Switching Senses

Previous brain imaging studies had shown that in blind people, visual brain areas are active during language-related tasks. However, it was not known whether this activity was actually necessary for language processing. Leonardo Cohen and colleagues asked blind and sighted subjects to respond to a noun with an appropriate matching verb as quickly as possible (e.g., say? eat? when they hear 'apple'). While the subjects were performing this simple task, the researchers used a technique called transcranial magnetic stimulation to disrupt brain activity in visual cortex. In sighted individuals, this manipulation had no effect. Blocking visual cortex activity in blind subjects, however, caused them to be less accurate in generating an appropriate verb. This was not due to an impairment in the ability to say words, but rather was due to an inability to think of the correct verb (a semantic error).

In the current study, all of the blind individuals had lost their sight early in life; it remains unclear whether a similar reorganization of the brain occurs in people who lose their sight at later ages.

Author contact:
Leonardo Cohen (NINDS, NIH, Bethesda, MD, USA)
Tel: +1 301 496 9782
E-mail: cohenl@ninds.nih.gov

Also available online.

(C) Nature Neuroscience press release.

Message posted by: Trevor M. D'Souza