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Electrical synapses coordinate activity in the suprachiasmatic nucleus
Michael A Long1, Michael J Jutras, Barry W Connors
1Department of Neuroscience, Brown University, Providence, Rhode Island 02912, USA.
Nature Neuroscience
|December 8, 2004
Summary
Electrical synapses in the suprachiasmatic nucleus (SCN) synchronize neuron firing. This synchrony is crucial for normal circadian rhythms, as shown by dampened activity in knockout mice lacking these connections.
Area of Science:
- Neuroscience
- Chronobiology
- Cellular Electrophysiology
Background:
- The suprachiasmatic nucleus (SCN) acts as the body's master circadian pacemaker.
- SCN neurons exhibit circadian variations in firing rate and millisecond-scale spiking synchrony.
- The mechanisms underlying SCN neuronal synchrony remain largely unknown.
Purpose of the Study:
- To investigate the role of electrical synapses in mediating SCN neuronal synchrony.
- To determine the impact of electrical synapses on circadian behavior.
Main Methods:
- Paired whole-cell recordings in rat SCN to identify electrical coupling.
- Electrophysiological recordings in wild-type and connexin36-knockout mice.
- Behavioral analysis of circadian activity rhythms in knockout mice.
Main Results:
- Many SCN neurons communicate via electrical synapses.
- Electrical coupling directly predicted the degree of spontaneous spiking synchrony.
- Connexin36-deficient mice lacked SCN electrical synapses and displayed dampened circadian activity rhythms.
- Knockout mice showed delayed activity onset during transitions to constant darkness.
Conclusions:
- Electrical synapses are present in the SCN and synchronize neuronal spiking.
- SCN electrical synchrony is essential for robust circadian rhythmicity and normal behavioral timing.
- Connexin36 is a key component of SCN electrical synapses mediating circadian behavior.