¹Department of Anatomy and Neurobiology, Washington University School of Medicine, St Louis, MO, USA

Correspondence: Dr G Stoet, Department of Anatomy and Neurobiology, Washington University School of Medicine, Campus Box 8108, 660 South Euclid Avenue, St Louis, MO 63110, USA. Tel: +1 314 747 4095; Fax: +1 314 747 4370; E-mail: stoet@pcg.wustl.edu

Received 15 March 2005; Revised 26 August 2005; Accepted 31 August 2005; Published online 5 October 2005.

Abstract

In humans, the effects of subanesthetic doses of ketamine, an N-methyl-D-aspartate (NMDA) receptor antagonist, substantially impair executive control functions. Here, we consider whether ketamine exposure can provide an animal model for the effects of ketamine on executive control. Two monkeys (Macaca mulatta) performed a cued task-switching paradigm. We studied their behavior before and after a range of ketamine doses. We found that ketamine slowed overall performance and decreased overall accuracy, strongly impaired the capacity to ignore task-irrelevant information and, to a lesser degree, decreased accuracy when a task switch was required. This pattern of results is very similar to that found in studies of schizophrenic patients performing task-switching paradigms or the Stroop task. We conclude that ketamine in monkeys provides a good animal model for exploring the relationship between the glutamate system, executive control, and the symptoms of schizophrenia.