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Updated: May 11, 2026
Operant Procedures for Assessing Behavioral Flexibility in Rats
Published on: February 15, 2015
NMDA receptor antagonists distort visual grouping in rats performing a modified two-choice visual discrimination task
Katja Clarissa Ward1, Halima Zainab Khattak, Louise Richardson
1Neuronal Networks Group, School of Clinical and Experimental Medicine, University of Birmingham, Birmingham, B15 2TT, UK.
Rationale:
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.
Objectives:
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.
Insights
NMDA receptor antagonists impair visual perception in rats by increasing the signal needed for pattern discrimination. This new rodent model quantifies cognitive psychosis, aiding treatment development.
Area of Science:
- Neuroscience
- Psychopharmacology
- Visual Perception
Background:
- Pathological psychosis impairs visual perception, a condition mimicked by NMDA receptor antagonists.
- Current rodent models have limitations in assessing visual integration mechanisms.
Purpose of the Study:
- Develop a rodent task to distinguish effects on visual perception from nonspecific task performance effects.
- Investigate the impact of NMDA receptor antagonists on visual perception in rats.
Main Methods:
- Adapted Glass patterns for visual grouping assessment in rats using a two-choice visual discrimination task.
- Utilized a touchscreen apparatus and psychometric function fitting to quantify performance at varying pattern distortion levels.
Main Results:
- Low doses of ketamine and phencyclidine increased the signal quality required for pattern discrimination, indicating impaired visual perception.
- Higher doses impaired overall task performance, linked to stereotypic behavior and impulsivity.
Conclusions:
- The Glass pattern task effectively differentiates NMDA receptor antagonist effects on visual perception from motor/memory functions.
- The developed psychometric measure quantifies cognitive psychosis in rodents, applicable to human studies and therapeutic development.
