Computer-determined EEG patterns associated with memory-facilitating drugs and with ECS.

Cortical EEG patterns of rats were analyzed by computer following administration of analeptic drugs at doses previously shown to facilitate posttrial memory processes. The drugs produced an increase in the power of the EEG primarily by increasing the amount of activity in delta and lower-theta frequency bands. The increase in lower frequency theta was accompanied by a decrease in higher frequency theta, thus increasing the regularity in the theta band. Electroconvulsive shock, which disrupts posttrial memory processes, also increased delta activity, but it greatly lowered amplitudes throughout the EEG frequency spectrum. It is concluded that if any consistent relationship between the cortical EEG and posttrial memory processes exists, then increased amplitude and regularity in the delta and theta bands are associated with increased amounts of memory storage--at least in alert animals. Further studies are required to determine if a causal influence is involved in this correlation.