The role of the orbitofrontal cortex in human discrimination learning

Abstract

Several lines of evidence implicate the prefrontal cortex in learning but there is little evidence from studies of human lesion patients to demonstrate the critical role of this structure. To this end, we tested patients with lesions of the frontal lobe (n = 36) and healthy controls (n = 35) on two learning tasks: the weather prediction task (WPT), and an eight-pair concurrent visual discrimination task ('Choose'). Performance of both tasks was previously shown to be disrupted in patients with Parkinson's disease; the Choose deficit was only present when patients were medicated. Patients with damage to the orbitofrontal cortex (OFC) were significantly impaired on Choose, compared to both healthy controls and non-OFC lesion patients. The OFC lesion patients showed a mild deficit on the first 50 trials of the WPT, compared to the control subjects but not non-OFC lesion patients. The selective deficit in the OFC patients on Choose performance could not be attributed to the larger lesion size in this group, and the deficit was not correlated with the volume of damage to adjacent prefrontal subregions (e.g. anterior cingulate cortex). These data support the notion that the OFC play a role in normal discrimination learning, and suggest qualitative similarities in learning performance of patients with OFC damage and medicated PD patients.

Impaired acquisition rates of probabilistic associative learning in frontotemporal dementia is associated with fronto-striatal atrophy

“…Our results do not concur with this view as frontal regions and in particular the OFC, medial PFC and frontopolar cortex correlated with performance on the WPT as well. Our findings are therefore much more in line with other studies showing that lesions to the orbitofrontal cortex also significantly impairs performance on the WPT (Chase et al, 2008) as well as recent fMRI studies showing concurrent activations in striatal and frontal brain regions during WPT performance, including medial PFC and OFC activations (Aron et al, 2006; Poldrack and Foerde, 2008). …”

Neurogenetics and Pharmacology of Learning, Motivation, and Cognition

“…In reward learning tasks, models suggest that the orbitofrontal cortex maintains recent reinforcement experiences in an active working memory-like state, which can govern trial-to-trial behavioral adjustments through top-down projections (Frank and Claus, 2006;Deco and Rolls, 2004). Supporting this interpretation, orbitofrontal patients show impairments in early phases of acquisition in reinforcement tasks (Chase et al, 2008), as do patients with schizophrenia (Waltz et al, 2007). Moreover, recent studies reported a gene-dose effect of COMT on orbitofrontal activity during reward receipt (Figure 2b) (Dreher et al, 2009) and in lateral PFC during reward anticipation (Dreher et al, 2009;Yacubian et al, 2007).…”

Impaired implicit learning and feedback processing after stroke

“…The subsequent voxel-wise subtraction analysis showed that poor learners frequently had lesions in insular and striatal areas, but especially often within the inferior pre-frontal cortex (BA 10). Implicit learning is frequently impaired after prefrontal lesions (Barker et al, 2004, Chase et al, 2008 and probabilistic classification learning is facilitated by direct current stimulation of the prefrontal cortex (Kincses et al, 2004). The prefrontal cortex is thought to integrate information about the assumed value and prediction of outcomes into the processes of decision-making and the re-adjustment on this information based on related feedback (Liu et al, 2011).…”