α-Adrenergic receptors in auditory cue detection: α2 receptor blockade suppresses false alarm responding in the rat

Numerous studies have suggested a facilitatory role of the noradrenergic system in attention. Cognitive functions relating to attentive states—arousal, motivation, behavioral flexibility, and working memory—are enhanced by norepinephrine release throughout the brain. The present study addresses the role of the adrenergic system on stimulus validity and sustained attention within the auditory system. We examined the effects of adrenoceptor stimulation via systemic injection of α1 and α2-adrenoceptor antagonist and agonist drugs, prazosin (1 mg/kg), phenylephrine (0.1 mg/kg), yohimbine (1 mg/kg), and clonidine (0.0375 mg/kg), respectively. Our results indicate that α1-adrenergic stimulation is ineffective in modulating the biological assessment of auditory signal validity in the non-stressed rat, while α2-adrenoceptor antagonist and agonist drugs were effective in modulating both accuracy and response latencies in the habituated animal. Remarkably, blockade of α2-adrenoceptors significantly improved the animal's ability to correctly reject non-signal events. These findings indicate not only a state dependent noradrenergic component of auditory attentional processing, but a potential therapeutic use for drugs targeting norepinephrine release in neurological disorders ranging from Alzheimer's disease to schizophrenia.

► Measure of auditory vigilance in adult male rats.
► Examination of adrenoceptor modulation beyond alertness.
► Blockade of α2, but not α1, receptors improves focus and reduces false alarm responding.
► α2 adrenoceptor manipulation may prove beneficial in certain neurological disorders.