Causal investigations into orbitofrontal control of human decision making

Abstract

Although it is widely accepted that the orbitofrontal cortex (OFC) is important for decision making, its precise contribution to behavior remains a topic of debate. While many loss of function experiments have been conducted in animals, causal studies of human OFC function are relatively scarce. This review discusses recent causal investigations into the human OFC, with an emphasis on advances in network-based brain stimulation approaches to indirectly perturb OFC function. Findings show that disruption of human OFC impairs decisions that require mental simulation of outcomes. Taken together, these results support the idea that human OFC contributes to decision making by representing a cognitive map of the task environment, facilitating inference of outcomes not yet experienced. Future work may utilize similar non-invasive approaches in clinical settings to mitigate decision making deficits in neuropsychiatric disorders.

Figure 1:. Adaptive behavior in the devaluation task depends on the OFC.

A. Schematic of the devaluation task. Subjects first learn associations between cues (or actions) and food rewards. In a baseline session, subjects make choices among these cues (or actions). Next, devaluation can be achieved by feeding to satiety on one of the two foods. Choices between cues (or actions) are then reassessed in a probe session, typically under extinction conditions (i.e., cues/actions are offered but no reward is given). B. Subjects with intact OFC reduce choices for cues or actions previously paired with the now devalued reward in the probe choice session, whereas subjects with inactivated OFC continue to choose cues or actions predicting devalued rewards. C. Liking of the devalued food is not affected by OFC inactivation and decreases similarly in both groups.

Figure 2:. OFC networks and OFC-targeted brain stimulation.

A. Connectivity-based parcellation of OFC voxels into central/lateral (blue) and medial (red) OFC networks, adapted from [54]. B. Surface plots depict areas on lateral (top) and medial (bottom) surface that are connected with the central/lateral (blue) and medial (red) OFC networks. C. The indicated stimulation site in LPFC has high resting-state connectivity with the target area in the central/lateral OFC. TMS can be applied to individually identified coordinates within LPFC that show maximal connectivity with the OFC target.