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. Author manuscript; available in PMC: 2009 Feb 1.
Published in final edited form as: Neuropharmacology. 2007 Oct 22;54(2):365–374. doi: 10.1016/j.neuropharm.2007.10.006

Table 1.

PTZ Convulsion Endpoints

Progression of Convulsion
Endpoints		 Description
myoclonic (MC) twitch sudden involuntary muscle jerk
facial/forelimb (FF) clonus rapid writhing of the head and
neck with forelimb clonus
running/bouncing (RB) clonus whole-body clonus with jumping
and running movements
tonic hindlimb extension (THE) whole-body rigidity with caudal
extension of all limbs

As discussed in detail by Gale (1988), there are two qualitatively distinct components to the PTZ convulsion endpoints that are mediated by independent anatomical circuits. MC twitch and FF clonus are associated with forebrain circuits, whereas RB clonus and THE are associated with hindbrain circuits. Since genetic susceptibility to these two distinct convulsion types also may be distinct in mice (Kosobud and Crabbe, 1990), interpretations of the present studies will discuss MC twitch and FF clonus as similar types of convulsions and will similarly group results for RB clonus and THE.