On-line attentional selection from competing stimuli in opposite visual fields: effects on human visual cortex and...

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• Attentional selection is crucial for processing visual information.
• Competition between stimuli can occur even when they are in opposite visual hemifields.

Purpose of the Study:

• To investigate competition and attentional selection between targets and distractors in opposite visual hemifields using fMRI.
• To understand the neural mechanisms underlying the suppression of visual representations and the resolution of competition.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Participants viewed unilateral and bilateral visual displays with targets and distractors.
• Stimuli included high-contrast square-wave gratings of different orientations.

Main Results:

• Greater activation in the target-contralateral superior occipital gyrus for unilateral vs. bilateral displays, indicating target suppression.
• Increased activation in frontal and parietal regions, particularly the intraparietal sulcus (IPS), for bilateral displays.
• IPS showed enhanced functional coupling with occipital cortex during selection and repetition-suppression effects.

Conclusions:

• Competition between stimuli in opposite hemifields influences occipital cortex activity.
• The IPS plays a key role in resolving visual competition through attentional selection.