Figure 7.

Closed-loop frontal cortical control over ascending neuromodulatory activity. Distinct (though likely overlapping) regions of the frontal cortex send excitatory projections to distinct brainstem and forebrain nuclei: the cholinergic (ACh) basal nucleus of Meynert (BnM), the dopaminergic (DA) ventral tegmental area (VTA), the serotonergic (5HT) dorsal raphe (DR) and the noradrenergic (NAd) locus coeruleus (LC). The recruitment of these nuclei will then lead to an increase in neuromodulatory tone in the cortex, which in turn will shape network topology and information processing mode of local neural populations. In this way, microcolumns in the frontal cortex are able to effectively ‘steer’ the brain network into different information processing modes that befit the current challenges imposed on the system.