Largely garnered from studies in laboratory animals, the ventral pallidum (VP) is recognized as an integrator of sensory, emotional, and cognitive information with appropriate motoric responses. These functional complexities are reflected in behaviors associated with pain experiences, reward-motivated function, stress, social interaction and affiliation. With the increased resolution of modern-day human brain imaging technology, preclinical studies are being substantiated, and the role of the VP in the human emotional repertoire and psychiatric disorders is being clarified.
Several clinical reports point to VP involvement in disorders of motivation. For example, single-photon emission computed tomography of Parkinson's Disease (PD) patients with pathological gambling show enhanced resting state activity (regional cerebral blood flow) in the VP of these individuals compared with non-gambling PD patients (Cilia et al, 2008).
Functional magnetic resonance imaging can assess rapid responses of the brain to ‘unseen’ reward cues or cues that are recognized outside our awareness. Presentation of unseen cues for natural and drug-related rewards (Childress et al, 2008), or monetary rewards (Pessiglione et al, 2007), results in rapid activation of the VP before conscious recognition. These rapid responses also predict the positive affect responses to the same stimuli when presented in a visible manner, suggesting that the affective/motivational processes within and outside awareness are continuous and regulated by the VP (Childress et al, 2008).
Another behavior with high emotional valence is social affiliation, for example, pair bonding. Both the formation and the maintenance of pair bonding are associated with VP activation (assessed with structural magnetic resonance imaging and positron emission tomography) in non-human primates (Bales et al, 2007). It follows that a dysregulation of the VP and its limbic circuit may contribute to disorders of social bonding such as autism.
Positron emission tomography with receptor-selective radiotracers adds neurochemical assessments to studies on neuroanatomical substrates regulating emotional states. For example, increases in negative affect ratings by healthy human volunteers who are associated with sustained sadness (Zubieta et al, 2003) or sustained muscle pain (Zubieta et al, 2002) correlate with deactivation of μ-opioid receptors in the VP. By inference, these findings indicate that positive affect is regulated by activated μ-opioid receptors in the VP.
The imaging literature converges to indicate that VP transmission is involved in the emotional overlays of motivated behaviors. This interpretation is substantiated by preclinical studies on μ-opioid receptors in the VP, wherein these receptors are capable of inducing a profound and enduring plasticity (Mickiewicz et al, 2009). Future laboratory and clinical studies will aid in fully appreciating the role of the VP in emotional processing and motivated behaviors, and the psychiatric consequence of its dysregulation.
Bales KL, Mason WA, Catana C, Cherry SR, Mendoza SP (2007). Neural correlates of pair-bonding in a monogamous primate. Brain Res 1184: 245–253.
Childress AR, Ehrman RN, Wang Z, Li Y, Sciortino N, Hakun J et al (2008). Prelude to passion: limbic activation by ‘unseen’ drug and sexual cues. PLoS One 3: e1506.
Cilia R, Siri C, Marotta G, Isaias IU, De GD, Canesi M et al (2008). Functional abnormalities underlying pathological gambling in Parkinson disease. Arch Neurol 65: 1604–1611.
Mickiewicz AL, Dallimore JE, Napier TC (2009). The ventral pallidum is critically involved in the development and expression of morphine-induced sensitization. Neuropsychopharmacology 34: 874–886.
Pessiglione M, Schmidt L, Draganski B, Kalisch R, Lau H, Dolan RJ et al (2007). How the brain translates money into force: a neuroimaging study of subliminal motivation. Science 316: 904–906.
Zubieta JK, Ketter TA, Bueller JA, Xu Y, Kilbourn MR, Young EA et al (2003). Regulation of human affective responses by anterior cingulate and limbic mu-opioid neurotransmission. Arch Gen Psychiatry 60: 1145–1153.
Zubieta JK, Smith YR, Bueller JA, Xu Y, Kilbourn MR, Jewett DM et al (2002). mu-opioid receptor-mediated antinociceptive responses differ in men and women. J Neurosci 22: 5100–5107.
The authors declare no conflict of interest.
About this article
Cite this article
Napier, T., Mickiewicz, A. The role of the ventral pallidum in psychiatric disorders. Neuropsychopharmacol 35, 337 (2010). https://doi.org/10.1038/npp.2009.113
This article is cited by
Evaluation of brain structure abnormalities in children with autism spectrum disorder (ASD) using structural magnetic resonance imaging
The Egyptian Journal of Neurology, Psychiatry and Neurosurgery (2022)
Scientific Reports (2020)