SEROTONERGIC MODULATION OF CHOLINERGIC FUNCTION IN THE CENTRAL-NERVOUS-SYSTEM - COGNITIVE IMPLICATIONS

Accumulating evidence suggests that serotonin may modulate cholinergic function in several regions of the mammalian brain and that these ser otonergic/cholinergic interactions influence cognition. The first part of this review is an overview of histological, electrophysiological a nd pharmacological (in vitro, in vivo) data indicating that, in severa l brain regions (e.g., hippocampus, cortex and striatum), there are ne uroanatomical substrates for a serotonergic/cholinergic interaction, a nd that alterations in serotonergic activity may induce functional cha nges in cholinergic neurons. In the second part, the review focuses on experimental approaches showing or suggesting that central cholinergi c and serotonergic mechanisms are cooperating/interacting in the regul ation of cognitive functions. These arguments are based on lesion, int racerebral grafting and pharmacological techniques. It is concluded th at not all mnesic perturbations induced by concurrent manipulations of the serotonergic and cholinergic systems can be attributed to a serot onergic modification of the cholinergic system. The cognitive facultie s of an organism arise from interactions among several neurotransmitte r systems within brain structures such as, for instance, the hippocamp us or the cortex, but also from influences on memory of other general functions that may involve cerebral substrates different From those cl assically related to mnesic functions (e.g., attention, arousal, senso ry accuracy, etc.).