Simultaneous hippocampal microdialysis and electrophysiological measures from behaving rats

The authors have recently developed surgical and recording procedures which allow them to monitor levels of select neurochemicals (via microdialysis) simultaneous with measures of neuronal excitability (evoked response measures) within the hippocampal formation of freely moving adult rats. Measures of hippocampal norepinephrine (NE) and glutamate levels, along with measures of the dentate granule cell population spike amplitude (PSA) were then obtained before, during, and after tetanization of the medial perforant path using two separate tetanization paradigms. Results indicated that changes in NE and glutamate levels were strongly correlated with changes in the dentate granule cell PSA measure obtained following tetanization. The results indicate that this newly developed procedure can be effectively used to directly examine the relationship between neurochemical and neurophysiological changes associated with hippocampal neuroplasticity.