1School of Mathematical Sciences, University of Nottingham, Nottingham, UK
2School of Biomedical Sciences, University of Nottingham, Queen’s Medical Centre, Nottingham, UK
Monosynaptic projections from the hippocampus to medial prefrontal cortex (mPFC) are thought to be involved in regulating working memory. The neural dynamics of this connectivity were compared in vivo under control conditions and after kainic acid (KA) administration, using partial directed coherence analysis (PDC).
PDC is a statistical technique based on autoregressive modeling of multivariate time series in conjunction with the concept of Granger Causality and provides clues to directional connectivity and magnitude of information flow between neuronal ensembles. Hippocampal and mPFC local field potentials (LFPs) were recorded in isoflurane-anaesthetised rats with a 16-wire micro-electrode array and an 8-wire micro-electrode bundle respectively. Separate groups of rats were administered KA or received no drug treatment. PDC was applied to LFP data in animals with confirmed dorsal hippocampal and mPFC placements.
In the control group, PDC detected a stronger flow of information from lateral to medial hippocampal sites and from mPFC to the hippocampus. KA disrupted this directionality in the hippocampus, but did not alter directionality between mPFC and the hippocampus. These results suggest that a significant flow of information also occurs in the mPFC-to-hippocampus direction, and that acute-elevated neuronal activity, induced by KA administration, does not disrupt this inter-regional connectivity.