[Cortical biopotentials following intracortical injections of kainic acid]

The morphological analysis after intracortical injection of kainic acid revealed lesions of cell bodies and dendrites and intact afferents in the same cortical region. After the injection, the primary positive phase of cortical surface EPs during stimulation of the ventrolateral nucleus or contralateral forepaw disappeared whereas the negative phase remained though with a lesser amplitude, shortened latency, and not inverted in the deep cortical layers. The dendrite potential on the cortical stimulation was completely depressed in the poisoned cortical region. The initial positive phase seems to reflect the postsynaptic hyperpolarization of apical dendrites whereas the initial negative phase seems to consist of both pre- and postsynaptic components across the whole cortical diameter.