[Impulse activity of cultured rat cerebral cortex neurons]

Background spike activity and morphological characteristics of the visual cortex neurons 1-2 day old rats were investigated under conditions of long-term (up to 34 days) tissue cultures. Three types of unit activity were found: single (regular) spikes, bursts and group discharges. Background activity is shown to depend on the cultivation period. Regular firing of neurons for the first 7-15 cultivation days is changed later by bursts or group activity. These changes in neuronal activity coincide in time with the process of morphological maturation of synaptic connections. Strychnine caused a distinct increase in the mean frequency of background activity accompanied by separate series of group discharges. On the basis of the data obtained the problem on the genesis of the spontaneous activity in cortical neurons is discussed.