Repetitive Transcranial Direct Current Stimulation Induced Excitability Changes of Primary Visual Cortex and Visual...

Area of Science:

• Neuroscience
• Cognitive Science
• Neurostimulation

Background:

• Cortical excitability is a marker for motor learning.
• Transcranial direct current stimulation (tDCS) modulates cortical excitability non-invasively.
• The relationship between tDCS-induced excitability changes and visual perceptual learning is not well understood.

Purpose of the Study:

• To investigate the effect of tDCS on visual perceptual learning in healthy individuals.
• To measure changes in primary visual cortex (V1) excitability following tDCS.
• To explore the correlation between altered V1 excitability and visual learning outcomes.

Main Methods:

• A randomized, double-blind, sham-controlled study involving 30 healthy participants.
• Anodal, cathodal, or sham tDCS applied over V1 for four consecutive days.
• Participants performed a visual orientation-discrimination task (ODT) during stimulation; excitability assessed via phosphene thresholds (PTs) and paired-stimulation visual-evoked potentials (ps-VEP).

Main Results:

• Anodal tDCS significantly improved visual discrimination learning compared to sham (p < 0.003).
• Anodal tDCS increased cortical excitability, indicated by reduced PTs (p = 0.002) and increased ps-VEP ratios (p = 0.003).
• No significant effects on learning or excitability were observed with cathodal tDCS.

Conclusions:

• Anodal tDCS over V1 enhances visual perceptual learning and increases cortical excitability.
• tDCS is a promising non-invasive tool for modulating V1 excitability and improving visual perceptual learning.
• Further research can explore therapeutic applications of tDCS for visual processing disorders.