title: NMDA receptor antagonists distort visual grouping in rats performing a modified two-choice visual discrimination task.
abstract: BACKGROUND
  Visual perception is impaired during pathological psychosis, which can be mimicked by NMDA receptor antagonists. However, the underlying mechanisms are poorly understood, partly due to limits of current rodent models for visual integration.
  
  
  OBJECTIVE
  The objectives of the study are (1) to develop a rodent task that can differentiate between effects on perception and nonspecific effects on task performance and (2) to test whether NMDA receptor antagonists affect visual perception in rats.
  
  
  METHODS
  We used an adaptation of Glass patterns to assess visual grouping in rats using a two-choice visual discrimination task in an infrared touch screen conditioning chamber. After rats learned to discriminate between a radial and a concentric bipole pattern, the ability to discriminate between these patterns was tested at various levels of distortion and a psychometric function was fit to obtain the maximum task performance and signal level needed for half-maximum performance.
  
  
  RESULTS
  NMDA receptor antagonists ketamine and phencyclidine at low doses increased the signal quality needed to discriminate between the visual patterns, without affecting the ability to discriminate between undistorted images. At higher doses, the ability to perform the task even with undistorted images was impaired, which was associated with stereotypic behaviour and increased impulsivity.
  
  
  CONCLUSIONS
  The Glass pattern-based visual grouping task is able to differentiate the effect of psychotomimetic NMDA receptor antagonists on visual perception from the effects on motor and memory functions. The half-maximum performance signal level allows quantification of cognitive psychosis in rodents, which can be translated to human psychometric functions and can be used in the development of more effective treatments.
authors: Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, B15 2TT, UK.
authors: Katja Clarissa
authors: KC
authors: Ward
authors: Halima Zainab
authors: HZ
authors: Khattak
authors: Louise
authors: L
authors: Richardson
authors: Jonathan Loon Choon
authors: JL
authors: Lee
authors: Martin
authors: M
authors: Vreugdenhil
mesh_terms: D000818:Animals; D002755:Choice Behavior / Q000187:drug effects; D004193:Discrimination Learning / Q000187:drug effects*; D004195:Disease Models, Animal; D004305:Dose-Response Relationship, Drug; D018691:Excitatory Amino Acid Antagonists / Q000008:administration & dosage / Q000494:pharmacology*; D007175:Impulsive Behavior / Q000139:chemically induced; D007649:Ketamine / Q000008:administration & dosage / Q000494:pharmacology; D008297:Male; D008568:Memory / Q000187:drug effects; D010622:Phencyclidine / Q000008:administration & dosage / Q000494:pharmacology; D011594:Psychometrics; D011618:Psychotic Disorders / Q000503:physiopathology; D051381:Rats; D016194:Receptors, N-Methyl-D-Aspartate / Q000037:antagonists & inhibitors*; D013239:Stereotyped Behavior / Q000187:drug effects; D014796:Visual Perception / Q000187:drug effects*
chemical_list: D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; D007649:Ketamine; D010622:Phencyclidine
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