PATHWAY SPECIFICITY OF L-ISOPROTERENOL INDICATES BETA-ADRENERGIC MODULATION OF THE SCHAFFER COLLATERAL PATHWAY IN-FIELD CA1 IN THE RAT HIPPOCAMPAL SLICE

BEHAVIORAL relevance of norepinephrine is associated with neuronal pro cessing underlying arousal, affect, attention, learning and memory, an d is associated with beta-adrenergic modifications of neuronal activat ion in the hippocampal formation. This study utilized l-isoproterenol to initiate pathway-specific activation of afferents to hippocampal CA 1 pyramidal cells. The consistent effects of l-isoproterenol on the in itiation of action potentials to field CA1 pyramidal neurons to single -pulse stimulation was repeatedly associated with the activation of th e Schaffer collateral pathway. In contrast, I-isoproterenol plus singl e-pulse stimulation never elicited action potential initiation of the perforant pathway to CA1. We interpret these results as indicating tha t beta-adrenergic modification underlies the augmentation of informati on processing via the Schaffer collateral pathway in the trisynaptic c ircuit vs the direct perforant pathway.