Ketamine-induced distractibility: An oculomotor study in monkeys.
BACKGROUND
Administration of subanesthetic doses of ketamine, a noncompetitive N-methyl-D-aspartate receptor antagonist, induces a spectrum of behavioral disorders that are commonly observed in patients with schizophrenia. Although it has been demonstrated that poor antisaccade performance is a core dysfunction in schizophrenia, the ability of ketamine to induce an increased distractibility has not been demonstrated. The present study aimed to determine whether ketamine administration would reproduce the same antisaccade deficit as that observed in schizophrenic subjects.


METHODS
We studied the effect of acute ketamine or saline administration on the performance of two monkeys trained on a reflexive visually guided saccade task and an antisaccade task.


RESULTS
The main result is that ketamine administration induced a markedly increased antisaccade error rate and increased antisaccade latency, similar to that seen in schizophrenic subjects. Other impairments consisted of increased reflexive saccade latency and the presence of a gaze-evoked nystagmus.


CONCLUSIONS
This study supports the validity of ketamine as a pharmacological model of schizophrenia. Based on the known pharmacological effects of ketamine, further studies should allow the investigation of the pharmacological basis of distractibility.
Condy
Carine
C
INSERM U289, Hôpital Pitié-Salpêtrière, Paris, France.
Wattiez
Nicolas
N
Rivaud-Péchoux
Sophie
S
Gaymard
Bertrand
B
D000818:Animals; D001288:Attention / Q000187:drug effects*; D001522:Behavior, Animal; D002522:Chlorocebus aethiops; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology*; D005403:Fixation, Ocular / Q000187:drug effects; D007839:Functional Laterality; D007649:Ketamine / Q000494:pharmacology*; D008297:Male; D009483:Neuropsychological Tests / Q000706:statistics & numerical data; D011930:Reaction Time / Q000187:drug effects; D012438:Saccades / Q000187:drug effects*; D013647:Task Performance and Analysis
D018691:Excitatory Amino Acid Antagonists; D007649:Ketamine