Review of Orbitofrontal Cortex in Alcohol Dependence: A Disrupted Cognitive Map?

Abstract

Alcoholism is a persistent worldwide problem associated with long-lasting impairments to decision making processes. Some aspects of dysfunction are thought to reflect alcohol-induced changes to relevant brain areas such as the orbitofrontal cortex (OFC). In this review, we will examine how chronic alcohol exposure alters OFC function to potentially contribute to maladaptive decision making, and explore experimental behavioral approaches that may be better suited to test whether alcohol dependence disrupts OFC's function. We argue that although past works suggest impairments in aspects of OFC function, more information may be gained by specifically targeting tasks to the broader function of OFC as put forth by the recent hypothesis of OFC as a "cognitive map" of task space. Overall, we suggest that such a focus could provide a better understanding of how OFC function changes in alcohol dependence, and could inform better assessment tools and treatment options for clinicians working with this population.

Keywords: Alcohol dependence; Cognitive map; Decision making; Goal-directed; Orbitofrontal cortex.

Figure 1.

A recent hypothesis conceptualizes the orbitofrontal cortex (OFC) as providing a “cognitive map” of task space. In line with this hypothesis, alcohol dependence may alter decision-making by disrupting OFC function critical for inferring hidden task states. We argue that research using tasks targeted to this broader function will provide better understanding of how OFC changes in alcohol dependence, and could better inform future clinical practice for alcohol dependent populations.

Figure 2.

Example of task properties in reversal learning. In this scenario, reward delivery had previously occurred when the right lever was pressed, but has just switched unpredictably such that reward delivery now only occurs when the left lever is pressed. Properties in the task are distinguishable as observable (available through sensory experience) and unobservable (not available through sensory experience). Here, observable properties include both levers and cue lights, and other sensory information in the environment such as visual, auditory, or olfactory contextual cues. Unobservable properties include motivation to perform the task, expected reward value, and representation of task associative structure. Performance on reversal learning tasks relies on such unobservable properties, in particular the ability to infer the change in task structure following reversal of a previously-learned association. We propose that alcohol dependence may disrupt performance in tasks like reversal learning by altering the function of the orbitofrontal cortex, which is thought to be crucial in representing unobservable task properties.