Endogenous Attention Affects Decision-related Neural Activity but Not Afferent Visual Responses

Area of Science:

• Cognitive Neuroscience
• Visual Attention
• Electrophysiology

Background:

• Endogenous spatial attention improves behavioral responses and modulates neural activity, including electroencephalography (EEG) event-related potentials (ERPs).
• The impact of attention on early visual ERPs, like the C1 component, remains debated.
• The role of attention in the central parietal positivity (CPP), an ERP signature of evidence accumulation, is not fully understood.

Purpose of the Study:

• To investigate the effects of endogenous spatial attention on the C1 ERP component and the CPP.
• To determine if attention modulates early visual processing or later decision-making stages.
• To characterize attentional modulation of neural signals related to evidence accumulation.

Main Methods:

• A spatially cued contrast discrimination task was employed with checkerboard stimuli.
• Stimuli were designed for large C1 responses and varied in evidence strength to elicit CPP.
• EEG was recorded, and prestimulus alpha power and ERP components (C1, CPP) were analyzed.

Main Results:

• Prestimulus alpha power showed topographic shifts consistent with attentional deployment.
• No significant attention effect was observed on the C1 ERP component, despite robust C1 responses.
• The CPP exhibited an increased build-up rate on validly cued trials, indicating enhanced evidence accumulation.

Conclusions:

• Endogenous spatial attention does not appear to modulate the early C1 ERP component.
• Attention enhances behavioral performance by influencing the decision-making process, as reflected by the CPP.
• These findings suggest attentional benefits arise from mechanisms related to evidence accumulation rather than early sensory processing.