A fronto-parietal system for computing the egocentric spatial frame of reference in humans

Area of Science:

• Neuroscience
• Cognitive Neuroscience
• Neuroimaging

Background:

• Spatial orientation relies on body-centered coordinates, with the mid-sagittal plane being fundamental for left-right division.
• Understanding the neural basis of the mid-sagittal plane is key to comprehending egocentric spatial reference frames.

Purpose of the Study:

• To investigate the neural correlates of computing the subjective mid-sagittal plane using functional magnetic resonance imaging (fMRI).
• To determine the brain regions and hemispheric lateralization involved in establishing egocentric spatial reference frames.

Main Methods:

• Functional magnetic resonance imaging (fMRI) was employed with seven healthy subjects.
• Participants performed a task requiring detection of the subjective mid-sagittal plane crossing, contrasted with a control task involving movement direction changes.

Main Results:

• fMRI revealed increased neural signal in posterior parietal and lateral frontal premotor regions during the mid-sagittal plane computation task.
• Activation was more extensive in the right cerebral hemisphere, suggesting its dominant role.
• These findings align with neuropsychological and neurophysiological data from patients and monkeys.

Conclusions:

• A bilateral cortical network, predominantly right-hemisphere-based, is actively involved in computing the egocentric reference frame.
• This network, including posterior parietal and lateral frontal premotor areas, is essential for spatial orientation.
• The results support the role of the right hemisphere in maintaining spatial awareness and the mid-sagittal plane.