Prefrontal pathways for executive control
Helen Barbas
Boston University, Boston, MA. barbas@bu.edu
The prefrontal cortex in primates guides behavior by selecting relevant information, disregarding irrelevant information, and accessing motor control systems for action. In rhesus monkeys, distinct prefrontal cortices are linked with structures underlying sensory perception, cognition, and emotions. These topographically organized cortical pathways show remarkable regularity in their laminar organization, in patterns that can be predicted by a few structural features in the linked areas. Prefrontal axons terminating in the superficial versus the middle layers of superior temporal cortex are distinct at the synaptic level, in a pattern suggesting differences in efficacy of synaptic transmission across cortical layers. Moreover, prefrontal pathways project onto cortical excitatory neurons and onto distinct neurochemical classes of inhibitory neurons that also show regularity in their laminar distribution and differ in efficacy of inhibitory control. In addition, prefrontal pathways target subcortical structures, terminating onto excitatory as well as inhibitory systems in the amygdala and the thalamus, in patterns suggesting gating and recruitment of structures that may underlie the selection of relevant signals and suppression of irrelevant signals within a behavioral context. Quantitatively based maps of connections and their patterns may form the basis for investigating the dynamic recruitment of specific pathways underlying flexible behavior.