Task-dependent changes in cortical color representation measured by the functional MRI technique

Area of Science:

• Neuroscience
• Visual Perception
• Cognitive Science

Background:

• Color perception involves both categorical and continuous aspects.
• Previous research suggests distinct visual cortex regions process these aspects: early areas (V1-3) for continuous perception (color appearance) and higher areas (hV4, VO) for categorical perception.
• Understanding how task demands influence these representations is crucial.

Purpose of the Study:

• To investigate how task manipulation affects cortical representations in visual areas using identical color stimuli.
• To compare brain activity patterns during color appearance judgments versus color categorization tasks.
• To identify specific visual regions where task-related changes in color representation are most prominent.

Main Methods:

• Utilized functional magnetic resonance imaging (fMRI) to measure brain activity.
• Employed identical color stimuli across different experimental conditions.
• Manipulated participant tasks to focus on either color appearance (continuous) or color categorization (categorical) perception.
• Compared brain activity patterns between a diverted attention condition and active task conditions.

Main Results:

• Cortical activity patterns in visual areas changed significantly when participants performed color evaluation tasks compared to a diverted attention state.
• Differences in cortical activity were less pronounced in early visual cortex (V1-3) during color appearance judgments than during the color category task.
• Higher-order visual areas, including V3, hV4, and VO1/2, showed significant changes in activity patterns during the color category task.
• The anterior ventral cortex exhibited more pronounced differences between color appearance and categorization tasks.
• Color representation in early visual cortex under diverted attention more closely resembled that during color appearance judgments.

Conclusions:

• Task demands significantly modulate color representation across the visual cortex.
• Early visual cortex representations are more stable across tasks related to continuous color perception, aligning with diverted attention states.
• Higher-order visual areas demonstrate greater plasticity, with representations shifting substantially based on whether participants engage in color categorization or appearance judgments.
• These findings highlight the dynamic nature of visual processing and the role of cognitive tasks in shaping neural representations of color.