Broca's area and Wernicke’s area are linked together by a [[white matter]] fiber tract called the [[arcuate fasciculus]]. This [[axon]]al tract allows the [[neuron]]s betweenin these two brain regionsareas to work together to create vocal language. Further research indicates that, in approximatelyabout 98% of [[right-handed]] [[male]]s and 90-95% of right-handed [[female]]s, language and speech are subserved by the left hemisphere of the brain. AmongIn [[left-handed]] people, language is subserved fairly equally by the left, right, or both hemispheres.
There are several methods of determining hemisphere dominance in a living [[human]]. The [[Wada test]] involves introducing an [[anesthetic]] into one hemisphere of the brain through one of the two [[carotid artery | carotid arteries]]. Once one hemisphere is anesthetized, and a [[neuropsychology | neuropsychological]] exam is performed to determine dominance for such findingsfunctions as language production and comprehension, verbal memory, and visual memory. More modern, less invasive, and in some cases costlier techniques, such as [[functional magnetic resonance imaging]] and [[transcranial magnetic stimulation]] can also be used to determine dominance, but their use is controversial and still considered experimental at most centers.
