Electrical synapses coordinate activity in the suprachiasmatic nucleus.
In the suprachiasmatic nucleus (SCN), the master circadian pacemaker, neurons show circadian variations in firing frequency. There is also considerable synchrony of spiking across SCN neurons on a scale of milliseconds, but the mechanisms are poorly understood. Using paired whole-cell recordings, we have found that many neurons in the rat SCN communicate via electrical synapses. Spontaneous spiking was often synchronized in pairs of electrically coupled neurons, and the degree of this synchrony could be predicted from the magnitude of coupling. In wild-type mice, as in rats, the SCN contained electrical synapses, but electrical synapses were absent in connexin36-knockout mice. The knockout mice also showed dampened circadian activity rhythms and a delayed onset of activity during transition to constant darkness. We suggest that electrical synapses in the SCN help to synchronize its spiking activity, and that such synchrony is necessary for normal circadian behavior.
Long
Michael A
MA
Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA.
Jutras
Michael J
MJ
Connors
Barry W
BW
Burwell
Rebecca D
RD
D000200:Action Potentials; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D017630:Connexins / Q000172:deficiency / Q000502:physiology; D004594:Electrophysiology; D066298:In Vitro Techniques; D051379:Mice; D018345:Mice, Knockout; D009474:Neurons / Q000502:physiology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D011930:Reaction Time; D013493:Suprachiasmatic Nucleus / Q000502:physiology*; D013569:Synapses / Q000378:metabolism / Q000502:physiology*; D000097004:Gap Junction delta-2 Protein
D017630:Connexins; D000097004:Gap Junction delta-2 Protein