People with autism show specific deficits in some attentional tasks and better than normal performance in others. Attentional processing is carried out in the brain in large part by the basal forebrain cholinergic system, modulated by the amygdala. Both the basal forebrain and the amygdala have been shown to be atypical in autistic brains, with the central nucleus of the amygdala (CN) containing unusually small, densely packed neurons and the substantia inominata/nucleus basalis (SI/nBM) region of the basal forebrain containing exceedingly high levels of BDNF, a neurotrophic factor that is implicated in neuronal excitability. The aim of this project is to use an animal model to determine whether these known abnormalities of autistic brains can themselves mediate the atypical attentional patterns of behavior seen in autism. Neural recordings will be obtained in the SI/nBM and CN of rats during attentional tasks comparable to those impaired in autistics and that have been shown to be dependent upon function of the basal forebrain cholinergic system. Neural activity and behavior will be monitored after partial lesions of the CN and after infusion of high levels of BDNF into the SI/nBM.