Neurobehavioral responses of neonatal rats to previously experienced odors of different concentrations

Carmi, Osnat; Leon, Michael

doi:10.1016/0165-3806(91)90207-y

Cited by 10 publications

(8 citation statements)

References 12 publications

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“…By using the present mapping method, we have confirmed that early learning increases the uptake of 2-DG in odor-dependent foci without greatly changing the overall pattern of the response (Coopersmith and Leon, 1984;Sullivan and Leon, 1986;Do et al, 1988;Sullivan et al, 1989Sullivan et al, , 1990Carmi and Leon, 1991). In addition, this method has allowed us to detect widespread, learning-associated increases in glomerular layer uptake occurring distant from the odor-dependent foci.…”

Section: Discussionsupporting

confidence: 82%

Spatial distribution of [14C]2-deoxyglucose uptake in the glomerular layer of the rat olfactory bulb following early odor preference learning

Johnson

Leon

1996

J. Comp. Neurol.

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Previous work has shown that odors induce focal uptake of [14C]2-deoxyglucose (2-DG) within the glomerular layer of the main olfactory bulb and that the amount of 2-DG accumulated in these foci increases after early odor learning. To determine if learning-associated changes in 2-DG uptake occur across the entire glomerular layer, we have mapped uptake throughout the layer at fixed angles in coronal sections through the bulb. Resulting arrays for individual bulbs were corrected for differing bulb size and averaged across experimental groups to address the spatial distribution of uptake. The average arrays revealed at least three discrete fields of uptake in naive, peppermint-exposed rats at postnatal day 19 that were not seen in air-exposed littermates. In agreement with previous studies, early preference training with peppermint odor given on postnatal days 1-18 increased 2-DG uptake at postnatal day 19 within odor-dependent patches of uptake in the posterior half of the midlateral bulb, whereas odor-dependent, ventrolateral patches of uptake did not increase to the same extent. In addition, early preference learning was associated with significantly increased 2-DG uptake average over the entire analyzed glomerular layer. These increases were smaller than those within odor-dependent foci and were distributed widely across the glomerular layer, showing low overlap between trained and control rats in anterior regions where peppermint odor did not stimulate 2-DG uptake. The widely distributed increases in 2-DG uptake after learning may reflect changed activity of centrifugal projections that diffusely innervate the glomerular layer.

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Section: Discussionsupporting

confidence: 82%

Spatial distribution of [14C]2-deoxyglucose uptake in the glomerular layer of the rat olfactory bulb following early odor preference learning

Johnson

Leon

1996

J. Comp. Neurol.

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“…As shown in Figure 3, most modules showed increased 2-DG uptake with increasing odorant concentration, as has been reported previously (Stewart et al, 1979;Carmi and Leon, 1991;Johnson et al, 1999). However, there were a few interesting exceptions.…”

Section: Activity Patterns Change With Odorant Concentrationsupporting

confidence: 63%

“…Odors that do not change with concentration would be expected to have a largely stable pattern of glomerular activation. Indeed, spatial activity patterns across different odorant concentrations commonly are relatively constant (Stewart et al, 1979;Carmi and Leon, 1991;Guthrie and Gall, 1995;Cinelli et al, 1995;Joerges et al, 1997). Increased concentrations of odorants increase the amount of activity in responsive glomeruli (Stewart et al, 1979;Guthrie and Gall, 1995;Cinelli et al, 1995;Joerges et al, 1997;Friedrich and Korsching, 1997;Johnson et al, 1999;Rubin and Katz, 1999).…”

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confidence: 99%

Modular representations of odorants in the glomerular layer of the rat olfactory bulb and the effects of stimulus concentration

2000

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To study the mechanism whereby odorants are encoded in the nervous system, we studied the glomerular-layer activity patterns in the rat olfactory bulb evoked by closely related odorants from different chemical families. These odorants had a common straight-chain hydrocarbon structure, but differed systematically in their functional groups. Neural activity was mapped across the entire glomerular layer by using the ¿(14)C2-deoxyglucose method. Group responses were averaged and compared by using data matrices. The glomerular activity patterns that resulted from this analysis were comprised of modules. Unique combinations of modules were activated by each odorant, demonstrating what may be part of the neural code for odorants. Most of the modules were clustered together in the bulb, perhaps providing for enhanced contrast between related chemicals by means of lateral inhibition. We also determined whether changes in odorant concentration would affect spatial patterns of glomerular activity. Two odorants, pentanal and 2-hexanone, evoked different patterns at increased concentrations, with additional glomeruli being recruited at a great distance from glomeruli in which activity was evoked at lower concentrations. Humans report that both of these odorants change in perceived odor with increasing concentration. Three other odorants (pentanoic acid, methyl pentanoate, and pentanol) did not recruit new areas of glomerular activation with increasing concentration, and humans do not report a changed odor across concentrations of these odorants. The results suggest that changes in modular glomerular activity patterns could underlie altered odor perception across odorant concentrations, and they provide additional support for a combinatorial, spatially based code in the olfactory system.

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“…Rat pups exposed to an odor for 10 minutes with tactile stimulation daily from PNDs 1 through 18 will express a preference for the odorant when tested on PND 19 (Sullivan and Leon, 1986;Wilson et al, 1987;Carmi and Leon, 1991). Within the main olfactory bulb, the focal glomerular uptake of L14C]2DG in response to the trained odor stimulation is enhanced in the trained pups compared to the pups exposed to clean air and given tactile stimulation (Coopersmith and Leon, 1984;Carmi and Leon, 1991).…”

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confidence: 96%

Early olfactory enrichment and deprivation both decrease β‐adrenergic receptor density in the main olfactory bulb of the rat

Woo¹,

Leon²

1995

J of Comparative Neurology

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The density of noradrenergic locus coeruleus projections and beta-adrenergic receptors in the main olfactory bulb of the rat increases with age. Both beta 1- and beta 2-adrenergic receptor subtypes exhibit laminar distributions, with focal regions of high receptor density present within the neuropil of individual glomeruli. Since the first synaptic contacts between olfactory receptor neurons and bulbar neurons occur within the glomeruli, early olfactory experiences possibly could influence the density or distribution of beta-adrenergic receptors in the bulb. We therefore investigated the effects of olfactory deprivation and early olfactory enrichment on the density and distribution of beta-adrenergic receptors in the main olfactory bulb. Animals were subjected to either unilateral naris closure on postnatal day 1 or odor training from postnatal days 1-18. Bulbs were removed on postnatal day 19 and subjected to quantitative autoradiography using the beta-adrenergic receptor antagonist [125I]iodopindolol and specific receptor subtype antagonists ICI 118,551 (beta 2-antagonist) and ICI 89,406 (beta 1-antagonist). Unilateral naris occlusion decreased both the number of beta 2 glomerular foci and the density of beta 1 and beta 2 receptors in the deprived bulb compared to the nondeprived bulb. Early odor training resulted in a significant decrease in the number, area, and receptor density of beta 2 glomerular foci in the midlateral region of the bulb. The distribution of beta 2 glomerular foci also differs with these two sensory manipulations. Changes in beta-adrenergic receptor density in response to both early learning and olfactory deprivation may be induced by a transient increase in olfactory bulb norepinephrine.

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Neurobehavioral responses of neonatal rats to previously experienced odors of different concentrations

Cited by 10 publications

References 12 publications

Spatial distribution of [14C]2-deoxyglucose uptake in the glomerular layer of the rat olfactory bulb following early odor preference learning

Spatial distribution of [14C]2-deoxyglucose uptake in the glomerular layer of the rat olfactory bulb following early odor preference learning

Modular representations of odorants in the glomerular layer of the rat olfactory bulb and the effects of stimulus concentration

Early olfactory enrichment and deprivation both decrease β‐adrenergic receptor density in the main olfactory bulb of the rat

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