A non-spatial, stimulus-comparison working memory task in rats and disruption by scopolamine

Area of Science:

• Cognitive Neuroscience
• Animal Behavior
• Pharmacology

Background:

• Working memory is crucial for complex cognition, involving information maintenance and manipulation.
• Existing animal models often focus on spatial tasks, limiting understanding of non-spatial working memory.
• There is a need for tasks that assess the central executive component of working memory in animals.

Purpose of the Study:

• To introduce and validate a non-spatial stimulus-comparison task for evaluating working memory in rats.
• To investigate whether this task engages the central executive component of working memory.
• To examine the effects of a muscarinic antagonist on task performance.

Main Methods:

• Rats were trained on a non-spatial task requiring comparison of light and tone stimuli.
• Performance was assessed based on correct lever responses after a delay.
• The effects of scopolamine and N-methyl scopolamine on accuracy and bias were measured.

Main Results:

• Rats acquired the task rapidly (approx. 30 sessions) without response bias.
• Performance accuracy decreased with longer retention intervals.
• Scopolamine impaired accuracy and stimulus discriminability, but not response bias.

Conclusions:

• The non-spatial stimulus-comparison task effectively evaluates working memory in rats.
• The task may involve the central executive component of working memory.
• Cholinergic systems, specifically muscarinic receptors, play a role in this non-spatial working memory process.