Reward, hedonic experience and the brain
In a recent paper in Nature Neuroscience, Morten Kringelbach summarizes the research on orbitofrontal cortex and its relation in organizing behaviour. In this paper, Kringelbach presents a new, integrated model of the functions of the orbitofrontal cortex. THE HUMAN ORBITOFRONTAL CORTEX: LINKING REWARD TO HEDONIC EXPERIENCE By Morten L. Kringelbach Nature Reviews Neuroscience 6, 691-702 […]
In a recent paper in Nature Neuroscience, Morten Kringelbach summarizes the research on orbitofrontal cortex and its relation in organizing behaviour. In this paper, Kringelbach presents a new, integrated model of the functions of the orbitofrontal cortex.
THE HUMAN ORBITOFRONTAL CORTEX: LINKING REWARD TO HEDONIC EXPERIENCE
By Morten L. Kringelbach
Nature Reviews Neuroscience 6, 691-702 (2005)
Abstract
Hedonic experience is arguably at the heart of what makes us human. In recent neuroimaging studies of the cortical networks that mediate hedonic experience in the human brain, the orbitofrontal cortex has emerged as the strongest candidate for linking food and other types of reward to hedonic experience. The orbitofrontal cortex is among the least understood regions of the human brain, but has been proposed to be involved in sensory integration, in representing the affective value of reinforcers, and in decision making and expectation. Here, the functional neuroanatomy of the human orbitofrontal cortex is described and a new integrated model of its functions proposed, including a possible role in the mediation of hedonic experience.
Summary
- The prefrontal cortex seems to be essential for the control and organization of behaviour. In particular, it has been linked to the relative cognitive sophistication that has been reached by higher primates, especially humans. However, the functions of one of its constituent regions, the orbitofrontal cortex, have remained enigmatic.
- In terms of neuroanatomical connectivity, the primate orbitofrontal cortex is uniquely placed to integrate sensory and autonomic information to modulate behaviour through both visceral and motor systems.
- Recent neuroimaging studies in humans have confirmed the role of the human orbitofrontal cortex as a nexus for sensory integration, modulation of visceral reactions, and participation in learning, prediction and decision making for emotional and reward-related behaviours. But these studies have also shown that the human orbitofrontal cortex is a highly heterogeneous brain region that encompasses many different functions.
- In particular, the human orbitofrontal cortex has been found to represent not only the reward value and expected reward value of foods and other reinforcers, but also their subjective pleasantness. This link to subjective hedonic processing could provide a basis for further exploration of the brain systems involved in the conscious experience of pleasure and reward, and, as such, offer a unique method for studying the hedonic quality of human experience.
- Based on the available evidence from neuroimaging and neuropsychology, a tentative new model of the functional neuroanatomy of the orbitofrontal cortex is offered with medial–lateral and posterior–anterior distinctions, in which the implicit reward value is assigned early on in the hierarchy for each type of reinforcer, with a further progression up the processing hierarchy (reflecting the effects of combinations of stimuli) towards areas that are connected to brain regions necessary for conscious hedonic processing.
- At present, little is known about the functional and structural development of the human orbitofrontal cortex in children and adolescents. However, further investigation of the link to hedonic processing could potentially lead to a better understanding of and novel treatments for disorders linked to anhedonia, such as depression, obesity and eating disorders.
