title: Theta oscillations decrease spike synchrony in the hippocampus and entorhinal cortex.
abstract: Oscillations and synchrony are often used synonymously. However, oscillatory mechanisms involving both excitation and inhibition can generate non-synchronous yet coordinated firing patterns. Using simultaneous recordings from multiple layers of the entorhinal-hippocampal loop, we found that coactivation of principal cell pairs (synchrony) was lowest during exploration and rapid-eye-movement (REM) sleep, associated with theta oscillations, and highest in slow wave sleep. Individual principal neurons had a wide range of theta phase preference. Thus, while theta oscillations reduce population synchrony, they nevertheless coordinate the phase (temporal) distribution of neurons. As a result, multiple cell assemblies can nest within the period of the theta cycle.
authors.affiliation: NYU Neuroscience Institute, Langone Medical Center, New York University, , New York, NY 10016, USA.
authors.forename: Kenji
authors.initials: K
authors.lastname: Mizuseki
authors.forename: György
authors.initials: G
authors.lastname: Buzsaki
mesh_terms: D000200:Action Potentials / Q000502:physiology*; D000818:Animals; D004594:Electrophysiology / Q000379:methods; D018728:Entorhinal Cortex / Q000166:cytology / Q000502:physiology*; D006624:Hippocampus / Q000166:cytology / Q000502:physiology*; D008297:Male; D009474:Neurons / Q000502:physiology*; D051381:Rats; D020318:Rats, Long-Evans; D012890:Sleep / Q000502:physiology*; D012895:Sleep, REM / Q000502:physiology*; D013826:Theta Rhythm / Q000502:physiology*
keywords: brain states; cell assemblies; place cells; synchrony; temporal coordination; theta oscillations