Your Brain

Brain plasticity and lateralization

Lateralization of language to the left hemisphere is a process that begins very early in life. Wernicke’s area is visibly distinctive in the left hemisphere of the fetus by the twenty-sixth gestational week. The left hemisphere is specialized for language, and the right to music. A recent study videotaped the mouth of the baby (five until twelve months) found that      :

·         During smiling, the babies had greater opening of the left side of the mouth (the side controlled by the right hemisphere)

·         During babbling, the babies had greater opening of the right side (controlled by the left hemisphere).

Left hemisphere involvement at this very early stage of productive language development and there is also evidence of considerable plasticity. Under certain circumstances, the right hemisphere can take over many of language function. An impressive illustration of plasticity is provided by children who have undergone of procedure known as hemispherectomy, it is used to treat otherwise intractable cases of epilepsy. In cases of left hemispherectomy after language acquisition has begun, children experience an initial period of aphasia and then reacquire a linguistic system. UCLA professor Susan Curtiss and colleagues hypothesize that the latent linguistics ability of the right hemisphere is “freed” by the removal of the diseased left hemisphere.

In adult, however surgical removal of the left hemisphere inevitably results in severe loss of language function, whereas adults who had had their right hemispheres removed retain their language abilities. The plasticity of the brain decreases with age and with the increasing specialization of the different hemispheres and region of the brain. Some evidence suggests that the right hemisphere also plays a role in the earliest of language acquisition. Children with prenatal, perinatal, or childhood brain lessons in the right hemisphere can show delays and impairments in babbling and vocabulary learning, whereas children with early left hemisphere lessons demonstrate impairment in their ability to form phrases and sentences.