仮名短期記憶走査に関連する脳磁界αリズムの時空間的変動

抄録

Magnetoencephalograms (MEGs) recorded with a 37-channel SQUID magnetometer were used to detectregional changes in spontaneous cortical activity accompanying a short-term memory scan. Graphical identification (GI) and phonemical identification (PI) for the same probe were required when subjects scan memory in a Sternberg paradigm. Japanese kana-characters were used as the probe and target items in the experiment.
For two subjects, reaction time (RT) increased linearly with memory set size (MSZ). The slope of the regression line relating RT to MSZ in the GI task was significantly larger (p<0.001) than the one in the PI task. The spontaneous cortical rhythms in the alpha (8-13Hz) band were found to be suppressed while subjects scanned memory for visually presented probe characters. The largest suppression in the alpha band was observed at the occipital region. The suppression time (ST) of the variance in the alpha band measured at the occipital region increased linearly with RT in the GI task, whereas the ST was invariable in the PI task.