Dysphasia accompanies destruction of various cortical speech areas. After several weeks to several months the patient relearns the use of language, though he may never regain his original verbal proficiency. Functional plasticity of the dominant hemisphere is such that the remaining ipsilateral normally functioning cortex devoted to speech is capable of carrying on during language processes in the comprehension and execution of speech. If there is extensive destruction of the dominant hemisphere in youth, the nondominant hemisphere assumes such functions. How well this transfer to the nondominant hemisphere occurs after complete destruction of the dominant hemisphere in adulthood remains unknown.
The various cortical speech areas and immediately subjacent subcortical areas may be excised in the dominant hemisphere and yet the remaining ipsilateral speech areas are active during those transactions which accompany speech and are sufficient for the comprehension and execution of speech. This means that, in addition to the traditional
ROBERTS HL. Functional Plasticity in Cortical Speech Areas and Integration of Speech. AMA Arch NeurPsych. 1958;79(3):275-283. doi:10.1001/archneurpsyc.1958.02340030039005