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While the auditory cortex is necessary for sound localization, we do not yet know the underlying mechanisms that lead to the behavior. To address this gap, we have designed and executed a series of experiments aimed at describing the neuroethology of sound localization in the pallid bat, an animal which relies on passive hearing of prey-generated noise when foraging. We have made three primary discoveries. First, we have discovered how the external ear filters incoming sounds before they reach the sensory epithelium. Low frequency spectral notches, important for the perception of sound source elevation, depend on the presence of the conspicuous tragus. Second, we developed a sound localization task to test the behavior of the pallid bat. Pallid bats demonstrate remarkable sound localization acuity of ~4° near the midline, and we show that the high frequency range of prey-generated noise (20-30 kHz) is the predominant bandwidth used for azimuth localization. Last, we describe the 2D spatial selectivity of auditory cortex neurons and propose a population code for 2D sound localization. Our data suggests that the extent of active cortex is constrained systematically by the horizontal and elevational sound source direction. We describe preliminary results that indicate the chemogenetic inhibitory DREADDs system is a viable method for answering questions about the necessity of these auditory cortex populations to sound localization behavior. Collectively, the research contained in this dissertation provides insight into the way the auditory system is able to compute representations of external space from sound filtered by the external ear and supports the notion of the pallid bat as a viable model from which basic understandings of mammalian sound localization can be obtained.

Social mammals with more numerous and stronger social relationships live longer, healthier lives. Despite the established importance of social relationships, our understanding of the neurobiological mechanisms by which they are pursued, formed, and maintained in primates remains largely confined to highly controlled laboratory settings which do not allow natural, dynamic social interactions to unfold. In this review, we argue that the neurobiological study of primate social behavior would benefit from adopting a neuroethological approach, that is, a perspective grounded in natural, species-typical behavior, with careful selection of animal models according to the scientific question at hand. We highlight macaques and marmosets as key animal models for human social behavior and summarize recent findings in the social domain for both species. We then review pioneering studies of dynamic social behaviors in small animals, which can inspire studies in larger primates where the technological landscape is now ripe for an ethological overhaul.

There are 3559 species of mosquitoes in the world (Harbach 2018) but, so far, only a handful of them have been a focus of olfactory neuroscience and neurobiology research. Here we discuss mosquito olfactory anatomy and function and connect these to mosquito ecology. We highlight the least well-known and thus most interesting aspects of mosquito olfactory systems and discuss promising future directions. We hope this review will encourage the insect neuroscience community to work more broadly across mosquito species instead of focusing narrowly on the main disease vectors.

Recently, insect-machine hybrid robots have been developed that incorporate insects into robots or incorporate machines into insects. Most previous studies were motivated to use the function of insects for robots, but this technology can also prove to be useful as an experimental tool for neuroethology. We reviewed hybrid robots in terms of the closed-loop between an insect, a robot, and the real environment. The incorporated biological components provided the robot sensory signals that were received by the insects and the adaptive functions of the brain. The incorporated artificial components permitted us to understand the biological system by controlling insect behavior. Hybrid robots thus extend the roles of mobile robot experiments in neuroethology for both model evaluation and brain function analysis.

To understand the brain is to understand behaviour. However, understanding behaviour itself requires consideration of sensory information, body movements and the animal's ecology. Therefore, understanding the link between neurons and behaviour is a multi-level problem, which can be achieved when considering Marr's three levels of understanding: behaviour, computation, and neural implementation. Rather than establishing direct links between neurons and behaviour, the matter boils down to understanding two transitions: the link between neurons and brain computation on one hand, and the link between brain computations and behaviour on the other hand. The field of insect navigation illustrates well the power of such two-sided endeavour. We provide here examples revealing that each transition requires its own approach with its own intrinsic difficulties, and show how modelling can help us reach the desired multi-level understanding.

Spiders show a broad range of motions in addition to walking and running with their eight coordinated legs taking them towards their resources and away from danger. The usefulness of all these motions depends on the ability to control and adjust them to changing environmental conditions. A remarkable wealth of sensory receptors guarantees the necessary guidance. Many facets of such guidance have emerged from neuroethological research on the wandering spiderCupiennius saleiand its allies, although sensori-motor control was not the main focus of this work. The present review may serve as a springboard for future studies aiming towards a more complete understanding of the spider’s control of its different types of motion. Among the topics shortly addressed are the involvement of lyriform slit sensilla in path integration, muscle reflexes in the walking legs, the monitoring of joint movement, the neuromuscular control of body raising, the generation of vibratory courtship signals, the sensory guidance of the jump to flying prey and the triggering of spiderling dispersal behavior. Finally, the interaction of sensors on different legs in oriented turning behavior and that of the sensory systems for substrate vibration and medium flow are addressed.

From the mid-19th century until the 1980's, frogs and toads provided important research models for many fundamental questions in visual neuroscience. In the present century, they have been largely neglected. Yet they are animals with highly developed vision, a complex retina built on the basic vertebrate plan, an accessible brain, and an experimentally useful behavioural repertoire. They also offer a rich diversity of species and life histories on a reasonably restricted physiological and evolutionary background. We suggest that important insights may be gained from revisiting classical questions in anurans with state-of-the-art methods. At the input to the system, this especially concerns the molecular evolution of visual pigments and photoreceptors, at the output, the relation between retinal signals, brain processing and behavioural decision-making.

C. elegans nematodes are a well-established model organism in numerous fields of experimental biology. In nature, C. elegans live in a rich 3-dimensional environment. However, their behavior has been assessed almost exclusively on the open, flat surface of NGM (Nematode Growth Medium) plates, the golden standard for C. elegans culture in the lab. We present two methods to build 3-dimensional behavioral arenas for C. elegans, by casting, and by directly 3D printing NGM hydrogel. The latter is achieved by using a highly customized fused deposition modeling (FDM) 3D-printer, modified to employ NGM hydrogel as ink. The result is the advancement of 3-dimensional complexity of behavioral assays. To demonstrate the potential of our method, we use the 3D-printed arenas to assess C. elegans physical barriers crossing. C. elegans decision to cross physical obstacles is affected by aging, physiological status (i.e., starvation), and prior experience. The 3D-printed structures can be used to spatially confine C. elegans behaviors, i.e., egg laying. We consider these findings a decisive step toward characterizing C. elegans 3-dimensional behavior, an area long overlooked due to technical constrains. We envision our method of 3D-printing NGM arenas as a powerful tool in behavioral neurogenetics, neuroethology, and invertebrate model organisms’ neurobiology.

We have a growing understanding of the light-sensing organs and light-influenced behaviours of animals with distributed visual systems, but we have yet to learn how these animals convert visual input into behavioural output. It has been suggested they consolidate visual information early in their sensory-motor pathways, resulting in them being able to detect visual cues (spatial resolution) without being able to locate them (spatial vision). To explore how an animal with dozens of eyes processes visual information, we analysed the responses of the bay scallop Argopecten irradians to both static and rotating visual stimuli. We found A. irradians distinguish between static visual stimuli in different locations by directing their sensory tentacles towards them and were more likely to point their extended tentacles towards larger visual stimuli. We also found that scallops track rotating stimuli with individual tentacles and with rotating waves of tentacle extension. Our results show, to our knowledge for the first time that scallops have both spatial resolution and spatial vision, indicating their sensory-motor circuits include neural representations of their visual surroundings. Exploring a wide range of animals with distributed visual systems will help us learn the different ways non-cephalized animals convert sensory input into behavioural output.

The temporal course and the severity of the involution of sensory systems through aging can be critical since they ensure the ability to perceive and recognize the world. In older people, sensory impairments significantly increase their risk of biological, psychological, and social impoverishment. Besides this, olfactory loss is considered an early biomarker in Alzheimer’s disease (AD) neurodegenerative process. Here we studied olfactory ethograms in middle-aged male and female gold-standard C57BL/6 mice and 3xTg-AD mice, a genetic model of AD that presents cognitive dysfunction and a conspicuous neuropsychiatric-like phenotype. A paradigm involving 1-day food deprivation was used to investigate the ethological patterns shown in the olfactory inspection of a new cage and the sniffing, finding, and eating of hidden food pellets. The sniffing–find–eat temporal patterns were independent of the loss of weight and unveiled (fast) olfactory signatures in Alzheimer’s disease, differing from those (slow progressive) in normal aging. Male 3xTg-AD mice exhibited an early signature than female mice, opposite to animals with normal aging. The sequence of actions was correlated in male and female 3xTg-AD mice in contrast to control mice. Social isolation, naturally occurring in male 3xTg-AD due to the death of cage mates, emphasized their olfactory patterns and disrupted the behavioral correlates. The paradigm provided distinct contextual, sex, and genotype olfactory ethogram signatures useful to investigate olfactory function in normal and AD-pathological aging. Isolation had an impact on enhancing the changes in the olfactory signature here described, for the first time, in the 3xTg-AD model of Alzheimer’s disease.

The communication behaviors of vocal fish and electric fish are among the vertebrate social behaviors best understood at the level of neural circuits. Both forms of signaling rely on midbrain inputs to hindbrain pattern generators that activate peripheral effectors (sonic muscles and electrocytes) to produce pulsatile signals that are modulated by frequency/repetition rate, amplitude and call duration. To generate signals that vary by sex, male phenotype, and social context, these circuits are responsive to a wide range of hormones and neuromodulators acting on different timescales at multiple loci. Bass and Zakon (2005) reviewed the behavioral neuroendocrinology of these two teleost groups, comparing how the regulation of their communication systems have both converged and diverged during their parallel evolution. Here, we revisit this comparison and review the complementary developments over the past 16 years. We (a) summarize recent work that expands our knowledge of the neural circuits underlying these two communication systems, (b) review parallel studies on the action of neuromodulators (e.g., serotonin, AVT, melatonin), brain steroidogenesis (via aromatase), and social stimuli on the output of these circuits, (c) highlight recent transcriptomic studies that illustrate how contemporary molecular methods have elucidated the genetic regulation of social behavior in these fish, and (d) describe recent studies of mochokid catfish, which use both vocal and electric communication, and that use both vocal and electric communication and consider how these two systems are spliced together in the same species. Finally, we offer avenues for future research to further probe how similarities and differences between these two communication systems emerge over ontogeny and evolution.

Summary Animals that communicate by vocal means must make their own calls salient against a background of environmental noise. A new study of green tree frogs demonstrates that input from the lungs to the middle ear reduces interfering noise and thus enhances call detection.

Many species from diverse and often distantly related animal groups (e.g. monkeys, crows, fish and bees) have a sense of number. This means that they can assess the number of items in a set – its ‘numerosity’. The brains of these phylogenetically distant species are markedly diverse. This Review examines the fundamentally different types of brains and neural mechanisms that give rise to numerical competence across the animal tree of life. Neural correlates of the number sense so far exist only for specific vertebrate species: the richest data concerning explicit and abstract number representations have been collected from the cerebral cortex of mammals, most notably human and nonhuman primates, but also from the pallium of corvid songbirds, which evolved independently of the mammalian cortex. In contrast, the neural data relating to implicit and reflexive numerical representations in amphibians and fish is limited. The neural basis of a number sense has not been explored in any protostome so far. However, promising candidate regions in the brains of insects, spiders and cephalopods – all of which are known to have number skills – are identified in this Review. A comparative neuroscientific approach will be indispensable for identifying evolutionarily stable neuronal circuits and deciphering codes that give rise to a sense of number across phylogeny.

The marble burying (MB) test, a classical test based on the natural tendency of rodents to dig in diverse substrates and to bury small objects, is sensitive to some intrinsic and extrinsic factors. Here, under emerging neuroethological quantitative and qualitative analysis, the MB performance of 12-month-old male and female 3xTg-AD mice for Alzheimer’s disease and age-matched counterparts of gold-standard C57BL6 strain with normal aging unveiled sex-dependent signatures. In addition, three temporal analyses, through the (1) time course of the performance, and (2) a repeated test schedule, identified the optimal time frames and schedules to detect sex- and genotype-dependent differences. Besides, a (3) longitudinal design from 12 to 16 months of age monitored the changes in the performance with aging, worsening in AD-mice, and modulation through the repeated test. In summary, the present results allow us to conclude that (1) the marble burying test is responsive to genotype, sex, aging, and its interactions, (2) the male sex was more sensitive to showing the AD-phenotype, (3) longitudinal assessment shows a reduction in females with AD pathology, (4) burying remains stable in repeated testing, (5) the time-course of marbles burying is useful, and (6) burying behavior most likely represents perseverative and/or stereotyped-like behavior rather than anxiety-like behavior in 3xTg-AD mice.

The anatomy, neurophysiology, and behavioral roles of the mechanosensory lateral line system of cichlid fishes are reviewed. The lateral line system of cichlids shares fundamental anatomical features characteristic of all bony fishes and is composed of cranial lateral line canals, a trunk canal (or canals) containing canal neuromasts, and superficial neuromasts on the skin of the head, trunk, and tail. Cichlids typically have narrow cranial lateral line canals, but several genera have reduced or widened canals. A single, continuous trunk canal, which is common among bony fishes, is rare among cichlids, which typically have a disjunct trunk canal (or variations thereof) that is otherwise rare among other teleost families. Lateral line neuroanatomy and neurophysiology is well known in only a small number of cichlid species that serve as models for the study of the neuroethology of feeding and social behavior. The ability to study cichlids in the field and in the laboratory and carry out genetic and genomic analyses of complex phenotypes provides unique opportunities for novel integrative studies of the behavior and sensory ecology of these extraordinary fishes.

All insects, including pest insects and vectors of human and animal diseases, use their olfactory system to locate host resources and avoid dangers in their environment. Typically, odor information is coded in a combinatorial fashion in the primary olfactory centers. Insects, however, also possess several olfactory circuits that are narrowly tuned and highly conserved, which allows the dissection of their relevance in guiding complex behaviors, such as courtship, feeding and oviposition. Each specific neural circuit offers an opportunity for highly defined control and manipulation of the associated behavior. Today, we can define the chemosensory systems of model organisms such as Drosophila, linking the tools of chemical ecology with those of neurogenetics and neurobiology. This cross-disciplinary approach has isolated specific olfactory neural circuits that are indeed critical for insect behavior. In this chapter, we identify and define these olfactory-labeled lines, as well as provide examples from the literature.

Coevolutionary adaptation leads to modifications of sensory physiology and behavioral responses of predators and prey. From the ecological point of view, insect hearing and acoustic behavior are an attractive study area for researchers in entomology, animal behavior, and neuroethology. Recent technical advances in sound-recording equipment and molecular techniques have contributed to understanding the evolution of acoustic communication, including sexual dialogue, intraspecific competition, and the interspecific arms race between predators (e.g., bats) and prey (e.g., moths). Singing male moths exploit ultrasound-induced freezing responses of potential female mates or unwelcome rival males to enhance mating success. Freezing responses to ultrasound by moths are originally an antipredator reaction to echolocating insectivorous bats. The aim of Chap. 5 is to provide a sensory-behavioral explanation of the freezing response of insects during predator–prey interaction.

Here, we compare birdsong and human musicality using insights from songbird neuroethology and evolution. For example, neural recordings during songbird duetting and other coordinated vocal behaviors could inform mechanistic hypotheses regarding human brain function during music-making. Furthermore, considering songbird evolution as a model system suggests that selection favoring certain culturally transmitted behaviors can indirectly select for associated underlying neural functions.

Summary Food represents a limiting resource for the growth and developmental progression of many animal species. As a consequence, competition over food, space, or other resources can trigger territoriality and aggressive behavior. In the monarch butterfly, Danaus plexippus, caterpillars feed predominantly on milkweed, raising the possibility that access to milkweed is critical for growth and survival. Here, we characterize the role of food availability on aggression in monarch caterpillars and find that monarch caterpillars display stereotyped aggressive lunges that increase during development, peaking during the fourth and fifth instar stages. The number of lunges toward a conspecific caterpillar was significantly increased under conditions of low food availability, suggesting resource defense may trigger aggression. These findings establish monarch caterpillars as a model for investigating interactions between resource availability and aggressive behavior under ecologically relevant conditions and set the stage for future investigations into the neuroethology of aggression in this system., Graphical Abstract, Highlights • Monarch caterpillars display stereotyped aggressive behavior • Aggression is triggered by limited food availability • Aggression peaks during the late stages of caterpillar development, Biological Sciences; Entomology; Behavioral Neuroscience

Natural goal-directed behaviors often involve complex sequences of many stimulus-triggered components. Understanding how brain circuits organize such behaviors requires mapping the interactions between an animal, its environment, and its nervous system. Here, we use continuous brain-wide neuronal imaging to study the full performance of mating by the C. elegans male. We show that as each mating unfolds in its own sequence of component behaviors, the brain operates similarly between instances of each component, but distinctly between different components. When the full sensory and behavioral context is taken into account, unique roles emerge for each neuron. Functional correlations between neurons are not fixed, but change with behavioral dynamics. From the contribution of individual neurons to circuits, our study shows how diverse brain-wide dynamics emerge from the integration of sensory perception and motor actions within their natural context.

Animals communicate in response to different tasks, including alarm calls, allocation of food, courtship, and mating. Different types of signals are used by animals to communicate, such as chemical signals, vocalisations, colour patterns, and movements. Animal colouration and visual communication have fascinated researchers for decades. Behavioural, anatomical and functional studies are commonly used to study visual communication in both vertebrates and invertebrates. Cuttlefish are well known for possessing intricate body patterns. Cuttlefish use these colourful and dynamic displays to communicate with mates, camouflage, and pursue prey. The cuttlefish central nervous system processes all the visual stimuli and coordinates the expression of postures, body movements, skin textures and colourations that form a body pattern. Interestingly, many species of cuttlefish are colour blind but possess polarisation vision and polarisation patterns in their bodies, which are potentially used for communication with conspecifics.The objective of this thesis is to analyse the mechanisms influencing visual communication and colour patterns in a small coastal cuttlefish Sepia plangon. The mourning cuttlefish S. plangon is a small species with a mantle length (ML) < 140 mm. This species inhabits coastal waters and prefers to forage in seaweed and seagrass environments. It is located to a maximum depth of 85 meters and is active during the day.After introducing the topic of this thesis in detail in chapter 1, we analysed the ontogenetic changes of S. plangon body patterns from embryos to adults in chapter 2. The first description of S. plangon eggs and embryos is included in this chapter. However, because the eggs were collected from their natural environment, only late embryonic development was described. The number and complexity of the body patterns of S. plangon changed throughout the lifespan, transitioning from three body patterns in embryos to a maximum of 18 in males. Seven patterns were exclusive to males and used only during reproductive behaviour. Therefore, in chapter 3, we analysed courtship, mating, and agonistic competition of S. plangon. Three sex ratios were used to study mate choice: 1Male(M):1F(F), 2M:1F, and 1M:2F. Polarised and unpolarised filters were placed between the animals to test the effect of modifying polarised stimuli in the reproductive behaviour of S. plangon. 3D printed cuttlefish models were used to manipulate specific traits (two body sizes, two postures, four body patterns) and determine which factor was crucial to successful mating. The components of the body patterns, reproductive behaviours and visual signals were analysed. We found that only sex ratio had a significant effect on male courtship frequency. Agonistic competition between males included visual signals, and most males avoided fighting. Small males (ML < 80 mm) used a deceptive display to mimic female patterns, avoid male competitions, and mate with females. The dynamic changes in body patterns were the most crucial element for successful matings, as the static body pattern in the 3D cuttlefish models did not trigger any reproductive behaviour. Fifty-seven components of the body patterns and 18 body patterns were observed during courtship, mating and male competitions, but further analysis revealed that only four body patterns and six components displayed in a specific order were determinant for mating.In chapter 4, we used magnetic resonance imaging (MRI) and diffusion MRI (dMRI) to investigate ontogenetic changes in brain structure and connectivity of S. plangon. Brain volumes and tractography were estimated from a hatchling, a juvenile, a male, and a female S. plangon. Forty-seven lobes and twelve brain centres were identified. Volumetric differences were found across the motor and visual centres. Tractography estimations revealed new connections in the posterior chromatophore, lateral pedal, posterior pedal, brachial, dorsolateral, interbasal, and optic lobes. The differences in brain volume and connections across the different life stages of S. plangon are likely related to the development of body patterns.The findings from this thesis expand our current knowledge on cuttlefish embryonic development, body pattern changes, visual communication and structural organisation of the brain. Furthermore, this thesis introduces the use of modern technology (MRI) to study the cuttlefish brain, which showed connections in the brain of S. plangon previously unknown.

Animals display wide-ranging evolutionary adaptations based on their ecological niche. Octopuses explore the seafloor with their flexible arms using a specialized "taste by touch" system to locally sense and respond to prey-derived chemicals and movement. How the peripherally distributed octopus nervous system mediates relatively autonomous arm behavior is unknown. Here, we report that octopus arms use a family of cephalopod-specific chemotactile receptors (CRs) to detect poorly soluble natural products, thereby defining a form of contact-dependent, aquatic chemosensation. CRs form discrete ion channel complexes that mediate the detection of diverse stimuli and transduction of specific ionic signals. Furthermore, distinct chemo- and mechanosensory cells exhibit specific receptor expression and electrical activities to support peripheral information coding and complex chemotactile behaviors. These findings demonstrate that the peripherally distributed octopus nervous system is a key site for signal processing and highlight how molecular and anatomical features synergistically evolve to suit an animal's environmental context.

In insects, locomotion is the result of rhythm generating thoracic circuits and their modulation by sensory reflexes and by inputs from the two head ganglia, the cerebral and the gnathal ganglia (GNG), which act as higher order neuronal centers playing different functions in the initiation, goal-direction, and maintenance of movement. Current knowledge on the various roles of major neuropiles of the cerebral ganglia (CRG), such as mushroom bodies (MB) and the central complex (CX), in particular, are discussed as well as the role of the GNG. Thoracic and head ganglia circuitries are connected by ascending and descending neurons. While less is known about the ascending neurons, recent studies in large insects and Drosophila have begun to unravel the identity of descending neurons and their appropriate roles in posture and locomotion. Descending inputs from the head ganglia are most important in initiating and modulating thoracic central pattern generating circuitries to achieve goal directed locomotion. In addition, the review will also deal with some known monoaminergic descending neurons which affect the motor circuits involved in posture and locomotion. In conclusion, we will present a few issues that have, until today, been little explored. For example, how and which descending neurons are selected to engage a specific motor behavior and how feedback from thoracic circuitry modulate the head ganglia circuitries. The review will discuss results from large insects, mainly locusts, crickets, and stick insects but will mostly focus on cockroaches and the fruit fly, Drosophila.

The R6/2 transgenic mouse model of Huntington's disease (HD) shows a disintegration of circadian rhythms that can be delayed by pharmacological and non-pharmacological means. Since the molecular machinery underlying the circadian clocks is intact, albeit progressively dysfunctional, we wondered if light phase shifts could modulate the deterioration in daily rhythms in R6/2 mice. Mice were subjected to four x 4 hour advances in light onset. R6/2 mice adapted to phase advances, although angles of entrainment increased with age. A second cohort was subjected to a jet-lag paradigm (6 hour delay or advance in light onset, then reversal after 2 weeks). R6/2 mice adapted to the original shift, but could not adjust accurately to the reversal. Interestingly, phase shifts ameliorated the circadian rhythm breakdown seen in R6/2 mice under normal LD conditions. Our previous finding that the circadian period (tau) of 16 week old R6/2 mice shortens to approximately 23 hours may explain how they adapt to phase advances and maintain regular circadian rhythms. We tested this using a 23 hour period light/dark cycle. R6/2 mice entrained to this cycle, but onsets of activity continued to advance, and circadian rhythms still disintegrated. Therefore, the beneficial effects of phase-shifting are not due solely to the light cycle being closer to the tau of the mice. Our data show that R6/2 mice can adapt to changes in the LD schedule, even beyond the age when their circadian rhythms would normally disintegrate. Nevertheless, they show abnormal responses to changes in light cycles. These might be caused by a shortened tau, impaired photic re-synchronization, impaired light detection and/or reduced masking by evening light. If similar abnormalities are present in HD patients, they may suffer exaggerated jet-lag. Since the underlying molecular clock mechanism remains intact, light may be a useful treatment for circadian dysfunction in HD.

Since their discovery in insects, pheromones are considered as ubiquitous and stereotyped chemical messengers acting in intraspecific animal communication. Here we studied the effect of pheromones in a different context as we investigated their capacity to induce persistent modulations of associative learning and memory. We used honey bees, Apis mellifera, and combined olfactory conditioning and pheromone preexposure with disruption of neural activity and two-photon imaging of olfactory brain circuits, to characterize the effect of pheromones on olfactory learning and memory. Geraniol, an attractive pheromone component, and 2-heptanone, an aversive pheromone, improved and impaired, respectively, olfactory learning and memory via a durable modulation of appetitive motivation, which left odor processing unaffected. Consistently, interfering with aminergic circuits mediating appetitive motivation rescued or diminished the cognitive effects induced by pheromone components. We thus show that these chemical messengers act as important modulators of motivational processes and influence thereby animal cognition., David Baracchi et al. show that honey bees exposed to geraniol, a component of an attractant pheromone, exhibit improved olfactory learning and memory while the opposite effect was seen in honey bees exposed to the aversive pheromone, 2- heptanone. These changes occurred through a modulation of appetitive motivation without affecting odor processing, suggesting an important role for pheromones as modulators of motivational and learning processes.

Retinal ganglion cells (RGCs) were one of the first classes of sensory neurons to be described in terms of a receptive field (RF). Over the last six decades, our understanding of the diversity of RGC types and the nuances of their response properties has grown exponentially. We will review the current understanding of RGC receptive fields (RFs) mostly from studies in mammals, but including work from other vertebrates as well. We will argue for a new paradigm that embraces the fluidity of RGC RFs with an eye toward the neuroethology of vision. Specifically, we will focus on (1) different methods for measuring RGC RFs, (2) RF models, (3) feature selectivity and the distinction between fluid and stable RF properties, and (4) ideas about the future of understanding RGC RFs.