scholarly journals Origin of basal activity in mammalian olfactory receptor neurons

2010 ◽  
Vol 136 (5) ◽  
pp. 529-540 ◽  
Author(s):  
Johannes Reisert
Keyword(s):  
Olfactory Receptor ◽  
Information Transfer ◽  
Odorant Receptor ◽  
Olfactory Receptor Neurons ◽  
Odorant Receptors ◽  
Action Potential Firing ◽  
Response Characteristics ◽  
Basal Activity ◽  
Receptor Neurons ◽  
Different Response

Mammalian odorant receptors form a large, diverse group of G protein–coupled receptors that determine the sensitivity and response profile of olfactory receptor neurons. But little is known if odorant receptors control basal and also stimulus-induced cellular properties of olfactory receptor neurons other than ligand specificity. This study demonstrates that different odorant receptors have varying degrees of basal activity, which drives concomitant receptor current fluctuations and basal action potential firing. This basal activity can be suppressed by odorants functioning as inverse agonists. Furthermore, odorant-stimulated olfactory receptor neurons expressing different odorant receptors can have strikingly different response patterns in the later phases of prolonged stimulation. Thus, the influence of odorant receptor choice on response characteristics is much more complex than previously thought, which has important consequences on odor coding and odor information transfer to the brain.

scholarly journals Olfactory receptor responses to sex pheromone components in the redbanded leafroller moth.

1975 ◽  
Vol 65 (2) ◽  
pp. 179-205 ◽  
Author(s):  
R J O'Connell
Keyword(s):  
Sex Pheromone ◽  
Olfactory Receptor ◽  
Olfactory Receptor Neurons ◽  
Response Frequency ◽  
Active Compounds ◽  
Odor Quality ◽  
Response Characteristics ◽  
Redbanded Leafroller ◽  
Pheromone Components ◽  
Receptor Neurons

Electrical responses of single olfactory receptor neurons of the male redbanded leafroller moth were elicited by each of the principle components of the sex pheromone and six other behaviorally active compounds. Response frequencies to equal intensities of each of these compounds and changes in response frequency with increasing amounts of any one compound, varied from receptor to receptor. These differences in response characteristics appear to be due to factors intrinsic to the olfactory recptor neuron and not to factors external to it. The encoding of odor quality by these receptor neurons cannot be in the simple presence or absence of activity in any one of them. Rather, odor quality may be encoded by the pattern of activity which invariably arises across an ensemble of receptor neurons, each having its own distribution of sensitivities.

Excitation, inhibition, and suppression by odors in isolated toad and rat olfactory receptor neurons

2000 ◽  
Vol 279 (1) ◽  
pp. C31-C39 ◽  
Author(s):  
Magdalena Sanhueza ◽  
Oliver Schmachtenberg ◽  
Juan Bacigalupo
Keyword(s):  
Firing Rate ◽  
Olfactory Receptor ◽  
Receptor Potential ◽  
Cell Voltage ◽  
Underlying Mechanism ◽  
Olfactory Receptor Neurons ◽  
Action Potential Firing ◽  
Potential Firing ◽  
A Cell ◽  
Receptor Neurons

Vertebrate olfactory receptor neurons (ORNs) exhibit odor-induced increases in action potential firing rate due to an excitatory cAMP-dependent current. Fish and amphibian ORNs also give inhibitory odor responses, manifested as decreases in firing rate, but the underlying mechanism is poorly understood. In the toad, an odor-induced Ca2+-activated K+ current is responsible for the hyperpolarizing receptor potential that causes inhibition. In isolated ORNs, a third manner by which odors affect firing is suppression, a direct and nonspecific reduction of voltage-gated and transduction conductances. Here we show that in whole cell voltage-clamped toad ORNs, excitatory or inhibitory currents were not strictly associated to a particular odorant mixture. Occasionally, both odor effects, in addition to suppression, were concurrently observed in a cell. We report that rat ORNs also exhibit odor-induced inhibitory currents, due to the activation of a K+ conductance closely resembling that in the toad, suggesting that this conductance is widely distributed among vertebrates. We propose that ORNs operate as complex integrator units in the olfactory epithelium, where the first events in the process of odor discrimination take place.

scholarly journals Optimal compressed sensing strategies for an array of nonlinear olfactory receptor neurons with and without spontaneous activity

2019 ◽  
Vol 116 (41) ◽  
pp. 20286-20295 ◽  
Author(s):  
Shanshan Qin ◽  
Qianyi Li ◽  
Chao Tang ◽  
Yuhai Tu
Keyword(s):  
Compressed Sensing ◽  
Olfactory Receptor ◽  
Dynamic Range ◽  
Olfactory Receptor Neurons ◽  
Receptor Interaction ◽  
Trade Off ◽  
Odor Receptor ◽  
Basal Activity ◽  
Receptor Neurons ◽  
Coding Capacity

There are numerous different odorant molecules in nature but only a relatively small number of olfactory receptor neurons (ORNs) in brains. This “compressed sensing” challenge is compounded by the constraint that ORNs are nonlinear sensors with a finite dynamic range. Here, we investigate possible optimal olfactory coding strategies by maximizing mutual information between odor mixtures and ORNs’ responses with respect to the bipartite odor-receptor interaction network (ORIN) characterized by sensitivities between all odorant–ORN pairs. For ORNs without spontaneous (basal) activity, we find that the optimal ORIN is sparse—a finite fraction of sensitives are zero, and the nonzero sensitivities follow a broad distribution that depends on the odor statistics. We show analytically that sparsity in the optimal ORIN originates from a trade-off between the broad tuning of ORNs and possible interference. Furthermore, we show that the optimal ORIN enhances performances of downstream learning tasks (reconstruction and classification). For ORNs with a finite basal activity, we find that having inhibitory odor–receptor interactions increases the coding capacity and the fraction of inhibitory interactions increases with the ORN basal activity. We argue that basal activities in sensory receptors in different organisms are due to the trade-off between the increase in coding capacity and the cost of maintaining the spontaneous basal activity. Our theoretical findings are consistent with existing experiments and predictions are made to further test our theory. The optimal coding model provides a unifying framework to understand the peripheral olfactory systems across different organisms.

scholarly journals Randomness of spontaneous activity and information transfer in neurons

2008 ◽  
pp. S133-S138
Author(s):  
L Košťál ◽  
P Lánský
Keyword(s):  
Spontaneous Activity ◽  
Neuronal Activity ◽  
Coefficient Of Variation ◽  
Olfactory Receptor ◽  
Information Transfer ◽  
Olfactory Receptor Neurons ◽  
Information Coding ◽  
Receptor Neurons ◽  
Evoked Activity

The analysis of information coding in neurons requires methods that measure different properties of neuronal signals. In this paper we review the recently proposed measure of randomness and compare it to the coefficient of variation, which is the frequently employed measure of variability of spiking neuronal activity. We focus on the problem of the spontaneous activity of neurons, and we hypothesize that under defined conditions, spontaneous activity is more random than evoked activity. This hypothesis is supported by contrasting variability and randomness obtained from experimental recordings of olfactory receptor neurons in rats.

scholarly journals Ir76b is a Co-receptor for Amine Responses in Drosophila Olfactory Neurons

2021 ◽  
Vol 15 ◽  
Author(s):  
Alina Vulpe ◽  
Karen Menuz
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Olfactory Receptor Neurons ◽  
Odorant Receptors ◽  
Olfactory Neurons ◽  
Bona Fide ◽  
Receptor Neurons ◽  
Large Families ◽  
Odorant Binding

Two large families of olfactory receptors, the Odorant Receptors (ORs) and Ionotropic Receptors (IRs), mediate responses to most odors in the insect olfactory system. Individual odorant binding “tuning” OrX receptors are expressed by olfactory neurons in basiconic and trichoid sensilla and require the co-receptor Orco. The situation for IRs is more complex. Different tuning IrX receptors are expressed by olfactory neurons in coeloconic sensilla and rely on either the Ir25a or Ir8a co-receptors; some evidence suggests that Ir76b may also act as a co-receptor, but its function has not been systematically examined. Surprisingly, recent data indicate that nearly all coeloconic olfactory neurons co-express Ir25a, Ir8a, and Ir76b. Here, we demonstrate that Ir76b and Ir25a function together in all amine-sensing olfactory receptor neurons. In most neurons, loss of either co-receptor abolishes amine responses. In contrast, amine responses persist in the absence of Ir76b or Ir25a in ac1 sensilla but are lost in a double mutant. We show that responses mediated by acid-sensing neurons do not require Ir76b, despite their expression of this co-receptor. Our study also demonstrates that one population of coeloconic olfactory neurons exhibits Ir76b/Ir25a-dependent and Orco-dependent responses to distinct odorants. Together, our data establish the role of Ir76b as a bona fide co-receptor, which acts in partnership with Ir25a. Given that these co-receptors are among the most highly conserved olfactory receptors and are often co-expressed in chemosensory neurons, our data suggest Ir76b and Ir25a also work in tandem in other insects.

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