Dopaminergic modulation of semantic priming in healthy volunteers.
BACKGROUND
Semantic priming is a function related to prefrontal cortical (PFC) networks and is lateralized. There is evidence that semantic priming underlies dopaminergic modulation. It is known that the D1-receptor is more abundant in prefrontal networks; however, until now there have been no studies investigating the selective modulation of semantic priming with dopamine agonists. Furthermore, D1 receptor dysfunction has been described in schizophrenia, and patients with formal thought disorder seem to have disturbed focusing of associations and increased indirect priming.


METHODS
With a subtraction design, we compared the influence of pergolide (D1/D2 agonist) with bromocriptine (D2 agonist) and placebo, in a randomized, double-blind, crossover design in 40 healthy male volunteers. Subjects performed a lateralized lexical decision task including direct and indirect related prime-target pairs (stimulus onset asynchrony = 750 msec).


RESULTS
Only on pergolide a decrease of the indirect priming in the left hemisphere presentations was found.


CONCLUSIONS
These findings point to a potential selective modulation of agonists with a D1 component on the focusing of semantic associations. The clinical relevance of this study is that it might help the development of therapeutic strategies for treating cognitive deficits in schizophrenia and Parkinson's disease, which are highly relevant to the functional outcome.
Roesch-Ely
Daniela
D
Psychiatry Hospital, University of Heidelberg, Heidelberg, Bad Homburg, Germany. daniela_roesch@med.uni-heidelberg.de
Weiland
Stephan
S
Scheffel
Hans
H
Schwaninger
Markus
M
Hundemer
Hans-Peter
HP
Kolter
Thomas
T
Weisbrod
Matthias
M
D000328:Adult; D003430:Cross-Sectional Studies; D003657:Decision Making / Q000187:drug effects / Q000502:physiology; D004298:Dopamine / Q000378:metabolism*; D018491:Dopamine Agonists / Q000494:pharmacology*; D004311:Double-Blind Method; D007839:Functional Laterality; D006801:Humans; D008297:Male; D009483:Neuropsychological Tests; D010153:Paired-Associate Learning / Q000187:drug effects* / Q000502:physiology; D010479:Pergolide / Q000494:pharmacology*; D010775:Photic Stimulation / Q000379:methods; D011930:Reaction Time / Q000187:drug effects / Q000502:physiology; D012660:Semantics; D013997:Time Factors; D014794:Visual Fields / Q000187:drug effects / Q000502:physiology
D018491:Dopamine Agonists; D010479:Pergolide; D004298:Dopamine