Inferring patterns of hemispheric specialization for individual subjects from laterality data: a two-task criterion

Area of Science:

• Neuroscience
• Cognitive Psychology
• Cerebral Lateralization

Background:

• Hemispheric specialization, the lateralization of cognitive functions to one brain hemisphere, is a fundamental aspect of brain organization.
• Individual differences in hemispheric specialization patterns exist, but reliable methods for their assessment are needed.

Purpose of the Study:

• To investigate whether the relative magnitude of asymmetry scores on visual half-field tasks for words and faces can differentiate between typical and atypical patterns of hemispheric specialization.
• To validate this method against established techniques like sodium amytal testing.

Main Methods:

• Sixty-three subjects (31 dextrals, 32 sinistrals) performed visual half-field tasks assessing word and face recognition.
• Asymmetry scores (Right Visual Field - Left Visual Field) were calculated for both tasks.
• Subjects were classified into 'Typical' or 'Atypical' groups based on the relative magnitude of their word versus face asymmetry scores.

Main Results:

• The proportion of subjects classified as typical or atypical using this method aligned with established estimates from sodium amytal testing.
• This consistency was observed in both right-handed (dextrals) and left-handed (sinistrals) individuals.

Conclusions:

• The relative magnitude of asymmetry scores on left and right hemisphere specialized tasks effectively indexes individual differences in hemispheric specialization patterns.
• This visual half-field task approach offers a non-invasive method for assessing individual variations in brain lateralization.