Transcranial Magnetic Stimulation Reveals Executive Control Dissociation in the Rostral Prefrontal Cortex

Area of Science:

• Cognitive Neuroscience
• Neuroscience
• Experimental Psychology

Background:

• The rostral prefrontal cortex (rPFC) is implicated in executive functions, but its specific roles remain unclear.
• Previous research highlights the rPFC's importance in complex cognitive tasks.
• Understanding the distinct functions within the rPFC is essential for cognitive neuroscience.

Purpose of the Study:

• To investigate the differential roles of the right rostrolateral PFC (RLPFC) and right rostromedial PFC (RMPFC) in executive functions.
• To examine the impact of disrupting RLPFC and RMPFC activity on task-switching performance.
• To elucidate the specific involvement of RLPFC and RMPFC in prospective memory (PM) and working memory (WM) tasks.

Main Methods:

• Utilized transcranial magnetic stimulation (TMS) with continuous theta burst stimulation (cTBS) to temporarily inhibit targeted brain regions.
• Applied cTBS over the right RLPFC, right RMPFC, and a control vertex site in 18 healthy volunteers.
• Assessed performance on a task-switching paradigm including spatial detection (SD), prospective memory (PM), and working memory (WM) tasks.

Main Results:

• cTBS over the RLPFC significantly increased switching costs in error rates when switching to the PM task.
• cTBS over the RMPFC significantly decreased switching costs in error rates when switching to the WM task.
• Performance differences were observed compared to the control vertex site, indicating region-specific effects.

Conclusions:

• The findings provide evidence for a differential role of the RLPFC and RMPFC in executive functions.
• The RLPFC is specifically involved in prospective memory tasks.
• The RMPFC plays a specific role in working memory tasks.