laterality index
Quantitative measure expressing the degree of functional asymmetry between brain hemispheres, typically calculated from neuroimaging activation data.
Full Definition
The laterality index (LI) is a statistical measure used to quantify functional brain asymmetry, particularly for language and motor functions. It is calculated using activation data from neuroimaging studies, typically expressed as (L-R)/(L+R) where L and R represent activation strength in left and right hemispheres respectively. Values range from -1 (completely right-lateralized) to +1 (completely left-lateralized), with 0 indicating bilateral activation. The laterality index is crucial in clinical settings for determining language dominance before neurosurgical procedures and in research for studying hemispheric specialization. Different calculation methods and thresholds exist, making standardization important for comparative studies.
Usage
Usage note: Commonly abbreviated as LI; calculation methods should be specified in research contexts.
In Context
- "The patient's laterality index of 0.8 confirmed strong left hemisphere language dominance." — Presurgical fMRI report
- "Laterality indices were calculated for each subject using a bootstrap resampling approach." — Neuroimaging methodology paper