Scientific Understanding of Consciousness
Consciousness as an Emergent Property of Thalamocortical Activity

Pain and Pleasure Systems

Return to   —   Fear ---- Pleasure

Science 13 February 2009: Vol. 323. no. 5916, pp. 890 - 891

Pains and Pleasures of Social Life

Matthew D. Lieberman and Naomi I. Eisenberger

Department of Psychology, 1285 Franz Hall, University of California at Los Angeles, Los Angeles, CA 90095-1563, USA.

Neuroscientists have identified neural systems responsible for experiences of pain and pleasure.

The cortical pain network consists primarily of the dorsal anterior cingulate cortex (dACC), insula, and somatosensory cortex, with subcortical contributions from the periaqueductal gray and thalamus. Whereas the somatosensory cortex is associated with sensory aspects of cutaneous physical pain (e.g., its location on the body), the dACC is associated with the distressing aspect of pain.

The brain's reward circuitry consists of neural structures receiving the neurotransmitter dopamine from the ventral tegmental area, and responds to physically rewarding stimuli such as food, drugs, and sexual activity. The nucleus accumbens in ventral striatum plays a critical role in reward learning and pleasurable states, while the ventromedial prefrontal cortex and amygdala are also major dopaminergic targets that have been implicated in reward processes

 

Nucleus Accumbens — Pleasure Center of the Brain

The "pleasure center" of the brain was discovered in 1954 by James Olds and Peter Milner of McGill University, when they accidentally implanted an electrode into the nucleus accumbens of a rat and discovered that the rodent became very energized. (Shermer; Believing Brain, 118)

The pleasure effect has since been found in all mammals tested, including people who have undergone brain surgery and had their nucleus accumbens stimulated. The word they use to describe the effect was orgasm. (Shermer; Believing Brain, 118)

Behaviors experienced as rewarding and pleasurable depend on the release of dopamine from the ventral tegmental area (VTA) in the brainstem and its availability in the nucleus accumbens in the basal forebrain. (Damasio; Looking for Spinoza, 63)

The reward circuit includes the ventral tegmental area, the nucleus accumbens, the medial forebrain bundle, and the septum, as well as portions of the thalamus and hypothalamus. (Linden; Compass of Pleasure, 9)

When neurons in the ventral tegmental area (VTA) are active, spikes travel along axons to terminals in the nucleus accumbens, triggering the release of neurotransmitter dopamine. (Linden; Compass of Pleasure, 15)

Neurons of the VTA also send dopamine releasing axons to other brain regions, including the amygdala and the anterior cingulate cortex, which are emotional centers; the dorsal striatum, involved in some forms of habit learning; the hippocampus, involved in memory for facts and events; and the prefrontal cortex, a region that controls judgment and planning. (Linden; Compass of Pleasure, 16)

The intense, euphoric pleasure that comes with falling in love corresponds to strong activation of the dopaminergic pleasure circuit -- the VTA and its targets, like the caudate nucleus. The pattern of activation is similar to responses to cocaine or heroin. (Linden; Compass of Pleasure, 102)

 

Pain Neural Pathways

Pain neural pathways are shown in a diagram.

Link to — Pain Neural Pathways Diagram

 

Orbital Cortex in Rewards and Punishers

Orbital cortex may be especially involved in working memories about rewards and punishments. (LeDoux; Emotional Brain, 285)

Emotion and motivation are linked by the property that both involve rewards and punishers. (Rolls; Emotion Explained, 1)

 

Link to — More Discussion — Pleasure or Pain

Pain network consists of the dorsal anterior cingulate cortex (dACC), insula (Ins), somatosensory cortex (SSC), thalamus (Thal), and periaqueductal gray (PAG). This network is implicated in physical and social pain processes.

 

Reward or pleasure network consists of the ventral tegmental area (VTA), ventral striatum (VS), ventromedial prefrontal cortex (VMPFC), and the amygdala (Amyg). This network is implicated in physical and social rewards.

Science 13 February 2009: Vol. 323. no. 5916, pp. 890 – 891; Pains and Pleasures of Social Life; Matthew D. Lieberman and Naomi I. Eisenberger; Department of Psychology, 1285 Franz Hall, University of California at Los Angeles, Los Angeles, CA 90095-1563, USA