Navigation Links
Neural mapping paints a haphazard picture of odor receptors
Date:2/3/2009

CAMBRIDGE, Mass., Feb. 3, 2009 -- Despite the striking aromatic differences between coffee, peppermint, and pine, a new mapping of the nose's neural circuitry suggests a haphazard patchwork where the receptors for such disparate scents are as likely as not to be neighbors.

Inexplicably, this seemingly random arrangement is faithfully preserved across individuals and even species, with cells that process the same scent located in precisely the same location on the olfactory bulb, the brain's first processing station for odors.

The crazy-quilt map of odor-processing neurons on the front lines of the olfactory system is described by Harvard University neuroscientists in the February issue of the journal Nature Neuroscience.

"It had been thought that the layout of the olfactory bulb was variable from individual to individual, but followed a chemotopic order where cells handling similar odor responses are near each other," says Markus Meister, the Jeff C. Tarr Professor of Molecular and Cellular Biology in Harvard's Faculty of Arts and Sciences. "Here we show that the layout is actually very precise -- the same from animal to animal -- but doesn't appear to follow any chemotopic order whatsoever."

Working with mice and rats, Meister and colleague Venkatesh N. Murthy recorded neural responses to several hundred distinct odors, including anise, beer, cloves, coffee, ginger, lemon, orange, peppermint, pine, rose, and even fox pheromones. The neuroscientists found that across individuals and even across the two species, bundles of neurons from a given type of odor receptor -- known as glomeruli -- were found in almost exactly the same spot on the olfactory bulb, a sensory structure measuring some four to five millimeters across and located at the very front of the brain.

"Glomeruli from different receptors line the surface of the olfactory bulb like an array of close-packed marbles," says Murthy, professor of molecular and cellular biology at Harvard. "Across individuals the location of a given glomerulus varies by only one array position. Compared to the size of the map, this represents a remarkable developmental precision of one part in 1,000."

Meister and Murthy then analyzed whether nearby glomeruli detect similar odors, such as those with similar chemical structures. Neuroscientists have previously hypothesized axes of similarities along which odors might be classified.

"One might expect that nearby glomeruli should have similar odor sensitivities," Meister says, "but we were surprised to find this was not the case. The odor response spectra of two neighboring glomeruli were as dissimilar as those of distant glomeruli."

This seemingly haphazard layout of sensory properties stands in marked contrast to other brain maps, such as those governing vision, touch, and hearing. In these three cases, our brains represent the outside world using ordered maps -- such as when neighboring points in visual space activate neighboring points on the retina.

"That sort of arrangement makes sense, since most brain computation is local, relying on short connections between nearby cells," Murthy says. "This is necessary because the connections between neurons occupy most of the volume available to the brain, and long-distance connections require more of this volume."

Meister and Murthy suspect that the deliberate randomness in rodents' odor maps is likely also found in humans, which have only one-third as many receptors but are capable, in some extreme cases, of discerning tens of thousands of distinct smells.


'/>"/>

Contact: Steve Bradt
steve_bradt@harvard.edu
617-496-8070
Harvard University
Source:Eurekalert

Related biology news :

1. I feel your pain: Neural mechanisms of empathy
2. Obesity starts in the head? 6 newly discovered genes for obesity have a neural effect
3. Neural mechanisms of value bias in the human visual cortex
4. NeuralIQ Expands Global Leadership Team, Names Donnie Blanks CEO
5. Neural cell transplants may help those with Parkinsons disease
6. MIT aids creation of neural prosthetic devices
7. Neural stem cell study reveals mechanism that may play role in cancer
8. Studies offer guide as protein interaction mapping comes of age
9. New rainforest mapping technology gets huge support
10. Mapping a clan of mobile selfish genes
11. Chemical equator discovery will aid pollution mapping
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:3/30/2017)... -- The research team of The Hong Kong Polytechnic ... by adopting ground breaking 3D fingerprint minutiae recovery and matching technology, ... accuracy for use in identification, crime investigation, immigration control, security of ... ... A research team led by Dr ...
(Date:3/28/2017)... , March 28, 2017 ... Biometrics), Hardware (Camera, Monitors, Servers, Storage Devices), Software (Video ... and Region - Global Forecast to 2022", published by ... in 2016 and is projected to reach USD 75.64 ... 2017 and 2022. The base year considered for the ...
(Date:3/24/2017)... 2017 Research and Markets has announced the ... & Trends - Industry Forecast to 2025" report to their ... The Global ... CAGR of around 15.1% over the next decade to reach approximately ... the market estimates and forecasts for all the given segments on ...
Breaking Biology News(10 mins):
(Date:10/10/2017)... ... October 10, 2017 , ... For the second time ... US2020 STEM Mentoring Award. Representatives of the FirstHand program travelled to Washington, D.C. ... US2020. , US2020’s mission is to change the trajectory of STEM education in ...
(Date:10/10/2017)... ... October 10, 2017 , ... The ... prestigious awards honoring scientists who have made outstanding contributions to analytical ... during Pittcon 2018, the world’s leading conference and exposition for laboratory science, which ...
(Date:10/9/2017)... ... October 09, 2017 , ... ... the medical journal, Epilepsia, Brain Sentinel’s SPEAC® System which uses the surface ... detecting generalized tonic-clonic seizures (GTCS) using surface electromyography (sEMG). The prospective multicenter ...
(Date:10/6/2017)... ... October 06, 2017 , ... On ... and webinar on INSIGhT, the first-ever adaptive clinical trial for glioblastoma (GBM). The ... The event is free and open to the public, but registration is required. ...
Breaking Biology Technology: