# Enhanced expression of activity‐regulated cytoskeleton‐associated protein in the medial prefrontal cortex is involved in working memory performance

## TL;DR

This study shows that increased levels of the protein Arc in the medial prefrontal cortex help rats perform better in working memory tasks.

## Contribution

The study demonstrates for the first time that mPFC Arc protein is involved in working memory performance in rats.

## Key findings

- Rats with higher mPFC Arc protein performed better in working memory tasks with a 10-second delay.
- Blocking Arc protein synthesis in the mPFC impaired working memory performance.
- Enhanced Arc expression in the mPFC correlates with successful working memory task execution.

## Abstract

Working memory (WM) is a cognitive function important for guiding the on‐going or upcoming behavior. A memory‐related protein Arc (activity‐regulated cytoskeleton‐associated protein) is implicated in long‐term memory consolidation. Recent evidence further suggests the involvement of hippocampal Arc in spatial WM. The medial prefrontal cortex (mPFC) is a key brain region mediating WM. However, the role of mPFC Arc in WM is still uncertain. To investigate whether mPFC Arc protein is involved in WM performance, delayed non‐match to sample (DNMS) T‐maze task was performed in rats with or without blocking new synthesis of mPFC Arc. In DNMS task, a 10‐s or 30‐s delay between the sample run and the choice run was given to evaluate WM performance. To block new Arc protein synthesis during the DNMS task, Arc antisense oligodeoxynucleotides (ODNs) were injected to the bilateral mPFC. The results show that, in rats without surgery for cannula implantation and subsequent intracerebral injection of ODNs, WM was functioning well during the DNMS task with a delay of 10 s but not 30 s, which was accompanied with a significantly increased level of mPFC Arc protein, indicating a possible link between enhanced Arc protein expression and the performance of WM. After preventing the enhancement of mPFC Arc protein expression with Arc antisense ODNs, rat's WM performance was impaired. These findings support enhanced mPFC Arc protein expression playing a role during WM performance.