Reward sensitivity predicts dopaminergic response in spatial neglect.

Area of Science:

• Neuroscience
• Neurology
• Psychology

Background:

• Spatial neglect, a common deficit after stroke, can be influenced by motivation, particularly monetary reward.
• Dopaminergic agents have shown mixed results in treating neglect, lacking clear predictors for treatment response.
• Incentive motivation's effects are mediated by dopaminergic pathways, which are often compromised in stroke patients.

Purpose of the Study:

• To investigate the relationship between the modulatory effects of reward and dopaminergic drugs on spatial neglect.
• To test if dopaminergic stimulation interacts with incentive motivation in patients with neglect.

Main Methods:

• A single-dose, double-blind, crossover study comparing Co-careldopa and placebo.
• Utilized a modified visual cancellation task in patients with right hemisphere stroke-induced neglect.
• Categorized patients into reward responders and non-responders based on their performance.

Main Results:

• Monetary reward improved visual search performance in patients with neglect.
• Co-careldopa enhanced visual search only in the absence of reward.
• An interaction revealed that only reward non-responders benefited from Co-careldopa, while reward responders showed no drug effect.
• Intact dorsal striatum integrity correlated with responsiveness to incentive motivation.

Conclusions:

• Dopaminergic modulation of spatial neglect follows an inverted U-shaped dose-response curve.
• The effectiveness of dopaminergic drugs is dependent on the integrity of the brain's reward system.
• Behavioral responses to anticipated reward can predict dopaminergic treatment outcomes in neglect.