Short‐lasting exposure to one odour decreases general reactivity in the olfactory bulb of adult rats

Buonviso, Nathalie; Gervais, R.; Chalansonnet, Monique; Chaput, Michel

doi:10.1046/j.1460-9568.1998.00266.x

Cited by 38 publications

(38 citation statements)

References 25 publications

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“…Taken together, these results show that activation of the OB alone, in the absence of motivated odor investigation, is sufficient to lead to long-lasting changes in olfactory perception. In agreement with data showing that changes in OB neural responses (28)(29)(30) and in OB neurogenesis occur because of olfactory enrichment (31), we clearly show that manipulation of the OB network is sufficient to produce long-lasting perceptual changes. Both the manipulations performed in our model, i.e., synaptic plasticity within the existing inhibitory network or changes in the structure of this inhibitory network, due for example to changes in neurogenesis of inhibitory interneurons (not explicitly modeled here), could be at the basis of the observed changes in olfactory perception.…”

Section: Discussionsupporting

confidence: 92%

Broad activation of the olfactory bulb produces long-lasting changes in odor perception

Mandairon

Stack

Kiselycznyk

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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A number of electrophysiological experiments have shown that odor exposure alone, unaccompanied by behavioral training, changes the response patterns of neurons in the olfactory bulb. As a consequence of these changes, across mitral cells in the olfactory bulb, individual odors should be better discriminated because of previous exposure. We have previously shown that a daily 2-h exposure to odorants during 2 weeks enhances rats' ability to discriminate between chemically similar odorants. Here, we first show that the perception of test odorants is only modulated by enrichment with odorants that activate at least partially overlapping regions of the olfactory bulb. Second, we show that a broad activation of olfactory bulb neurons by daily local infusion of NMDA into both olfactory bulbs enhances the discrimination between chemically related odorants in a manner similar to the effect of daily exposure to odorants. Computational modeling of the olfactory bulb suggests that activity-dependent plasticity in the olfactory bulb can support the observed modulation in olfactory discrimination capability by enhancing contrast and synchronization in the olfactory bulb. Last, we show that blockade of NMDA receptors in the olfactory bulb impairs the effects of daily enrichment, suggesting that NMDA-dependent plasticity is involved in the changes in olfactory processing observed here. discrimination ͉ enrichment ͉ plasticity B ehavioral enrichment is thought to be a major modulator of animals' ability to learn behavioral tasks. It has been shown many times that an enriched environment during development dramatically increases animals' learning and memory abilities during adult life (1, 2). Enrichment during adult life can counteract learning disabilities due to absence of NMDA receptors in genetically modified mice (3), as well as the decrease in learning capabilities seen in older rodents (4,5). Most studies investigating the beneficial effects of enriched housing environments focus on complex learning tasks such as the Morris water maze (5-7) or the Hebb-Williams maze (8) that have been linked to hippocampal function (9-11). In contrast to previous studies, we here focus on sensory perception, a predeterminant of all learning tasks in animals. Using olfactory perception in rats, we have recently shown for the first time that sensory enrichment during a relatively short period improves animals' sensory discrimination capabilities in an odor-unspecific manner (12). Here, we show that the modulation of olfactory discrimination abilities due to daily enrichment with odorants arises in the first olfactory sensory structure, the olfactory bulb (OB). First, we show that enrichment only affects the perception of those odorants that activate at least partially overlapping regions of the OB, suggesting that nonspecific activation of OB neurons suffices to produce lasting changes in perception and that spatial specificity of odor responses is of importance in this process. Second, we show that unspecific activation of OB neurons via l...

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Section: Discussionsupporting

confidence: 92%

Broad activation of the olfactory bulb produces long-lasting changes in odor perception

Mandairon

Stack

Kiselycznyk

et al. 2006

Proc. Natl. Acad. Sci. U.S.A.

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“…For example, following associative conditioning in rat pups, mitral cells display more suppression to the trained odorant (Wilson and Leon 1988b). Similar results have also been observed following simple odor exposure in adults (Buonviso et al 1998;Buonviso and Chaput 2000;Fletcher and Wilson 2003).…”

Section: Experience-induced Olfactory Plasticitysupporting

confidence: 77%

Neural correlates of olfactory learning: Critical role of centrifugal neuromodulation

Fletcher¹,

Chen²

2010

Learn. Mem.

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The mammalian olfactory system is well established for its remarkable capability of undergoing experience-dependent plasticity. Although this process involves changes at multiple stages throughout the central olfactory pathway, even the early stages of processing, such as the olfactory bulb and piriform cortex, can display a high degree of plasticity. As in other sensory systems, this plasticity can be controlled by centrifugal inputs from brain regions known to be involved in attention and learning processes. Specifically, both the bulb and cortex receive heavy inputs from cholinergic, noradrenergic, and serotonergic modulatory systems. These neuromodulators are shown to have profound effects on both odor processing and odor memory by acting on both inhibitory local interneurons and output neurons in both regions.For most mammals, olfaction plays an important role in many aspects of life, such as mate attraction and recognition, motherinfant attachment, navigation, as well as detection of predators. Not surprisingly, mammals, especially rodents, have demonstrated an exceptional capability to quickly learn, remember, and discriminate odors. Past research has shown that the early stages of olfactory processing display a remarkable degree of plasticity and can play a significant role in olfactory learning. One striking feature of this system is the surprisingly large amount of centrifugal influence on odor processing in the early olfactory pathways. Both the olfactory bulb and piriform cortex receive input from multiple neuromodulatory regions releasing acetylcholine, norepinephrine, and serotonin. These neuromodulators are known to play a major role in learning-related events such as changes in arousal, attention to novel or salient stimuli, and emotional states such as stress or fear. Similar to other sensory systems, both physiological and behavioral experiments have shown that these neuromodulators can have profound effects on odor processing as well as olfactory learning and memory. Here, we focus on learning-induced plasticity in the early olfactory pathways and the role that centrifugal neuromodulation plays in facilitating this process.

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“…Among these brain structures, the OB is known to be the locus of a high level of plasticity linked to memory [7]–[10]. The responses of mitral cells, the relay cells of the OB are modulated by associative learning [11]–[13] as well as by prolonged passive exposure to odors [14]. The oscillatory behavior of the OB is also modulated by learning [15] as is the immediate early gene responsiveness of bulbar interneurons [16]–[19].…”

Section: Introductionmentioning

confidence: 99%

Consolidation of an Olfactory Memory Trace in the Olfactory Bulb Is Required for Learning-Induced Survival of Adult-Born Neurons and Long-Term Memory

et al. 2010

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BackgroundIt has recently been proposed that adult-born neurons in the olfactory bulb, whose survival is modulated by learning, support long-term olfactory memory. However, the mechanism used to select which adult-born neurons following learning will participate in the long-term retention of olfactory information is unknown. We addressed this question by investigating the effect of bulbar consolidation of olfactory learning on memory and neurogenesis.Methodology/Principal FindingsInitially, we used a behavioral ecological approach using adult mice to assess the impact of consolidation on neurogenesis. Using learning paradigms in which consolidation time was varied, we showed that a spaced (across days), but not a massed (within day), learning paradigm increased survival of adult-born neurons and allowed long-term retention of the task. Subsequently, we used a pharmacological approach to block consolidation in the olfactory bulb, consisting in intrabulbar infusion of the protein synthesis inhibitor anisomycin, and found impaired learning and no increase in neurogenesis, while basic olfactory processing and the basal rate of adult-born neuron survival remained unaffected. Taken together these data indicate that survival of adult-born neurons during learning depends on consolidation processes taking place in the olfactory bulb.Conclusion/SignificanceWe can thus propose a model in which consolidation processes in the olfactory bulb determine both survival of adult-born neurons and long-term olfactory memory. The finding that adult-born neuron survival during olfactory learning is governed by consolidation in the olfactory bulb strongly argues in favor of a role for bulbar adult-born neurons in supporting olfactory memory.

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Short‐lasting exposure to one odour decreases general reactivity in the olfactory bulb of adult rats

Cited by 38 publications

References 25 publications

Broad activation of the olfactory bulb produces long-lasting changes in odor perception

Broad activation of the olfactory bulb produces long-lasting changes in odor perception

Neural correlates of olfactory learning: Critical role of centrifugal neuromodulation

Consolidation of an Olfactory Memory Trace in the Olfactory Bulb Is Required for Learning-Induced Survival of Adult-Born Neurons and Long-Term Memory

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