Biomedical subjects

Masato Fukuda

Publications and source records attributed to Masato Fukuda.

23 records · Page 2Linked to original sources

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

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↗

PubMed2002

[Introduction of the electronic anesthesia record keeping system].

Based on five-year experience, we have evaluated the electronic anesthesia record keeping system (DS 5300 OR, Fukuda Denshi, Tokyo), which is the first commercially available system combined with an anesthesia monitor in Japan. Although keying in of text with a keyboard on the screen remains to be improved, the user interface of touch screens is easy to use. It seems to be a great advantage that physiologic variables are automatically and accurately captured very minute. The record is more complete, legible, and accurate than a hand-written record. Both long-term storage and search for the data are much easier. The investment in this system is affordable even for small hospitals. Although there might be some areas in which improvement is needed, we are satisfied with its usefulness and reliability.

Anesthesia↗