Directional asymmetries in interhemispheric transmission time: evidence from visual evoked potentials

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neurophysiology

Background:

• Interhemispheric transfer time (IHTT) measures communication speed between brain hemispheres.
• Previous research suggests potential directional asymmetry in IHTT, but findings are varied.
• Visual evoked potentials (VEPs) are a key tool for measuring IHTT.

Purpose of the Study:

• To test the hypothesis of directional asymmetry in IHTT.
• To determine if IHTT is faster from the right-to-left hemisphere compared to left-to-right.
• To investigate this asymmetry using both meta-analysis and a novel experimental design.

Main Methods:

• Meta-analysis of 18 published experiments on VEP-based IHTT.
• A new experiment recording VEPs from parietal electrodes.
• Utilizing lateral visual field presentations with a complex stimulus recognition and choice response task.

Main Results:

• Meta-analysis revealed a significant predominance of faster right-to-left IHTTs across studies.
• The new experiment also found significantly faster right-to-left IHTT.
• Directional asymmetry was observed in VEPs during a complex cognitive task.

Conclusions:

• Interhemispheric transfer of visual information is directionally asymmetric.
• Transmission from the right hemisphere to the left hemisphere is consistently faster.
• This asymmetry is evident in VEP measures during demanding cognitive processing.