Inhibitory control and affective processing in the prefrontal cortex: neuropsychological studies in the common marmoset.

The orbitofrontal cortex has been ascribed a role in the inhibitory control, as well as in the emotional control, of behaviour. While damage to the orbitofrontal cortex in humans and non-human primates can cause inflexibility, impulsiveness and emotional disturbance, the relationship between these effects are unclear. Excitotoxic lesion studies in marmosets comparing the effects of cell loss within specific regions of the prefrontal cortex on performance of a range of behavioural tests reveal that mechanisms of response inhibition are not unique to the orbitofrontal cortex. Instead they are present in distinct cognitive domains for lowerorder as well as higher-order processing throughout the prefrontal cortex. Thus, the lateral prefrontal cortex is involved in the selection and control of action based upon higher-order rules while the orbitofrontal and medial prefrontal cortex may be involved in different but complementary forms of lower-order rule learning, their roles dissociable, as a result of their differential contribution to different types of associative learning.