Question: Why are deaf people's and hearing people's brains different?

Rebecca Dewey answered on 24 Jun 2015:

Our brains and bodies are our life story. So much of them is shaped by our environment and our experiences. When a person is born (or even before they are born) and the brain is developing, we grow a part of the brain called the auditory cortex. The function of the auditory cortex is to process sounds that we hear through our ears.

The brains of deaf people have no sound going into them, whereas the brains of hearing people do have sound coming in constantly from the ears, from a couple of months before you are born, until you die. This difference in the experience of the brains can cause all sorts of things to happen. First, the hearing person’s auditory cortex is continually stimulated by sounds, so it keeps good and strong. Also, the auditory cortex sometimes needs help from other parts of the brain to process certain sounds, such as when a sound comes from an object that we can see – the visual cortex will get involved to help us decode what the sounds mean, or if a sound is coming from a moving source – areas of the brain that process movement will get involved to help us figure out what’s going on. In deaf people, they won’t make any of those links between the auditory cortex and other areas of the brain.

On the flip side, the auditory cortex is a perfectly good area of braincells that just aren’t being used in a deaf person – so they might get recruited to help with a different task. Particularly as hearing is one of the senses, the auditory cortex contains *sensory* braincells. That makes it particularly suited to processing other *sensory* information, such as vision or touch. We think that in some deaf people, the auditory cortex does just that – it makes connections with the vision and touch areas and starts to help them out. This is exactly what I’m investigating right now!