In research published in Neuron today, "Working Memory Enhances Cortical Representations via Spatially-Specific Coordination of Spike Times," Behrad Noudoost, MD, PhD, associate professor of ophthalmology and visual sciences, ferrets out the importance of working memory in neural coordination. The findings bring Noudoost, who specializes in cognitive neuroscience and visual processing, and his colleagues one step closer to explaining how working memory impairment—often seen in a variety of mental disorders—interferes with sensory processing.
Working Memory and Attention
To understand the neural coordination required for visual information processing, consider a student learning a math problem who must focus on a whiteboard. To accomplish this goal, a first layer of neurons gets the information. In coordination with other neurons in the first layer, they process and send to the next layer and the next layer until the information is fully processed.
If the student looks at the whiteboard, then at a friend, then back to the teacher, they are alternating their goals between different visual objects. Noudoost and his colleagues found these switches between goals generate oscillatory brain waves, which affect the coordinated activity of neurons in visual parts of the brain.
Via this change in coordinated responses of neurons, the brain is capable of selecting a visual object for better processing. In other words, when we keep a goal in our working memory, these oscillatory waves help our neurons coordinate better to further process visual items related to that goal.
"This is new information," said Noudoost. "We knew that when a person is trying to process information, that sensory signal is enhanced, but we didn’t know that the coordinated oscillating wave induced by what is held in working memory is behind the sensory enhancement."
Coordination is the Key for a Stronger Signal
Without coordination between neurons sending information from one stage of processing to the next, the signal gets weaker as it goes on and information gets lost.
"Imagine a group of people all saying the same sentence," explained Noudoost. "If each person is speaking at their own pace and timing, you won't hear more than a hum of the crowd. But if they all chant the same thing in unison, then this coordination makes the signal stronger, and you can clearly hear what they chant."
Patients with attention deficit hyperactivity disorder, schizophrenia, autism, and Parkinson’s disease, who usually suffer from working memory problems, might have different or missing oscillating/coordinating brain waves.
"We don’t know that answer yet, but this study shows us the direction for finding it," Noudoost said.
The study was funded by the National Institutes of Health, the National Science Foundation, and an unrestricted grant from Research to Prevent Blindness.