Thu, 21 Aug 2008 13:58:33 BST CiteULike: nelmor's Koulakov http://www.citeulike.org/user/nelmor/author/Koulakov CiteULike.org en-gb Copyright © 2004-2008 citeulike.org http://www.citeulike.org/user/nelmor/article/2152801 <i>J Neurophysiol, Vol. 98, No. 6. (1 December 2007), pp. 3134-3142.</i><br /><br />We present a model for olfactory coding based on spatial representation of glomerular responses. In this model distinct odorants activate specific subsets of glomeruli, dependent on the odorant's chemical identity and concentration. The glomerular response specificities are understood statistically, based on experimentally measured distributions of activation thresholds. A simple version of the model, in which glomerular responses are binary (the all-or-nothing model), allows us to account quantitatively for the following results of human/rodent olfactory psychophysics: 1) just noticeable differences in the perceived concentration of a single odor (Weber ratios) are as low as dC/C [~=] 0.04; 2) the number of simultaneously perceived odors can be as high as 12; and 3) extensive lesions of the olfactory bulb do not lead to significant changes in detection or discrimination thresholds. We conclude that a combinatorial code based on a binary glomerular response is sufficient to account for several important features of the discrimination capacity of the mammalian olfactory system. 10.1152/jn.00560.2007 Olfactory Coding With All-or-Nothing Glomeruli Alexei Koulakov Alan Gelperin Dmitry Rinberg doi:10.1152/jn.00560.2007 J Neurophysiol, Vol. 98, No. 6. (1 December 2007), pp. 3134-3142. 2007-12-20T19:29:05-00:00 2007 J Neurophysiol 98 6 3134 3142 model olfactory olfactory-bulb http://www.citeulike.org/user/nelmor/article/815353 <i>Journal of neuroscience, Vol. 26, No. 34. (August 2006), pp. 8857-8865.</i><br /><br />Responses of mitral cells represent the results of the first stage of odor processing in the olfactory bulb. Most of our knowledge about mitral cell activity has been obtained from recordings in anesthetized animals. We compared odor-elicited changes in firing rate of mitral cells in awake behaving mice and in anesthetized mice. We show that odor-elicited changes in mitral cell firing rate were larger and more frequently observed in the anesthetized than in the awake condition. Only 27% of mitral cells that showed a response to odors in the anesthetized state were also odor responsive in the awake state. The amplitude of their response in the awake state was smaller, and some of the responses changed sign compared with their responses in the anesthetized state. The odor representation in the olfactory bulb is therefore sparser in awake behaving mice than in anesthetized preparations. A qualitative explanation of the mechanism responsible for this phenomenon is proposed. Sparse Odor Coding in Awake Behaving Mice Dmitry Rinberg Alex Koulakov Alan Gelperin Journal of neuroscience, Vol. 26, No. 34. (August 2006), pp. 8857-8865. 2006-08-24T09:07:19-00:00 2006 Journal of neuroscience 26 34 8857 8865 extracellular methods mice olfactory