Distinct effects of trial-driven and task Set-related control in primary visual cortex

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Visual Perception

Background:

• Task sets configure cognitive processes for stimulus-driven responses.
• Visual attention to expected stimuli modulates neural responses in primary visual cortex (V1) retinotopically on a trial-by-trial basis.
• The retinotopic specificity of mechanisms maintaining task sets over extended periods remains unclear.

Purpose of the Study:

• To investigate whether task set maintenance mechanisms in V1 exhibit retinotopic specificity.
• To differentiate the retinotopic responses during various task components: cue-driven preparation, trial-driven processing, task initiation, and task maintenance.

Main Methods:

• Used BOLD fMRI to measure brain activity in V1 during an attention-demanding discrimination task.
• Examined responses in V1 portions specialized for different visual eccentricities.
• Tasks involved unimodal (auditory or visual) and selective intermodal (visual and auditory) attention.

Main Results:

• Retinotopic patterns of trial-driven and cue-driven activity varied with the attended stimulus.
• Retinotopic patterns of task-initiation and task-maintenance activity were stimulus-independent.
• Only trial-driven activity retinotopy was affected by inter-modal distraction; task performance correlated with task-specific modulations in both trial-driven and task-maintenance activity, which were in opposite directions.

Conclusions:

• Confirmed at least two distinct top-down control processes for V1.
• A trial-by-trial process modulates V1 activity retinotopically across eccentricity sectors.
• A longer-epoch process, for task maintenance, operates without retinotopic specificity across eccentricity sectors.