[Changes in neocortex function in the direct action of optical radiation]

Direct action of ultraviolet radiation with wavelength of 280, 310 and 365 nm increased the amplitude of neocortex EEG and enhanced the epileptiform activity in the penicillin--induced epileptic focus, whereas action of superthreshold radiation with wavelength of 580 and 630 nm decreased the EEG amplitude and suppressed the epileptiform activity. The mechanism of ultraviolet radiation effect on the neocortical electrical activity seems to be based on changes in permeability of neuronal membranes for Na and K ions and on following depolarization of the membranes, whereas the action of visible radiation leads to the heat injuring of neurons in the irradiated area which evokes irreversible suppression of their activity and reducing of their EEG amplitude.