Many insects rely on path integration to define direct routes back to their nests. When shuttling... more Many insects rely on path integration to define direct routes back to their nests. When shuttling hundreds of meters back and forth between a profitable foraging site and a nest, navigational errors accumulate unavoidably in this compass- and odometer-based system. In familiar terrain, terrestrial landmarks can be used to compensate for these errors and safely guide the insect back to its nest with pin-point precision. In this study, we investigated the homing strategies employed by Camponotus fulvopilosus ants when repeatedly foraging no more than 1.25 m away from their nest. Our results reveal that the return journeys of the ants, even when setting out from a feeder from which the ants could easily get home using landmark information alone, are initially guided by path integration. After a short run in the direction given by the home vector, the ants then switched strategies and started to steer according to the landmarks surrounding their nest. We conclude that even when foraging...
Philosophical Transactions of the Royal Society B: Biological Sciences
Ants are ecologically one of the most important groups of insects and exhibit impressive capabili... more Ants are ecologically one of the most important groups of insects and exhibit impressive capabilities for visual learning and orientation. Studies on numerous ant species demonstrate that ants can learn to discriminate between different colours irrespective of light intensity and modify their behaviour accordingly. However, the findings across species are variable and inconsistent, suggesting that our understanding of colour vision in ants and what roles ecological and phylogenetic factors play is at an early stage. This review provides a brief synopsis of the critical findings of the past century of research by compiling studies that address molecular, physiological and behavioural aspects of ant colour vision. With this, we aim to improve our understanding of colour vision and to gain deeper insights into the mysterious and colourful world of ants. This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in ar...
Philosophical Transactions of the Royal Society B: Biological Sciences
Ball rolling dung beetles use a wide range of cues to steer themselves along a fixed bearing, inc... more Ball rolling dung beetles use a wide range of cues to steer themselves along a fixed bearing, including the spectral gradient of scattered skylight that spans the sky. Here, we define the spectral sensitivity of the diurnal dung beetle Kheper lamarcki and use the information to explore the orientation performance under a range of spectral light combinations. We find that, when presented with spectrally diverse stimuli, the beetles primarily orient to the apparent brightness differences as perceived by their green photoreceptors. Under certain wavelength combinations, they also rely on spectral information to guide their movements, but the brightness and spectral directional information is never fully disentangled. Overall, our results suggest the use of a dichromatic, primitive colour vision system for the extraction of directional information from the celestial spectral gradient to support straight-line orientation. This article is part of the theme issue ‘Understanding colour visi...
Philosophical Transactions of the Royal Society B: Biological Sciences
Colour vision allows animals to use the information contained in the spectrum of light to control... more Colour vision allows animals to use the information contained in the spectrum of light to control important behavioural decisions such as selection of habitats, food or mates. Among arthropods, the largest animal phylum, we find completely colour-blind species as well as species with up to 40 different opsin genes or more than 10 spectral types of photoreceptors, we find a large diversity of optical methods shaping spectral sensitivity, we find eyes with different colour vision systems looking into the dorsal and ventral hemisphere, and species in which males and females see the world in different colours. The behavioural use of colour vision shows an equally astonishing diversity. Only the neural mechanisms underlying this sensory ability seems surprisingly conserved—not only within the phylum, but even between arthropods and the other well-studied phylum, chordates. The papers in this special issue allow a glimpse into the colourful world of arthropod colour vision, and besides gi...
Unusual amongst dung beetles, Scarabaeus galenus digs a burrow that it provisions by making repea... more Unusual amongst dung beetles, Scarabaeus galenus digs a burrow that it provisions by making repeated trips to a nearby dung pile. Even more remarkable is that these beetles return home moving backwards, with a pellet of dung between their hind legs. Here, we explore the strategy that S. galenus uses to find its way home. We find that, like many other insects, they use path integration to calculate the direction and distance to their home. If they fail to locate their burrow, the beetles initiate a distinct looping search behaviour that starts with a characteristic sharp turn, we have called a ‘turning point’. When homing beetles are passively displaced or transferred to an unfamiliar environment, they initiate a search at a point very close to the location of their fictive burrow—that is, a spot at the same relative distance and direction from the pick-up point as the original burrow. Unlike other insects, S. galenus do not appear to supplement estimates of the burrow location with ...
The sun is the most prominent source of directional information in the heading direction network ... more The sun is the most prominent source of directional information in the heading direction network of the diurnal, ball-rolling dung beetle Kheper lamarcki. If this celestial body is occluded from the beetle's field of view, the distribution of the relative weight between the directional cues that remain shifts in favour of the celestial pattern of polarised light. In this study, we continue to explore the interplay of the sun and polarisation pattern as directional cues in the heading direction network of K. lamarcki. By systematically altering the intensity and degree of the two cues, we effectively change the relative reliability as they appear to the dung beetle. The response of the beetle to these modifications allows us to closely examine how the weighting relationship of these two sources of directional information is influenced and altered in the heading direction network of the beetle. We conclude that the process by which K. lamarcki relies on directional information is ...
<em>Absolute Change in Direction_Data set</em>: Absolute angular change in direction ... more <em>Absolute Change in Direction_Data set</em>: Absolute angular change in direction for all conditions (test and control) tested. In total, 9 conditions were tested. 15 individuals were tested in each condition. <em>GLM model</em>: A Generalised linear model was used to assess the relationship between degree of polarisation and probability of a turn (&gt;45°).
Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic ef... more Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic effects on domestic cats,1-3 for its medicinal properties,4,5 as well as for its powerful repellent action on insects.6,7 Catnip extracts have been proposed as a natural alternative to synthetic insect repellents, such as N,N-diethyl-3-methylbenzamide (DEET),8,9 but how catnip triggers aversion in insects is not known. Here, we show that, both in Drosophila melanogaster flies and Aedes aegypti mosquitoes, the major mediator of catnip repellency is the widely conserved chemical irritant receptor TRPA1. In vitro, both catnip extract and its active ingredient nepetalactone can directly activate fly and mosquito TRPA1. In vivo, D. melanogaster and Ae. aegypti TRPA1 mutants are no longer repelled by catnip and nepetalactone. Interestingly, our data show that some, but not all, fly and mosquito TRPA1 variants are catnip targets. Moreover, unlike the broad TRPA1 agonist allyl isothiocyanate (AITC) (an active ingredient of tear gas and wasabi), catnip does not activate human TRPA1. Our results support the use of catnip and nepetalactone as insect-selective irritants and suggest that, despite TRPA1's broad conservation, insect TRPA1 can be targeted for the development of safe repellents.
Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic ef... more Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic effects on domestic cats,1-3 for its medicinal properties,4,5 as well as for its powerful repellent action on insects.6,7 Catnip extracts have been proposed as a natural alternative to synthetic insect repellents, such as N,N-diethyl-3-methylbenzamide (DEET),8,9 but how catnip triggers aversion in insects is not known. Here, we show that, both in Drosophila melanogaster flies and Aedes aegypti mosquitoes, the major mediator of catnip repellency is the widely conserved chemical irritant receptor TRPA1. In vitro, both catnip extract and its active ingredient nepetalactone can directly activate fly and mosquito TRPA1. In vivo, D. melanogaster and Ae. aegypti TRPA1 mutants are no longer repelled by catnip and nepetalactone. Interestingly, our data show that some, but not all, fly and mosquito TRPA1 variants are catnip targets. Moreover, unlike the broad TRPA1 agonist allyl isothiocyanate (AITC) (an active ingredient of tear gas and wasabi), catnip does not activate human TRPA1. Our results support the use of catnip and nepetalactone as insect-selective irritants and suggest that, despite TRPA1's broad conservation, insect TRPA1 can be targeted for the development of safe repellents.
Proceedings of the Royal Society B: Biological Sciences, 2019
Colour processing at early stages of visual pathways is a topic of intensive study both in verteb... more Colour processing at early stages of visual pathways is a topic of intensive study both in vertebrate and invertebrate species. However, it is still unclear how colour learning and memory formation affects an insect brain in the peripheral processing stages and high-order integration centres, and whether associative colour experiences are reflected in plasticity of underlying neuronal circuits. To address this issue, we used Camponotus blandus ants as their proven colour learning and memory capabilities, precisely controllable age and experience, and already known central visual pathways offer unique access to analyse plasticity in neuronal circuits for colour vision in a miniature brain. The potential involvement of distinct neuropils—optic lobes (OLs), mushroom body (MB) input (collar) and output (vertical lobe), anterior optic tubercle (AOTU) and central complex (CX)—in associative colour experiences was assessed by quantification of volumetric and synaptic changes (MB collar) di...
Ants are a well-characterized insect model for the study of visual learning and orientation, but ... more Ants are a well-characterized insect model for the study of visual learning and orientation, but the extent to which colour vision is involved in these tasks remains unknown. We investigated the colour preference, learning and memory retention of Camponotus blandus foragers under controlled laboratory conditions. Our results show that C. blandus foragers exhibit a strong innate preference for ultraviolet (UV, 365 nm) over blue (450 nm) and green (528 nm) wavelengths. The ants can learn to discriminate 365 nm from either 528 nm or 450 nm, independent of intensity changes. However, they fail to discriminate between 450 nm and 528 nm. Modelling of putative colour spaces involving different numbers of photoreceptor types revealed that colour discrimination performance of individual ants is best explained by dichromacy, comprising a short-wavelength (UV) receptor with peak sensitivity at about 360 nm, and a long-wavelength receptor with peak sensitivity between 470 nm and 560 nm. Forager...
Camponotus rufipes workers are characterized by an age-related polyethism. In the first weeks of ... more Camponotus rufipes workers are characterized by an age-related polyethism. In the first weeks of adult life, young workers perform tasks inside the nest before they switch to multimodal foraging tasks outside. We tested the hypothesis that this transition is accompanied by profound adaptations in the peripheral and central visual system. Our results show that C. rufipes workers of all tested ages (between 1-42 days) express three genes encoding for ultraviolet (UV), blue (BL) and long wavelength (LW) sensitive opsins in their retina, which are likely to provide the substrate for trichromatic color vision. Expression levels of all three opsin genes increased significantly within the first two weeks of adulthood and following light exposure. Interestingly, the volumes of all three optic neuropils (lamina, medulla, lobula) showed corresponding volume increases. Tracing of connections to higher visual centers in the mushroom bodies (MBs) revealed only one optic pathway, the anterior sup...
This meeting was held at the Stazione Zoologica Anton Dohrn, Naples, Italy, from 6th-13th July 20... more This meeting was held at the Stazione Zoologica Anton Dohrn, Naples, Italy, from 6th-13th July 2011. It was sponsored through a collaboration between IBRO (the International Brain Research Organisation) and the Kemali Foundation. Notably, it is the first IBRO sponsored School specifically in invertebrate neuroscience. The meeting was attended by early career researchers from countries around the Mediterranean basin and highlighted the research opportunities that this field can offer to neuroscientists at the start of their careers. Students participating in the School were introduced to a range of important invertebrate model systems. The utility of these models in addressing fundamental neurobiological problems, especially those relating to human neurological disorders, was extensively discussed. In this review, two of the participating students provide a summary of this meeting with a view to encouraging support for further activity in this arena in the future. One of the aims of the Kemali foundation is to foster enduring collaborations between scientists in the Mediterranean region. Given the enthusiastic networking both during and after the meeting, there is much promise that this goal will be realised.
Path integration is a general mechanism used by many animals to maintain an updated record of the... more Path integration is a general mechanism used by many animals to maintain an updated record of their position in relation to a set reference point.1-11 To do this, they continually integrate direction and distance information into a memorized home vector. What remains unclear is how this vector is stored, maintained, and utilized for successful navigation. A recent computational model based on the neuronal circuitry of the insect central complex suggests that home vector memories are encoded across a set of putative memory neurons and maintained through ongoing recurrent neural activity.12 To better understand the nature of the home vector memory and experimentally assess underlying mechanisms for maintaining it, we performed a series of experiments on the path integrating dung beetle Scarabaeus galenus.13 We found that, while the directional component of the home vector was maintained for up to 1 h, the distance component of the vector memory decreased gradually over time. Using cold-induced anesthesia, we disrupted the neural activity of beetles that had stored a home vector of known length and direction. This treatment diminished both components of the home vector memory, but by different amounts-the homing beetles lost their distance memory before their directional memory. Together, these findings present new insights into the functional properties of home vector memories and provide the first empirical evidence that a biological process that can be disrupted by cold-induced anesthesia is essential to support homing by path integration.
Many insects rely on path integration to define direct routes back to their nests. When shuttling... more Many insects rely on path integration to define direct routes back to their nests. When shuttling hundreds of meters back and forth between a profitable foraging site and a nest, navigational errors accumulate unavoidably in this compass- and odometer-based system. In familiar terrain, terrestrial landmarks can be used to compensate for these errors and safely guide the insect back to its nest with pin-point precision. In this study, we investigated the homing strategies employed by Camponotus fulvopilosus ants when repeatedly foraging no more than 1.25 m away from their nest. Our results reveal that the return journeys of the ants, even when setting out from a feeder from which the ants could easily get home using landmark information alone, are initially guided by path integration. After a short run in the direction given by the home vector, the ants then switched strategies and started to steer according to the landmarks surrounding their nest. We conclude that even when foraging...
Philosophical Transactions of the Royal Society B: Biological Sciences
Ants are ecologically one of the most important groups of insects and exhibit impressive capabili... more Ants are ecologically one of the most important groups of insects and exhibit impressive capabilities for visual learning and orientation. Studies on numerous ant species demonstrate that ants can learn to discriminate between different colours irrespective of light intensity and modify their behaviour accordingly. However, the findings across species are variable and inconsistent, suggesting that our understanding of colour vision in ants and what roles ecological and phylogenetic factors play is at an early stage. This review provides a brief synopsis of the critical findings of the past century of research by compiling studies that address molecular, physiological and behavioural aspects of ant colour vision. With this, we aim to improve our understanding of colour vision and to gain deeper insights into the mysterious and colourful world of ants. This article is part of the theme issue ‘Understanding colour vision: molecular, physiological, neuronal and behavioural studies in ar...
Philosophical Transactions of the Royal Society B: Biological Sciences
Ball rolling dung beetles use a wide range of cues to steer themselves along a fixed bearing, inc... more Ball rolling dung beetles use a wide range of cues to steer themselves along a fixed bearing, including the spectral gradient of scattered skylight that spans the sky. Here, we define the spectral sensitivity of the diurnal dung beetle Kheper lamarcki and use the information to explore the orientation performance under a range of spectral light combinations. We find that, when presented with spectrally diverse stimuli, the beetles primarily orient to the apparent brightness differences as perceived by their green photoreceptors. Under certain wavelength combinations, they also rely on spectral information to guide their movements, but the brightness and spectral directional information is never fully disentangled. Overall, our results suggest the use of a dichromatic, primitive colour vision system for the extraction of directional information from the celestial spectral gradient to support straight-line orientation. This article is part of the theme issue ‘Understanding colour visi...
Philosophical Transactions of the Royal Society B: Biological Sciences
Colour vision allows animals to use the information contained in the spectrum of light to control... more Colour vision allows animals to use the information contained in the spectrum of light to control important behavioural decisions such as selection of habitats, food or mates. Among arthropods, the largest animal phylum, we find completely colour-blind species as well as species with up to 40 different opsin genes or more than 10 spectral types of photoreceptors, we find a large diversity of optical methods shaping spectral sensitivity, we find eyes with different colour vision systems looking into the dorsal and ventral hemisphere, and species in which males and females see the world in different colours. The behavioural use of colour vision shows an equally astonishing diversity. Only the neural mechanisms underlying this sensory ability seems surprisingly conserved—not only within the phylum, but even between arthropods and the other well-studied phylum, chordates. The papers in this special issue allow a glimpse into the colourful world of arthropod colour vision, and besides gi...
Unusual amongst dung beetles, Scarabaeus galenus digs a burrow that it provisions by making repea... more Unusual amongst dung beetles, Scarabaeus galenus digs a burrow that it provisions by making repeated trips to a nearby dung pile. Even more remarkable is that these beetles return home moving backwards, with a pellet of dung between their hind legs. Here, we explore the strategy that S. galenus uses to find its way home. We find that, like many other insects, they use path integration to calculate the direction and distance to their home. If they fail to locate their burrow, the beetles initiate a distinct looping search behaviour that starts with a characteristic sharp turn, we have called a ‘turning point’. When homing beetles are passively displaced or transferred to an unfamiliar environment, they initiate a search at a point very close to the location of their fictive burrow—that is, a spot at the same relative distance and direction from the pick-up point as the original burrow. Unlike other insects, S. galenus do not appear to supplement estimates of the burrow location with ...
The sun is the most prominent source of directional information in the heading direction network ... more The sun is the most prominent source of directional information in the heading direction network of the diurnal, ball-rolling dung beetle Kheper lamarcki. If this celestial body is occluded from the beetle's field of view, the distribution of the relative weight between the directional cues that remain shifts in favour of the celestial pattern of polarised light. In this study, we continue to explore the interplay of the sun and polarisation pattern as directional cues in the heading direction network of K. lamarcki. By systematically altering the intensity and degree of the two cues, we effectively change the relative reliability as they appear to the dung beetle. The response of the beetle to these modifications allows us to closely examine how the weighting relationship of these two sources of directional information is influenced and altered in the heading direction network of the beetle. We conclude that the process by which K. lamarcki relies on directional information is ...
<em>Absolute Change in Direction_Data set</em>: Absolute angular change in direction ... more <em>Absolute Change in Direction_Data set</em>: Absolute angular change in direction for all conditions (test and control) tested. In total, 9 conditions were tested. 15 individuals were tested in each condition. <em>GLM model</em>: A Generalised linear model was used to assess the relationship between degree of polarisation and probability of a turn (&gt;45°).
Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic ef... more Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic effects on domestic cats,1-3 for its medicinal properties,4,5 as well as for its powerful repellent action on insects.6,7 Catnip extracts have been proposed as a natural alternative to synthetic insect repellents, such as N,N-diethyl-3-methylbenzamide (DEET),8,9 but how catnip triggers aversion in insects is not known. Here, we show that, both in Drosophila melanogaster flies and Aedes aegypti mosquitoes, the major mediator of catnip repellency is the widely conserved chemical irritant receptor TRPA1. In vitro, both catnip extract and its active ingredient nepetalactone can directly activate fly and mosquito TRPA1. In vivo, D. melanogaster and Ae. aegypti TRPA1 mutants are no longer repelled by catnip and nepetalactone. Interestingly, our data show that some, but not all, fly and mosquito TRPA1 variants are catnip targets. Moreover, unlike the broad TRPA1 agonist allyl isothiocyanate (AITC) (an active ingredient of tear gas and wasabi), catnip does not activate human TRPA1. Our results support the use of catnip and nepetalactone as insect-selective irritants and suggest that, despite TRPA1's broad conservation, insect TRPA1 can be targeted for the development of safe repellents.
Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic ef... more Catnip (Nepeta cataria) is a common garden herb well known for its euphoric and hallucinogenic effects on domestic cats,1-3 for its medicinal properties,4,5 as well as for its powerful repellent action on insects.6,7 Catnip extracts have been proposed as a natural alternative to synthetic insect repellents, such as N,N-diethyl-3-methylbenzamide (DEET),8,9 but how catnip triggers aversion in insects is not known. Here, we show that, both in Drosophila melanogaster flies and Aedes aegypti mosquitoes, the major mediator of catnip repellency is the widely conserved chemical irritant receptor TRPA1. In vitro, both catnip extract and its active ingredient nepetalactone can directly activate fly and mosquito TRPA1. In vivo, D. melanogaster and Ae. aegypti TRPA1 mutants are no longer repelled by catnip and nepetalactone. Interestingly, our data show that some, but not all, fly and mosquito TRPA1 variants are catnip targets. Moreover, unlike the broad TRPA1 agonist allyl isothiocyanate (AITC) (an active ingredient of tear gas and wasabi), catnip does not activate human TRPA1. Our results support the use of catnip and nepetalactone as insect-selective irritants and suggest that, despite TRPA1's broad conservation, insect TRPA1 can be targeted for the development of safe repellents.
Proceedings of the Royal Society B: Biological Sciences, 2019
Colour processing at early stages of visual pathways is a topic of intensive study both in verteb... more Colour processing at early stages of visual pathways is a topic of intensive study both in vertebrate and invertebrate species. However, it is still unclear how colour learning and memory formation affects an insect brain in the peripheral processing stages and high-order integration centres, and whether associative colour experiences are reflected in plasticity of underlying neuronal circuits. To address this issue, we used Camponotus blandus ants as their proven colour learning and memory capabilities, precisely controllable age and experience, and already known central visual pathways offer unique access to analyse plasticity in neuronal circuits for colour vision in a miniature brain. The potential involvement of distinct neuropils—optic lobes (OLs), mushroom body (MB) input (collar) and output (vertical lobe), anterior optic tubercle (AOTU) and central complex (CX)—in associative colour experiences was assessed by quantification of volumetric and synaptic changes (MB collar) di...
Ants are a well-characterized insect model for the study of visual learning and orientation, but ... more Ants are a well-characterized insect model for the study of visual learning and orientation, but the extent to which colour vision is involved in these tasks remains unknown. We investigated the colour preference, learning and memory retention of Camponotus blandus foragers under controlled laboratory conditions. Our results show that C. blandus foragers exhibit a strong innate preference for ultraviolet (UV, 365 nm) over blue (450 nm) and green (528 nm) wavelengths. The ants can learn to discriminate 365 nm from either 528 nm or 450 nm, independent of intensity changes. However, they fail to discriminate between 450 nm and 528 nm. Modelling of putative colour spaces involving different numbers of photoreceptor types revealed that colour discrimination performance of individual ants is best explained by dichromacy, comprising a short-wavelength (UV) receptor with peak sensitivity at about 360 nm, and a long-wavelength receptor with peak sensitivity between 470 nm and 560 nm. Forager...
Camponotus rufipes workers are characterized by an age-related polyethism. In the first weeks of ... more Camponotus rufipes workers are characterized by an age-related polyethism. In the first weeks of adult life, young workers perform tasks inside the nest before they switch to multimodal foraging tasks outside. We tested the hypothesis that this transition is accompanied by profound adaptations in the peripheral and central visual system. Our results show that C. rufipes workers of all tested ages (between 1-42 days) express three genes encoding for ultraviolet (UV), blue (BL) and long wavelength (LW) sensitive opsins in their retina, which are likely to provide the substrate for trichromatic color vision. Expression levels of all three opsin genes increased significantly within the first two weeks of adulthood and following light exposure. Interestingly, the volumes of all three optic neuropils (lamina, medulla, lobula) showed corresponding volume increases. Tracing of connections to higher visual centers in the mushroom bodies (MBs) revealed only one optic pathway, the anterior sup...
This meeting was held at the Stazione Zoologica Anton Dohrn, Naples, Italy, from 6th-13th July 20... more This meeting was held at the Stazione Zoologica Anton Dohrn, Naples, Italy, from 6th-13th July 2011. It was sponsored through a collaboration between IBRO (the International Brain Research Organisation) and the Kemali Foundation. Notably, it is the first IBRO sponsored School specifically in invertebrate neuroscience. The meeting was attended by early career researchers from countries around the Mediterranean basin and highlighted the research opportunities that this field can offer to neuroscientists at the start of their careers. Students participating in the School were introduced to a range of important invertebrate model systems. The utility of these models in addressing fundamental neurobiological problems, especially those relating to human neurological disorders, was extensively discussed. In this review, two of the participating students provide a summary of this meeting with a view to encouraging support for further activity in this arena in the future. One of the aims of the Kemali foundation is to foster enduring collaborations between scientists in the Mediterranean region. Given the enthusiastic networking both during and after the meeting, there is much promise that this goal will be realised.
Path integration is a general mechanism used by many animals to maintain an updated record of the... more Path integration is a general mechanism used by many animals to maintain an updated record of their position in relation to a set reference point.1-11 To do this, they continually integrate direction and distance information into a memorized home vector. What remains unclear is how this vector is stored, maintained, and utilized for successful navigation. A recent computational model based on the neuronal circuitry of the insect central complex suggests that home vector memories are encoded across a set of putative memory neurons and maintained through ongoing recurrent neural activity.12 To better understand the nature of the home vector memory and experimentally assess underlying mechanisms for maintaining it, we performed a series of experiments on the path integrating dung beetle Scarabaeus galenus.13 We found that, while the directional component of the home vector was maintained for up to 1 h, the distance component of the vector memory decreased gradually over time. Using cold-induced anesthesia, we disrupted the neural activity of beetles that had stored a home vector of known length and direction. This treatment diminished both components of the home vector memory, but by different amounts-the homing beetles lost their distance memory before their directional memory. Together, these findings present new insights into the functional properties of home vector memories and provide the first empirical evidence that a biological process that can be disrupted by cold-induced anesthesia is essential to support homing by path integration.
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