Lateralization of speech and language
Only published papers are included; for preprints, see Papers.
Last Updated: May 2024
Speech and language functions have long been argued to be lateralized to the left hemisphere (in most individuals). However, there has also been a lot of controversy related to these claims and the following questions remain unresolved:
→ Do different components of speech and language show different degrees of lateralization?
→ Are there any innate hemispheric biases for speech perception or articulation?
→ Is the language network bilateral in early childhood and only becomes lateralized later in life, or is language processing left-lateralized from the start?
→ Can speech/language processing be typical-like when it is lateralized to the right hemisphere, or are there always deficits associated with atypical lateralization?
→ Which developmental conditions are associated with atypically lateralized speech and/or language, and why?
→ Does the right hemisphere language network support recovery in aphasia?
The list goes on.
In this line of work, we are trying to shed some light on some of these questions.
The right-hemisphere language network
Language processing has long been known to recruit frontal and temporal areas in the left hemisphere, but also—to a lesser degree—the homotopic areas in the right hemisphere. This paper shows these hemispheric biases in a large sample of over 800 individuals who have all performed an extensively validated language localizer task.
Reduced language lateralization in autism
This paper uses individual subject fMRI analyses to examine the degree of language lateralization in individuals with autism spectrum disorders and finds that such individuals have less strongly left-lateralized language networks due to the greater engagement of the right hemisphere. Furthermore, the right hemisphere engagement appears to be maladaptive.
No cost to a right-lateralized language network, at least in cases of early brain damage
This paper examines language processing in an individual with early extensive damage to her left temporal lobe and shows that typical language processing, as measured with fMRI and behaviorally, can be supported by the right hemisphere language network.
