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Biomedical subjects

Yuki Kawakubo

Publications and source records attributed to Yuki Kawakubo.

7 recordsLinked to original sources
PubMed2006

Phonetic mismatch negativity predicts verbal memory deficits in schizophrenia.

Deficits in auditory sensory memory at the electrophysiological level as indexed by mismatch negativity and those in auditory verbal memory at the neuropsychological level have been independently demonstrated in previous studies of schizophrenia. We predicted a specific association between these indices in schizophrenia. Mismatch negativities elicited by change in tone duration and phoneme duration were recorded in 23 schizophrenia patients, who were also evaluated for auditory verbal memory and executive function. Lower amplitude of mismatch negativity under the phoneme-duration condition was significantly associated with worse verbal memory. Phoneme-duration mismatch negativity was not correlated with executive function, nor was tone-duration mismatch negativity correlated with verbal memory. These results suggest that electrophysiological auditory sensory memory dysfunction underlies the basis for neuropsychological auditory verbal memory deficits in schizophrenia.

Adult↗
PubMed2006

Decreased prefrontal activation during letter fluency task in adults with pervasive developmental disorders: a near-infrared spectroscopy study.

Functional neuroimaging studies have suggested that dysfunction of prefrontal cortex (PFC) is present in persons with pervasive developmental disorders (PDD). Recently, the development of near-infrared spectroscopy (NIRS) has enabled noninvasive bedside measurement of regional cerebral blood volume. Although NIRS enables the noninvasive clarification of brain functions in many psychiatric disorders, it has not yet been used to examine subjects with PDD. The aim of our study was to conduct an NIRS cognitive activation study to verify PFC dysfunction in PDD. The subjects were 10 adults with PDD and 10 age- and gender-matched healthy subjects. Hemoglobin concentration changes were measured with a 24-channel NIRS machine during the letter fluency task. While the number of words generated during the letter fluency task did not differ significantly between groups, the analysis of covariance including IQ as a confounding covariate showed that the PDD group was associated with bilateral reduction in oxy-hemoglobin concentration change as compared with the control group. The statistical results did not change when only IQ-matched high-functioning subjects (N=7) were included. Moreover, reduced oxy-hemoglobin concentration change for the right PFC was significantly correlated with verbal communication deficits within the PDD group. The present findings are consistent with proposed prefrontal dysfunction in PDD subjects identified by other neuroimaging modalities. The present results may be also potentially useful for applying NIRS to clinical settings of child psychiatry.

Adolescent↗
PubMed2006

Procedural memory predicts social skills in persons with schizophrenia.

Despite a growing number of studies that have investigated the relationship between neurocognition and psychosocial outcome in schizophrenia, no studies have looked at the relationship between procedural memory and social skills measures in schizophrenia. The goal of this study was to investigate whether procedural memory, often preserved in schizophrenia, could predict nonverbal social skills in chronic patients with schizophrenia. Fourteen outpatients with schizophrenia participated in our study. Procedural memory was evaluated using the Mirror Reading Test, and nonverbal and verbal social skills were evaluated using a structured role play test. As predicted, there was a significant positive correlation between the learning index of the Mirror Reading Test and nonverbal skills (Spearman rho=0.559, p = 0.038), but not for verbal communication skills or processing skills. Although preliminary, these results provide the first evidence of an association between procedural memory and nonverbal social skills in patients with schizophrenia.

Adult↗
PubMed2005

Delayed automatic detection of change in speech sounds in adults with autism: a magnetoencephalographic study.

OBJECTIVE: Autism is a form of pervasive developmental disorder in which dysfunction in interpersonal relationships and communication is fundamental. This study evaluated neurophysiological abnormalities at the basic level of language processing, i.e. automatic change detection of speech and non-speech sounds, using magnetoencephalographic recording of mismatch response elicited by change in vowels and tones. METHODS: The auditory magnetic mismatch field (MMF) was evaluated in 9 adults with autism and 19 control subjects using whole-head magnetoencephalography. The MMF in response to the duration change of a pure tone or vowel /a/ and that in response to across-phoneme change between vowels /a/ and /o/, were recorded. RESULTS: The groups were not significantly different in MMF power under any conditions. However, the autism group showed a left-biased latency prolongation of the MMF particularly under the across-phoneme change condition, and this latency delay was significantly associated with greater symptom severity. CONCLUSIONS: These results suggest that adults with autism are associated with delayed processing for automatic change detection of speech sounds. These electrophysiological abnormalities at the earliest level of information processing may contribute to the basis for language deficits observed in autism. SIGNIFICANCE: These results provide the first evidence for delayed latency of phonetic MMF in adults with autism.

Acoustic Stimulation↗
PubMed2004

Spatial attention in individuals with pervasive developmental disorders using the gap overlap task.

The present study examined spatial attention in individuals with pervasive developmental disorders (PDD) using the gap overlap task and analyzed the express saccade, which is defined by its extremely short reaction time, as a measure of the state of attention. Participants were required to move their eyes to the target stimulus appearing on the left or right side of a fixation point. In this task, participants had to disengage their attention from the central fixation point and shift it to the peripheral target stimulus. In the gap condition, the fixation point disappeared 200 ms before the target stimulus was presented, and in the overlap condition, the fixation point remained while the target stimulus was presented. Saccade latencies were not different between the groups. However, the express saccade was more frequent in the PDD group than in the normal group in the overlap condition. We conclude that individuals with PDD have deficiencies in attentional engagement. Moreover, our study suggests that analysis of the express saccade will be useful in further examinations of attentional processes in PDD.

Adult↗
PubMed2004

Developmental change of neurocognitive motor behavior in a continuous performance test with different interstimulus intervals.

OBJECTIVE: We investigated the neurocognitive process of motor control using event-related potentials during a cued continuous performance test with different interstimulus intervals in healthy children, and examined their neurocognitive process in motor execution and in motor inhibition. METHODS: Twenty-eight children group by age (9 years n=8, 11 years n=9, 13 years n=11) and 10 adults participated. In cued continuous performance test, subjects were asked to press a button when '9' appeared immediately after '1.' To maintain uncertainty in the stimulus series, we used 3 interstimulus intervals between the warning stimulus and subsequent target (800 ms, 1500 ms, 3000 ms). RESULTS: Effects of different interstimulus intervals were observed in the reaction time of hits regardless of the age of the subject. In adults, spatial distribution of the P3 component elicited by targets was centro-parietal maximum that was discriminable from the distribution of No-go P3, which was characterized by centro-parietal dominant distribution under all interstimulus interval (ISI) conditions. However, in younger children (9 years), the P3 component elicited by No-go distributed to the centro-frontal area, and P2/N2 with a significant anterior negative/posterior positive distribution was observed. As age increased, the dominant distribution of No-go P3 shifted significantly to a more anterior area compared with that of Target P3, and significantly prolonged ISI brought No-go P3 with centro-frontal dominant distribution that might indicate motor inhibition. CONCLUSIONS: These results indicated that behavioral change in the developmental course might be concerned with automatization of orientation and evaluation of stimulus relevance. Furthermore, efficient motor control might be enabled by establishment of an inhibitory process in the anterior area, in addition to an executive process in the posterior area.

Adolescent↗