When stroke or brain injury damages a part of the brain controlling movement or sensation or language, other parts of the brain can learn to compensate for this damage. It’s been thought that this is a case of one region taking over the lost function. Two new studies show us the story is not so simple, and help us understand the limits of this plasticity.
While brain laterality exists widely among animal species, the strong dominance of right-handedness in humans is something of an anomaly. As this implies a left-hemisphere dominance for motor function, it’s been suggested that the evolution of language (also mainly a function of the left hemisphere) may be behind the right-handed bias, leading to a search for a connection between hand preference and language disorders. To date, no convincing evidence has been found.
Many genes have been implicated in autism; one of them is the CNTNAP2 gene. This gene (which is also implicated in specific language disorder) is most active during brain development in the frontal lobe. An imaging study involving 32 children, half of whom had autism, has revealed that regardless of their diagnosis, the children carrying the risk variant showed communication problems within and with the frontal lobe. The frontal lobe was over-connected to itself and poorly connected to the rest of the brain, particularly the back of the brain.
Why do women tend to be better than men at recognizing faces? Two recent studies give a clue, and also explain inconsistencies in previous research, some of which has found that face recognition mainly happens in the right hemisphere part of the face fusiform area, and some that face recognition occurs bilaterally. One study found that, while men tended to process face recognition in the right hemisphere only, women tended to process the information in both hemispheres.