Article

Specific effects of idazoxan in a distraction task: Evidence that endogenous norepinephrine plays a role in selective attention in rats

Department of Psychology, Cornell University, Ithaca, New York 14853-6301, USA.
Behavioral Neuroscience (Impact Factor: 3.25). 11/1995; 109(5):903-11. DOI: 10.1037//0735-7044.109.5.903
Source: PubMed

ABSTRACT Rats were injected with the alpha 2-adrenergic antagonist idazoxan (IDZ) prior to testing on vigilance and distraction tasks. In the vigilance task, rats responded with nose pokes to brief visual cues presented at variable intervals following trial onset. The distraction task was similar except that irrelevant odor cues (distractors) were presented in the interval prior to light onset on some trials. IDZ injection had no effect on performance in the vigilance task. In the distraction task, however, the higher IDZ dose (1.0 mg/kg) modulated the propensity to make a premature response when the distractors were presented. Notably, the direction of the effect varied with the rats' baseline level of distractibility. This pattern of effects suggests that endogenous norepinephrine (NE) influences distractibility and/or selective attention.

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    • "Ablation of the ascending NE system increases distractibility (Carli et al., 1983) but agonists of the inhibitory alpha-2 autoreceptor, which decrease NE tone, suppress distractibility (Clark et al., 1989; Witte and Marrocco, 1997). Moreover, the effects of alpha-2 antagonists on distractibility are dependant on individual variation in baseline distractibility (Bunsey and Strupp, 1995). Additionally, it remains unclear whether variations in NE levels within the normal physiological range predict distractibility. "
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    • "In the present study, atipamezole administration enhanced cognitive function, specifically ED set-shifting, that had been compromised by CUS treatment. Blockade of α 2 -adrenergic autoreceptors enhances NE release in brain regions such as neocortex (Devauges and Sara, 1990; Garcia et al., 2004; Haapalinna et al., 1998), and improves performance in various learning and memory tests (Bunsey and Strupp, 1995; Devauges and Sara, 1990; Sara et al., 1994). Atipamezole has been shown to enhance acquisition in a linear-arm maze test, improve choice accuracy of poorly performing rats in a delayed three-choice test (Haapalinna et al., 1998), and facilitate passive avoidance retention in aged rats (Riekkinen et al., 1992). "
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