Optogenetic suppression of the nucleus reuniens selectively impairs encoding during spatial working memory

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Behavioral Neuroscience

Background:

• The nucleus reuniens (Re) serves as a key anatomical bridge between the hippocampus (HPC) and medial prefrontal cortex (mPFC).
• Re is essential for HPC-mPFC oscillatory synchrony and its inhibition impairs spatial working memory (SWM).
• The precise role of the Re in the encoding, maintenance, and retrieval phases of SWM remains unclear.

Purpose of the Study:

• To investigate the specific role of the nucleus reuniens in the encoding, maintenance, and retrieval of spatial information during a SWM task.
• To determine which phase of the SWM task is most affected by Re activity modulation.

Main Methods:

• Rats were trained on a T-maze delayed-non-match-to-position (DNMP) task, a measure of SWM.
• Optogenetic techniques were used to inhibit the activity of the nucleus reuniens during different phases of the DNMP task.

Main Results:

• Optogenetic inhibition of the Re during the sample phase significantly reduced choice accuracy in the DNMP task.
• Re suppression during the delay or choice phases did not significantly affect task performance.
• These findings indicate a critical role for the Re during the initial encoding of spatial information.

Conclusions:

• The nucleus reuniens plays a crucial role in the encoding of spatial information necessary for successful spatial working memory.
• The Re's contribution to SWM is specific to the encoding phase, highlighting its importance in acquiring spatial data.