Cerebral laterality differences in handedness: a mental rotation study with NIRS

Area of Science:

• Neuroscience
• Cognitive Psychology
• Neuroimaging

Background:

• Spatial cognition is typically right-hemisphere dominant in right-handed individuals.
• Hemispheric laterality for spatial tasks in left-handers remains less understood.
• Understanding handedness differences in brain function is crucial for cognitive neuroscience.

Purpose of the Study:

• To investigate and compare cerebral hemispheric laterality for spatial cognition between right-handed and left-handed women.
• To determine if spatial task performance shows different patterns of brain activation based on handedness.

Main Methods:

• Utilized near-infrared spectroscopy (NIRS) to measure cerebral activations in frontal and parietal lobes.
• Compared brain activity during a mental rotation task in healthy right-handed and left-handed women.
• Calculated the right-hemispheric dominance index (RI) to quantify cerebral laterality.

Main Results:

• Right-handers demonstrated right-hemispheric dominance (RI>0) in both frontal and parietal lobes.
• Left-handers exhibited slight left-hemispheric dominance (RI<0) in both frontal and parietal lobes.
• Left-handers showed significantly greater activation in the left-superior parietal lobule compared to right-handers.

Conclusions:

• Spatial cognition exhibits distinct cerebral laterality patterns between left-handed and right-handed individuals.
• Left-handers may rely more on left-hemisphere regions, particularly the superior parietal lobule, for spatial tasks.
• These findings contribute to a nuanced understanding of brain organization and handedness.