Single pulse electrical stimulation in white matter modulates iEEG visual responses in human early visual cortex

Area of Science:

• Neuroscience
• Biomedical Engineering

Background:

• Electrical stimulation is a growing method for modulating brain networks in clinical settings.
• The precise mechanisms by which single electrical pulses influence connected neuronal populations remain unclear, with possibilities including excitation, inhibition, or noise addition.

Purpose of the Study:

• To investigate how single electrical pulses modulate neuronal processing of visual stimuli.
• To differentiate the effects of electrical stimulation from visual processing in the brain.

Main Methods:

• Utilized intracranial EEG (iEEG) in two human subjects with clinically implanted electrodes.
• Delivered single electrical pulses to white matter tracts connected to visual cortex electrodes.
• Employed finite impulse response modeling to analyze broadband and evoked potential responses.

Main Results:

• Single pulses caused transient broadband increases followed by suppression, acting additively with visual responses.
• Prominent brain stimulation evoked potentials were observed.
• Visual evoked potentials were modulated, increasing in amplitude when stimulation preceded visual onset, suggesting enhanced input strength or synchrony.

Conclusions:

• Electrical stimulation in the visual system has dual effects: additive impacts on broadband power (potentially via noise) and amplification of synchronous visual inputs.
• Findings suggest that single pulses can enhance visual processing by increasing the strength or synchrony of neural inputs.