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<title>Abstact: Whisking is controlled</title>

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J Neurophysiol. 2010 Nov;104(5):2532-42. Epub 2010 Sep 15.
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Cannabinoids reveal separate controls for whisking amplitude and timing in rats.
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Pietr MD, Knutsen PM, Shore DI, Ahissar E, Vogel Z. <br>
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Department of Neurobiology, The Weizmann Institute of Science, Rehovot, Israel.

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Whisking is controlled by multiple, possibly functionally segregated, motor <br>
sensory-motor loops. While testing for effects of endocannabinoids on whisking, <br>
we uncovered the first known functional segregation of channels controlling whisking <br>
amplitude and timing. Channels controlling amplitude, but not timing, were modulated <br>
by cannabinoid receptor type 1 (CB1R). Systemic administration of CB1R agonist <br>
Δ(9)-tetrahydrocannabinol (Δ(9)-THC) reduced whisking spectral power across all <br>
tested doses (1.25-5 mg/kg), whereas whisking frequency was affected at only very high <br>
doses (5 mg/kg). Concomitantly, whisking amplitude and velocity were significantly <br>
reduced in a dose-dependent manner (25-43 and 26-50%, respectively), whereas cycle <br>
duration and bilateral synchrony were hardly affected (3-16 and 3-9%, respectively). <br>
Preadministration of CB1R antagonist SR141716A blocked Δ(9)-THC-induced kinematic <br>
alterations of whisking, and when administered alone, increased whisking amplitude and <br>
velocity but affected neither cycle duration nor synchrony. These findings indicate <br>
that whisking amplitude and timing are controlled by separate channels and that <br>
endocannabinoids modulate amplitude control channels.<br>
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