The procedural memory system is associated with basal-ganglia circuits in the frontal lobe and further investigation of this particular hypothesis could aid in the development of a clinical neurological picture of what the underlying causes of SLI are. Scientific studies of speech and language
Some of the earliest neuroscientific discoveries were related to the discovery that damage to certain areas of the brain related to impairments in language, such as the discovery of Wernickes area and Brocas area. Lesions in these parts of the brain impair language comprehension and language production, respectively. Paul Broca was the first to note that the left hemisphere of the brain appeared to be localized for language function, particularly for right handed patients. Modern neuroscientific research has verified this, though language may be lateralizaed to the right hemisphere in some right-handed individuals. Developmental verbal dyspraxia
In 1990, it was reported that the several generations of the KE family had developmental verbal dyspraxia and orofacial praxis that were inherited in a typical autosomal dominant pattern. Further analysis traced this inheritance pattern back to mutations in the FOXP2 genes. These studies have allowed scientists to begin to investigate how changes to one gene can alter human communication. FOXP2 is the first gene that has been identified that is specifically linked to speech and language production. Mutant alleles of the normal FOXP2 gene have been found to be the cause of severe speech impairments. Specific language impairment
Neuroimaging techniques, such as structural and functional MRI, found no significant differences between individuals with SLI and normal controls.
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