Dissociable contributions of the orbitofrontal and lateral prefrontal cortex of the marmoset to performance on a detour reaching task

To gain insight into the nature and neural specificity of the relationship between simple problem solving, inhibitory control and prefrontal cortex, c omparison of the effects of excitotoxic lesions of the orbitofrontal and la teral prefrontal cortex were examined on the performance of common marmoset s on a detour reaching task. Monkeys were required to inhibit reaching dire ctly for food reward in a transparent box and instead make a detour reach a round to the side of the box either having had (i) no prior experience on t he task (experiment 1) or (ii) previous experience in reaching around the s ides of an opaque box (experiment 2). Whilst monkeys with orbitofrontal les ions had difficulty in inhibiting direct reaches to visible food reward (ex periment 1), they could resist this prepotent response tendency following e xtensive prior experience of detour reaching with an opaque box (experiment 2). In marked contrast, monkeys with lateral prefrontal lesions exhibited no difficulty in inhibiting reaching to visible food reward or acquiring de tour reaching per se (experiment 1). However, having been given the opportu nity to acquire an efficient detour reaching strategy to hidden food reward these lateral prefrontal lesioned monkeys were impaired at transferring th is strategy to the new context in which the food reward was made visible (e xperiment 2). This double dissociation between the effects of orbitofrontal and lateral prefrontal lesions on detour reaching provides evidence for a clear distinction in the level of control over responding exerted by the or bitofrontal and lateral prefrontal cortex, consistent with hierarchical ord ering of response control processes within prefrontal cortex.