Language in the nondominant right hemisphere

Area of Science:

• Neuroscience
• Neurolinguistics
• Neurosurgery

Background:

• Evaluating language function in the nondominant hemisphere is crucial for surgical planning.
• Intractable seizures often necessitate surgical intervention, requiring careful mapping of critical brain functions.

Purpose of the Study:

• To assess language capabilities in the right nondominant hemisphere during cortical stimulation.
• To investigate the relationship between right and left hemisphere language systems.

Main Methods:

• Three patients undergoing cortical resection for intractable seizures were tested.
• Linguistic tasks of increasing complexity (object naming, sentence completion, responsive naming) were administered during cortical stimulation.
• Wada's test was performed to compare hemispheric function.

Main Results:

• The highest error rate occurred during sentence completion, while the most complex task (responsive naming) yielded no errors.
• Wada's test did not impair function in the right nondominant hemisphere but did in the left dominant hemisphere.
• These results suggest a distinct right-hemisphere language system.

Conclusions:

• A right nondominant language system exists, anatomically and functionally connected to the left dominant system.
• This right-hemisphere system plays a passive role under normal conditions and is not essential for left-hemisphere language function.
• Understanding this dual-hemisphere language network is vital for neurosurgical procedures.