Neuromagnetic Investigations of Cortical Regions Underlying Short-Term Memory

摘要

Spontaneous neuronal activity of the brain within the alpha frequency bandwidthis found to be suppressed in visual cortex when comparing a rotated, and possibly inverted object with an object previously seen to determine whether they are identical. Moreover, the pattern of suppression adjusts to task demands. Thus, visual cortex participates in the processes of mental imagery. A mathematical solution for the magnetic inverse problem has been developed to determine the locations of alpha suppression within the brain based on magnetic field measurements of the magnetic field power across the scalp. Behavioral studies of a person's loss of memory for the loudness of a tone can be characterized by a decaying exponential dependence on time. The characteristic lifetime is found to match to within 0.2 sec the individual's lifetime for the decay of the neuronal activation trace in primary determined neuromagnetically. Mental imagery of a target, visual cortex participation, alpha rhythm suppression, localization of cortical activity, magnetic power inverse solution, sensory memory, decay of auditory memory, central tendancy.