As seen previously, there are different parts of the cerebrum such as the motor cortex and the somatosensory cortex which are specialised in function. Alongside motor, sensory and specific cortex regions such as hearing and vision, there is also an area tasked with language comprehension and speech.
This is called Broca’s area and it works alongside the auditory processing area and the motor cortex to accomplish one potential sequence of speech: hearing, processing and speaking.
Underactivity of Broca’s area has been shown in people with a stutter. The hearing-processing-speaking loop can follow this pattern: auditory information is sensed by the auditory cortex and passed on to Wernicke’s area that processes it to create language comprehension in both written and spoken form; then, if a response is to be made, Broca’s area initiates the processing of what is to be communicated in language, before the motor cortex executes the signals linked to getting the relevant movement in speech i.e. the chest, neck, jaw, tongue and lips.
This creates sound speech. Since the motor cortex handles all other parts of the body, sign language expression would follow the same loop. Perhaps instead of the auditory cortex to Wernicke’s area connection, a visual cortex to Wernicke’s area connection would take place instead for the first part of language comprehension.