The development of bicuculline-induced epileptiform discharges in embryonic turtle cortex

The appearance of bicuculline-induced epileptiform discharges was studied in embryonic turtle cortex using extracellular recording techniques. Drug-induced discharges occurred at an early stage of cortical plate formation, suggesting that mechanisms for synchronizing neuronal discharges are functional at this stage. Discharges originated in the medial cortex and increased in amplitude and decreased in frequency with development. gamma-Aminobutyric acid (GABA)-containing neurons and functional GABA receptors are present in advance of excitatory synchronizing mechanisms and may have a non-synaptic role in corticogenesis.