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Functional transformations of odor inputs in the mouse olfactory bulb.

Adam Y, Livneh Y, Miyamichi K, Groysman M, Luo L, Mizrahi A - Front Neural Circuits (2014)

Bottom Line: Mitral cells population activity was heterogeneous and only mildly correlated with the olfactory receptor neuron (ORN) inputs, supporting the view that discrete input maps undergo significant transformations at the output level of the OB.In contrast, both MCs and GL-INs showed diverse temporal response patterns, suggesting that GL-INs could contribute to the transformations MCs undergo at slow time scales.Our data suggest that sensory odor maps are transformed by TCs and MCs in different ways forming two distinct and parallel information streams.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Institute of Life Sciences, The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem Jerusalem, Israel.

ABSTRACT
Sensory inputs from the nasal epithelium to the olfactory bulb (OB) are organized as a discrete map in the glomerular layer (GL). This map is then modulated by distinct types of local neurons and transmitted to higher brain areas via mitral and tufted cells. Little is known about the functional organization of the circuits downstream of glomeruli. We used in vivo two-photon calcium imaging for large scale functional mapping of distinct neuronal populations in the mouse OB, at single cell resolution. Specifically, we imaged odor responses of mitral cells (MCs), tufted cells (TCs) and glomerular interneurons (GL-INs). Mitral cells population activity was heterogeneous and only mildly correlated with the olfactory receptor neuron (ORN) inputs, supporting the view that discrete input maps undergo significant transformations at the output level of the OB. In contrast, population activity profiles of TCs were dense, and highly correlated with the odor inputs in both space and time. Glomerular interneurons were also highly correlated with the ORN inputs, but showed higher activation thresholds suggesting that these neurons are driven by strongly activated glomeruli. Temporally, upon persistent odor exposure, TCs quickly adapted. In contrast, both MCs and GL-INs showed diverse temporal response patterns, suggesting that GL-INs could contribute to the transformations MCs undergo at slow time scales. Our data suggest that sensory odor maps are transformed by TCs and MCs in different ways forming two distinct and parallel information streams.

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Spatiotemporal response patterns of TCs, GL-INs and MCs. (A)—TCs, (B)—MCs and (C)—GL-INs. Top left—activation map from a single OB for a single odor (Butanal). Each cell is denoted by a dot, gray dots represent non-responsive cells, color-code represent the peak ΔF/F for 15 s stimulation with Butanal. Responses in each bulb were normalized to the highest response. Top right—example of the response traces for four cells (marked by a number on the map). Gray—single trials; black—mean response. Bottom—correlation of the response patterns of all pairs of cells responding to the same odor in each bulb (up to seven odors for a pair), plotted as a function of the distance between the cells (TCs, n = 19918 pairs from six OBs, GL-INs—16383 pairs from six OBs, MCs—3229 pairs from 10 OBs). Thick line—mean correlation binned every 100 µm. Black dots—correlation between all possible pairs of the cells from the examples in the top panels.
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Figure 9: Spatiotemporal response patterns of TCs, GL-INs and MCs. (A)—TCs, (B)—MCs and (C)—GL-INs. Top left—activation map from a single OB for a single odor (Butanal). Each cell is denoted by a dot, gray dots represent non-responsive cells, color-code represent the peak ΔF/F for 15 s stimulation with Butanal. Responses in each bulb were normalized to the highest response. Top right—example of the response traces for four cells (marked by a number on the map). Gray—single trials; black—mean response. Bottom—correlation of the response patterns of all pairs of cells responding to the same odor in each bulb (up to seven odors for a pair), plotted as a function of the distance between the cells (TCs, n = 19918 pairs from six OBs, GL-INs—16383 pairs from six OBs, MCs—3229 pairs from 10 OBs). Thick line—mean correlation binned every 100 µm. Black dots—correlation between all possible pairs of the cells from the examples in the top panels.

Mentions: Finally, we studied the combined spatial and temporal patterns of each population by calculating the similarities between the temporal response patterns of all cells responding to the same odor in each OB (Figure 9, top panels). Specifically, we calculated all pairwise correlations between the traces, and then plotted these values as a function of the distance between the cells. As expected, TCs at all distances responded similarly to the same odor reflecting their faithfulness to the stimulus in space and time (Figure 9A). In contrast, MC responses were heterogeneous at all distances, although along long odor presentation nearby cells had higher probability to respond similarly (average R = 0.62 ± 0.35 at 0–50 µm distance compared with R = 0.34 ± 0.44 at 500–550 µm distance, p < 0.0001, T-test, Figure 9B). Notably, GL-INs’ temporal patterns were heterogeneous at all distances even for nearby pairs. These heterogeneous patterns were also evident when calculated only between pairs of cells imaged simultaneously in the same imaging plane (data not shown) suggesting that nearby GL-INs (with high probability to be connected to the same glomerulus) can process the same odor with distinct temporal patterns.


Functional transformations of odor inputs in the mouse olfactory bulb.

Adam Y, Livneh Y, Miyamichi K, Groysman M, Luo L, Mizrahi A - Front Neural Circuits (2014)

Spatiotemporal response patterns of TCs, GL-INs and MCs. (A)—TCs, (B)—MCs and (C)—GL-INs. Top left—activation map from a single OB for a single odor (Butanal). Each cell is denoted by a dot, gray dots represent non-responsive cells, color-code represent the peak ΔF/F for 15 s stimulation with Butanal. Responses in each bulb were normalized to the highest response. Top right—example of the response traces for four cells (marked by a number on the map). Gray—single trials; black—mean response. Bottom—correlation of the response patterns of all pairs of cells responding to the same odor in each bulb (up to seven odors for a pair), plotted as a function of the distance between the cells (TCs, n = 19918 pairs from six OBs, GL-INs—16383 pairs from six OBs, MCs—3229 pairs from 10 OBs). Thick line—mean correlation binned every 100 µm. Black dots—correlation between all possible pairs of the cells from the examples in the top panels.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4219419&req=5

Figure 9: Spatiotemporal response patterns of TCs, GL-INs and MCs. (A)—TCs, (B)—MCs and (C)—GL-INs. Top left—activation map from a single OB for a single odor (Butanal). Each cell is denoted by a dot, gray dots represent non-responsive cells, color-code represent the peak ΔF/F for 15 s stimulation with Butanal. Responses in each bulb were normalized to the highest response. Top right—example of the response traces for four cells (marked by a number on the map). Gray—single trials; black—mean response. Bottom—correlation of the response patterns of all pairs of cells responding to the same odor in each bulb (up to seven odors for a pair), plotted as a function of the distance between the cells (TCs, n = 19918 pairs from six OBs, GL-INs—16383 pairs from six OBs, MCs—3229 pairs from 10 OBs). Thick line—mean correlation binned every 100 µm. Black dots—correlation between all possible pairs of the cells from the examples in the top panels.
Mentions: Finally, we studied the combined spatial and temporal patterns of each population by calculating the similarities between the temporal response patterns of all cells responding to the same odor in each OB (Figure 9, top panels). Specifically, we calculated all pairwise correlations between the traces, and then plotted these values as a function of the distance between the cells. As expected, TCs at all distances responded similarly to the same odor reflecting their faithfulness to the stimulus in space and time (Figure 9A). In contrast, MC responses were heterogeneous at all distances, although along long odor presentation nearby cells had higher probability to respond similarly (average R = 0.62 ± 0.35 at 0–50 µm distance compared with R = 0.34 ± 0.44 at 500–550 µm distance, p < 0.0001, T-test, Figure 9B). Notably, GL-INs’ temporal patterns were heterogeneous at all distances even for nearby pairs. These heterogeneous patterns were also evident when calculated only between pairs of cells imaged simultaneously in the same imaging plane (data not shown) suggesting that nearby GL-INs (with high probability to be connected to the same glomerulus) can process the same odor with distinct temporal patterns.

Bottom Line: Mitral cells population activity was heterogeneous and only mildly correlated with the olfactory receptor neuron (ORN) inputs, supporting the view that discrete input maps undergo significant transformations at the output level of the OB.In contrast, both MCs and GL-INs showed diverse temporal response patterns, suggesting that GL-INs could contribute to the transformations MCs undergo at slow time scales.Our data suggest that sensory odor maps are transformed by TCs and MCs in different ways forming two distinct and parallel information streams.

View Article: PubMed Central - PubMed

Affiliation: Department of Neurobiology, Institute of Life Sciences, The Edmond and Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem Jerusalem, Israel.

ABSTRACT
Sensory inputs from the nasal epithelium to the olfactory bulb (OB) are organized as a discrete map in the glomerular layer (GL). This map is then modulated by distinct types of local neurons and transmitted to higher brain areas via mitral and tufted cells. Little is known about the functional organization of the circuits downstream of glomeruli. We used in vivo two-photon calcium imaging for large scale functional mapping of distinct neuronal populations in the mouse OB, at single cell resolution. Specifically, we imaged odor responses of mitral cells (MCs), tufted cells (TCs) and glomerular interneurons (GL-INs). Mitral cells population activity was heterogeneous and only mildly correlated with the olfactory receptor neuron (ORN) inputs, supporting the view that discrete input maps undergo significant transformations at the output level of the OB. In contrast, population activity profiles of TCs were dense, and highly correlated with the odor inputs in both space and time. Glomerular interneurons were also highly correlated with the ORN inputs, but showed higher activation thresholds suggesting that these neurons are driven by strongly activated glomeruli. Temporally, upon persistent odor exposure, TCs quickly adapted. In contrast, both MCs and GL-INs showed diverse temporal response patterns, suggesting that GL-INs could contribute to the transformations MCs undergo at slow time scales. Our data suggest that sensory odor maps are transformed by TCs and MCs in different ways forming two distinct and parallel information streams.

Show MeSH
Related in: MedlinePlus