The results of the analysis, according to Niebur, suggested that when the monkeys were paying close attention to the stimuli, "the amount of synchronous firing appeared to increase in a sizable fraction of the neurons involved in these tasks."

Such a mechanism could have intriguing connections to basic nerve cell structure and function, Hsiao notes. Nerve cells frequently receive incoming signals from not just one but several different branch-like structures known as dendrites. Unless the signal is very strong, receiving a signal on any one dendrite doesn't necessarily guarantee that the nerve cell will pass on the message.

"If all the neurons upstream are firing synchronously, though, that strongly increases the possibility that the nerve cell will pass the message on downstream," says Hsiao, an associate professor of neuroscience. "We were lucky that these three groups could come together for this team effort," Hsiao comments. "The Mind-Brain Institute is one of a very few places in the U.S. where you could see such a unique and close collaboration between experimental, theoretical, and computational neuroscientists."

All 3 research groups plan to follow up on the finding in the future.

"I'd like to go back to an earlier stage in this process, and look for some type of oscillatory signal that we're thinking could proceed these synchronized nerve cell firings," Johnson, a professor of neuroscience, says.

Niebur and Hsiao expressed interest in finding out what happens to synchrony rates if the test subjects fail to successfully complete the task they're concentrating on. Steinmetz's current research includes an investigation how strongly the neurons need to synchron
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Contact: Michael Purdy
mcp@jhu.edu
410-516-7160
Johns Hopkins University
7-Mar-2000