Direct cortical stimulation of human posteromedial cortex
Brett L Foster1, Josef Parvizi1
1From the Laboratory of Behavioral and Cognitive Neuroscience (B.L.F., J.P.), Stanford Human Intracranial Cognitive Electrophysiology Program, Stanford University, CA; and Departments of Neurosurgery and Neuroscience (B.L.F.), Baylor College of Medicine, Houston, TX. bfoster@bcm.edu parvizi@stanford.edu.
Neurology
|January 20, 2017
Summary
Direct brain stimulation of the posteromedial cortex (PMC) did not yield observable effects. Further research with advanced stimulation methods is needed to understand the PMC's role in cognition and consciousness.
Area of Science:
- Neuroscience
- Cognitive Neuroscience
- Brain Stimulation
Background:
- The posteromedial cortex (PMC) is a key region within the default mode network (DMN).
- The DMN is active during internally focused cognitive processes like autobiographical memory recall.
- The precise causal role of the PMC in human cognition remains incompletely understood.
Purpose of the Study:
- To investigate the causal role of the posteromedial cortex (PMC) in human cognition.
- To determine the effects of direct electric brain stimulation (EBS) on the PMC.
Main Methods:
- Utilized intracranial EEG electrodes during presurgical epilepsy monitoring.
- Performed 885 direct electric brain stimulation (EBS) trials across the PMC in 25 patients.
- Recorded behavioral and subjective responses to PMC stimulation.
Main Results:
- Stimulation of areas adjacent to the PMC caused predictable somatomotor or visual effects.
- Direct electric brain stimulation (EBS) within the PMC boundaries produced no observable behavioral or subjective effects.
- Null effects were consistent even at PMC sites showing electrophysiologic responses during autobiographical recall.
Conclusions:
- Standard functional mapping via direct electric brain stimulation (EBS) of the human PMC yielded null results.
- Advanced stimulation paradigms are necessary to elucidate the PMC's contribution to cognition.
- Current theories on the PMC and DMN's role in consciousness may require re-evaluation.
