Medial Prefrontal Cortex Cells Show Dynamic Modulation With the Hippocampal Theta Rhythm De.pdfVIP

HIPPOCAMPUS 15:000–000 (2005) Medial Prefrontal Cortex Cells Show Dynamic Modulation With the Hippocampal Theta Rhythm Dependent on Behavior James M. Hyman, Eric A. Zilli, Amanda M. Paley, and Michael E. Hasselmo ABSTRACT: Both the hippocampus and the medial prefrontal cortex known about how these two areas work together dur- are essential for successful performance in learning- and memory- ing active processing tasks despite the large anatomical related tasks. Within the hippocampus the theta rhythm plays an inte- distance. gral role in the timing of action potentials of hippocampal neurons responding to elements of any given task. Medial prefrontal cortex Rodent research has begun to develop the argument (mPFC) neurons display firing rate changes to specific facets of behavio- that the rat medial prefrontal cortex is homologous to ral tasks (Jung et al., 1998. Cereb Cortex 8:437–450). We recorded units the monkey and human dorsolateral prefrontal cortex in the mPFC and field potentials in the hippocampus to determine (Groenewegen, 1988; Brown and Bowman, 2002; whether behaviorally correlated mPFC cells fired with phase relation- ships to the hippocampal theta rhythm. In two different behavioral tasks Uylings et al., 2003). Lesions of the medial prefrontal (running a linear track and foraging in two distinct environments) we cortex (mPFC) in rat impair performance on goal- found mPFC cells that alternated between theta entrained firing and and delay-