Spatial stimulus configuration and attentional selection: extrastriate and superior parietal interactions

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Attention

Background:

• The intraparietal sulcus (IPS) is crucial for resolving stimulus competition.
• IPS activity varies with the spatial configuration of competing stimuli.
• IPS lesions impair selection, particularly with horizontally arranged stimuli.

Purpose of the Study:

• To determine if the influence of stimulus configuration on attention originates in early visual cortex or the IPS.
• To investigate the neural basis of attentional selection based on spatial arrangement.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was used to measure brain activity.
• Participants performed peripheral orientation discrimination or central letter detection tasks.
• Peripheral stimuli (gratings) and a central letter stream were presented in varying spatial configurations.

Main Results:

• Left IPS activity increased for horizontal versus vertical stimulus configurations, but only during peripheral attention tasks.
• Similar configuration effects were observed in extrastriate visual cortex.
• Connectivity between superior parietal cortex and extrastriate cortex strengthened with competing distracters during peripheral attention.

Conclusions:

• The spatial configuration effect on competing stimuli arises from the attentional priority map in the IPS.
• This effect is not solely based on sensory maps in early visual cortex.