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Dot Test for Dopamine Loss

A pilot study by a multi-disciplinary team of investigators at Georgetown University suggests that a simple dot test could help doctors gauge the extent of dopamine loss in individuals with Parkinson’s disease. The test is a sequential learning task that does not require complex motor skills, which tend to decline in people with PD. Lead author Katherine R. Gamble works in the Cognitive Aging Laboratory, led by the study’s senior investigator, Darlene Howard, PhD, Davis Family Distinguished Professor in the department of psychology and member of the Georgetown Center for Brain Plasticity and Recovery. Their study is being presented at Neuroscience 2013, the annual meeting of the Society for Neuroscience.

In the Triplet Learning Task (TLT), participants see four open circles, see two red dots appear, and are asked to respond when they see a green dot appear. Unbeknownst to them, the location of the first red dot predicts the location of the green target. Participants learn implicitly where the green target will appear, and they become faster and more accurate in their responses. The TLT tests implicit learning, a type of learning that occurs without awareness or intent, which relies on the caudate nucleus, an area of the brain affected by loss of dopamine. Previous studies have shown that the caudate region in the brain underlies implicit learning. In the study, PD participants implicitly learned the dot pattern with training, but a loss of dopamine appears to negatively impact that learning compared to healthy older adults.

Georgetown University Medical Center. “Simple dot test may help gauge progression of dopamine loss in Parkinson’s disease.” ScienceDaily, 9 Nov. 2013. Web. 11 Nov. 2013.

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