Even while undertaking a simple task such as walking across a room, your brain has to integrate information from a variety of senses and then evaluate each for reliability — all in fractions of a second.
That you usually make the journey without incident is a tribute to the incredible computing power of the brain, according to a new study that finds that the brain employs a strategy to weigh each sensory cue in proportion to its reliability and react accordingly.
“This work shows that the brain accomplishes this task using an optimal strategy that is the best way to combine the signals and that it can all be traced to the level of single neurons in the visual cortex,” said Dora Angelaki, Ph.D., chair of neuroscience at Baylor College of Medicine in Houston, who conducted the study with colleagues from Washington University in St. Louis, Mo., and the University of Rochester in Rochester, N.Y.
In the study, Angelaki and her colleagues trained macaques to perform a task that involved determining the direction in which they were going (heading discrimination) based on what they saw on a screen (visual cues) and the motion of the platform on which they rested (vestibular cues). The cues varied in their reliability at random, but the animals were able to take that into account and accomplish their tasks.
At an even more basic level, the researchers were able to trace this ability to evaluate the reliability of the sensory cues to the responses of single multisensory neurons that combine their inputs to obtain an optimal response.
“This is a network property,” Angelaki said. “The most reliable cue makes the whole network of neurons respond more strongly.”
While she acknowledged this is basic research, she noted “it could apply to a spectrum of diseases that affect sensory processing and decision making. It could have major implications in diseases such as schizophrenia or autism.”
The paper is important for theoretical neuroscience as well as neuroscience in general, added Angelaki.
“We identified the neurons involved in their theoretical optimal behavior that has been previously demonstrated in human behavior,” she said. “At Baylor, I can collaborate with people who treat diseases in which there are sensory deficits. We can figure out what goes wrong with the cascade of events.”
“The brain essentially can break down a seemingly high-level behavioral task into a set of much simpler operations performed simultaneously by many neurons,” said Gregory C. DeAngelis, Ph.D., of the University of Rochester, a co-author on the paper.
Other researchers who took part in the study include neuroscientists Drs. Christopher R. Fetsch of Washington University and Alexandre Pouget of the University of Rochester.
Funding for the study, which was published in the online edition of Nature Neuroscience, came from the National Institutes of Health, the National Science Foundation, the Multidisciplinary University Research Initiative and the James McDonnell Foundation.
Source: Baylor College of Medicine