Hippocampal Slow Oscillation: A Novel EEG State and Its Coordination with Ongoing Neocortical Activity

• DOI: 10.1523/jneurosci.5594-05.2006
• Publication Date: 2006-06-08T15:42:39Z
• Authors: T. Wolansky; E. A. Clement; S. R. Peters; M. A. Palczak; C. T. Dickson
• Keywords: Entorhinal cortex; Local field potential; Neocortex

State-dependent EEG in the hippocampus (HPC) has traditionally been divided into two activity patterns: theta, a large-amplitude, regular oscillation with bandwidth of 3-12 Hz, and large-amplitude irregular (LIA), less signal broadband characteristics. Both these patterns have linked to memory functions subserved by HPC. Here we describe, using extracellular field recording techniques naturally sleeping urethane-anesthetized rats, novel state present during deactivated stages sleep anesthesia that is characterized prominent slow frequency (< or =1 Hz) rhythm. We called this hippocampal (SO) because its similarity correspondence previously described neocortical SO. Almost all units recorded exhibited differential spiking behavior SO as compared other states. Although occurred situations similar SO, it demonstrated some independence initiation, coordination, coherence. The was abolished sensory stimulation cholinergic agonism enhanced increasing anesthetic depth muscarinic receptor antagonism. Laminar profile analyses showed phase shift current sink-source alternations stratum lacunosum-moleculare CA1. This, along correlated oscillatory multiunit superficial entorhinal cortex suggests may be coordinated through input arriving via temporo-ammonic pathway. This favorable milieu for synchronization-dependent synaptic plasticity within between ensembles.