Cold Spring Harbor, NY -- A team co-led by neuroscientists at Cold Spring Harbor Laboratory (CSHL) has shed light -- literally -- on circuitry underlying the olfactory system in mammals, giving us a new view of how that system may pull off some of its most amazing feats.
It has long been known from behavioral experiments that rodents, for instance, can tell the difference between two quite similar odors in a single sniff. But in such instances, what precisely happens in the "wiring" leading from sensory neurons in the nose to specialized cells in the olfactory bulb that gather the signals and transmit them to the brain? How can this occur within the brief span of a single respiratory cycle -- one inhalation and one exhalation?
Using a new method of exploring this question, CSHL scientists, in collaboration with researchers at Harvard University and the National Centre for Biological Science in Bangalore, India, have assembled evidence suggesting that the olfactory bulb in mice is not merely a relay station between the nose and brain, as many have supposed. Their data, published today in Nature Neuroscience, indicates that "there are many more information output channels leaving the olfactory bulb [en route to the cortex] than the number of information types entering it," from sensory receptors in the nose.
This complexity in sensory coding, which the team speculates may help the brain rapidly make highly accurate odor distinctions, became evident when the team used beams of light to activate highly specialized cells within the olfactory bulb, as prelude to measuring their electrical activity during single respiratory cycles.
Using beams of light to trace the circuit
The first step of the investigation involved using genetic engineering to generate a line of mice whose sensory neurons expressed a gene borrowed from a kind of algae that make them fire when beams of light are focused upon them.
|Contact: Peter Tarr|
Cold Spring Harbor Laboratory