Wha is BOLD??

The brain is the largest consumer of oxygenated blood in the human body. When neural activity increases in certain areas of the brain, during talking or pondering a problem for example, perfusion of those areas are hence increased. This change in blood supply can be detected by fMRI or functional magnetic resonance imaging thanks to two phenomena:

• the different signals of oxyhemoglobin and deoxyhemoglobin,
• and the increased local perfusion.

With the BOLD (blood oxygen level dependent) technique it is possible to map a patient’s brain before a risky surgery so that important areas such as Broca’s or Wernicke’s can be spared.

Just recently, in a research paper published in Nature, scientists at The University of California at Berkeley claim to have figured out a way to predict the image that their subject is looking at.

Their experiement consisted of two phases. In the first phase the subjects were asked to view 1750 images and their brain activity was monitored with fMRI. This means that every 4 seconds a MRI scan was obtained. During the second phase the subjects were shown 120 novel images, and the software, based on previous experience, “guessed” what image the subjects were looking at.