Description
- Abstract:
- The neocortical-entorhinal-hippocampal circuit has been shown to play an important role in memory formation and consolidation. Furthermore, the entorhinal cortex (EC) and the hippocampus are thought to be key components of the brain�s spatial processing system. I examine both of these aspects using quantitative analysis of single-neuron and network activity. In part 1, I investigate the dynamics of the neocortical-entorhinal-hippocampal circuit in anesthetized mice where cortical neurons alternate between a depolarized and spiking �UP� state and a hyperpolarized and quiescent �DOWN� state. I first demonstrate an explicit-duration hidden Markov model algorithm for inferring UP-DOWN states (UDS) from both membrane potential and local field potential recordings. I then apply this method to study UDS in superficial neurons of the medial and lateral EC (MEC and LEC). MEC, but not LEC, neurons are shown to selectively decouple from the neocortical UDS and exhibit persistent UP states whose duration is quantized in units of neocortical UDS cycles. In contrast, LEC, but not MEC, neurons are found to display periods of pronounced 2-4Hz oscillations which are phase-locked to the ongoing UDS. In part 2, I examine the hippocampal �rate� and �temporal� codes for position in freely behaving mice. The spatial and temporal firing properties of hippocampal neurons in GluA1 knockout (KO) mice are found to be dramatically altered relative to wild-type mice, and the network theta and gamma oscillations are also markedly reduced in the KO animals. I then examine the precession of hippocampal neurons� spike phase relative to the theta rhythm, and demonstrate a novel dependence of the temporal code on behavior. These studies reveal important mechanisms by which the EC could shape neocortical-hippocampal interactions during sleep, and advance our understanding of how the hippocampal �rate� and �temporal� codes are generated and relate to behavior.
- Notes:
- Thesis (Ph.D. -- Brown University (2011)
Access Conditions
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Citation
McFarland, James M.,
"Single-Neuron and Network Dynamics in the Neocortical-Entorhinal-Hippocampal Circuit"
(2011).
Physics Theses and Dissertations.
Brown Digital Repository. Brown University Library.
https://doi.org/10.7301/Z0DR2SQ2
