Hippocampal neurochemical and electrophysiological measures from freely moving rats

This paper describes surgical and recording procedures that have been devel oped which permit the simultaneous monitoring of levels of select neurochem icals (via microdialysis) and measures of dentate-evoked held potentials wi thin the hippocampal formation of freely moving adult rats. To test and eva luate these procedures, they were employed to examine changes in hippocampa l neurochemistry and neuronal excitability associated with the establishmen t and maintenance of hippocampal long-term potentiation (LTP), Measures of hippocampal norepinephrine (NE) and glutamate levels along with measures of the dentate granule cell population spike amplitude (PSA) mere obtained be fore, during, and after tetanization of the medial perforant path using two separate tetanization paradigms. Results obtained using these new procedur es in several animals indicated that changes in NE and glutamate levels wer e strongly correlated with increases in the dentate granule cell PSA measur e obtained following tetanization. The results indicate that this newly dev eloped procedure can be effectively used to directly examine the relationsh ip between neurochemical and neurophysiological changes associated with hip pocampal neuroplasticity, (C) 1999 Academic Press.