The synaptic regulation of pyramldal cell excitability will be examined in the hippocampal slice preparation. Two approaches will be used. The characteristics of the acidic amino acid receptors present on pyramidal cells will be determined with quantitative pharmacological methods. Intracellular recordings will be obtained from pyramidal cells, and dose response curves to receptor agonists will be constructed before and after perfusion with known concentrations of antagonists. The data will be analyzed by the Schild method. The results of these experiments should allow us to choose appropriate concentrations of antagonists for selective blockage of certain acidic amino acid receptors. This information will be used in an attempt to identify the receptor(s) underlying the epileptiform burst response and the Schaffer-commissural EPSP in the CAl region. Intrad endritic recordings will be made from pyramidal cells in order to study a form of non-hyperpolarizing dendritic inhibition. Paired pulse experiments will be done to determine if conductance shunting is a prominant mechanism for dendritic inhibition. The data should allow a better understanding of the functional consequences of integration of excitatory and inhibitory synaptic potentials in pyramidal cell dendrites.
