• Cerebrovascular Disease
• Extrapyramidal & Movement Disorders

• Cerebrovascular Disease
• Extrapyramidal & Movement Disorders
• Neurology

Steven C. Cramer MD, University of California, Irvine, California, USA, discussed the findings of a study on the effects of reward-based training on motor learning (originally to be presented by Leonardo G. Cohen, MD, National Institutes of Health, Bethesda, Maryland, USA) [Abe M et al. Curr Biol 2011]. “I think what Leo[nardo] has done has given us a completely new way of thinking about that subject in the context of stroke recovery,” said Dr. Cramer. “I'm not familiar with a study that used reward principles to modulate motor learning, particularly in the long term.”

The study used a tracking pinch force task to determine the effects of reward versus punishment in training. Right-handed healthy subjects were randomly assigned to a rewarded (n=13), punished (n=12), or neutral control (n=13) training group. Subjects were instructed to pinch a force transducer between the right thumb and index finger so that a red cursor remained within a blue target [Abe M et al. Curr Biol 2011]. The blue target moved in a pattern similar to a sine wave. Greater force moved the cursor up, and lesser force moved the cursor down.

Baseline measurements of task performance were taken for all subjects, followed by a training session (4 blocks of 20 trials) under different conditions. Subjects in the rewarded group were told they would earn money based on the amount of time they were on the target, while those in the punished group were told they would lose money for any time off the target. The neutral subjects were told they would receive $40 at the end of the training regardless of the time. Feedback was given after each trial. After training was completed, subjects were tested without the influence of reward or punishment immediately, and after 6 hours, 24 hours, and 30 days.

Mean error was similar across all 3 groups at baseline (p=0.86 for rewarded vs neutral; p=0.91 for rewarded vs punished) and when measured just after training (p=0.77 for rewarded vs neutral; p=0.23 for rewarded vs punished). The groups' performance began to diverge at subsequent time points. At 6 hours post training, the rewarded group performed significantly better than the other 2 groups (p<0.05)—an effect that persisted through 30 days (Figure 1).

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Figure 1.

Effect of Reward and Punishment on Motor Skill Retention After Training

Reproduced from Abe M et al. Reward Improves Long-Term Retention of a Motor Memory through Induction of Offline Memory Gain. Current Biology 2011;21(7):557–562. With permission from Elsevier.

Training people under a reward-based system led to substantial long-term retention of a newly acquired motor memory—an advantage that developed through stabilization of offline memory gains in subsequent days [Abe M et al. Curr Biol 2011]. Dr. Cramer said, “Day 30 is long-term learning, and it begins to sound relevant to our patients and the kind of plasticity we want to induce through whatever means possible.” According to the authors, training in rewarded conditions may be beneficial both in education and in the treatment of patients with neurocognitive disorders and brain injuries [Abe M et al. Curr Biol 2011].

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