N-methyl-D-aspartate receptors and information processing: human choice reaction time under a subanaesthetic dose of ketamine.
Ketamine is an N-methyl-D-aspartate antagonist that induces cognitive dysfunctions. The purpose of the present study was to investigate the effects of a subanesthetic dose of ketamine on human information processing, using the additive factor method. During perfusion of a subanesthetic dose of ketamine (0.5 mg/kg over 60 min) or a placebo (randomized double-blind, cross-over design), eight adults (aged 22-33, mean=27) performed a two-choice visual reaction time (RT) task. Signal intensity, stimulus-response mapping, and foreperiod duration were manipulated. The effects of these three variables were found to be additive on RT, indicating that three independent stages - namely, stimulus preprocessing, response selection and motor selection- were manipulated. Ketamine altered RT performance in a specific way: it interacted with foreperiod duration but its effect was additive with those of signal intensity and stimulus-response mapping. These results show that ketamine specifically affects the stage of motor adjustment, which suggests that the glutamatergic system plays an important role in motor processes.
Guillermain
Y
Y
Centre de Recherches en Neurosciences Cognitives, Centre National de la Recherche Scientifique, 13402 Marseille Cedex 20, France.
Micallef
J
J
Possamaï
C
C
Blin
O
O
Hasbroucq
T
T
D000161:Acoustic Stimulation; D000328:Adult; D018592:Cross-Over Studies; D004311:Double-Blind Method; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005260:Female; D006801:Humans; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D008606:Mental Processes / Q000187:drug effects* / Q000502:physiology; D010775:Photic Stimulation; D011930:Reaction Time / Q000187:drug effects* / Q000502:physiology; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors* / Q000502:physiology
D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine