Disconnecting force from money: effects of basal ganglia damage on incentive motivation.
Bilateral basal ganglia lesions have been reported to induce a particular form of apathy, termed auto-activation deficit (AAD), principally defined as a loss of self-driven behaviour that is reversible with external stimulation. We hypothesized that AAD reflects a dysfunction of incentive motivation, a process that translates an expected reward (or goal) into behavioural activation. To investigate this hypothesis, we designed a behavioural paradigm contrasting an instructed (externally driven) task, in which subjects have to produce different levels of force by squeezing a hand grip, to an incentive (self-driven) task, in which subjects can win, depending on their hand grip force, different amounts of money. Skin conductance was simultaneously measured to index affective evaluation of monetary incentives. Thirteen AAD patients with bilateral striato-pallidal lesions were compared to thirteen unmedicated patients with Parkinson's; disease (PD), which is characterized by striatal dopamine depletion and regularly associated with apathy. AAD patients did not differ from PD patients in terms of grip force response to external instructions or skin conductance response to monetary incentives. However, unlike PD patients, they failed to distinguish between monetary incentives in their grip force. We conclude that bilateral striato-pallidal damage specifically disconnects motor output from affective evaluation of potential rewards.
Schmidt
Liane
L
Laboratoire INSERM U610, Institut Fédératif de Recherches en Neurosciences, Université Pierre et Marie Curie (Paris 6), Site Pitié-Salpêtrière, F-75013 Paris, France.
d'Arc
Baudouin Forgeot
BF
Lafargue
Gilles
G
Galanaud
Damien
D
Czernecki
Virginie
V
Grabli
David
D
Schüpbach
Michael
M
Hartmann
Andreas
A
Lévy
Richard
R
Dubois
Bruno
B
Pessiglione
Mathias
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001479:Basal Ganglia / Q000503:physiopathology*; D001480:Basal Ganglia Diseases / Q000473:pathology / Q000503:physiopathology / Q000523:psychology*; D001931:Brain Mapping / Q000379:methods; D005260:Female; D005712:Galvanic Skin Response; D018737:Hand Strength; D006801:Humans; D008279:Magnetic Resonance Imaging / Q000379:methods; D008297:Male; D008875:Middle Aged; D009042:Motivation; D010300:Parkinson Disease / Q000473:pathology / Q000503:physiopathology / Q000523:psychology; D011596:Psychomotor Disorders / Q000209:etiology / Q000473:pathology / Q000503:physiopathology; D011597:Psychomotor Performance; D012201:Reward; D012720:Severity of Illness Index