Study Reveals Unique Brain Lateralization in Atypical Left-Handers

Approximately 10% of the population is left-handed, and a notable subset of these individuals display a phenomenon known as atypical language lateralization. Unlike the majority who process language predominantly in their left hemisphere, these atypical left-handers utilize their right hemisphere for speech. This distinctive brain organization has long intrigued neuroscientists, prompting investigations into how it influences cognitive functions and behavior.

Recent research conducted by the Neuropsychology and Functional Neuroimaging Group at Universitat Jaume I, led by César Ávila, provides new insights into this phenomenon. The study, published in eLife, demonstrates that for atypical left-handers, language functions mostly reside in the right hemisphere, while inhibitory control—an essential mechanism for regulating impulses—is primarily managed by the left hemisphere.

This research highlights that, in these individuals, the typical hemispheric specialization is reversed or altered. Notably, the inhibitory control, which is usually associated with the right hemisphere, shifts to the left in this group. The findings also suggest that these unique brain patterns extend beyond the cerebral cortex, involving subcortical circuits and increased connectivity between hemispheres via the corpus callosum, particularly with greater white matter volume.

While atypical lateralization correlates with some cognitive differences, the study did not find a direct link between brain organization and inhibitory performance efficiency. Moreover, atypical lateralization is associated with a higher prevalence of neurodevelopmental traits linked to conditions such as schizophrenia, dyslexia, and autism spectrum disorders. The study analyzed 86 participants—50 with typical left-hemisphere language dominance and 36 with right-hemisphere dominance—none of whom were right-handed. Interestingly, factors such as bilingualism or musical training did not significantly influence lateralization patterns.

The research team aims to further explore how these brain organization differences manifest in children and adolescents, potentially influencing learning and development. Understanding these variations could have significant implications for early diagnosis and intervention in neurodevelopmental disorders, as well as insights into brain plasticity, language processing, and cognitive rehabilitation, especially in populations with brain injuries or psychiatric conditions.

Source: https://medicalxpress.com/news/2025-06-atypical-left-handers-brain-hemisphere.html