Odor Trails Research Articles

Sector search strategies for odor trail tracking

Ants, mice, and dogs often use surface-bound scent trails to establish navigation routes or to find food and mates, yet their tracking strategies remain poorly understood. Chemotaxis-based strategies cannot explain casting, a characteristic sequence of wide oscillations with increasing amplitude performed upon sustained loss of contact with the trail. We propose that tracking animals have an intrinsic, geometric notion of continuity, allowing them to exploit past contacts with the trail to form an estimate of where it is headed. This estimate and its uncertainty form an angular sector, and the emergent search patterns resemble a "sector search." Reinforcement learning agents trained to execute a sector search recapitulate the various phases of experimentally observed tracking behavior. We use ideas from polymer physics to formulate a statistical description of trails and show that search geometry imposes basic limits on how quickly animals can track trails. By formulating trail tracking as a Bellman-type sequential optimization problem, we quantify the geometric elements of optimal sector search strategy, effectively explaining why and when casting is necessary. We propose a set of experiments to infer how tracking animals acquire, integrate, and respond to past information on the tracked trail. More generally, we define navigational strategies relevant for animals and biomimetic robots and formulate trail tracking as a behavioral paradigm for learning, memory, and planning.

Dogs display owner-specific expectations based on olfaction

Most current knowledge about dogs’ understanding of, and reacting to, their environment is limited to the visual or auditory modality, but it remains unclear how olfaction and cognition are linked together. Here we investigate how domestic dogs search for their owners using their excellent olfactory sense. We raise the question whether dogs have a representation of someone when they smell their track. The question is what they expect when they follow a trail or whether they perceive an odour as a relevant or non-relevant stimulus. We adopted a classical violation-of-expectation paradigm—and as targets we used two persons that were both important to the dog, usually the owners. In the critical condition subjects could track the odour trail of one target, but at the end of the trail they find another target. Dogs showed an increased activity when the person did not correspond with the trail compared to a control condition. Moreover, we found huge individual differences in searching behaviour supporting the assumption that dogs are only able to smell when they really sniff, and that the temperature has an influence on dogs performance. Results are discussed in the light of how cognitive abilities, motivation and odour perception influence each other.

Redefining the study of sexual dimorphism in bats: following the odour trail

Abstract Sexual dimorphism is the condition in which males and females of the same species are easily distinguished by specific traits (secondary sex characteristics), often related to body size, colour patterns, weapons, and ornaments. Males of many mammal species tend to be larger or more ornamented than females, and these characteristics tend to be more pronounced in polygynous, diurnal, and open‐habitat species. Bats have long been considered a largely non‐sexually dimorphic group due to lack of conspicuous differences in body size and other cranial and skeletal characters. However, bats, like many mammals, exhibit a diverse array of soft‐tissue integumentary glands and non‐glandular odour‐producing structures with intense odorous substances that have not been thoroughly investigated, although postulated functions include facilitating mate selection in their generally polygynous associations. To date, there has been no systematic assessment of the occurrence or expression of sexually dimorphic traits in bats, many of which show intriguing sexual dimorphism in soft tissue, and most of which involve intense odours. In this study, we review evidence of integumentary glands and non‐glandular odour‐producing structures known in bats, as a first step towards identifying future research pathways to study sexual dimorphism in bats. Highly variable glands and non‐glandular odour‐producing structures have been noticed in ten different regions of the body, but are most frequently found on the head and the ventral region of the neck. They have been described in nearly 9% of bat species and in 70% of 21 extant bat families. Our review, based on extremely scattered and unevenly detailed literature, unveils the extraordinary sexual dimorphism that has been observed in Chiroptera to date, identifying not only target body parts where sexually dimorphic traits are likely to be found, but also critical avenues for future investigation and discoveries, and stressing the importance of the timing of secondary sexual trait observations, behavioural studies, and chemical analyses.

Spatial allocation without spatial recruitment in bumblebees

AbstractAny foraging animal is expected to allocate its efforts among resource patches that vary in quality across time and space. For social insects, this problem is shifted to the colony level: the task of allocating foraging workers to the best patches currently available. To deal with this task, honeybees rely upon differential recruitment via the dance language, while some ants use differential recruitment on odor trails. Bumblebees, close relatives of honeybees, should also benefit from optimizing spatial allocation but lack any targeted recruitment system. How bumblebees solve this problem is thus of immense interest to evolutionary biologists studying collective behavior. It has been thought that bumblebees could solve the spatial allocation problem by relying on the summed individual decisions of foragers, who occasionally sample and shift to alternative resources. We use field experiments to test the hypothesis that bumblebees augment individual exploration with social information. Specifically, we provide behavioral evidence that, when higher-concentration sucrose arrives at the nest, employed foragers abandon their patches to begin searching for the better option; they are more likely to accept novel resources if they match the quality of the sucrose solution experienced in the nest. We explored this strategy further by building an agent-based model of bumblebee foraging. This model supports the hypothesis that using social information to inform search decisions is advantageous over individual search alone. Our results show that bumblebees use a collective foraging strategy built on social modulation of individual decisions, providing further insight into the evolution of collective behavior.

Research Spotlights

We have two Research Spotlights papers in the lineup this issue. The first of these, “Persistent Homology of Geospatial Data: A Case Study with Voting," written by Michelle Feng and Mason Porter, is quite timely. The article begins with a gentle introduction into the what and why of persistent homology (PH): after converting the point cloud of data into a series of simplicial complexes at different scales, the homology groups are computed at each scale, with homological features tracked across scales. It is generally assumed that persistence of features can then be used to distinguish signal (important patterns) from noise. Of concern is the method of converting the data into the simplicial complexes. The authors argue that PH using the simplicial complexes computed via the distance-based approach can lead to erroneous assumptions or missed characteristics about the voting data they consider. They propose to counter these deficiencies by developing two new methods, one based on adjacency networks and one that utilizes level sets to capture the manifold nature of the data, for building a filtered simplicial complex. The dramatic differences achieved by varying the complexes on the resulting PH are colorfully illustrated and interpreted for real voter data. Readers may appreciate not only the tools used and results obtained, but also the broad range of problems---transportation networks, spatial demography, granular materials, biological structures---identified by the authors for which the new approaches may prove relevant. An animal's ability to localize odor sources and follow trails of odor is key to many aspects of its survival. Authors Nour Riman, Jonathan D. Victor, Sebastian D. Boie, and Bard Ermentrout focus their article, “The Dynamics of Bilateral Olfactory Search and Navigation," on providing a comprehensive mathematical analysis of the dynamics of the differential equations that model the way that animals use bilateral information to navigate odor sources. When odor sensors are located at two different positions of the body, it enables comparison of odor concentrations and thus allows the animal to determine whether to move toward or away from the stimulus. Tropotaxis in the present context refers to the movement of the animal in response to an odor directly toward or away from the source of the odor. The sensor angles, which the animal can control, play an important role in enabling the animal to find and follow a trail. The other model parameters include sensor length and sensitivity to concentration change. The authors investigate tropotaxis as functions of the model parameters under varying conditions for the odor sources and trails. In some cases, the authors are able to reduce the dynamics to a planar system. Graphical illustrations compliment the discussion of the behavior. The paper concludes with a discussion of future research, particularly with respect to exploring the effects of noise on the models. It is the hope that this new “understanding [of] the underlying dynamics of the bilateral model will help in building models that use bilateral information together with other strategies."

The Dynamics of Bilateral Olfactory Search and Navigation

Animals use stereo sampling of odor concentration to localize sources and follow odor trails. We analyze the dynamics of a bilateral model that depends on the simultaneous comparison between odor concentrations detected by left and right sensors. The general model consists of three differential equations for the positions in the plane and the heading. When the odor landscape is an infinite trail, then we reduce the dynamics to a planar system whose dynamics have just two fixed points. Using an integrable approximation (for short sensors) we estimate the basin of attraction. In the case of a radially symmetric landscape, we again can reduce the dynamics to a planar system, but the behavior is considerably richer with multi-stability, isolas, and limit cycles. As in the linear trail case, there is also an underlying integrable system when the sensors are short. In odor landscapes that consist of multiple spots and trail segments, we find periodic and chaotic dynamics and characterize the behavior on trails with gaps and that turn corners.

Working qualities of search dogs of German and Belgian shepherd breeds

The main tasks for which canine units of law enforcement agencies of Ukraine use search dogs are: inspection of various areas and search operations to identify persons who have committed or intend to commit offenses, their odors and things, detection of persons moving or hiding in the condition of limited visibility in the area; prosecution of offenders, their detention, protection and escort; inspection of trucks and localization of persons hiding in these vehicles; odorological identification of odorous traces of detainees and their belongings; strengthening the personal security of law enforcement officers during their service; psychological impact on offenders. The fundamentals for the active use of dogs in official activities are the physiological features of the olfactory analyser and the physical capabilities of the dog's body. The most common breeds used to perform the outlined tasks are: German shepherd, Bloodhound, Belgian shepherd (Malinois) and others. The article reflects the comparative characteristics of the working qualities of search dogs of German and Belgian (Malinois) shepherd dogs of different sexes and ages. The study was conducted on service dogs in the Canine Training Center of the State Border Guard Service of Ukraine located in Velyki Mosty, Sokal district, Lviv region. The working qualities of search dogs were assessed by the skills of obedience, protection, pursuit of a person on his odor trail, secure of the area and detection of a person hiding and moving, selection of odorous objects (things), search and detection of objects (things). It is fixed that the working qualities of search dogs are influenced by breed and sex. Among the males of the German and Belgian (Malinois) Shepherd breeds, the service dogs of the German Shepherd breed were noted for the best working qualities, and among the female – the Belgian Shepherd (Malinois) breeds. A generalized assessment of all four sections of the studied breeds showed that the best performance was in males of the German Shepherd breed (325.4 points) and females of the Belgian Shepherd breed (Malinois) (325.9 points), and among individuals of different sexes – males compared to females of the German Shepherd breed and females compared to males of the Belgian Shepherd (Malinois) breed. Two-year-old males and one-year-old females of the German shepherd breed and two-year-old females of the Belgian Shepherd breed (Malinois) were noted for the best working qualities in terms of skills to be evaluated. As for males of the last breed, their testing qualities almost did not depend on age. The strength of the influence of the breed of service dogs on their working qualities in the skills to be assessed ranged from 0.6 to 6.8 %, sex – from 0.1 to 7.3 % and age - from 0.1 to 11.4 %. The general assessment of service dogs in all sections was generally influenced by their age (1.6 %).

Conspecific chemical cues facilitate mate trailing by invasive Argentine black and white tegus.

Squamate reptiles (snakes and lizards) rely on chemical cues from conspecifics to search the environment for potential mates. How such cues are used by invasive species to facilitate reproduction, especially seasonally, is a key question that can inform management practices. The Argentine black and white tegu (Salvator merianae) is an invasive reptile species in south Florida threatening native fauna in biodiverse regions such as Everglades National Park. While some information exists on the reproductive ecology of this species in its native range in South America, the chemical ecology of S. merianae is unclear especially in its invasive range. By testing both male (n = 7) and female (n = 7) tegus in a Y-maze apparatus, we assessed if either sex follows chemical trails left by conspecifics and if behaviors were sex- or season-specific. We conducted three types of trials where conspecifics created odor trails: Male-only (male scent only in base and one arm of Y), Female-only, and Male vs. female. Males did not preferentially follow scent trails from either sex, but they did differentially investigate conspecific scent from both sexes. Seasonally, males showed increased rates of chemosensory sampling (rates of tongue-flicking) during the spring (breeding season; March-May) compared to fall (non-breeding season; September-November). Males also had reduced turning and pausing behavior while trailing in the spring. Female tegus exhibited stronger conspecific trailing abilities than males, following both male and female scent trails, and they explored the maze less before making an arm choice. Females also investigated the scent trails intensely compared to males (more passes in scented arms, more time with scent trails). Our results demonstrate for the first time that females of an invasive reptile species can follow conspecific scent trails. Given the strong female responses to odor, sex-specific targeting of tegus via application of a conspecific chemical cue in traps could enhance removal rates of females during the breeding season.

A ball is not a Kong: Odor representation and search behavior in domestic dogs (Canis familiaris) of different education.

There has been a growing interest in the cognitive skills of domestic dogs, but most current knowledge about dogs' understanding of their environment is limited to the visual or auditory modality. Although it is well known that dogs have an excellent olfactory sense and that they rely on olfaction heavily when exploring the environment or recognizing individuals, it remains unclear whether dogs perceive odors as representing specific objects. In the current study, we examined this aspect of dogs' perception of the world. Dogs were presented with a violation-of-expectation paradigm in which they could track the odor trail of one target (Target A), but at the end of the trail, they found another target (Target B). We explored (a) what dogs expect when they smell the trail of an object, (b) how they search for an object, and (c) how their educational background influences their ability to find a hidden object, by comparing family dogs and working dogs that had passed exams for police or rescue dogs. We found that all subjects showed a flexible searching behavior, with the working dogs being more effective but the family dogs learning to be effective over trials. In the first trial, dogs showed measurable signs of "surprise" (i.e., further searching for Target A) when they found Target B, which did not correspond to the odor of Target A from the trail. We conclude that dogs represent what they smell and search flexibly, which is independent from their educational background. (PsycINFO Database Record

Carpenter ants use diverse antennae sampling strategies to track odor trails.

Directed and meaningful animal behavior depends on the ability to sense key features in the environment. Among the different environmental signals, olfactory cues are critically important for foraging, navigation and social communication in many species, including ants. Ants use their two antennae to explore the olfactory world, but how they do so remains largely unknown. In this study, we used high-resolution videography to characterize the antennae dynamics of carpenter ants (Camponotus pennsylvanicus). Antennae are highly active during both odor tracking and exploratory behavior. When tracking, ants used several distinct behavioral strategies with stereotyped antennae sampling patterns (which we call 'sinusoidal', 'probing' and 'trail following'). In all behaviors, left and right antennae movements were anti-correlated, and tracking ants exhibited biases in the use of left versus right antenna to sample the odor trail. These results suggest non-redundant roles for the two antennae. In one of the behavioral modules (trail following), ants used both antennae to detect trail edges and direct subsequent turns, suggesting a specialized form of tropotaxis. Lastly, removal of an antenna resulted not only in less accurate tracking but also in changes in the sampling pattern of the remaining antenna. Our quantitative characterization of odor trail tracking lays a foundation to build better models of olfactory sensory processing and sensorimotor behavior in terrestrial insects.

Tracking of unfamiliar odors is facilitated by signal amplification through anoctamin 2 chloride channels in mouse olfactory receptor neurons.

Many animals follow odor trails to find food, nesting sites, or mates, and they require only faint olfactory cues to do so. The performance of a tracking dog, for instance, poses the question on how the animal is able to distinguish a target odor from the complex chemical background around the trail. Current concepts of odor perception suggest that animals memorize each odor as an olfactory object, a percept that enables fast recognition of the odor and the interpretation of its valence. An open question still is how this learning process operates efficiently at the low odor concentrations that typically prevail when animals inspect an odor trail. To understand olfactory processing under these conditions, we studied the role of an amplification mechanism that boosts signal transduction at low stimulus intensities, a process mediated by calcium‐gated anoctamin 2 chloride channels. Genetically altered Ano2 −/− mice, which lack these channels, display an impaired cue‐tracking behavior at low odor concentrations when challenged with an unfamiliar, but not with a familiar, odor. Moreover, recordings from the olfactory epithelium revealed that odor coding lacks sensitivity and temporal resolution in anoctamin 2‐deficient mice. Our results demonstrate that the detection of an unfamiliar, weak odor, as well as its memorization as an olfactory object, require signal amplification in olfactory receptor neurons. This process may contribute to the phenomenal tracking abilities of animals that follow odor trails.

Blown by the wind: the ecology of male courtship display behavior in orchid bees.

Many insects rely on chemical signals to transmit precise information on the location, identity, and quality of potential mates. Chemical signals are often broadcasted at sites with physical properties that maximize signal propagation and signal transmission. Male neotropical orchid bees (Euglossini) perch and display on vertical branches and tree trunks in the forest to expose volatile blends (perfumes) that they previously collected from their environment. Previous studies have shown that the chemical composition of perfume blends is highly differentiated even between closely related species. However, variation in behavioral components of perfume exposure and male display remain poorly understood. We conducted a four-year study on orchid bee display sites (8 species) in pacific Costa Rica, using field observations along with chemical analysis and cage experiments to assess display niche partitioning among sympatric species. We evaluated the influence of physical factors (terrain, wind, light) on the distribution of perch sites and on display behavior, and tested a prediction of the sex pheromone-analogue hypothesis, i.e., that displaying males have above-average quantities or qualities of acquired perfumes. Males of different species displayed in the same general area and sometimes in close proximity to each other, but partitioned the display niche by selecting different perch diameters, display heights, and by displaying at different times of the day. Most perch sites were located inside the forest on elevated ground, especially along ridges, where stronger winds may help disperse perfume signals. Furthermore, the angular position of displaying males on perches was narrowly determined by wind direction, with males being positioned on the downwind side of the perch, where they would be most conspicuous to conspecifics approaching on an odor trail. Although our results generally support the hypothesis that perfumes serve as pheromone analogues, we did not find differences in the perfume composition of males caught at display perches and males captured at chemical baits. This suggests that, while chemical communication is an integral part of orchid bee display, male display activity is not determined by the history of, and success in, volatile acquisition.

Multiple orientation cues in an Australian trunk-trail-forming ant, Iridomyrmex purpureus

Ants use multiple cues for navigating to a food source or nest location. Directional information is derived from pheromone trails or visual landmarks or celestial objects. Some ants use the celestial compass information along with an ‘odometer’ to determine the shortest distance home, a strategy known as path integration. Some trail-following ants utilise visual landmark information whereas few of the solitary-foraging ants rely on both path integration and visual landmark information. However, it is unknown to what degree trail-following ants use path integration and we investigated this in a trunk-trail-following ant, Iridomyrmex purpureus. Trunk-trail ants connect their nests to food sites with pheromone trails that contain long-lasting orientation information. We determined the use of visual landmarks and the ability to path integrate in a trunk-trail forming ant. We found that experienced animals switch to relying on visual landmark information, and naïve individuals rely on odour trails. Ants displaced to unfamiliar locations relied on path integration, but, surprisingly, they did not travel the entire homebound distance. We found that as the homebound distance increased, the distance ants travelled relying on the path integrator reduced.

The Sensory Ecology of Ant Navigation: From Natural Environments to Neural Mechanisms.

Animals moving through the world are surrounded by potential information. But the components of this rich array that they extract will depend on current behavioral requirements and the animal's own sensory apparatus. Here, we consider the types of information available to social hymenopteran insects, with a specific focus on ants. This topic has a long history and much is known about how ants and other insects use idiothetic information, sky compasses, visual cues, and odor trails. Recent research has highlighted how insects use other sensory information for navigation, such as the olfactory cues provided by the environment. These cues are harder to understand because they submit less easily to anthropomorphic analysis. Here, we take an ecological approach, considering first what information is available to insects, then how different cues might interact, and finally we discuss potential neural correlates of these behaviors.

The influence of host species and location in the host detection ability of tiphiid (Hymenoptera: Tiphiidae) parasitoids.

Tiphia vernalis Rohwer and Tiphia popilliavora Rohwer are ectoparasitoids of root-feeding larvae of the Japanese beetle, Popillia japonica Newman, and oriental beetles, Anomala orientalis Waterhouse (Coleoptera: Scarabaeidae). Little is known about the influence of host species and location in the host detection ability of tiphiid wasps. In this study, we examined the response of female T. popilliavora wasps, an understudied Tiphia species, to potential host stimuli using dual choice tests in an observation chamber filled with soil. T. popilliavora wasps were able to successfully discriminate the trails containing body odor or frass of P. japonica grubs from trails without cues. Frass trails of P. japonica grubs elicited stronger responses than body odor trails. We also examined the preference of host cues by tiphiid wasps using dual choice behavioral assays. Both T. vernalis and T. popilliavora wasps did not show preference toward trails that either contained P. japonica or A. orientalis cues. In addition, we also determined the detection of host cues by tiphiid wasps in a dual-choice test for cues presented at varying soil depths. Wasps were able to successfully discriminate between the Y-tube arms with and without cues when the cues of P. japonica were buried at a depth of 2 cm. In contrast, both Tiphia species were unable to distinguish between the Y-tube arms with and without cues when the cues were buried at a depth of 5 cm. Thus, our findings suggest that once Tiphia wasps land on the ground, they can detect the presence of their specific hosts, just below the soil surface by exploiting the kairomones present in grub body odor trails and frass and once the wasps are in the soil, they use the same cues to direct themselves to the host grubs.

Role of self-generated odor cues in contextual representation.

As first demonstrated in the patient H.M., the hippocampus is critically involved in forming episodic memories, the recall of “what” happened “where” and “when.” In rodents, the clearest functional correlate of hippocampal primary neurons is the place field: a cell fires predominantly when the animal is in a specific part of the environment, typically defined relative to the available visuospatial cues. However, rodents have relatively poor visual acuity. Furthermore, they are highly adept at navigating in total darkness. This raises the question of how other sensory modalities might contribute to a hippocampal representation of an environment. Rodents have a highly developed olfactory system, suggesting that cues such as odor trails may be important. To test this, we familiarized mice to a visually cued environment over a number of days while maintaining odor cues. During familiarization, self-generated odor cues unique to each animal were collected by re-using absorbent paperboard flooring from one session to the next. Visual and odor cues were then put in conflict by counter-rotating the recording arena and the flooring. Perhaps surprisingly, place fields seemed to follow the visual cue rotation exclusively, raising the question of whether olfactory cues have any influence at all on a hippocampal spatial representation. However, subsequent removal of the familiar, self-generated odor cues severely disrupted both long-term stability and rotation to visual cues in a novel environment. Our data suggest that odor cues, in the absence of additional rule learning, do not provide a discriminative spatial signal that anchors place fields. Such cues do, however, become integral to the context over time and exert a powerful influence on the stability of its hippocampal representation. © 2014 The Authors. Hippocampus Published by Wiley Periodicals, Inc.

Phase-Dependent Visual Control of the Zigzag Paths of Navigating Wood Ants

Animals sometimes take sinuous paths to a goal. Insects, tracking an odor trail on the ground [1-3] or moving up an odor plume in the air [4, 5], generally follow zigzag paths. Some insects [6-8] take a zigzag approach to visual targets, perhaps to obtain parallax information. How does an animal keep its overall path in the direction of the goal without disrupting a zigzag pattern? We describe here the wood ant's strategy when guided by a familiar visual scene. If their travel direction is correct, ants face the goal briefly after each turning point along their zigzag path. If the direction is wrong, they turn rapidly at this point to place the scene correctly on their retina. Such saccade-like turns are rare elsewhere in the zigzag. Similarly, when the scene is made to jump to a new position on their retina, ants wait until an expected goal-facing phase of the zigzag before turning to correct the imposed error. Correctly timed, intermittent control allows an animal to adjust its path without compromising additional roles for the zigzag pattern in gathering visual information or in using odor cues for guidance.

Rats track odour trails accurately using a multi-layered strategy with near-optimal sampling

Tracking odour trails is a crucial behaviour for many animals, often leading to food, mates or away from danger. It is an excellent example of active sampling, where the animal itself controls how to sense the environment. Here we show that rats can track odour trails accurately with near-optimal sampling. We trained rats to follow odour trails drawn on paper spooled through a treadmill. By recording local field potentials (LFPs) from the olfactory bulb, and sniffing rates, we find that sniffing but not LFPs differ between tracking and non-tracking conditions. Rats can track odours within ~1 cm, and this accuracy is degraded when one nostril is closed. Moreover, they show path prediction on encountering a fork, wide 'casting' sweeps on encountering a gap and detection of reappearance of the trail in 1-2 sniffs. We suggest that rats use a multi-layered strategy, and achieve efficient sampling and high accuracy in this complex task.

Modeling fruit fly olfactory receptor neuron-responses

Event Abstract Back to Event Modeling fruit fly olfactory receptor neuron-responses Johannes Nehrkorn1, 2, 3, 4, 5*, Ayse Yarali3, 5, Tuba Oguz3, 4, Hiromu Tanimoto3 and Andreas V. Herz1, 2, 4 1 Ludwig-Maximilians-Universität München, Department of Biology II, Germany 2 Bernstein Center for Computational Neuroscience Munich, Germany 3 Max Planck Institute of Neurobiology, Germany 4 Graduate School of Systemic Neurosciences, Germany 5 These authors contributed equally, Germany Olfaction is critical for fundamental survival skills such as finding food, mate and shelter. Insect olfactory systems are ideally suited to study the neural basis of olfaction since they follow the same design principles and fulfill the same behavioral functions as mammalian olfactory systems but consist of much fewer neurons. In addition, mathematical models of these relatively simple neural systems can be readily implemented in technical devices. Here, we present a mathematical model to describe the response properties of fruit fly olfactory receptor neurons (ORNs). These first-order olfactory neurons have been repeatedly modeled in the past. However, all previous models ignored the influence of odor concentration, despite its pronounced effect on the “meaning” of an odor as well as its importance in tracking odor trails. To fill this gap, our model includes both odor-identity and odor-concentration. Hallem and Carlson (2006) have characterized the responses of 24 fruit fly ORN types to 19 odors across four concentrations. We take these data to fit a sigmoidal odor concentration-ORN response curve for each odor-ORN pair. Based on the parameter distribution of these sample odor-ORN pairs, we then implement a larger model consisting of 24 ORNs and 110 odors. We directly compare the predictions of this model to the corresponding large dataset of Hallem and Carlson (2006) at the single odor concentration they used. The model captures salient features of the data in terms of ORN odor tuning-widths and perceptive distances between the odors. Furthermore, we find the combinatorial odor codes to be expanding with increasing odor concentration, mimicking functional imaging data (e.g.,Root et al. 2007). In addition to fitting well with experimental data and successfully encoding odor-concentration as well as odor-identity, the model is described by only few parameters. It can thus serve as a realistic, reliable and simple input layer to models of the insect olfactory pathway attempting to explain, e.g., learning of odor-identity and -concentration or effects of odor mixtures. Acknowledgements This work was supported by the Bundesministerium für Bildung und Forschung (BMBF) through the Bernstein Focus Neural Basis of Learning (H.T. and A.V.M.H.). Keywords: Drosophila, Olfaction Conference: Bernstein Conference 2012, Munich, Germany, 12 Sep - 14 Sep, 2012. Presentation Type: Poster Topic: Sensory processing and perception Citation: Nehrkorn J, Yarali A, Oguz T, Tanimoto H and Herz AV (2012). Modeling fruit fly olfactory receptor neuron-responses. Front. Comput. Neurosci. Conference Abstract: Bernstein Conference 2012. doi: 10.3389/conf.fncom.2012.55.00251 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 10 May 2012; Published Online: 12 Sep 2012. * Correspondence: Mr. Johannes Nehrkorn, Ludwig-Maximilians-Universität München, Department of Biology II, Planegg-Martinsried, Germany, johannes.nehrkorn@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Johannes Nehrkorn Ayse Yarali Tuba Oguz Hiromu Tanimoto Andreas V Herz Google Johannes Nehrkorn Ayse Yarali Tuba Oguz Hiromu Tanimoto Andreas V Herz Google Scholar Johannes Nehrkorn Ayse Yarali Tuba Oguz Hiromu Tanimoto Andreas V Herz PubMed Johannes Nehrkorn Ayse Yarali Tuba Oguz Hiromu Tanimoto Andreas V Herz Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Morris Water Maze Test for Learning and Memory Deficits in Alzheimer's Disease Model Mice

The Morris Water Maze (MWM) was first established by neuroscientist Richard G. Morris in 1981 in order to test hippocampal-dependent learning, including acquisition of spatial memoryand long-term spatial memory 1. The MWM is a relatively simple procedure typically consisting of six day trials, the main advantage being the differentiation between the spatial (hidden-platform) and non-spatial (visible platform) conditions 2-4. In addition, the MWM testing environment reduces odor trail interference 5. This has led the task to be used extensively in the study of the neurobiology and neuropharmacology of spatial learning and memory. The MWM plays an important role in the validation of rodent models for neurocognitive disorders such as Alzheimer’s Disease 6, 7. In this protocol we discussed the typical procedure of MWM for testing learning and memory and data analysis commonly used in Alzheimer’s disease transgenic model mice.