The limbic lobe, on the other hand, is restricted to portions of the cortical mantle on the medial side of each hemisphere (Heimer and Van Hoesen 2006). The limbic lobe encompasses the hippocampus and parahippocampal gyri, lateral basal cortical amygdala, cingulate and insular cortices, as well as their pathways to the orbitofrontal cortex (OFC). The cingulate cortex has been implicated in attention, emotional processing, decision-making, and motor initiation (reviewed by Paus 2001), while the insular cortex is involved in processing of multimodal sensory information (reviewed by Nagai et al. 2007). The OFC, particularly in the right hemisphere, appears to be a neural substrate for mechanisms of inhibition and has been implicated in substance use disorders (reviewed by Dom et al. 2005). OFC projections to the basolateral amygdala provide local inhibitory influences through GABAergic neurotransmission. Failure to regulate the amygdala due to aberrant OFC volume or projections may cause impairment in learning to inhibit a prepotent response to obtain reward, or difficulty adjusting to new reward contingencies (e.g. Man et al. 2009).
