Comparative effects of scopolamine and amphetamine upon behavioral reactivity and visual evoked potentials to flashes in rats.

Two experiments employed a total of 14 male Holtzman rats in which averaged visual evoked response (VER) at cortex and behavioral reactivity to photic stimuli were examined following administration of varying dosages of either scopolamine (and methyl scopolamine) or dextroamphetamine, and of saline. The augmentation in behavioral activity produced by scopolamine and dextroamphetamine was associated with differential patterns of changes in VERs. Scopolamine reduced the amplitude of the early negative component, enhanced the early positive component, and blocked the attenuation of the late negative wave normally associated with heightened behavioral activity. Amphetamine produced relatively selective decrements in the late negative wave, which at higher dosages related to flash sequence. This information is of interest in utilizing VERs to help distinguish different antecedents of "behavioral arousal" to photic stimulation. (18 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)