Biomedical subjects

Kazunori Matsumoto

Publications and source records attributed to Kazunori Matsumoto.

5 recordsLinked to original sources

PubMed2006

Psychophysiological differences in identical twins discordant for schizophrenia: a critical index for the onset of schizophrenia.

It has been hypothesized that not only genetic but also environmental factors contribute to the onset of schizophrenia. We therefore conducted psychophysiological studies on a pair of identical twins discordant for schizophrenia, to differentiate non-genetic from genetic indexes possibly associated with this disease. The affected and unaffected twins were 28 year-old females. The affected twin was diagnosed as having schizophrenia based on the Diagnosis and Statistical Manual of Mental Disorders, third edition revised (DMS-III-R), whereas the unaffected twin had no psychiatric disorders. The brain potentials evoked by visual stimulation (visual event-related potential [visual ERP]) were recorded. The components of the visual ERP, which are believed to reflect pattern cognition, semantic processing and the failure to use preceding word information, were compared with normal subjects. Both twins showed abnormal semantic processing and similar failure to use preceding word information. Abnormality of semantic processing was marked in the affected twin. These results indicate that failure to use preceding word information might reflect only genetic factors, whereas abnormal semantic processing might reflect both genetic and non-genetic factors because the affected twin was considered to show accelerated deterioration after the disease onset. However, only the affected twin showed abnormal pattern cognition, which might be attributable to non-genetic factors such as an acquired vulnerability to schizophrenia. We suggest that the impairment of pattern cognition evaluated by visual ERP may be a critical index for the onset of schizophrenia.

Adult↗

PubMed2005

An fMRI study of verbal self-monitoring: neural correlates of auditory verbal feedback.

The ability to recognize one's own inner speech is essential for a sense of self. The verbal self-monitoring model proposes that this process entails a communication from neural regions involved in speech production to areas of speech perception. According to the model, if the expected verbal feedback matches the perceived feedback, then there would be no change in activation in the lateral temporal cortices. We investigated the neural correlates of verbal self-monitoring in a functional magnetic resonance (fMRI) study. Thirteen healthy male volunteers read aloud presented adjectives and heard their auditory feedback which was experimentally modified. Decisions about the source of the feedback were made with a button-press response. We used a 'clustered' fMRI acquisition sequence, consisting of periods of relative silence in which subjects could speak aloud and hear the feedback in the absence of scanner noise, and an event-related design which allowed separate analysis of trials associated with correct attributions and misattributions. Subjects made more misattribution responses when the feedback was a distorted version of their voice. This condition showed increased superior temporal activation relative to the conditions of hearing their own voice undistorted and hearing another person's voice. Furthermore, correct attributions during this condition were associated with greater temporal activation than misattributions. These findings support the self-monitoring model as mismatches between expected and actual auditory feedback were associated with greater temporal activation.

Adult↗

PubMed2005

Reduced word-repetition effect in the event-related potentials of thought-disordered patients with schizophrenia.

Repetition effect in event-related potentials (ERPs) was studied in 10 non-thought-disordered (non-TD) patients with schizophrenia, 8 thought-disordered (TD) patients with schizophrenia, and 10 normal control subjects while they performed a semantic categorization task with incidental word repetitions. All patients were in a stable or partially remitted stage. Although both healthy control and non-TD groups produced more positive ERPs to the repeated words than to the new words (ERP repetition effect) for 250-500 ms, the TD group did not show the ERP repetition effect. These findings suggest that the abnormal attenuation of the ERP repetition effect during semantic processing may be more prominent in schizophrenic patients with thought disorder than in those without the symptom.

Adult↗

PubMed2004

Functional neuroimaging in mental disorders.

Recent advances in functional neuroimaging allow us to map neural activity in the living human brain with precise spatial and temporal resolution and provide an unprecedented opportunity to examine the neurocognitive components of mental disorders. In this article we aim to summarize the main functional neuroimaging findings in the major psychiatric disorders and the different methodological approaches that have been used to study them. We will discuss studies of the resting state and of activation during the performance of cognitive tasks, and studies focused on specific psychiatric symptoms. We will also review work on functional connectivity, discuss future directions in the field and consider how functional neuroimaging may contribute to clinical practice.

Journal Article↗

PubMed2002

The effect of feeding habitats on dietary shifts during the growth in a benthophagous suction-feeding fish.

Several mechanisms of fish ontogenetic dietary shifts, which have important ecological implications, have been proposed. We studied the mechanism of dietary shifts of a benthophagous fish Goniistius zonatus, focusing on the effect of foraging on calcareous algal mat, one of its main feeding substrates, through comparison between two local populations (Morode and Arakashi) with different feeding ecology. The studied fish (11-29 cm SL) fed on various kinds of small invertebrates inhabiting the substrates, using a suctorial feeding mode without visual discrimination towards individual prey. At Morode, gut contents of small fish consisted of more epifaunal and less infaunal organisms than those of large fish, that is, mainly small crustaceans in small fish, and many invertebrates other than crustaceans in large fish. By contrast, at Arakashi, gut contents consisted mostly of epifaunal crustaceans regardless of fish size, i.e., fish showing no dietary shifts. At Morode, G. zonatus took foods mostly from thick calcareous algal mat, whereas fish foraged mainly on thin algal mat and bare rocks at Arakashi, the difference being due to the local differences in the substrate component. The algal mat of Morode harbored much larger amount of infaunal animals than any substrates of Arakashi. At Morode, large fish more forcefully and deeply thrust the mouth into thick algal mat than small fish, and was likely to suck up more infaunal prey using great suctorial force. The comparison clearly indicates that the dietary shifts of G. zonatus at Morode resulted from size-related efficiency in straining foods from heterogeneous micro-topography of thick algal mat.

Animals↗