Jean-Pierre Rospars

French National Institute for Agriculture, Food, and Environment (INRAE) | INRAE · Physiologie de l'Insecte : Signalisation et Communication (PISC)

Quick reactions to fast changes in the environment are crucial in animal behaviour and survival, for example to seize prey, escape predators, or negotiate obstacles. Here, we study the 'simple reaction time' that is the time elapsed between receptor stimulation and motor activation as typically shown in escape reactions, for mobile organisms of var...

Long-distance olfactory search behaviors depend on odor detection dynamics. Due to turbulence, olfactory signals travel as bursts of variable concentration and spacing and are characterized by long-tail distributions of odor/no-odor events, challenging the computing capacities of olfactory systems. How animals encode complex olfactory scenes to tra...

Raster plot of pseudo-populations of ORNs (A) and PNs (B) in response to the same frozen sequence of white-noise odor stimuli (correlation time 50 ms). Successive lines with the same color correspond to the repetition of the stimulation sequence in the same neuron. Below each raster, the population peri-stimulus time histogram is included. (EPS)

Parametrization of the shapes of PN linear filter sets. Short term linear filters of 97 PNs were time-shifted according to their onset times and the PC analysis was performed again. (A) Time-shifted linear filters sorted by decreasing θ (see Fig 4A). (B) First two principal components for the PN short-term filter set. Same conventions as in Fig 4D....

Comparison of whole antenna and peri-sensillum odor delivery devices. (A) Number of action potentials evoked until the firing frequency returned to baseline in response to 200-ms stimuli with different pheromone loads (n = 7). The 10 ng pheromone load used with the whole antenna stimulator induced approximatively the same ORN responses as 1 to 10 p...

Long-distance olfactory search behaviors depend on odor detection dynamics. Due to turbulence, olfactory signals travel as bursts of variable concentration and spacing and are characterized by long-tail distributions of odor/no-odor events, challenging the computing capacities of olfactory systems. How animals encode complex olfactory scenes to tra...

Self-locomotion is central to animal behaviour and survival. It is generally analysed by focusing on preferred speeds and gaits under particular biological and physical constraints. In the present paper we focus instead on the maximum speed and we study its order-of-magnitude scaling with body size, from bacteria to the largest terrestrial and aqua...

We propose to formally extend the notion of specific tension, i.e. force per cross-sectional area-classically used for muscles, to quantify forces in molecular motors exerting various biological functions. In doing so, we review and compare the maximum tensions exerted by about 265 biological motors operated by about 150 species of different taxono...

Despite their variety and complexity, living organisms obey simple scaling laws due to the universality of the laws of physics. In the present paper, we study the scaling between maximum speed and size, from bacteria to the largest mammals. While the preferred speed has been widely studied in the framework of Newtonian mechanics, the maximum speed...

The antennal lobe (AL) of the Noctuid moth Agrotis ipsilon has emerged as an excellent model for studying olfactory processing and its plasticity in the central nervous system. Odor-evoked responses of AL neurons and input-to-output transformations involved in pheromone processing are well characterized in this species. However, the intrinsic elect...

In the olfactory system of male moths, a specialized subset of neurons detects and processes the main component of the sex pheromone emitted by females. It is composed of several thousand first-order olfactory receptor neurons (ORNs), all expressing the same pheromone receptor, that contact synaptically a few tens of second-order projection neurons...

In nature, male moths are exposed to a complex plant odorant environment when they fly upwind to a sex pheromone source in their search for mates. Plant odors have been shown to affect responses to pheromone at various levels but how does pheromone affects plant odor perception? We recorded responses from neurons within the non-pheromonal "ordinary...

Biological olfaction outperforms chemical instrumentation in specificity, response time, detection limit, coding capacity, time stability, robustness, size, power consumption, and portability. This biological function provides outstanding performance due, in a large extent, to the unique architecture of the olfactory pathway, which combines a high...

The quality of electrophysiological recordings varies a lot due to technical and biological variability and neuroscientists inevitably have to select "good" recordings for further analyses. This procedure is time-consuming and prone to selection biases. Here, we investigate replacing human decisions by a machine learning approach. We define 16 feat...

The f I term of Drake's equation – the fraction of life-bearing planets on which ‘intelligent’ life evolved – has been the subject of much debate in the last few decades. Several leading evolutionary biologists have endorsed the thesis that the probability of intelligent life elsewhere in the universe is vanishingly small. A discussion of this thes...

A major challenge in sensory neuroscience is to elucidate the coding and processing of stimulus representations in successive populations of neurons. Here we recorded the spiking activity of receptor neurons (RNs) and mitral/tufted cells (MCs) in the frog olfactory epithelium and olfactory bulb respectively, in response to four odorants applied at...

Biological olfaction outperforms chemical instrumentation in specificity, response time, detection limit, coding capacity, time stability, robustness, size, power consumption, and portability. This biological function provides outstanding performance due, to a large extent, to the unique architecture of the olfactory pathway, which combines a high...

Biological olfaction outperforms chemical instrumentation in specificity, response time, detection limit, coding capacity, time stability, robustness, size, power consumption, and portability. This biological function provides outstanding performance due, to a large extent, to the unique architecture of the olfactory pathway, which combines a high...

INSECTS AND ROBOTS SEARCHING FOR ODOUR SOURCES IN TURBULENT PLUMES FACE THE SAME PROBLEM: the random nature of mixing causes fluctuations and intermittency in perception. Pheromone-tracking male moths appear to deal with discontinuous flows of information by surging upwind, upon sensing a pheromone patch, and casting crosswind, upon losing the plum...

casting and search game theory. Casting-surge is decomposed into a casting path (in red) and a surge path (straight line in black from p to t). A. If no direction information is available, spiral-surge achieves a competitive ratio r = 22.513. B. Given that the target is not downwind, zigzagging-surge achieves a competitive ratio r = 9.0554. (TIF)

Supporting text S1 includes: Segmentation of the On phase in firing response patterns, Receiver operating characteristic (ROC) analysis, On/Off neuron model equations, Casting and search game theory, References. (PDF)

Two-step casting: SK intact. This movie shows an example of the cyborg experiment with two-step casting: On→upwind surge, Off→casting 1 (crosswind zigzag), baseline→casting 2 (non-oriented spiral). (MOV)

Effect of stimulus and air-gap durations. (A) We stimulated On/Off neurons (n = 5) with different stimulus durations (a unique puff, stimulus duration from 100 ms to 1 s). On duration showed a linear dependence on stimulus duration (data are presented as mean±s.d.): On duration = 0.99×(stimulus duration) +18 ms (pearson correlation r2 = 0.97). (B)....

Simulation of the neuron model. (A). ORN population model considered as a non-homogeneous Poisson process with rate parameter λ(t). The population firing rate λ(t) was derived from experimental data (12). The instantaneous firing rate of 42 ORNs recorded for a stimulus dose of 1 ng and stimulus durations of 200 ms, 500 ms and 1 s was fitted as a su...

One-step casting: SK intact vs SK blocked. This movie shows two examples of the cyborg experiments with one-step casting: On→upwind surge, Off and baseline→spiral casting. The EAG input and On/Off neuron output are indicated in red and green, respectively. The movie contains two parts: channel SK intact and blocked. (MOV)

Pheromone detection with multiple neurons. (A). ROC analysis using three On/Off neurons recorded simultaneously (pheromone pulses of 200 ms, doses from 0.001 to 1 ng). Left: ROC curves calculated for single neurons as well as pairs and triplets (pheromone dose = 0.01 ng). Performance increases when the ROC curve is towards the left corner of the RO...

Chemosensory information is crucial for most insects to feed and reproduce. Olfactory signals are mainly used at a distance, whereas gustatory stimuli play an important role when insects directly contact chemical substrates. In noctuid moths, although the antennae are the main olfactory organ, they also bear taste sensilla. These taste sensilla det...

In this issue of Chemical Senses, Münch et al. present a thorough analysis of how mixtures of odorants interact with olfactory receptors (ORs) borne by olfactory receptor neurons (ORNs). Using fruit fly ORNs expressing the receptor OR22a, they provide a clear example of mixture interaction and confirm that the response of an ORN to a binary mixture...

Male moths are confronted with complex odour mixtures in a natural environment when flying towards a female-emitted sex pheromone source. Whereas synergistic effects of sex pheromones and plant odours have been observed at the behavioural level, most investigations at the peripheral level have shown an inhibition of pheromone responses by plant vol...

A statistical model of the population of first-order olfactory receptor neurons (ORNs) is proposed and analysed. It describes the relationship between stimulus intensity (odour concentration) and coding variables such as rate and latency of the population of several thousand sex-pheromone sensitive ORNs in male moths. Although these neurons likely...

In this paper, we present how the achievements related to NEUROCHEM project (FP7, Bio-ICT, Grant number 216916) have increased the understanding of the olfactory system and helped to develop novel computing architectures and models for chemical sensing. We present the developed computational models of the olfactory pathway of vertebrates and insect...

Sensory systems, both in the living and in machines, have to be optimized with respect to their environmental conditions. The pheromone subsystem of the olfactory system of moths is a particularly well-defined example in which rapid variations of odor content in turbulent plumes require fast, concentration-invariant neural representations. It is no...

The macroglomerular complex (MGC) is known as the olfactory sub-system processing pheromonal information. In the moth Manduca sexta, the projection neurons (PNs) arborizating in the MGC exhibit two types of responses to pheromone stimulation [1]: a simple monophasic long and tonic excitation (+) and a complex multiphasic pattern (excitation-inhibit...

Electrical parameters influencing the amplification factor of RP at soma. (A) Equilibrium potential of auxiliary cells Ea. (B) Equilibrium potential of leak current of soma Els. (C) Leak conductance of soma Gls. (D) Leak conductance of auxiliary cells Ga. (E) Capacitance of soma Cs. (F) Capacitance of auxiliary cell Ca. All parameters are influenti...

Electrical parameters influencing the relative amplification factor of RP at soma as a function pheromone-dependent conductance Gp. (A) Leak conductance at soma Gls. (B) Capacitance of auxiliary cell membranes Ca. For all other electrical parameters the curves obtained are practically superimposed and correspond to the curves for Gls = 1.5 nS and C...

Electrical parameters influencing the rising and falling times of RP and SP. Rising times (left column) and falling times (right column) of RP at soma (blue lines) and SP (red lines). (A, B) Conductance Ga at auxiliary cells. (C, D) Capacitance Ca at auxiliary cells. (E, F) Capacitance Cd at outer dendrite. Effect shown at low (0.1 nS), intermediat...

Electrical parameters influencing the height of RP at soma and SP. (A) Transepithelial potential Ea at auxiliary cells. (B) Leak battery at soma Els. (C, D) Leak conductance Gls at the inner dendrite and soma. (E) Conductance Ga at auxiliary cells. (F) Capacitance Ca at auxiliary cells. Effects shown at low (0.1 nS), intermediate (1 nS) and high (1...

In insects, olfactory receptor neurons (ORNs), surrounded with auxiliary cells and protected by a cuticular wall, form small discrete sensory organs--the sensilla. The moth pheromone-sensitive sensillum is a well studied example of hair-like sensillum that is favorable to both experimental and modeling investigations. The model presented takes into...

The inference of the rate-based model of the Hodgkin–Huxley neuron. (PDF)

For some moth species, especially those closely interrelated and sympatric, recognizing a specific pheromone component concentration ratio is essential for males to successfully locate conspecific females. We propose and determine the properties of a minimalist competition-based feed-forward neuronal model capable of detecting a certain ratio of ph...

The molecular mechanisms that control the binding of odorant to olfactory receptors and transduce this signal into membrane depolarization are reviewed. They are compared in vertebrates and insects for interspecific (allelochemicals) and intraspecific (pheromones) olfactory signals. Attempts to develop quantitative models of these multistage signal...

A frequent opinion among biologists upholds that biological evolution is contingent and, consequently, that man's apparition is a random event of very small probability. We present various arguments against this view, based on chemistry, molecular biology, evolutionary convergences, the existence of physical constraints on the structure of living b...

How information is transformed along synaptic processing stages is critically important to understand the neural basis of behavior in any sensory system. In moths, males rely on sex pheromone to find their mating partner. It is essential for a male to recognize the components present in a pheromone blend, their ratio, and the temporal pattern of th...

The response of insect olfactory receptor neurons (ORNs) to odorants involves the opening of Ca(2+)-permeable channels, generating an increase in intracellular Ca(2+) concentration. Here, we studied the downstream effect of this Ca(2+) rise in cultured ORNs of the moth Spodoptera littoralis. Intracellular dialysis of Ca(2+) from the patch pipette i...

A biochemical model of the receptor, G-protein and effector (RGE) interactions during transduction in the cilia of vertebrate olfactory receptor neurons (ORNs) was developed and calibrated to experimental recordings of cAMP levels and the receptor current (RC). The model describes the steps from odorant binding to activation of the effector enzyme...

Matlab script for solving the dynamic equations of the RGE model, when fitted to the three data sets tk05, d05 and etk05

In order to locate their mates, male moths have to detect and interpret specific blends of odours -pheromones- released by the females and dispersed by the wind. In male moths, sex pheromones are detected by specialized olfactory receptor neurons situated in cuticular sensilla on the antennae and processed within the Macro-Glomerular Complex (MGC)...

The oriental fruit moth Cydia molesta is an important pest and the behavioural role of olfactory signals such as pheromones and plant volatiles have been studied extensively in both sexes. To understand odour processing further, however, detailed knowledge of the anatomy of the olfactory system is crucial. In the present study, an atlas of the ante...

The primary olfactory centres share striking similarities across the animal kingdom. The most conspicuous is their subdivision into glomeruli, which are spherical neuropil masses in which synaptic contacts between sensory and central neurons occur. Glomeruli have both an anatomical identity (being invariant in location, size and shape) and a functi...

We modeled the firing rate of populations of olfactory receptor neurons (ORNs) responding to an odorant at different concentrations. Two cases were considered: a population of ORNs that all express the same olfactory receptor (OR), and a population that expresses many different ORs. To take into account ORN variability, we replaced single parameter...

To find a mating partner, moths rely on pheromone communication. Released in very low amounts, female sex pheromones are used by males to identify and localize females. Depending on the physiological state (i.e. age, reproductive state), the olfactory system of the males of the noctuid moth Agrotis ipsilon is 'switched on or off'. To understand the...

A biophysical model of receptor potential generation in the male moth olfactory receptor neuron is presented. It takes into account all pre-effector processes--the translocation of pheromone molecules from air to sensillum lymph, their deactivation and interaction with the receptors, and the G-protein and effector enzyme activation--and focuses on...

Functional significance of nonlinear mechanisms and sensitivity analysis of model parameters. (0.08 MB DOC)

In biological olfactory systems, interaction of odorant molecules with olfactory receptor proteins is driven by Brownian motion. As a result, at chemical equilibrium, the total number of bound receptors changes randomly in time. Here we investigate the role of this effect, known in physics as adsorption-desorption noise, in the discriminating abili...

Une synchronisation neuronale est observée dès le premier étage de traitement du système olfactif, à savoir le lobe antennaire chez l'insecte. Dans le cas du papillon de nuit Manduca sexta, cette synchronisation est plus importante en présence du mélange phéromonal qu'en présence d'un composé simple. Dans cet article, nous proposons un modèle du co...

The haematophagous bug Rhodnius prolixus has been a model system in insect physiology for a long time. Recently, several studies have been devoted to its sensory systems, including olfaction. However, few data are available on the basic organisation of the nervous system in this species. By means of neuronal backfills, histology, confocal microscop...

We analyze the first phase of information transduction in the model of the olfactory receptor neuron of the male moth Antheraea polyphemus. We predict such stimulus characteristics that enable the system to perform optimally, i.e., to transfer as much information as possible. Few a priori constraints on the nature of stimulus and stimulus-to-signal...

Neuronal responses evoked in sensory neurons by static stimuli of various intensities are usually characterized by their input-output transfer function, i.e. by plotting the firing frequency (or any other measurable neuron response) versus the corresponding stimulus intensity. The aim of the present article is to determine the stimulus intensities...

The concept of coding efficiency holds that sensory neurons are adapted, through both evolutionary and developmental processes, to the statistical characteristics of their natural stimulus. Encouraged by the successful invocation of this principle to predict how neurons encode natural auditory and visual stimuli, we attempted its application to olf...

Most olfactory receptor neurons (ORNs) express a single type of olfactory receptor that is differentially sensitive to a wide variety of odorant molecules. The diversity of possible odorant-receptor interactions raises challenging problems for the coding of complex mixtures of many odorants, which make up the vast majority of real world odors. Pure...

Fast information transfer in neuronal systems rests on series of action potentials, the spike trains, conducted along axons. Methods that compare spike trains are crucial for characterizing different neuronal coding schemes. In this paper we review recent results on the notion of spiking randomness, and discuss its properties with respect to the ra...

To study sensory neurons, the neuron response is plotted versus stimulus level. The aim of the present contribution is to determine how well two different levels of the incoming stimulation can be distinguished on the basis of their evoked responses. Two generic models of response function are presented and studied under the influence of noise. We...

s - A single PDF containing all abstracts in this Supplement is available here http://www. biomedcentral.co m/content/pdf/14 71-2202-8-S2-in fo.pdf