McGaughy JA, Hutchins DJ, Pimentel AJ, Pimentel CS, Swaine JA (2018) Dissociable effects of noradrenergic and cholinergic lesions of anterior cingulate cortex on distractibility. Neuroscience 2018 Abstracts 238.14 / ZZ15. Society for Neuroscience, San Diego, CA.
Summary: Prior data from our lab and others has shown that that the anterior cingulate cortex (ACC) of the rat is critically involved in many aspects of executive function and cognitive control. Previously, we have shown that excitotoxic lesions of the ACC produced deficits in the ability of male rats to filter salient distractors. Additionally, these same subjects were unable to reverse reinforcement contingencies when tested with complex stimuli (Newman and McGaughy 2011). These deficits in filtering were not attributable to impairments in conditional discrimination learning, impairments in reversal learning with uni-dimensional stimuli or a general distractibility to conspicuous, irrelevant stimuli. In the present study, male, Long-Evans rats were used to determine if lesions to the noradrenergic or cholinergic afferents to ACC could recapitulate the effects of excitotoxic lesions in the same area. Lesions were produced by infusion into rostral ACC of dopamine β hydroxylase saporin or 192 IgG-saporin to deplete norepinephrine or acetylcholine, respectively. After two weeks of recovery from surgery, rats were tested in an intradimensional/extradimensional set-shifting task. This test was selected because of it’s utility in translational neuroscience and it’s sensitivity to several aspects of executive function including susceptibility to salient distractors, the ability to form an attentional set, the ability to shift an attentional set and reversal learning. Preliminary data show that noradrenergic, but not cholinergic lesions recapitulate some, but not all, of the impairments found after excitotoxic lesion of ACC. Specifically noradrenergic lesioned rats were more susceptible to salient distractors than sham-lesioned rats. In contrast to the effects of excitotoxic lesions, noradrenergic lesions did not impair the ability to reverse reinforcement contingencies when using complex stimuli containing salient, irrelevant stimulus dimensions. The extent of the lesions to ACC were assessed using markers for norepinephrine transporters and acetylcholinesterase. Together these data support the hypothesis that norepinephrine in the ACC is critically involved in the ability to filter salient distractors. The significance of these findings will be discussed in terms of the relevance of these data to the treatment of several neuropsychiatric disorders including attention deficit hyperactivity disorder, depression and addiction.
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