title: Functional interaction of medial mediodorsal thalamic nucleus but not nucleus accumbens with amygdala and orbital prefrontal cortex is essential for adaptive response selection after reinforcer devaluation.
abstract: In nonhuman primates, reward-based decision making may be assessed through choices of objects overlying two different foods, one of which has been devalued by selective satiation. The most adaptive object choices yield the food of higher value. A large body of data identifies the amygdala and orbital prefrontal cortex (PFo) as neural mediators of adaptive responses to reinforcer devaluation. More recent work in nonhuman primates reveals the critical role of the medial, magnocellular portion of the mediodorsal nucleus of the thalamus (MDm) as well. Because both the nucleus accumbens (NA) and the MDm are anatomically related to the amygdala and PFo, and because both regions are implicated in reward processing, we tested whether either region necessarily interacts with the amygdala and PFo to mediate reinforcer devaluation effects. We used a crossed-disconnection design in which monkeys received amygdala and PFo lesions in one hemisphere combined with either NA or MDm lesions in the contralateral hemisphere. Monkeys that sustained NA disconnection, like controls, showed robust shifts in object choices in response to reinforcer devaluation. In contrast, monkeys that sustained MDm disconnection failed to adjust their object choices. Thus, MDm, but not NA, works together with the amygdala and PFo to support reward-based decision making.
authors.affiliation: Section on the Neurobiology of Learning and Memory, Laboratory of Neuropsychology, National Institute of Mental Health, Bethesda, Maryland 20892-4415, USA.
authors.forename: Alicia
authors.initials: A
authors.lastname: Izquierdo
authors.forename: Elisabeth A
authors.initials: EA
authors.lastname: Murray
mesh_terms: D000222:Adaptation, Physiological / Q000502:physiology*; D000679:Amygdala / Q000293:injuries / Q000502:physiology*; D000818:Animals; D001931:Brain Mapping; D003216:Conditioning, Operant; D004193:Discrimination Learning / Q000502:physiology; D005108:Extinction, Psychological / Q000502:physiology*; D007051:Ibotenic Acid / Q000633:toxicity; D008253:Macaca mulatta; D008279:Magnetic Resonance Imaging; D008297:Male; D020645:Mediodorsal Thalamic Nucleus / Q000293:injuries / Q000502:physiology*; D009434:Neural Pathways / Q000502:physiology; D009714:Nucleus Accumbens / Q000502:physiology; D010775:Photic Stimulation / Q000379:methods; D017397:Prefrontal Cortex / Q000293:injuries / Q000502:physiology*; D012054:Reinforcement, Psychology
chemical_list: D007051:Ibotenic Acid