scalp) and current source (arising out of the scalp) and a significantly weaker right frontal/temporal current sink than the comparison subjects. CONCLUSIONS: These results demonstrate impaired frontotemporal cortical networks for preattentive detection of change in speech sounds in schizophrenia. The language-related dysfunction in schizophrenia may be present at the early stage of auditory processing of relatively simple stimuli, such as phonemes, and not just at stages involving higher-order semantic processes.

Adult↗