Modulation of Visual Contrast Sensitivity with tRNS across the Visual System, Evidence from Stimulation and...

Area of Science:

• Neuroscience
• Visual Perception
• Non-invasive Brain Stimulation

Background:

• Transcranial random noise stimulation (tRNS) is known to enhance visual perception, particularly contrast detection.
• Previous research focused on tRNS over cortical areas, leaving the effects on different neural substrates in the retino-cortical pathway unexplored.

Purpose of the Study:

• To investigate if tRNS applied to the primary visual cortex (V1) and/or retina improves visual contrast detection.
• To determine the reproducibility and potential additive effects of tRNS on visual processing.

Main Methods:

• Visual contrast detection threshold (VCT) was measured during tRNS applied to V1 and/or retina.
• Individually optimized tRNS intensities (ind-tRNS) were determined and effects were retested within and across sessions.
• Simulations of the induced electric field were performed.

Main Results:

• Group-level tRNS significantly decreased VCT when applied to V1.
• Beneficial effects of ind-tRNS in V1 were reproducible within the same session but not in separate sessions.
• tRNS applied to the retina did not consistently reduce VCT, nor were additive effects observed for simultaneous V1 and retina stimulation.

Conclusions:

• tRNS significantly modulates visual contrast processing in V1.
• tRNS does not appear to enhance visual contrast detection when applied directly to the retina.
• The findings highlight V1 as a key target for tRNS-induced visual perception enhancement.