scholarly journals Modular structure of human olfactory receptor codes reflects the bases of odor perception

2019 ◽  
Author(s):  
Ji Hyun Bak ◽  
Seogjoo J. Jang ◽  
Changbong Hyeon
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Modular Structure ◽  
Dimensional Structure ◽  
Odor Perception ◽  
Human Odor ◽  
Olfactory Stimuli ◽  
Low Dimensional ◽  
Odor Space ◽  
Input Code

The circuits of olfactory signaling are reminiscent of complex computational devices. The olfactory receptor code, which represents the responses of receptors elicited by olfactory stimuli, is effectively an input code for the neural computation of odor sensing. Here, analyzing a recent dataset of the odorant-dependent responses of human olfactory receptors (ORs), we show that the space of human olfactory receptor codes is partitioned into a modular structure where groups of receptors are “labeled” for key olfactory features. Our analysis reveals a low-dimensional structure in the space of human odor perception, with the receptor groups as the bases to represent major features in the perceptual odor space. These findings provide a novel evidence that some fundamental olfactory features are already hard-coded at the level of ORs, separately from the higher-level neural circuits.

scholarly journals Primacy model and the evolution of the olfactory receptor repertoire

2018 ◽  
Author(s):  
Hamza Giaffar ◽  
Dmitry Rinberg ◽  
Alexei A. Koulakov
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Dimensional Structure ◽  
Sufficient Information ◽  
High Affinity ◽  
Receptor Repertoire ◽  
Wide Range ◽  
Evoked Activity ◽  
Low Dimensional ◽  
The Impact

For many animals, the neural activity in early olfactory circuits during a single sniff cycle contains sufficient information for fine odor discrimination. Whilst much is known about the transformations of neural representations in early olfactory circuits, exactly how odorant evoked activity in the main olfactory bulb shapes the perception of odors remains largely unknown. In olfaction, odorant identity is generally conserved over a wide range of conditions, including concentration. We present a theory of identity assignment in the olfactory system that accounts for this invariance with respect to stimulus intensity. We suggest that the identities of relatively few high affinity olfactory receptor types determine an odorant's perceived identity. This set of high-affinity receptors is defined as the primary set and the coding model based on their responses is called the primacy theory. In this study, we explore the impact that primacy coding may have on the evolution of the ensemble of olfactory receptors. A primacy coding mechanism predicts the arrangement of different receptor types in a low-dimensional structure that we call a primacy hull. We present several statistical analyses that can detect the presence of this structure, allowing the predictions of the primacy model to be tested experimentally.

scholarly journals Implications for human odor sensing revealed from the statistics of the odorant-receptor interactions

2018 ◽  
Author(s):  
Ji Hyun Bak ◽  
Seogjoo Jang ◽  
Changbong Hyeon
Keyword(s):  
High Throughput Screening ◽  
Odorant Receptor ◽  
Olfactory Receptors ◽  
Assay Method ◽  
Theoretic Approach ◽  
Screening Assay ◽  
Odor Perception ◽  
Activation Kinetics ◽  
High Throughput Screening Assay ◽  
Human Odor

Binding of odorants to olfactory receptors (ORs) elicits downstream chemical and neural signals, which are further processed to odor perception in the brain. Recently, Mainland et al. [Sci. data, (2015) 2:sdata20152] have measured ≳ 500 pairs of odorant-OR interaction by a high-throughput screening assay method, opening a new avenue to understanding the principles of human odor coding. Here, using a recently developed minimal model for OR activation kinetics [J. Phys. Chem. B (2017) 121, 1304–1311], we characterize the statistics of OR activation by odorants in terms of three empirical parameters: the half-maximum effective concentration EC50, the efficacy, and the basal activity. While the data size of odorants is still limited, the statistics offer meaningful information on the breadth and optimality of the tuning of human ORs to odorants, and allow us to relate the three parameters with the microscopic rate constants and binding affinities that define the OR activation kinetics. Despite the stochastic nature of the response expected at individual OR-odorant level, we assess that the confluence of signals in a neuron released from the multitude of ORs is effectively free of noise and deterministic with respect to changes in odorant concentration. Thus, setting a threshold to the fraction of activated OR copy number for neural spiking binarizes the electrophysiological signal of olfactory sensory neuron, thereby making an information theoretic approach a viable tool in studying the principles of odor perception.

Olfactory Stimuli and Oviposition in the Blowfly, Phormia Regina Meigen

1962 ◽  
Vol 39 (4) ◽  
pp. 603-615
Author(s):  
D. I. WALLIS
Keyword(s):  
Olfactory Receptors ◽  
Phormia Regina ◽  
Minor Role ◽  
Egg Distribution ◽  
Tactile Stimuli ◽  
Olfactory Stimuli ◽  
Behavioural Experiments ◽  
A Minor ◽  
Sensory Mechanisms

1. The work described attempts to elucidate the sensory mechanisms involved in the act of oviposition. 2. A brief account of the morphology of the ovipositor and the distribution of the various sensilla on it is given. 3. Behavioural experiments have shown unequivocally that receptors on the anal leaflets of the ovipositor are olfactory and can mediate oviposition. Flies are able to discriminate when antennal, palp and labellar receptors are blocked, but not when the ovipositor pegs are waxed over as well. A method for waxing the latter is described. 4. Sensilla on the antennae, labellum and ovipositor perceive the olfactory stimuli which are important in inducing oviposition. Possibly there are olfactory receptors at other sites which mediate other types of behaviour. 5. Tactile stimuli perceived mainly through sensilla on the ovipositor can play an important role in egg distribution and a minor role, possibly, in inducing oviposition. 6. All the evidence suggests the pegs are the olfactory receptors on the ovipositor which mediate oviposition. 7. A summary of factors known or suspected to influence oviposition is given.

scholarly journals Molecular Modelling of Oligomeric States of DmOR83b, an Olfactory Receptor in D. Melanogaster

2012 ◽  
Vol 6 ◽  
pp. BBI.S8990 ◽  
Author(s):  
K. Harini ◽  
R. Sowdhamini
Keyword(s):  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Insect Species ◽  
Agricultural Pests ◽  
Negative Effects ◽  
C Terminus ◽  
Receptor Neurons ◽  
Medical Importance ◽  
G Protein Coupled ◽  
Made In

After the discovery of the complete repertoire of D. melanogaster Olfactory Receptors (ORs), candidate ORs have been identified from at least 12 insect species from four orders (Coleoptera, Lepidoptera, Diptera, and Hymenoptera), including species of economic or medical importance. Although all ORs share the same G-protein coupled receptor structure with seven transmembrane domains, they share poor sequence identity within and between species, and have been identified mainly through genomic data analyses. To date, D. melanogaster remains the only insect species where ORs have been extensively studied, from expression pattern establishment to functional investigations. These studies have confirmed several observations made in vertebrates: one OR type is selectively expressed in a subtype of olfactory receptor neurons, and one olfactory neuron expresses only one type of OR. The olfactory mechanism, further, appears to be conserved between insects and vertebrates. Understanding the function of insect ORs will greatly contribute to the understanding of insect chemical communication mechanisms, particularly with agricultural pests and disease vectors, and could result in future strategies to reduce their negative effects. In this study, we propose molecular models for insect olfactory receptor co-receptor OR83b and its possible functional oligomeric states. The functional similarity of OR83b to GPCRs and ion channels has been exploited for understanding the structure of OR83b. We could observe that C-terminal region (TM4-7) of OR83b is involved in homodimer amd heterodimer formation (with OR22a) which suggests why C-terminus of insect ORs are highly conserved across different species. We also propose two possible ion channel pathways in OR83b: one formed by TM4-5 region with intracellular pore-forming domain and the other formed by TM5-6 with extracellular pore forming domain using analysis of the electrostatics distribution of the pore forming domain.

scholarly journals Organization and distribution of glomeruli in the bowhead whale olfactory bulb

2014 ◽  
Author(s):  
Takushi Kishida ◽  
J. G. M. Thewissen ◽  
Sharon Usip ◽  
John C George ◽  
Robert S Suydam
Keyword(s):  
Olfactory Bulb ◽  
Olfactory Receptor ◽  
Olfactory Receptors ◽  
Molecular Data ◽  
Dorsal Side ◽  
Bowhead Whale ◽  
Model Organisms ◽  
Marker Genes ◽  
Baleen Whales ◽  
Olfactory Receptor Genes

Although modern baleen whales still possess a functional olfactory systems that includes olfactory bulbs, cranial nerve I and olfactory receptor genes, their olfactory capabilities have been reduced profoundly. This is probably in response to their fully aquatic lifestyle. The glomeruli that occur in the olfactory bulb can be divided into two non-overlapping domains, a dorsal domain and a ventral domain. Recent molecular studies revealed that all modern whales have lost olfactory receptor genes and marker genes that are specific to the dorsal domain, and that a modern baleen whale possess only 60 olfactory receptor genes. Here we show that olfactory bulb of bowhead whales (Balaena mysticetus, Mysticeti) lacks glomeruli on the dorsal side, consistent with the molecular data. In addition, we estimate that there are more than 4,000 glomeruli in the bowhead whale olfactory bulb. Olfactory sensory neurons that express the same olfactory receptor in mice generally project to two specific glomeruli in an olfactory bulb, meaning that ratio of the number of olfactory receptors : the number of glomeruli is approximately 1:2. However, we show here that this ratio is not applicable to whales, indicating the limitation of mice as model organisms for understanding the initial coding of odor information among mammals.

scholarly journals Adaptive integrate-and-fire model reproduces the dynamics of olfactory receptor neuron responses in a moth

2019 ◽  
Vol 16 (157) ◽  
pp. 20190246 ◽  
Author(s):  
Marie Levakova ◽  
Lubomir Kostal ◽  
Christelle Monsempès ◽  
Philippe Lucas ◽  
Ryota Kobayashi
Keyword(s):  
Olfactory Receptor ◽  
Time Course ◽  
Olfactory Receptor Neuron ◽  
Receptor Activation ◽  
Olfactory Receptor Neurons ◽  
Response Dynamics ◽  
Spike Threshold ◽  
Olfactory Stimuli ◽  
Receptor Neurons ◽  
The Brain

In order to understand how olfactory stimuli are encoded and processed in the brain, it is important to build a computational model for olfactory receptor neurons (ORNs). Here, we present a simple and reliable mathematical model of a moth ORN generating spikes. The model incorporates a simplified description of the chemical kinetics leading to olfactory receptor activation and action potential generation. We show that an adaptive spike threshold regulated by prior spike history is an effective mechanism for reproducing the typical phasic–tonic time course of ORN responses. Our model reproduces the response dynamics of individual neurons to a fluctuating stimulus that approximates odorant fluctuations in nature. The parameters of the spike threshold are essential for reproducing the response heterogeneity in ORNs. The model provides a valuable tool for efficient simulations of olfactory circuits.

FINITE DIMENSIONAL STRUCTURE OF THE GPI DISCHARGE IN PATIENTS WITH PARKINSON'S DISEASE

2011 ◽  
Vol 21 (03) ◽  
pp. 175-186 ◽  
Author(s):  
DANIELA SABRINA ANDRES ◽  
DANIEL CERQUETTI ◽  
MARCELO MERELLO
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Lyapunov Exponent ◽  
Stochastic Systems ◽  
Rating Scale ◽  
Severe Disease ◽  
Dimensional Structure ◽  
Maximal Lyapunov Exponent ◽  
Embedding Dimension ◽  
Low Dimensional

Stochastic systems are infinitely dimensional and deterministic systems are low dimensional, while real systems lie somewhere between these two limit cases. If the calculation of a low (finite) dimension is in fact possible, one could conclude that the system under study is not purely random. In the present work we calculate the maximal Lyapunov exponent from interspike intervals time series recorded from the internal segment of the Globus Pallidusfrom patients with Parkinson's disease. We show the convergence of the maximal Lyapunov exponent at a dimension equal to 7 or 8, which is therefore our estimation of the embedding dimension for the system. For dimensions below 7 the observed behavior is what would be expected from a stochastic system or a complex system projecting onto lower dimensional spaces. The maximal Lyapunov exponent did not show any differences between tremor and akineto-rigid forms of the disease. However, it did decay with the value of motor Unified Parkinson's Disease Rating Scale -OFF scores. Patients with a more severe disease (higher UPDRS-OFF score) showed a lower value of the maximal Lyapunov exponent. Taken together, both indexes (the maximal Lyapunov exponent and the embedding dimension) remark the importance of taking into consideration the system's non-linear properties for a better understanding of the information transmission in the basal ganglia.

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