Biomedical subjects

Satoshi Ukai

Publications and source records attributed to Satoshi Ukai.

4 recordsLinked to original sources

PubMed2004

Slow repetitive transcranial magnetic stimulation increases somatosensory high-frequency oscillations in humans.

Repetitive transcranial magnetic stimulation (rTMS) has been proposed as a possible treatment for psychiatric and neurological disorders characterized by focal brain excitability, such as major depression and action myoclonus. However, the mechanism of modulating excitability by rTMS is unclear. We examined the changes in high frequency oscillations (HFOs) of somatosensory evoked potentials (SEPs) before and after slow rTMS over the right primary somatosensory cortex (0.5 Hz, 50 pulses, 80% motor threshold intensity). The HFOs, which represent a localized activity of intracortical inhibitory interneurons, were significantly increased after slow rTMS, while the SEPs were not changed. Our results suggest that slow rTMS affects cortical excitability by modulating the activity of the intracortical inhibitory interneurons beyond the time of the stimulation and that rTMS may have therapeutic effects on such disorders.

Adult↗

PubMed2004

Treatment of typical Charles Bonnet syndrome with donepezil.

Charles Bonnet syndrome (CBS) is characterized by the presence of complex visual hallucinations in psychologically normal people. Although visual hallucinations in the elderly are often associated with dementia with Lewy body (DLB), Alzheimer's disease and delirium, they are excluded from the diagnosis of typical CBS, as are cognitive or psychiatric disturbances, sleep disorders and focal neurological lesions. Here, we describe a patient with typical CBS, who responded to donepezil, a cholinesterase inhibitor, and has not shown any symptoms suggestive of Alzheimer's disease or DLB for approximately the past 40 months. However, follow-up examination of her clinical symptoms is necessary for a definite exclusion of Alzheimer's disease and DLB. The effectiveness of donepezil indicates that the patient's visual hallucinations might be related to dysfunction of cholinergic neurones, although she did not exhibit any cognitive decline, or morphological and physiological brain pathology. Because donepezil has fewer adverse effects than anticonvulsants and neuroleptic drugs, it may be a safer option for the treatment of CBS in the elderly.

Aged↗

PubMed2003

Interictal spikes in the fusiform and inferior temporal gyri of an epileptic patient with colored elementary visual auras: a 5-year longitudinal MEG ECD study.

Using equivalent current dipole (ECD) analysis of magnetoencephalography (MEG), we examined the locations of interictal spikes for 5 years in an epileptic patient who had experienced colored elementary visual auras that gradually disappeared with medication. During the period that the patient frequently experienced colored elementary visual auras, six of nine spikes occurred in the right fusiform and inferior temporal gyri. As the frequency of the visual auras decreased, the spikes were widely distributed in the right hemisphere, but were not localized to these areas. After the visual auras ceased, six of seven spikes occurred in the right transverse gyrus of Heschl. These results suggest that colored elementary visual auras of epileptic-positive symptoms originate in the fusiform and inferior temporal gyri and that these regions are involved in human color processing. This is the first MEG study suggesting that the fusiform gyrus and the inferior temporal cortex are related to human color processing.

Adult↗

PubMed2002

Parallel distributed processing neuroimaging in the Stroop task using spatially filtered magnetoencephalography analysis.

Parallel distributed processing neuroimaging in the Stroop color word interference task in five healthy subjects was studied. The total reaction time was set at 650 ms with a time window of 200 ms in steps of 50 ms. Spatially filtered magnetoencephalography analysis, as used in synthetic aperture magnetometry, was used. Neural activation began in the left posterior parietal-occipital area (150-250 ms post-stimulus), followed by the right prefrontal polar area (250-350 ms), the left dorsolateral prefrontal cortex (250-400 ms), and the mid- to lower- primary motor area (350-400 ms). Successive and temporally overlapping activation of various cortical regions were successfully estimated within a short 200 ms time interval, contrary to previous positron emission tomography and fMRI studies.

Adult↗