[June 24, 2010]
Brain Cells Rapidly Switch Activity for Different, Behaviorally Relevant Responses to Stimuli
At every moment, the brain is confronted with multiple stimuli that impact behavior. There are many potential responses to these stimuli, and the brain must choose those that are appropriate for the circumstance. This ability to coordinate, process, and use multiple information streams to select an optimal response is what is known as cognitive control. While the phenomenon has been widely studied, the neuronal mechanisms underlying this critical function are not well understood. SUNY Downstate Medical Center researchers have now demonstrated a key role for the hippocampus, the part of the brain involved in memory storage and navigation, in mediating cognitive control. The research, published this week in the online, open access journal PLoS Biology, comes from the Department of Physiology and Pharmacology and the Robert F. Furchgott Center for Neural and Behavioral Science at SUNY Downstate.
The paper’s corresponding author, Andre A. Fenton, PhD, explains, “Cognitive control describes a set of processes that are central to thinking. These processes enable analysis and processing of one stream of information from perceptions and memory without getting confused by other distinct streams of information. Although cognitive control is at the core of understanding how we think, how the electrical activity of neurons mediate cognitive control is unknown.” Dr. Fenton is associate professor of physiology and pharmacology at SUNY Downstate and visiting professor, Center for Neural Science, New York University.
The researchers investigated this issue by creating a circumstance where a rat had to process two competing streams of spatial information in order to avoid getting a mild shock. They showed that the hippocampus was crucial for this ability, and then revealed how hippocampal cells behaved while rats demonstrated cognitive control of the two information streams. In what amounts to a mind-reading exercise, they identified that neurons distributed throughout the hippocampus did not process both information streams simultaneously in parallel; instead, the information that was currently active "in the mind" appeared to toggle between the two streams. Subsets of the neural population formed cohesive subgroups of coactive cells for a short time before disbanding and emerging as a distinct group of coactive cells. These transiently-coupled neural subgroups coalesced, then disbanded and regrouped to toggle between processing one and then the other of the two streams of information. Typically the toggling happened every few seconds, but when the rat was close to getting shocked, the information in mind matched the information source that was more relevant for avoiding the shock.
Dr. Fenton continues, “In addition to revealing how a brain manages distinct streams of thought, the results are remarkable for a second reason. This dynamic grouping and regrouping of electrical brain activity was observed in the hippocampus, an area known for storing memories rather than the cognitive control of the information in memory. The clear participation of hippocampus in cognitive control helps make sense of the accumulating evidence that hippocampal abnormalities and failures of cognitive control are core but previously-unrecognized features of schizophrenia.”
SUNY Downstate Medical Center, founded in 1860, was the first medical school in the United States to bring teaching out of the lecture hall and to the patient’s bedside. A center of innovation and excellence in research and clinical service delivery, SUNY Downstate Medical Center comprises a College of Medicine, Colleges of Nursing and Health Related Professions, a School of Graduate Studies, a School of Public Health, University Hospital of Brooklyn, and an Advanced Biotechnology Park and Biotechnology Incubator.
SUNY Downstate ranks eighth nationally in the number of alumni who are on the faculty of American medical schools. More physicians practicing in New York City have graduated from SUNY Downstate than from any other medical school.