One of the key implications from the findings for neuroscience, Moore said, is that the way gamma rhythms appear to structure the processing of perception is more important than the mere firing rate of neurons in the sensory neocortex. Mice became better able to feel not because neurons became more active (they didn't), but because they were entrained by a precisely timed rhythm.
Although the study provides causal evidence of a functional importance for gamma rhythms, Moore acknowledged, it still leaves open important questions. The exact mechanism by which gamma rhythms affect sensation processing and attention are not proved, only hypothesized.
And in one experiment, optogenetically stimulated mice appeared less able to detect the most obvious and imposing of the sensations, even as they became more sensitive to the more subtle ones. In other experiments, however, their detection of major sensations was not compromised.
But the possible loss of sensitivity to stimuli that are easier to feel could be consistent with a shifting of attention to fainter ones, said Pritchett, also a former Brown and MIT student now at the Champalimaud Centre for the Unknown in Lisbon, Portugal.
"What we are showing is that, paradoxically, the rhythmic inhibitory input works to amplify threshold stimuli, possibly at the expense of salient stimuli," he said. "This is precisely what you would expect from a mechanism that might be responsible for selective attention in the brain."
Therefore, Siegle, Pritchett, and Moore say they do have a better feel now for what's going on in the brain.
|Contact: David Orenstein|