Figure 7
From: Basal forebrain activation controls contrast sensitivity in primary visual cortex
Simplified representation of BF, cortical and thalamic circuitry illustrating possible mechanisms of observed effects of BF stimulation. Cholinergic neurons in the NBM can influence cortical activity through either muscarinic receptors (mAChRs) located on both pyramidal neurons as well as inhibitory interneurons or through nicotinic receptors (nAChRs) located mostly presynaptically on the thalamocortical terminals. GABAergic neurons of the NBM also project to the cortex where they preferentially target other GABAergic interneurons. The effect of stimulating these neurons would thus mediate disinhibition in cortex. Another population of GABAergic neurons in the BF innervates the thalamic reticular nucleus, where - by a similar disinhibitory mechanism - they could enhance sensory signals relayed by the LGN from the retina to the cortex. Feedback connections from cortex to the LGN, which may contribute to BF stimulation related regulation of activity, are also shown.