Objective: Our purpose is to examine the effect of D2/D3 agonists on semantic priming.
Background: Dopamine seems to restrict the semantic network in semantic priming. However, which dopamine receptor mediates this effect is unknown.
Methods: To better understand the receptors involved, 15 nondemented Parkinson disease patients performed a lexical decision task before and 1 hour after they received their first morning medication dose, 8 after D2 and D3 agonists pramipexole or ropinirole, and 7 after L-dopa. Semantic priming was measured for closely, distantly, and unrelated word pairs across a stimulus onset asynchrony of 700 ms.
Results: Closely related pairs were recognized significantly faster than unrelated and distantly related pairs before the drugs, as well as after D2/D3 agents. After L-dopa, closely related pairs remained faster than unrelated, but not faster than distantly related pairs.
Conclusions: This suggests that D1 receptors may mediate the dopaminergic modulation of semantic priming.