title: Hemispheric dissociation of reward processing in humans: insights from deep brain stimulation.
abstract: Rewards have various effects on human behavior and multiple representations in the human brain. Behaviorally, rewards notably enhance response vigor in incentive motivation paradigms and bias subsequent choices in instrumental learning paradigms. Neurally, rewards affect activity in different fronto-striatal regions attached to different motor effectors, for instance in left and right hemispheres for the two hands. Here we address the question of whether manipulating reward-related brain activity has local or general effects, with respect to behavioral paradigms and motor effectors. Neuronal activity was manipulated in a single hemisphere using unilateral deep brain stimulation (DBS) in patients with Parkinson's disease. Results suggest that DBS amplifies the representation of reward magnitude within the targeted hemisphere, so as to affect the behavior of the contralateral hand specifically. These unilateral DBS effects on behavior include both boosting incentive motivation and biasing instrumental choices. Furthermore, using computational modeling we show that DBS effects on incentive motivation can predict DBS effects on instrumental learning (or vice versa). Thus, we demonstrate the feasibility of causally manipulating reward-related neuronal activity in humans, in a manner that is specific to a class of motor effectors but that generalizes to different computational processes. As these findings proved independent from therapeutic effects on parkinsonian motor symptoms, they might provide insight into DBS impact on non-motor disorders, such as apathy or hypomania.
authors: Motivation, Brain and Behavior (MBB) Team, Institut du Cerveau et de la Moelle Epinière (ICM), Hôpital de la Pitié-Salpêtrière, Paris, France; Inserm UMR 975, CNRS UMR 7225, Université Pierre et Marie Curie (UPMC - Paris 6), Hôpital de la Pitié-Salpêtrière, Paris, France.
authors: Stefano
authors: S
authors: Palminteri
authors: Giulia
authors: G
authors: Serra
authors: Anne
authors: A
authors: Buot
authors: Liane
authors: L
authors: Schmidt
authors: Marie-Laure
authors: ML
authors: Welter
authors: Mathias
authors: M
authors: Pessiglione
mesh_terms: D000978:Antiparkinson Agents / Q000008:administration & dosage / Q000627:therapeutic use; D003198:Computer Simulation; D003216:Conditioning, Operant / Q000502:physiology; D003463:Cues; D003627:Data Interpretation, Statistical; D046690:Deep Brain Stimulation; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D006801:Humans; D007858:Learning / Q000502:physiology; D007980:Levodopa / Q000008:administration & dosage / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D009042:Motivation; D010300:Parkinson Disease / Q000503:physiopathology / Q000523:psychology; D011597:Psychomotor Performance / Q000502:physiology; D012054:Reinforcement, Psychology; D012201:Reward; D014796:Visual Perception
chemical_list: D000978:Antiparkinson Agents; D007980:Levodopa
keywords: Deep brain stimulation; Hemispheric dissociation; Incentive motivation; Parkinson's disease; Reinforcement learning