Brain Activity Underlying Mental Imagery: Event-related Potentials During Mental Image Generation

Area of Science:

• Cognitive Neuroscience
• Neuroscience
• Psychology

Background:

• Mental imagery research explores its neural underpinnings.
• Key questions involve modality specificity and hemispheric specialization.

Purpose of the Study:

• To investigate the neural bases of mental imagery.
• To determine if mental imagery involves modality-specific brain areas.
• To examine hemispheric specialization in mental image generation.

Main Methods:

• Comparison of event-related potentials (ERPs) during word reading versus mental imagery generation.
• Stimuli presented visually and auditorily.
• Control task: proofreading words for misspellings.

Main Results:

• Mental imagery elicited a slow, late positivity in ERPs, maximal in occipital and posterior temporal regions.
• This pattern suggests involvement of modality-specific visual cortex.
• An asymmetry in ERPs indicated left-hemisphere specialization for mental image generation.
• Imagery-related ERP changes differed from those of a proofreading task.

Conclusions:

• Mental imagery engages modality-specific visual cortex.
• The left hemisphere plays a specialized role in generating mental images.
• ERP findings are specific to mental imagery and not general cognitive effort.