The effects of lesions to noradrenergic projections from the locus coeruleus and lateral tegmental cell groups on conditioned taste aversion in the rat.

Lesions of the coeruleo-cortical noradrenergic projections caused marked cortical noradrenaline depletions but were not associated with deficits in the acquisition or extinction of a conditioned taste aversion (CTA). Lesions of lateral tegmental noradrenergic projections resulted in marked hypothalamic noradrenaline depletions, enhanced neophobia to the novel taste of saccharin, unimpaired acquisition but prolonged extinction of the CTA. However, when animals with lateral tegmental noradrenergic lesions received extensive preconditioning exposure to saccharin, acquisition of the CTA was attenuated and extinction was more rapid than in controls. Alterations in CTA learning and extinction following lesions of the lateral tegmental noradrenergic system appear to reflect alterations in the way that animals with lesions react toward the hedonic aspects of taste-related stimuli rather than alterations in associational or attentional mechanisms.