Selective impairment of hippocampal gamma oscillations in connexin-36 knock-out mouse in vivo.
The physiological roles of neuronal gap junctions in the intact brain are not known. The recent generation of the connexin-36 knock-out (Cx36 KO) mouse has offered a unique opportunity to examine this problem. Recent in vitro recordings in Cx36 KO mice suggested that Cx36 gap junction contributes to various oscillatory patterns in the theta (approximately 5-10 Hz) and gamma (approximately 30-80 Hz) frequency ranges and affects certain aspects of high-frequency (>100 Hz) patterns. However, the relevance of these pharmacologically induced patterns to the intact brain is not known. We recorded field potentials and unit activity in the CA1 stratum pyramidale of the hippocampus in the behaving wild-type (WT) and Cx36 KO mice. Fast-field "ripple" oscillations (140-200 Hz) were present in both WT and KO mice and did not differ significantly in power, intraepisode frequency, or probability of occurrence. Thus, fast-field oscillations either may not require electrical synapses or may be mediated by a hitherto unknown class of gap junctions. Theta oscillations, recorded during either wheel running or rapid eye movement sleep, were not different either. However, the power in the gamma frequency band and the magnitude of theta-phase modulation of gamma power were significantly decreased in KO mice compared with WT controls during wheel running. This suggests that Cx36 interneuronal gap junctions selectively contribute to gamma oscillations.
Buhl
Derek L
DL
Center for Molecular and Behavioral Neuroscience, Rutgers University, The State University of New Jersey, Newark, New Jersey 07102, USA.
Harris
Kenneth D
KD
Hormuzdi
Sheriar G
SG
Monyer
Hanna
H
Buzsáki
György
G
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000502:physiology; D001683:Biological Clocks / Q000235:genetics*; D017630:Connexins / Q000172:deficiency* / Q000235:genetics; D004567:Electrodes, Implanted; D004569:Electroencephalography; D006624:Hippocampus / Q000502:physiology*; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009043:Motor Activity / Q000502:physiology; D017966:Pyramidal Cells / Q000502:physiology; D012815:Signal Processing, Computer-Assisted; D012890:Sleep / Q000235:genetics / Q000502:physiology; D000097004:Gap Junction delta-2 Protein
D017630:Connexins; D000097004:Gap Junction delta-2 Protein