Source memory performance is modulated by transcranial direct current stimulation over the left posterior parietal...

Area of Science:

• Neuroscience
• Cognitive Psychology

Background:

• Episodic memory retrieval is a complex cognitive function.
• The precise neural mechanisms underlying episodic memory retrieval remain incompletely understood.
• The left posterior parietal cortex (LPPC) has been implicated in memory processes, but its causal role requires further investigation.

Purpose of the Study:

• To investigate the causal role of the left posterior parietal cortex (LPPC) in episodic memory retrieval using transcranial direct current stimulation (tDCS).
• To determine if modulating LPPC activity affects source memory accuracy and recognition performance.

Main Methods:

• Thirty-six participants underwent three experimental sessions involving source memory tests.
• Participants received either anodal or cathodal tDCS over the LPPC, sham stimulation over the LPPC, or stimulation over the right primary motor cortex (M1).
• Block-randomization ensured unbiased group assignment and stimulation order.

Main Results:

• Cathodal stimulation of the LPPC significantly decreased source memory accuracy compared to sham or M1 stimulation.
• Anodal stimulation of the LPPC did not produce significant effects on source memory accuracy.
• Neither anodal nor cathodal stimulation over the LPPC affected old/new recognition performance.

Conclusions:

• These findings provide causal evidence for the involvement of the LPPC in episodic memory retrieval, specifically in distinguishing the context of memories.
• The results suggest that inhibitory stimulation of the LPPC selectively impairs source memory, highlighting its functional role in memory retrieval processes.