COGNITIVE FUNCTIONS OF CORTICAL ACETYLCHOLINE - TOWARD A UNIFYING HYPOTHESIS

Previous efforts aimed at attributing discrete behavioral functions to cortical cholinergic afferents have not resulted in a generally accep ted hypothesis about the behavioral functions mediated by this system, Moreover, attempts to develop such a unifying hypothesis have been pr esumed to be unproductive considering the widespread innervation of th e cortex by basal forebrain cholinergic neurons. In contrast to previo us descriptions of the rule of cortical acetylcholine (ACh) in specifi c behavioral phenomena (e.g., mediation of the behavioral effects of r eward loss) or mnemonic entities (e.g., working or reference memory), conical ACh is hypothesized to modulate the general efficacy of the co rtical processing of sensory or associational information. Specificall y, cortical cholinergic inputs mediate the subjects' abilities to dete ct and select stimuli and associations for extended processing and to allocate the appropriate processing resources to these functions. in a ddition to evidence from electrophysiological and behavioral studies o n the role of cortical ACh in sensory information processing and atten tion, this hypothesis is consistent with proposed functions of the lim bic and paralimbic networks in regulating the activity of the basal fo rebrain cholinergic neurons, Finally, while the proposed hypothesis im plies that changes in activity in cortical ACh simultaneously occur th roughout the cortex, the selectivity and precision of the functions of cholinergic function is due to its coordinated interactions with the activity of converging sensory or associational inputs. Finally, the d ynamic, escalating consequences of alterations in the activity of cort ical ACh (hypo- and hyperactivity) on cognitive functions are evaluate d.