Kyoto University · Medicine
Professor Akio Ikeda's research lab specializes in clinical and cognitive neuroscience, focusing on the electrophysiological mechanisms underlying human motor control and epilepsy. The lab investigates cortical potentials such as movement-related potentials and ictal direct current (DC) shifts using subdural and scalp electroencephalography in epilepsy patients, aiming to map functional brain networks involved in motor planning and seizure onset. Key research directions include the neurophysiology of cortical tremor, the role of the pre-supplementary motor area in cognitive motor control, and the use of intracranial recordings to precisely localize epileptogenic zones. The lab integrates neurophysiological recordings with clinical evaluation to advance understanding of both normal motor function and pathological brain states.
Figures are computed from collected data and may differ slightly.
Movement-related potentials (MRPs) were recorded from subdural electrodes chronically implanted in the interhemispheric fissure in two patients being evaluated for epilepsy surgery. Different types of movements (finger, foot, tongue and vocalization) were executed. Foot movements elicited a clearly defined, well-localized slow negativity or positivity (Bereitschaftspotential, BP) preceding electromyogram (EMG) onset. These BPs were seen from the contralateral primary motor foot area and also fro
Two patients with action tremor that was thought to originate in the cerebral cortex showed fine shivering-like finger twitching provoked mainly by action and posture. Surface EMG showed relatively rhythmic discharge at a rate of about 9 Hz, which resembled essential tremor. However, electrophysiologic studies revealed giant somatosensory evoked potentials (SEPs) with enhanced long-loop reflex and premovement cortical spike by the jerk-locked averaging method. Treatment with beta-blocker showed
In order to clarify further the characteristics of ictal direct current (DC) shifts in human epilepsy, we investigated them by subdural and scalp recording in six and three patients, respectively, both having mainly neocortical lobe epilepsy (five with frontal lobe epilepsy, two with parietal lobe epilepsy and two with temporal lobe epilepsy). By using subdural electrodes made of platinum, ictal DC shifts were observed in 85% of all the recorded seizures (89 seizures) among the six patients, and
To clarify the functional role of human pre-supplementary motor area (pre-SMA) in 'cognitive' motor control as compared with other non-primary motor cortices (SMA-proper and lateral premotor areas) and prefrontal area, we recorded epicortical field potentials by using subdural electrodes in five epileptic patients during presurgical evaluation, whose pre-SMA, SMA-proper, prefrontal and lateral premotor areas were defined by electric cortical stimulation and recent anatomical orientations accordi
These results agree with those of previous studies of ictal DC shifts in animals and suggest that ictal DC shifts may be helpful in delineating the epileptogenic area more precisely in human epilepsy.
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