Orbitofrontal Cortex - Functional Connectivity of The Orbitofrontal Cortex

Functional Connectivity of The Orbitofrontal Cortex

Tracer studies in monkeys have shown that the orbitofrontal cortex shares extensive connections with other association cortices, primary sensory and association cortices, limbic systems, and other subcortical areas. Corticocortical connections include extensive local projections to and from other prefrontal regions, as well as with motor, limbic, and sensory cortices. Areas projecting to motor areas are densely interconnected with other prefrontal cortical regions, reflecting integration for executive motor control.

Sensory cortices additionally share highly complex reciprocal connections with the orbitofrontal cortex. All sensory modalities are represented in connections with the orbitofrontal cortex, including extensive innervation from areas associated with olfaction and gustatory somatic responses. Somatosensory cortices including primary areas 1 and 2, particularly in areas associated with innervation of the hand and trigeminal complex, indicating the importance of the orbitofrontal cortex in face and hand sensation.

Functionally distinct pathways for auditory processing in the orbitofrontal cortex include a rostral stream associated with phonetic processing, and a more caudal stream terminating just posterior to the orbitofrontal cortex in the periarcuate prefrontal cortex associated with auditory-spatial processing, though these connections share extensive overlap. Both ventral and dorsal visual streams share connections with orbitofrontal cortical areas, including rich projections to and from the superior temporal pole, important for integration of spatial and object processing.

Connectivity of the orbitofrontal cortex with limbic areas includes reciprocal projections to granular, dysgranular, and agranular insular cortex, parahippocampal regions, and the hippocampus, particularly CA1 regions in a rostral-to caudal gradient. The orbitofrontal cortex additionally shares extensive reciprocal connections with the amygdala, and direct and indirect connections to the hypothalamus.

Additional subcortical projections are shared between the striatum, particularly ventral reward-related areas,. Connectivity with thalamic and periaqueductal grey areas further suggests a role for the orbitofrontal cortex in both inhibitory and excitatory regulation of autonomic function. Parallel processing loops in connectivity between cortico-striatal networks seem to be involved in the processing of goal-directed and habitual action, whereas cortico-limbic connectivity seems to be of prime importance for action selection, implicating the basolateral amygdala, and the integration of information into behavioral output

Though invasive tracer studies are largely not possible in humans, diffusion tensor imaging (DTI) tractography studies have also been used to map the connectivity of the orbitofrontal cortex to cortical and subcortical brain structures. Connections in the human orbitofrontal cortex follow a conserved pattern, similar to what is shown in tracer studies in rhesus macaques, but with a distinct pattern of connectivity with regions of the striatum.