The cerebellum specializes for language even in the absence of contralateral neocortical inputs

For decades, the cerebellum was believed to be primarily responsible for motor control. However, it is now understood that this structure contains regions that specialize in processing language. The mystery lies in how cerebellar language specialization develops during the early stages of life. The prevailing theory suggests that these specialized functions in the cerebellum rely heavily on the input provided by the neocortex in the opposite hemisphere, through established reciprocal connections.

To test this hypothesis, researchers conducted an experiment on a right-handed woman (referred to as EG) who suffered from the absence of most of her left temporal lobe, likely from birth. Due to this condition, her neocortical language network was primarily located in her right hemisphere. Through precision functional MRI scans, the study compared EG's cerebellar language network to that of 74 typically developing adults.

The findings revealed that EG's cerebellar language network exhibited a strong left-hemispheric bias, aligning with the atypical lateralization of language in her cerebral cortex. Despite this, the cerebellar regions in EG's right hemisphere still responded to language and contained language-selective areas, even though the neocortical left hemisphere lacked any language regions.

These observations challenge the notion that cerebellar specialization heavily depends on contralateral neocortical inputs, instead suggesting that there is some degree of independent organization within the cerebellum itself.