Medial prefrontal lesions impair performance in an operant delayed nonmatch to sample working memory task

Area of Science:

• Neuroscience
• Cognitive Science
• Behavioral Science

Background:

• Working memory is crucial for cognitive function and is often impaired in psychiatric disorders.
• The medial prefrontal cortex (mPFC) is implicated in working memory processes.
• Traditional maze tasks for studying mPFC in working memory are time-consuming and have high exploratory components.

Purpose of the Study:

• To investigate the role of the mPFC in working memory using a novel operant-based delayed nonmatch to sample (DNMS) task.
• To assess the mPFC's involvement in both the acquisition and performance phases of a working memory task with varying delays.

Main Methods:

• Excitotoxic lesions were created in the mPFC of mice.
• Mice were trained and tested on an operant DNMS working memory task.
• Performance was evaluated based on task acquisition and accuracy with introduced delays.

Main Results:

• Mice with mPFC lesions showed significant impairments in acquiring the DNMS task without delay.
• Lesioned mice also exhibited deficits in performing the task when delays were introduced.
• No differences were observed in trial length, reward collection, or lever-press latencies, ruling out motivation or mobility changes.

Conclusions:

• The operant DNMS task is dependent on the mPFC for working memory function.
• This task provides a more efficient method for studying mPFC-dependent working memory.
• The findings facilitate research into the physiology and circuit mechanisms of working memory.