A positron emission tomography study of visual and mental spatial exploration

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Understanding the neural basis of visual imagery is crucial for cognitive science.
• Distinguishing brain activity during perception versus imagination is an ongoing research challenge.

Purpose of the Study:

• To investigate the neural correlates of visual exploration versus mental exploration of a map.
• To identify brain regions involved in the generation and maintenance of visual mental images.

Main Methods:

• Normalized regional cerebral blood flow (NrCBF) was measured using positron emission tomography (PET) with oxygen-15-labeled water.
• Eight healthy young adults performed visual and mental map exploration tasks in darkness.
• NrCBF data were analyzed in conjunction with individual MRI scans to define regions of interest.

Main Results:

• Visual exploration activated bilateral visual processing areas (occipital, fusiform, lingual gyri) and parietal regions.
• Mental exploration, in contrast, activated the right superior occipital cortex, supplementary motor area, and cerebellar vermis.
• No activation was observed in the primary visual cortex during mental exploration.

Conclusions:

• The superior occipital cortex plays a specific role in the generation and maintenance of visual mental images.
• Distinct neural networks are engaged during visual perception and mental imagery.