Gating of somatosensory input by human prefrontal cortex

Area of Science:

• Neuroscience
• Neurophysiology
• Somatosensory System Research

Background:

• The prefrontal cortex (PFCx) plays a crucial role in higher cognitive functions and exerts top-down control over sensory processing.
• Understanding the modulatory influence of the PFCx on somatosensory pathways is essential for comprehending sensory integration and perception.

Purpose of the Study:

• To investigate the impact of focal dorsolateral prefrontal cortex (PFCx) lesions on somatosensory evoked potentials (SEPs).
• To determine if PFCx damage alters the amplitude and latency of specific SEP components.
• To explore the role of PFCx in the inhibitory modulation of sensory information processing.

Main Methods:

• Somatosensory evoked potentials (SEPs) were elicited by median nerve stimulation.
• SEPs were recorded in healthy control subjects and in patients with unilateral focal lesions in the dorsolateral PFCx.
• Analysis focused on amplitude changes of specific SEP components (N19, P26, N28, P45, N67) recorded over different scalp locations.

Main Results:

• Unilateral PFCx lesions significantly increased the amplitude of the P26 component (postcentral areas 1 and 2).
• Enhanced amplitudes were also observed for N28, P45, and N67 SEP components over post-rolandic and frontal electrodes.
• The N19 component (postcentral area 3b) remained unaffected by PFCx lesions.

Conclusions:

• The dorsolateral prefrontal cortex (PFCx) exerts an inhibitory influence on somatosensory processing.
• PFCx damage leads to disinhibition and enhanced sensory processing, particularly affecting later SEP components.
• These modulatory effects are likely mediated by corticocortical connections between the PFCx and parietal sensory areas.