Furudono, Y.; Cruz, G.; Lowe, G. (2013) Glomerular input patterns in
the mouse olfactory bulb evoked by retronasal odor stimuli.
Experiments by the CSHL team explain how these components of
the mouse olfactory bulb estimate the total activity across the bulb.
Published in Neuron, scientists at Cold Spring Harbor Laboratory (CSHL) report their discovery of a neural circuit in
the mouse olfactory bulb that explains how our mammalian cousins (and by extension, we) are able to adjust the gain on intense odors.
Two - photon microscopy image of a layer of
the mouse olfactory bulb (viewed head - on from the front) containing relay stations call glomeruli — places where bundles of axons and dendrites meet.
Neurons in
the mouse olfactory bulb fire in a relatively narrow range, up to a few hundred times per second.
Not exact matches
So if you look at whole brains, the
bulbs look like these tiny afterthoughts; if you look at a
mouse or a rat, the
olfactory bulb seems quite big.
The team was able to view the responses of tens of neurons at a time to signals arriving in the
olfactory bulb from the
mouse's odor detectors, called
olfactory sensory neurons, located in the nose.
The scientists focused on the production of new neurons in adult
mice, in particular those neurons that integrate into the
olfactory bulb, the brain region responsible for analyzing odors.
Lawrence Katz of the Duke University Medical Center and his colleagues discovered that once signals reach the accessory
olfactory bulb they are mapped out into distinct patterns of nerve cell activity that vary according to the traits that enable a
mouse to identify desirable mates, such as species and sex.
Now researchers report that by inserting ultra-fine electrodes into the brains of live
mice, they have identified which neural cells in the accessory
olfactory bulb fire when one
mouse checks out another's pheromonal fingerprint.
Normal
mice with p16 had fewer neural stem cells in one part of the brain and fewer new neurons in the
olfactory bulb, again demonstrating p16's ability to inhibit regeneration.
A cross-section of the
olfactory bulb of a
mouse is shown here; relatively youthful cells, born during the animal's adulthood, glow green.
Whereas 65 percent of new neurons in wild
mice ended up in the
olfactory bulb, little more than 9 percent of the mutants» neurons were able to complete the journey.
These are the questions guiding the work of Florin Albeanu, who is using the
olfactory bulb and
olfactory cortex of
mice as the subject of his current studies.