Subjects With Visual Impairment Use ‘Blindsight’ – They Turn Their Eyes Towards Motion, Brightness And Color
The visual information from eyes is sent into the brain unconsciously even if you are not aware. One example of unconscious seeing is a phenomenon called “blindsight” [Subjects have no awareness, but their brains can see] in subjects with visual impairment, caused by damage to a part of the brain called the visual cortex. Although it is already reported that the patients with damage in the visual cortex, who were not aware of seeing, can walk and avoid obstacles, it was not proved whether this was really blindsight. In this new study, the international collaborative research team including Assistant Professor Masatoshi YOSHIDA and Professor Tadashi ISA from The National Institute for Physiological Sciences, The National Institutes of Natural Sciences, Japan and Professor Laurent Itti from the University of Southern California demonstrated that blindsight in monkeys is available not only under the specific conditions of the laboratory, but also in everyday environments. This research result appeared in Current Biology as an electronic version.
The researchers previously showed blindsight in monkeys – monkeys with damage in the visual area of the brain are able to turn their eyes to ‘unseen’ visual stimuli. At this time, the research team examined whether blindsight occurs not only under the specific conditions of the laboratory, but also in everyday environments. They recorded eye movements of the blindsight monkeys freely watching video clips of everyday life scenes. They found that the monkeys were able to turn their eyes to the prominent portions in term of motion, brightness or color. By looking at eye movements of the monkeys with visual disability, we can understand where they pay attention, although they do not see.
Assistant Professor YOSHIDA said, “this new finding indicates that blindsight can be used in the everyday life of patients with hemianopia by cerebrovascular disorder. Then there is the possibility that patients with visual impairment can recover their hidden visual function by rehabilitation.” He also said “measurement of eye movements during viewing movie clips can be an efficient method to examine how well the patients can see unconsciously”.
This research was conducted by an international research team consisting of researchers from The National Institute for Physiological Sciences, The National Institutes of Natural Sciences (Japan), University of Southern California (USA) and Queen’s University (Canada). This research was supported by Human Frontier Science Program (International Scientific Collaborations; 2005-2008), Grant-in-Aid for Scientific Research (MEXT, Japan) and the Japan Society for the Promotion of Science (JSPS).
National Institute for Physiological Sciences