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Understanding odor information segregation in the olfactory bulb by means of mitral and tufted cells.

Polese D, Martinelli E, Marco S, Di Natale C, Gutierrez-Galvez A - PLoS ONE (2014)

Bottom Line: This capacity to ignore concentration information does not preclude the olfactory system from estimating concentration itself.The results of the experiments were visualized using principal components analysis and analyzed with hierarchical clustering to unveil the structure of the high-dimensional output space.An important conclusion is also that the morphological difference between the principal neurons is not key to achieve odor information segregation.

View Article: PubMed Central - PubMed

Affiliation: Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, Roma, Italy.

ABSTRACT
Odor identification is one of the main tasks of the olfactory system. It is performed almost independently from the concentration of the odor providing a robust recognition. This capacity to ignore concentration information does not preclude the olfactory system from estimating concentration itself. Significant experimental evidence has indicated that the olfactory system is able to infer simultaneously odor identity and intensity. However, it is still unclear at what level or levels of the olfactory pathway this segregation of information occurs. In this work, we study whether this odor information segregation is performed at the input stage of the olfactory bulb: the glomerular layer. To this end, we built a detailed neural model of the glomerular layer based on its known anatomical connections and conducted two simulated odor experiments. In the first experiment, the model was exposed to an odor stimulus dataset composed of six different odorants, each one dosed at six different concentrations. In the second experiment, we conducted an odor morphing experiment where a sequence of binary mixtures going from one odor to another through intermediate mixtures was presented to the model. The results of the experiments were visualized using principal components analysis and analyzed with hierarchical clustering to unveil the structure of the high-dimensional output space. Additionally, Fisher's discriminant ratio and Pearson's correlation coefficient were used to quantify odor identity and odor concentration information respectively. Our results showed that the architecture of the glomerular layer was able to mediate the segregation of odor information obtaining output spiking sequences of the principal neurons, namely the mitral and external tufted cells, strongly correlated with odor identity and concentration, respectively. An important conclusion is also that the morphological difference between the principal neurons is not key to achieve odor information segregation.

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Hierarchical clustering of input patterns in the odor morphing experiment.We performed hierarchical clustering based on k-means on a sequence of binary mixtures going from odor C to odor E through intermediate mixtures (morphing) along with the odor patterns of the 6 odors - 6 concentrations experiment. Clustering results are presented as a dendogram in terms of the distance to the k-means nearest cluster. Odors are identified by color, where high concentrations are plotted in a solid line and low concentrations are plotted in a dashed line.
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pone-0109716-g005: Hierarchical clustering of input patterns in the odor morphing experiment.We performed hierarchical clustering based on k-means on a sequence of binary mixtures going from odor C to odor E through intermediate mixtures (morphing) along with the odor patterns of the 6 odors - 6 concentrations experiment. Clustering results are presented as a dendogram in terms of the distance to the k-means nearest cluster. Odors are identified by color, where high concentrations are plotted in a solid line and low concentrations are plotted in a dashed line.

Mentions: We applied first the hierarchical clustering to the input odors. The results are shown as a dendogram in figure 5. We can see that there is no evident grouping of the odors in the input space. Odors at different concentrations do not group all together. High (solid line) and low (dashed line) concentrations of odors do not seem to cluster together either. So clearly odor identity and odor concentration information are mixed up at the input space.


Understanding odor information segregation in the olfactory bulb by means of mitral and tufted cells.

Polese D, Martinelli E, Marco S, Di Natale C, Gutierrez-Galvez A - PLoS ONE (2014)

Hierarchical clustering of input patterns in the odor morphing experiment.We performed hierarchical clustering based on k-means on a sequence of binary mixtures going from odor C to odor E through intermediate mixtures (morphing) along with the odor patterns of the 6 odors - 6 concentrations experiment. Clustering results are presented as a dendogram in terms of the distance to the k-means nearest cluster. Odors are identified by color, where high concentrations are plotted in a solid line and low concentrations are plotted in a dashed line.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4214673&req=5

pone-0109716-g005: Hierarchical clustering of input patterns in the odor morphing experiment.We performed hierarchical clustering based on k-means on a sequence of binary mixtures going from odor C to odor E through intermediate mixtures (morphing) along with the odor patterns of the 6 odors - 6 concentrations experiment. Clustering results are presented as a dendogram in terms of the distance to the k-means nearest cluster. Odors are identified by color, where high concentrations are plotted in a solid line and low concentrations are plotted in a dashed line.
Mentions: We applied first the hierarchical clustering to the input odors. The results are shown as a dendogram in figure 5. We can see that there is no evident grouping of the odors in the input space. Odors at different concentrations do not group all together. High (solid line) and low (dashed line) concentrations of odors do not seem to cluster together either. So clearly odor identity and odor concentration information are mixed up at the input space.

Bottom Line: This capacity to ignore concentration information does not preclude the olfactory system from estimating concentration itself.The results of the experiments were visualized using principal components analysis and analyzed with hierarchical clustering to unveil the structure of the high-dimensional output space.An important conclusion is also that the morphological difference between the principal neurons is not key to achieve odor information segregation.

View Article: PubMed Central - PubMed

Affiliation: Istituto per la Microelettronica e Microsistemi, Consiglio Nazionale delle Ricerche, Roma, Italy.

ABSTRACT
Odor identification is one of the main tasks of the olfactory system. It is performed almost independently from the concentration of the odor providing a robust recognition. This capacity to ignore concentration information does not preclude the olfactory system from estimating concentration itself. Significant experimental evidence has indicated that the olfactory system is able to infer simultaneously odor identity and intensity. However, it is still unclear at what level or levels of the olfactory pathway this segregation of information occurs. In this work, we study whether this odor information segregation is performed at the input stage of the olfactory bulb: the glomerular layer. To this end, we built a detailed neural model of the glomerular layer based on its known anatomical connections and conducted two simulated odor experiments. In the first experiment, the model was exposed to an odor stimulus dataset composed of six different odorants, each one dosed at six different concentrations. In the second experiment, we conducted an odor morphing experiment where a sequence of binary mixtures going from one odor to another through intermediate mixtures was presented to the model. The results of the experiments were visualized using principal components analysis and analyzed with hierarchical clustering to unveil the structure of the high-dimensional output space. Additionally, Fisher's discriminant ratio and Pearson's correlation coefficient were used to quantify odor identity and odor concentration information respectively. Our results showed that the architecture of the glomerular layer was able to mediate the segregation of odor information obtaining output spiking sequences of the principal neurons, namely the mitral and external tufted cells, strongly correlated with odor identity and concentration, respectively. An important conclusion is also that the morphological difference between the principal neurons is not key to achieve odor information segregation.

Show MeSH
Related in: MedlinePlus