Slow oscillations in the mouse hippocampus entrained by nasal respiration.

Author: Yanovsky Y1, Ciatipis M, Draguhn A, Tort AB, Brankačk J.
1Institute for Physiology and Pathophysiology, University Heidelberg, 69120 Heidelberg, Germany, Spinal Cord Injury Center, Heidelberg University Hospital, 69118 Heidelberg, Germany, and Brain Institute, Federal University of Rio Grande do Norte, RN 59056-450 Natal, Rio Grande do Norte, Brazil.
Conference/Journal: J Neurosci.
Date published: 2014 Apr 23
Other: Volume ID: 34 , Issue ID: 17 , Pages: 5949-64 , Special Notes: doi: 10.1523/JNEUROSCI.5287-13.2014 , Word Count: 194

Different types of network oscillations occur in different behavioral, cognitive, or vigilance states. The rodent hippocampus expresses prominent θ oscillations at frequencies between 4 and 12 Hz, which are superimposed by phase-coupled γ oscillations (30-100 Hz). These patterns entrain multineuronal activity over large distances and have been implicated in sensory information processing and memory formation. Here we report a new type of oscillation at near-θ frequencies (2-4 Hz) in the hippocampus of urethane-anesthetized mice. The rhythm is highly coherent with nasal respiration and with rhythmic field potentials in the olfactory bulb: hence, we called it hippocampal respiration-induced oscillations. Despite the similarity in frequency range, several features distinguish this pattern from locally generated θ oscillations: hippocampal respiration-induced oscillations have a unique laminar amplitude profile, are resistant to atropine, couple differently to γ oscillations, and are abolished when nasal airflow is bypassed by tracheotomy. Hippocampal neurons are entrained by both the respiration-induced rhythm and concurrent θ oscillations, suggesting a direct interaction between endogenous activity in the hippocampus and nasal respiratory inputs. Our results demonstrate that nasal respiration strongly modulates hippocampal network activity in mice, providing a long-range synchronizing signal between olfactory and hippocampal networks.
hippocampus, network oscillations, rodent, urethane, γ oscillations, θ rhythm

PMID: 24760854