Lesions of the amygdala central nucleus alter performance on a selective attention task

Previous studies showed a role for the amygdala central nucleus (CN) in attentional processing during the acquisition of Pavlovian associations. Both the acquisition of conditioned orienting responses and the surprise-induced enhancement in the ability of conditioned stimuli to enter into new associations depend on the integrity of CN. In this experiment, the role of CN in the performance of a well-learned selective attention task was examined. Rats with ibotenic acid lesions of CN and control rats first learned a discrete-trial, multiple-choice reaction time task. On each trial, after a constant-duration ready signal, the rats were required to poke their noses into one of three ports, guided by the brief illumination of one of those ports. Rats with CN lesions were slower to acquire the task than control rats but showed equivalent asymptotic sustained performance. Subsequent attentional challenges, which included reducing the duration of the port illumination and varying the duration of the ready signal, had greater impact on the performance of lesioned than control rats. These data resemble those reported from similar tasks after damage to the basal forebrain (BF) system. Together with earlier findings, these data support a role for CN in modulating visuospatial attention in action as well as in the acquisition of associations, perhaps by way of its projections to BF cholinergic systems.