The initial visual performance modulates the effects of anodal transcranial direct current stimulation over the...

Area of Science:

• Neuroscience
• Ophthalmology
• Rehabilitation Science

Background:

• Transcranial direct current stimulation (tDCS) shows potential for modulating cortical excitability and improving visual function.
• Individual differences in baseline performance may explain the variability in tDCS modulation effects.
• Understanding these individual differences is crucial for optimizing tDCS efficacy.

Purpose of the Study:

• To investigate how initial performance influences contrast sensitivity function (CSF) after tDCS.
• To determine if baseline visual function affects the outcomes of tDCS applied to the occipital cortex.
• To explore personalized tDCS strategies based on individual visual capabilities.

Main Methods:

• Fifty healthy participants were divided into anodal, cathodal, and sham tDCS groups.
• Contrast sensitivity function (CSF) was measured before and after a 20-minute tDCS session.
• Electrodes were placed on the primary occipital cortex (Oz) and Cz at 1.5 mA intensity.

Main Results:

• At the group level, neither anodal nor cathodal tDCS significantly affected the area under the log CSF (AULCSF) or contrast sensitivity (CS) compared to sham.
• A negative correlation was observed between initial performance and AULCSF change following anodal tDCS.
• Individuals with poorer initial contrast sensitivity showed greater improvements after anodal tDCS.

Conclusions:

• Initial performance significantly modulates the effects of anodal tDCS over the occipital cortex on CSF.
• The primary occipital cortex (Oz) plays a critical role in visual function modulation by tDCS.
• These findings support the development of personalized tDCS protocols tailored to individual baseline performance for enhanced visual rehabilitation.