Extinction-induced spatial dispersion in the radial arm maze: Arrest by ethanol

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Investigated adaptive changes in response to extinction by making provisions that permitted behavior to shift away from trained routine. The baiting of 4 arms in an 8-arm radial maze increasingly restricted movements by 32 male Sprague-Dawley rats to those arms: The unbaited arms afforded a new direction for behavior to take during extinction. Withdrawal of reward was followed by an immediate and active expansion of visited sites, and previously unrewarded arms were regularly sampled. This was one consequence of extinction; the other was the decline in overall rate of arm entry, whether arms were previously baited or not. Ethanol (1.5 or 2.0 g/kg) eliminated the spatial dispersions attendant on nonreward but did not affect the decline in overall responsiveness. It is concluded that ethanol's deletion of extinction-induced spatial variability may account for its impairment on reversal and other kinds of tasks that require a shift away from old patterns of behavior. (23 ref) (PsycINFO Database Record (c) 2006 APA, all rights reserved)

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