scholarly journals Dopamine promotes instrumental motivation, but reduces reward-related vigour

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
John P Grogan ◽  
Timothy R Sandhu ◽  
Michele T Hu ◽  
Sanjay G Manohar

We can be motivated when reward depends on performance, or merely by the prospect of a guaranteed reward. Performance-dependent (contingent) reward is instrumental, relying on an internal action-outcome model, whereas motivation by guaranteed reward may minimise opportunity cost in reward-rich environments. Competing theories propose that each type of motivation should be dependent on dopaminergic activity. We contrasted these two types of motivation with a rewarded saccade task, in patients with Parkinson’s disease (PD). When PD patients were ON dopamine, they had greater response vigour (peak saccadic velocity residuals) for contingent rewards, whereas when PD patients were OFF medication, they had greater vigour for guaranteed rewards. These results support the view that reward expectation and contingency drive distinct motivational processes, and can be dissociated by manipulating dopaminergic activity. We posit that dopamine promotes goal-directed motivation, but dampens reward-driven vigour, contradictory to the prediction that increased tonic dopamine amplifies reward expectation.

Author(s):  
J.P. Grogan ◽  
T.R. Sandhu ◽  
M.T. Hu ◽  
S.G. Manohar

SummaryWe can be motivated when reward depends on performance, or merely by the prospect of a guaranteed reward. Performance-dependent (contingent) reward is instrumental, relying on an internal action-outcome model, whereas motivation by guaranteed reward may serve to minimise opportunity cost in reward-rich environments. Competing theories propose that each type of motivation should be dependent on dopaminergic activity. We contrasted these two types of motivation with a rewarded saccade task, in patients with Parkinson’s disease (PD). When PD patients were ON dopamine, they had greater response vigour (peak saccadic velocity) for contingent rewards, whereas when PD patients were OFF medication, they had greater vigour for guaranteed rewards. These results support the view that reward expectation and contingency drive distinct motivational processes, and can be dissociated by manipulating dopaminergic activity. We posit that dopamine is necessary for goal-directed motivation, but dampens reward-driven vigour, challenging the theory that tonic dopamine encodes reward expectation.


2015 ◽  
Vol 86 (11) ◽  
pp. e4.92-e4
Author(s):  
Kinan Muhammed ◽  
Sanjay Manohar ◽  
George Tofaris ◽  
Graham Lennox ◽  
Marko Bogdanovic ◽  
...  

Apathy is increasingly appreciated to be a major problem in Parkinson's disease (PD), with up to 70% of cases affected. The mechanisms underlying the condition are poorly understood and objective detection methods are lacking. We used eye movement and pupil modulation in response to rewards as metrics of motivation to assess the relation of reward sensitivity to apathy and influence of dopaminergic medication.30 patients with idiopathic PD, tested ON and OFF medication, and healthy age-matched participants made saccades for different monetary rewards. Saccadic peak velocity and pupil diameter were measured using an infrared eye-tracker, while apathy was indexed by Lille Apathy Rating Scale scores.PD patients ON demonstrated increased saccadic velocity and pupil diameter as reward magnitude increased, just like controls. This reward sensitivity was blunted in PD patients OFF dopaminergic medication. Crucially, apathetic PD patients exhibited significantly less pupillary reward sensitivity than more motivated PD cases.Saccadic velocity and pupil diameter are influenced by reward magnitude, with the degree of modulation varying with motivation levels across individuals. These indices provide novel, objective behavioural measures for assessing clinical apathy in PD. Dopaminergic medication may also be an effective treatment for apathy by increasing reward sensitivity, independent of effects on motor control.


1993 ◽  
Vol 5 (4) ◽  
pp. 83-87 ◽  
Author(s):  
A.F.G. Leentjens ◽  
W.W. Van Den Broek

SummaryIn this review article, based on a literature study, present ideas upon the relation between M. Parkinson and concomittant depression are dicussed. After a short introduction, it is demonstrated that epidemiological studies show that a common pathophysiological basis can be assumed. Briefly pheno-menological aspects are mentioned, whereafter the changes in the different neurotransmittersystems are discussed in greater detail. The ratio of dopaminergic and serotonergic activities in the basal ganglia constitute an important determinant for the severity of motor symptoms in Parkinson's disease. Reduced serotonergic metabolism may be a compensatory mechanism for the reduced dopaminergic activity. At the same time, a reduced serotonergic activity can predispose to a depression. Lower activities in parts of the dopaminergic, serotonergic and noradrenergic systems may each be responsible for part of the affective symptomatology in depressed Parkinson patients.


Author(s):  
Simo Nuuttila ◽  
Mikael Eklund ◽  
Juho Joutsa ◽  
Elina Jaakkola ◽  
Elina Mäkinen ◽  
...  

AbstractGlabellar tap or reflex (GR) is an old bedside clinical test used in the diagnostics of Parkinson’s disease (PD), but its diagnostic value is unclear. This study examines the diagnostic validity and reliability of GR in PD in relation to brain dopaminergic activity. GR was performed on 161 patients with PD, 47 patients with essential tremor (ET) and 40 healthy controls immediately prior to dopamine transporter (DAT) [123I]FP-CIT SPECT scanning. The binding ratios were investigated with consideration of the GR result (normal/abnormal). In addition, the consistency of the GR was investigated with 89 patients after a mean follow-up of 2.2 years. PD and ET patients had higher GR scores than healthy controls (p < 0.001), but there was no difference in GR between PD and ET patients (p = 0.09). There were no differences in the ratio of abnormal to normal GRs between the PD and ET groups (73% vs. 64% abnormal, respectively, p = 0.13) or in DAT binding between PD patients with abnormal and normal GRs (p > 0.36). Over follow-up, the GR changed from abnormal to normal in 20% of PD patients despite the presence of clinically typical disease. The sensitivity and specificity of GR for differentiating PD from ET were 78.3% and 36.2%, respectively. Although GR has been used by clinicians in the diagnostics of PD, it does not separate PD from ET. It also shows considerable inconsistency over time, and abnormal GR has no relationship with dopamine loss. Its usefulness should be tested for other clinical diagnostic purposes.


1999 ◽  
Vol 46 (3) ◽  
pp. 359-365 ◽  
Author(s):  
Joakim Tedroff ◽  
Anna Ekesbo ◽  
Erik Rydin ◽  
Bengt L�ngstr�m ◽  
Gisela Hagberg

2007 ◽  
Vol 25 (10) ◽  
pp. 3132-3136 ◽  
Author(s):  
Janneke Koerts ◽  
Klaus L. Leenders ◽  
Marthe Koning ◽  
Axel T. Portman ◽  
Marije Van Beilen

2018 ◽  
Vol 27 ◽  
pp. 17-20 ◽  
Author(s):  
Anshul Srivastava ◽  
Vinay Goyal ◽  
Sanjay Kumar Sood ◽  
Ratna Sharma

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