Cortical Distance but Not Physical Distance Modulates Attentional Rhythms

Area of Science:

• Cognitive Neuroscience
• Visual Perception
• Neuroscience

Background:

• Attentional spotlight is known to be rhythmic, sampling objects discretely.
• The neural basis of these attentional rhythms is not well understood.
• Understanding attentional rhythms is key to understanding visual attention mechanisms.

Purpose of the Study:

• To investigate the neural site of attentional rhythms.
• To examine the effect of interhemispheric communication on attentional rhythms.
• To determine if cortical or physical distance modulates attentional rhythms.

Main Methods:

• Modulated cortical distances of visual stimuli (gratings) while keeping retinal distance constant.
• Utilized stimuli on different (cortically far) or same (cortically near) sides of the vertical meridian.
• Analyzed stimulus onset asynchrony (SOA) from 0.1s to 1.08s to detect rhythms below 50 Hz.

Main Results:

• Attentional rhythms (theta and alpha frequencies) were observed when stimuli were on opposite sides of the vertical meridian (cortically far).
• No attentional rhythms were detected when stimuli were on the same side of the vertical meridian (cortically near).
• Results indicate a significant modulation by cortical distance.

Conclusions:

• Attentional rhythms are influenced by the cortical processing distance between stimuli.
• The interhemispheric divide plays a critical role in the manifestation of attentional rhythms.
• Physical distance does not appear to be a determining factor for attentional rhythms.