Glutamate and Synaptic Plasticity at Mammalian Primary Olfactory Synapses<sup>a</sup>

Ennis, Matthew; Linster, Christiane; Aroniadou‐Anderjaska, Vassiliki; Ciombor, Kelly J.; Shipley, Michael T.

doi:10.1111/j.1749-6632.1998.tb10606.x

Cited by 46 publications

(37 citation statements)

References 16 publications

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“…The computational modeling presented here shows that (i) the modulation of OB synapses known to exhibit activity-dependent plasticity (15)(16)(17) suffices to produce changes in OB processing that can underlie the perceptual changes reported here and (ii) that OB architecture and its widespread dendritic interactions can explain the observed relatively nonspecific effects of olfactory enrichment. The model shows that activation with a single chemical can produce changes in a large area of the OB and that these would effect the processing of other odorants, as long as partially overlapping areas of the OB are activated.…”

Section: Discussionmentioning

confidence: 99%

“…In the simulations presented here, based on experimental evidence showing activity-dependent plasticity of these synapses (15)(16)(17), we varied the impact of OSNs onto mitral cell dendrites and of mitral cells onto granule cells in an activity-dependent manner. Synaptic strengths were first calculated from the parameters given in Table 2, which is published as supporting information on the PNAS web site, and responses to simulated odorants were obtained.…”

Section: Methodsmentioning

confidence: 99%

“…Because of the long-lasting changes in odor perception after daily exposure to odorants, we hypothesized that an activity-dependent synaptic plasticity at the level of two synapses could produce changes in OB processing that affect a wide array of odors. We therefore implemented a simple activitydependent hebbian learning rule at the synapse between OSNs and mitral cells and between mitral and granule cells; both of these synapse types have been shown to undergo activity-dependent plasticity experimentally (15)(16)(17).…”

Section: Experiments 3: Computational Modelmentioning

confidence: 99%

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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: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Experiments 3: Computational Modelmentioning

confidence: 99%

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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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“…Indeed, behavioral and functional mapping experiments indicate functional plasticity at the level of olfactory glomeruli both during early odor preference learning and also in adult rodents (Yuan et al, 2002;Fletcher and Wilson, 2003;McLean and Harley, 2004). Despite these data on the system level, there has to date been little evidence for olfactory plasticity at the level of olfactory nerve (ON)3 MC synapses except one report suggesting that ON3 MC synapses can express long-term potentiation (LTP) (Ennis et al, 1998).…”

Section: Introductionmentioning

confidence: 99%

Long-Term Depression at Olfactory Nerve Synapses

Mutoh¹,

Yuan²,

Knöpfel³

2005

J. Neurosci.

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The synapses formed by the olfactory nerve (ON) convey sensory information to olfactory glomeruli, the first stage of central odor processing. Morphological and behavioral studies suggest that glomerular odor processing is plastic in neonate rodents. However, long-term synaptic plasticity, a cellular correlate of functional and structural plasticity, has not yet been demonstrated in this system. Here, we report that ON3mitral cell (MC) synapses of 5-to 8-d-old mice express long-term depression (LTD) after brief low-frequency ON stimulation. Pharmacological techniques and imaging of presynaptic calcium signals demonstrate that ON-MC LTD is expressed presynaptically and requires the activation of metabotropic glutamate receptors but does not require fast synaptic transmission. LTD at the ON3 MC synapse is potentially relevant for the establishment, maintenance, and experience-dependent refinement of odor maps in the olfactory bulb.

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“…To investigate whether postsynaptic target neurons in the olfactory bulb may directly regulate ORN survival signaling at the glomerular synapse of mature ORNs, we took advantage of the fact that ORNs use an NMDA receptor-containing synapse. The ORN postsynaptic targets (mitral and tufted cells) contain combinations of both NMDA and metabotropic glutamate receptors (Ennis et al, 1998;Montague and Greer, 1999;Salin et al, 2001) and are therefore susceptible to undergo excitotoxic cell death at high levels of stimulation. We first used immunocytochemistry and reverse transcription-PCR for the NR1 subunit of the NMDA receptor to rule out expression of NMDA receptors on ORNs themselves (data not shown).…”

Section: Orn Target Neurons In the Olfactory Bulb Die After Excitotoxmentioning

confidence: 99%

Axonal Dynactin p150^GluedTransports Caspase-8 to Drive Retrograde Olfactory Receptor Neuron Apoptosis

Carson

Saleh²,

Nicholson³

et al. 2005

J. Neurosci.

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Olfactory receptor neurons (ORNs) undergo caspase-mediated retrograde apoptosis after target removal (bulbectomy), in which axonal caspase-9 and caspase-3 activation leads to terminal apoptosis in ORN soma of the olfactory epithelium. Here, we show that caspase-8 can act as an initiator of ORN apoptosis after bulbectomy and also after synaptic instability is induced by NMDA-mediated excitotoxic death of ORN target neurons in the olfactory bulb. Caspase-8 and caspase-3 are sequentially activated within ORN presynaptic terminals, and caspase-8 complexes with dynactin p150Glued , (a retrograde motor protein) and is transported retrogradely, preceding axonal caspase-3 activation and apoptosis of ORN cell bodies. Focal in vivo inhibition of initiator caspase activation or microtubule-dependent transport (with Taxol) at the lesioned axon terminus results in a significant reduction in retrograde axonal caspase-8 and caspase-3 activation and inhibition of retrograde ORN death. Caspase-8 activation and retrograde transport after NMDA lesion is similarly reduced in mice null for p75, the low-affinity nerve growth factor receptor. The retrograde apoptosis of ORNs thus involves a novel mechanism that used p75 in the local activation of caspase-8. Once caspase-8 is maximally activated in the presynaptic terminal, it is transported retrogradely by the motor complex dynactin/dynein, a process that can be inhibited focally to inhibit ORN apoptosis after acute axonal lesion. These data have revealed a novel mechanism of retrograde apoptosis, in which caspase-8 complexes directly with axonal dynactin p150Glued to reveal a differential vulnerability of subpopulations of ORNs to undergo apoptosis after axonal damage and the loss of olfactory bulb target neurons.

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Glutamate and Synaptic Plasticity at Mammalian Primary Olfactory Synapses^a

Cited by 46 publications

References 16 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

Long-Term Depression at Olfactory Nerve Synapses

Axonal Dynactin p150^GluedTransports Caspase-8 to Drive Retrograde Olfactory Receptor Neuron Apoptosis

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Glutamate and Synaptic Plasticity at Mammalian Primary Olfactory Synapsesa

Cited by 46 publications

References 16 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

Long-Term Depression at Olfactory Nerve Synapses

Axonal Dynactin p150GluedTransports Caspase-8 to Drive Retrograde Olfactory Receptor Neuron Apoptosis

Contact Info

Product

Resources

About

Glutamate and Synaptic Plasticity at Mammalian Primary Olfactory Synapses^a

Axonal Dynactin p150^GluedTransports Caspase-8 to Drive Retrograde Olfactory Receptor Neuron Apoptosis