Correlation between function and structure in "epileptic" human hippocampal tissue maintained in vitro.

Intracellular and extracellular recordings were obtained from the CA1 region and gyrus dentatus of human hippocampi that had been surgically removed for treatment of intractable seizures. Pathologic diagnoses were obtained, and electrophysiologic results were correlated with degree of principal cell loss (sclerosis) in the regions studied. Extracellular field potentials were absent or smaller in amplitude, with abnormal characteristics, in sclerotic regions. In all regions, regardless of the degree of sclerosis, individual pyramidal or granule cells could be penetrated. These neurons showed apparently normal electrophysiologic characteristics and intact excitatory synaptic input. No signs of hyperexcitability were observed.