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Habituation of glomerular responses in the olfactory bulb following prolonged odor stimulation reflects reduced peripheral input.

Ogg MC, Bendahamane M, Fletcher ML - Front Mol Neurosci (2015)

Bottom Line: Currently, it is unclear if this decrease is a function of adaptation of peripheral olfactory sensory neuron (OSN) responses or reflects depression of bulb circuits.To test whether depression of OSN terminals contributed to this habituation, olfactory nerve layer (ON) stimulation was used to drive glomerular layer responses in the absence of peripheral odor activation of the OSNs.The difference in response between odor and electrical stimulation following odor habituation provides evidence that odor response reductions measured in the glomerular layer of the OB are most likely the result of OSN adaptation processes taking place in the periphery.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA.

ABSTRACT
Following prolonged odor stimulation, output from olfactory bulb (OB) mitral/tufted (M/T) cells is decreased in response to subsequent olfactory stimulation. Currently, it is unclear if this decrease is a function of adaptation of peripheral olfactory sensory neuron (OSN) responses or reflects depression of bulb circuits. We used wide-field calcium imaging in anesthetized transgenic GCaMP2 mice to compare excitatory glomerular layer odor responses before and after a 30-s odor stimulation. Significant habituation of subsequent glomerular odor responses to both the same and structurally similar odorants was detected with our protocol. To test whether depression of OSN terminals contributed to this habituation, olfactory nerve layer (ON) stimulation was used to drive glomerular layer responses in the absence of peripheral odor activation of the OSNs. Following odor habituation, in contrast to odor-evoked glomerular responses, ON stimulation-evoked glomerular responses were not habituated. The difference in response between odor and electrical stimulation following odor habituation provides evidence that odor response reductions measured in the glomerular layer of the OB are most likely the result of OSN adaptation processes taking place in the periphery.

No MeSH data available.


Related in: MedlinePlus

Thirty seconds odor exposure uniformly decreases subsequent glomerular responses, regardless of initial intensity. (A) Responses of each glomerulus before and 1 min after the habituating odor exposure are plotted against each other. The dashed line has a slope of unity. The solid best-fit line is parallel to the line with a slope of unity, indicating that glomeruli maintain their relative odor responses following habituation. The downward shift of the line reflects the effect of habituation across glomeruli. (B) Psuedo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification before (Pre) and after (Post) the habituating odor exposure. (C) The glomerular responses shown in (B), normalized to the maximum glomerulus in each representation, illustrating that glomeruli maintain their relative odor responses following habituation, as discussed in (A).
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Figure 2: Thirty seconds odor exposure uniformly decreases subsequent glomerular responses, regardless of initial intensity. (A) Responses of each glomerulus before and 1 min after the habituating odor exposure are plotted against each other. The dashed line has a slope of unity. The solid best-fit line is parallel to the line with a slope of unity, indicating that glomeruli maintain their relative odor responses following habituation. The downward shift of the line reflects the effect of habituation across glomeruli. (B) Psuedo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification before (Pre) and after (Post) the habituating odor exposure. (C) The glomerular responses shown in (B), normalized to the maximum glomerulus in each representation, illustrating that glomeruli maintain their relative odor responses following habituation, as discussed in (A).

Mentions: To determine if there was an effect of response intensity on the amount of habituation, we compared the responses of each glomerulus before and 1 min after habituating odor exposure (Figures 2A,B). Linear regression analysis yielded a best-fit line with a slope (1.1 ± 0.1, not significant) showing that habituation has a uniform effect regardless of response intensity, and does not disproportionately decrease the response of either strongly or weakly responding glomeruli. The uniform reduction leaves relative glomerular response magnitudes of individual odor representations intact following prolonged odor stimulation. This effect is illustrated in Figure 2C, which highlights the similarity of pre- and post-habituation odor maps when they are normalized to the maximally responding glomerulus in each odor representation.


Habituation of glomerular responses in the olfactory bulb following prolonged odor stimulation reflects reduced peripheral input.

Ogg MC, Bendahamane M, Fletcher ML - Front Mol Neurosci (2015)

Thirty seconds odor exposure uniformly decreases subsequent glomerular responses, regardless of initial intensity. (A) Responses of each glomerulus before and 1 min after the habituating odor exposure are plotted against each other. The dashed line has a slope of unity. The solid best-fit line is parallel to the line with a slope of unity, indicating that glomeruli maintain their relative odor responses following habituation. The downward shift of the line reflects the effect of habituation across glomeruli. (B) Psuedo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification before (Pre) and after (Post) the habituating odor exposure. (C) The glomerular responses shown in (B), normalized to the maximum glomerulus in each representation, illustrating that glomeruli maintain their relative odor responses following habituation, as discussed in (A).
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4585128&req=5

Figure 2: Thirty seconds odor exposure uniformly decreases subsequent glomerular responses, regardless of initial intensity. (A) Responses of each glomerulus before and 1 min after the habituating odor exposure are plotted against each other. The dashed line has a slope of unity. The solid best-fit line is parallel to the line with a slope of unity, indicating that glomeruli maintain their relative odor responses following habituation. The downward shift of the line reflects the effect of habituation across glomeruli. (B) Psuedo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification before (Pre) and after (Post) the habituating odor exposure. (C) The glomerular responses shown in (B), normalized to the maximum glomerulus in each representation, illustrating that glomeruli maintain their relative odor responses following habituation, as discussed in (A).
Mentions: To determine if there was an effect of response intensity on the amount of habituation, we compared the responses of each glomerulus before and 1 min after habituating odor exposure (Figures 2A,B). Linear regression analysis yielded a best-fit line with a slope (1.1 ± 0.1, not significant) showing that habituation has a uniform effect regardless of response intensity, and does not disproportionately decrease the response of either strongly or weakly responding glomeruli. The uniform reduction leaves relative glomerular response magnitudes of individual odor representations intact following prolonged odor stimulation. This effect is illustrated in Figure 2C, which highlights the similarity of pre- and post-habituation odor maps when they are normalized to the maximally responding glomerulus in each odor representation.

Bottom Line: Currently, it is unclear if this decrease is a function of adaptation of peripheral olfactory sensory neuron (OSN) responses or reflects depression of bulb circuits.To test whether depression of OSN terminals contributed to this habituation, olfactory nerve layer (ON) stimulation was used to drive glomerular layer responses in the absence of peripheral odor activation of the OSNs.The difference in response between odor and electrical stimulation following odor habituation provides evidence that odor response reductions measured in the glomerular layer of the OB are most likely the result of OSN adaptation processes taking place in the periphery.

View Article: PubMed Central - PubMed

Affiliation: Department of Anatomy and Neurobiology, University of Tennessee Health Science Center Memphis, TN, USA.

ABSTRACT
Following prolonged odor stimulation, output from olfactory bulb (OB) mitral/tufted (M/T) cells is decreased in response to subsequent olfactory stimulation. Currently, it is unclear if this decrease is a function of adaptation of peripheral olfactory sensory neuron (OSN) responses or reflects depression of bulb circuits. We used wide-field calcium imaging in anesthetized transgenic GCaMP2 mice to compare excitatory glomerular layer odor responses before and after a 30-s odor stimulation. Significant habituation of subsequent glomerular odor responses to both the same and structurally similar odorants was detected with our protocol. To test whether depression of OSN terminals contributed to this habituation, olfactory nerve layer (ON) stimulation was used to drive glomerular layer responses in the absence of peripheral odor activation of the OSNs. Following odor habituation, in contrast to odor-evoked glomerular responses, ON stimulation-evoked glomerular responses were not habituated. The difference in response between odor and electrical stimulation following odor habituation provides evidence that odor response reductions measured in the glomerular layer of the OB are most likely the result of OSN adaptation processes taking place in the periphery.

No MeSH data available.


Related in: MedlinePlus