The orbitofrontal cortex: reward, emotion and depression

Abstract

The orbitofrontal cortex in primates including humans is the key brain area in emotion, and in the representation of reward value and in non-reward, that is not obtaining an expected reward. Cortical processing before the orbitofrontal cortex is about the identity of stimuli, i.e. ′what′ is present, and not about reward value. There is evidence that this holds for taste, visual, somatosensory, and olfactory stimuli. The human medial orbitofrontal cortex represents many different types of reward, and the lateral orbitofrontal cortex represents non-reward and punishment. Not obtaining an expected reward can lead to sadness, and feeling depressed. The concept is advanced that an important brain region in depression is the orbitofrontal cortex, with depression related to over-responsiveness and over-connectedness of the non-reward-related lateral orbitofrontal cortex, and to under-responsiveness and under-connectivity of the reward-related medial orbitofrontal cortex. Evidence from large-scale voxel-level studies and supported by an activation study is described that provides support for this hypothesis. Increased functional connectivity of the lateral orbitofrontal cortex with brain areas that include the precuneus, posterior cingulate cortex, and angular gyrus is found in patients with depression, and is reduced towards the levels in controls when treated with medication. Decreased functional connectivity of the medial orbitofrontal cortex with medial temporal lobe areas involved in memory is found in patients with depression. Some treatments for depression may act by reducing activity or connectivity of the lateral orbitofrontal cortex. New treatments that increase activity or connectivity of the medial orbitofrontal cortex may be useful for depression. These concepts, and that of increased activity in non-reward attractor networks, have potential for advancing our understanding and treatment of depression. The focus is on the orbitofrontal cortex in primates including humans, because of differences of operation of the orbitofrontal cortex, and indeed of reward systems, in rodents. Finally, the hypothesis is developed that the orbitofrontal cortex has a special role in emotion and decision-making in part because as a cortical area it can implement attractor networks useful in maintaining reward and emotional states online, and in decision-making.

Enhanced amygdala-frontal operculum functional connectivity during rest in women with chronic neck pain: Associations with impaired conditioned pain modulation

“…Note that we did not use a subdivision for the pallidum, so further research will be needed to examine which subpart is specifically altered. The orbitofrontal cortex plays a key role in emotional processing, reward and decision-making ( Rolls et al, 2020 ) and is part of the salience network ( Bhatt et al, 2019 ).…”

Attractor cortical neurodynamics, schizophrenia, and depression

“…Major depressive disorders are generally accompanied by (1) altered incentive and reward processing, evidenced by motivation, apathy, and anhedonia; (2) impaired modulation of anxiety and worry, manifested by generalized, social, and panic anxiety, and oversensitivity to negative feedback; (3) inflexibility of thought and behavior in association with changing reinforcement contingencies, apparent as ruminative thoughts of self-reproach, pessimism, and guilt, and inertia toward initiating goal-directed behavior; (4) altered integration of sensory and social information, as evidenced by mood-congruent processing biases; (5) impaired attention and memory, shown as performance deficits on tests of attention set-shifting and maintenance, and autobiographical and short-term memory; and (6) visceral disturbances, including altered weight, appetite, sleep, and endocrine and autonomic function. This section describes an attractor-based theory of some of the brain mechanisms that are related to depression 13 , and tests of the theory 11 .…”

“…This approach to understanding depression has been investigated by large-scale neuroimaging studies of functional connectivity and brain activations in people with depression vs controls 11 .…”

A Neuroscience Levels of Explanation Approach to the Mind and the Brain

“…The relation between mental events and brain events ( Kim, 1998 , 2011 ) is also important in psychiatry ( Dijkstra and De Bruin, 2016 ). For example, we may find that functional connectivities between some brain areas are different in schizophrenia and depression, and are correlated with the symptoms ( Rolls et al, 2020 ; Rolls, 2021a ). Moreover, in some brain areas, the neural (fMRI BOLD signal) activations to a set of stimuli are directly correlated with their subjective pleasantness ( Grabenhorst and Rolls, 2011 ; Rolls, 2018a , 2019 , 2021b ), and these reward systems appear to operate abnormally in depression ( Rolls et al, 2020 ).…”

“…For example, we may find that functional connectivities between some brain areas are different in schizophrenia and depression, and are correlated with the symptoms ( Rolls et al, 2020 ; Rolls, 2021a ). Moreover, in some brain areas, the neural (fMRI BOLD signal) activations to a set of stimuli are directly correlated with their subjective pleasantness ( Grabenhorst and Rolls, 2011 ; Rolls, 2018a , 2019 , 2021b ), and these reward systems appear to operate abnormally in depression ( Rolls et al, 2020 ). Another example of the relation between the brain and the mind is that damage to the orbitofrontal cortex impairs emotional behavior ( Bechara et al, 2000 ; Fellows, 2011 ; Rolls, 2019 ; Rolls et al, 2020 ) and subjective emotional experience ( Hornak et al, 2003 ).…”