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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 decreases subsequent glomerular responses to that odor for several minutes. (A) Pseudo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification. One minute after the habituating odor exposure (1 min Post), glomerular responses are decreased from their baseline (Pre). After 6 min, the responses have recovered (6 min Post). (B) GCamp2 fluorescence traces from the glomerulus indicated by arrows in (A). (C) The timeline of recovery from habituation. Mean normalized glomerular responses for all animals were reduced for several minutes post exposure. Error bars indicate SEM. *p < 0.05.
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Figure 1: Thirty seconds odor exposure decreases subsequent glomerular responses to that odor for several minutes. (A) Pseudo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification. One minute after the habituating odor exposure (1 min Post), glomerular responses are decreased from their baseline (Pre). After 6 min, the responses have recovered (6 min Post). (B) GCamp2 fluorescence traces from the glomerulus indicated by arrows in (A). (C) The timeline of recovery from habituation. Mean normalized glomerular responses for all animals were reduced for several minutes post exposure. Error bars indicate SEM. *p < 0.05.

Mentions: To determine how a 30-s odor exposure impacts subsequent glomerular responses to that odor, we measured glomerular responses to 1-s odor pulses before and after a single prolonged exposure in ten animals (Figure 1). Following the habituation trial, the mean normalized glomerular responses changed (ANOVA: F(5,395) = 37.03, p < 0.0001), and post hoc tests showed significant reduction from baseline responses 1 min (70.1 ± 2.1%, n = 95), 2 min (73.8 ± 3.3%, n = 61), and 4 min (85.2 ± 2.5%, n = 49) post exposure (Figure 1C). Mean responses at 6 min (94.5 ± 2.5%, n = 61) and 11 min (96.6 ± 2.7%, n = 40) post-habituation were not significantly different from the baseline, indicating that recovery had occurred by 6 min.


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 decreases subsequent glomerular responses to that odor for several minutes. (A) Pseudo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification. One minute after the habituating odor exposure (1 min Post), glomerular responses are decreased from their baseline (Pre). After 6 min, the responses have recovered (6 min Post). (B) GCamp2 fluorescence traces from the glomerulus indicated by arrows in (A). (C) The timeline of recovery from habituation. Mean normalized glomerular responses for all animals were reduced for several minutes post exposure. Error bars indicate SEM. *p < 0.05.
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Figure 1: Thirty seconds odor exposure decreases subsequent glomerular responses to that odor for several minutes. (A) Pseudo-color glomerular responses to 2-heptanone (0.5% s.v.) at 10× magnification. One minute after the habituating odor exposure (1 min Post), glomerular responses are decreased from their baseline (Pre). After 6 min, the responses have recovered (6 min Post). (B) GCamp2 fluorescence traces from the glomerulus indicated by arrows in (A). (C) The timeline of recovery from habituation. Mean normalized glomerular responses for all animals were reduced for several minutes post exposure. Error bars indicate SEM. *p < 0.05.
Mentions: To determine how a 30-s odor exposure impacts subsequent glomerular responses to that odor, we measured glomerular responses to 1-s odor pulses before and after a single prolonged exposure in ten animals (Figure 1). Following the habituation trial, the mean normalized glomerular responses changed (ANOVA: F(5,395) = 37.03, p < 0.0001), and post hoc tests showed significant reduction from baseline responses 1 min (70.1 ± 2.1%, n = 95), 2 min (73.8 ± 3.3%, n = 61), and 4 min (85.2 ± 2.5%, n = 49) post exposure (Figure 1C). Mean responses at 6 min (94.5 ± 2.5%, n = 61) and 11 min (96.6 ± 2.7%, n = 40) post-habituation were not significantly different from the baseline, indicating that recovery had occurred by 6 min.

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