Effect of naloxone on analgesia induced by food deprivation

Naloxone (4 mg/kg) or saline was administered to animals under food deprived and non-deprived conditions prior to testing pain sensitivity in the tail flick test. Food deprived animals exhibited significantly elevated latencies in comparison to latencies observed under non-deprived conditions. This analgesia was diminished by treatment with the opiate receptor antagonist, naloxone. These findings suggest that analgesia induced by food deprivation is mediated in part by opiate receptor systems.     

The long-term effectiveness of different regimens of occlusion on recovery from early monocular deprivation in kittens.

Although the behavioural effects of an early period of monocular deprivation imposed on kittens can be very severe, resembling an extreme form of the human clinical condition deprivation amblyopia, they are not necessarily irreversible. Considerable behavioural as well as physiological recovery can occur if normal visual input is restored to the deprived eye sufficiently early, particularly if the other (initially non-deprived) eye is occluded at the same time (reverse occlusion). However, past work has shown that in many situations the improvement in the vision of the initially deprived eye that occurs during reverse occlusion is not retained following the subsequent introduction of binocular visual input. Furthermore, the vision of the other eye is often reduced as well, with the result that the eventual outcome is a condition of bilateral amblyopia. This study first examines the consequences of several periods of reverse occlusion whose onset and duration would be thought to maximize the opportunity for good and long-standing recovery of vision in the initially deprived eye. However, only in a very restricted set of exposure conditions did animals acquire good vision in one or both eyes; in most situations the final outcome was one of bilateral amblyopia. A second set of experiments examined the consequences of various regimens of part-time reverse occlusion, where the initially non-deprived eye was occluded for only part of each day to allow a period of binocular visual exposure, on kittens that had been monocularly deprived until 6, 8, 10 or 12 weeks of age. Whereas short or long daily periods of occlusion of the initially non-deprived eye resulted eventually in amblyopia in one, or usually both, eyes, certain intermediate occlusion times (3.5 or 5 h each day) resulted in recovery of normal acuities, contrast sensitivity and vernier acuity in both eyes, in animals that had been monocularly deprived until 6, 8 or 10 weeks of age, but not in animals deprived for longer periods. Experiments were done to establish some of the factors that contributed to the successful outcome associated with certain of the regimens of part-time reverse occlusion. It was established that recovery was just as good in animals in which the visual axes were vertically misaligned by means of prisms during the daily period of binocular visual exposure, thereby indicating that the visual input to the two eyes need not be concordant. However, animals that received equivalent visual exposure of the two eyes each day, but successively rather than simultaneously, all developed very severe bilateral amblyopia.(ABSTRACT TRUNCATED AT 400 WORDS)     

Memory of Location and Site Recognition in the Ant Formica uralensis (Hymenoptera: Formicidae)

Spatial recognition cues used in site fidelity in the ant Formica uralensis Ruzsky were studied using outdoor and laboratory arenas. Ant workers visiting symmetrically spaced feeders were colour-marked corresponding to the initial feeder visited during sampling. The effect of manipulating environmental cues on the mean 'spatial specialization' of the population was measured. Site recognition appears to be based on visual landmark/canopy cues. However, ants maintained some fidelity when shielded from these cues, suggesting the involvement of additional cues. When ridding our experimental device of olfactory deposits and shielding visual cues, site fidelity was lost. Idiothetic and/or geomagnetic cues are thought to provide spatial references to visual or olfactory landmarks. Altering nest position relative to the arena and changing the geomagnetic field within the arena in our study, however, did nothing to the site fidelity of visually deprived and non-deprived foragers.
We conclude that site fidelity is developed in a visually structured environment but supplemented by an olfactory backup system that is probably based on discrete home range markings rather than radial odour trails. We demonstrate furthermore that the visual component involved in site location can be stored in the memory of individual F. uralensis foragers during a 6-month hibernation period.     

Habitat use by beech martens in a fragmented landscape

We investigated key habitat features used by beech martens occupying a fragmented agricultural landscape. Locations of eight martens were radio-monitored daily for 4–12 months each. We evaluated the selection of home ranges within a geographic area, as well as the selection of habitat features within home ranges, using random simulations for comparison. Home ranges included more wood and scrub vegetation, and less arable land, than random simulations. They also included a higher proportion of watercourses with continuous vegetation along their verges, and were closer to these watercourses than random simulations. Within home ranges, beech martens used wood and scrub vegetation, and farm buildings, more intensively than expected, and arable land less than expected. On average, beech martens stayed close to watercourses (where most of the wood vegetation occurred) but not to farm buildings, indicating that only the former shaped beech marten movements. By these findings, arable land appeared to act as a seldom traversed barrier, making farm buildings uneasy to reach if they are located far from watercourses.     

Communal Nesting among Genetically Similar House Mice

From March to October 1986, 35 house mice, Mus domesticus, were fitted with radio-transmitters and tracked in and around a Colorado feed shed for an average of 5 (range 2 to 17) days. 5 of 36 simultaneously tracked pairs of lactating females used identical nesting sites. Genotypic similarity at 5 enzyme loci, assayed from biopsies of blood and toes, indicated that these females were more genetically alike than would be expected if pairing occurred randomly among females. We posit that female house mice recognize and preferentially form communal nests with close relatives. Aside from the communally nesting females, minimal overlap occurred among home ranges of lactating females. Only 4 of 10 adult male home ranges appreciably overlapped female home ranges. The home ranges of these 4 males overlapped less than the other adult male home ranges suggesting that males defend one or more females for access to mating. The possibility that communally nesting females are nursing each other's pups is discussed.     

Latrine utilization and feces recognition in the raccoon dog,Nyctereutes procyonoides

In the raccoon dog,Nyctereutes procyonoides, utilization of latrines (defecation and urination sites), and olfactory recognition and memorization of latrine feces were studied in captivity. All individuals living within a cage utilized 1 communal latrine. The continuous and communal utilization of the latrine was based on a behavioural trait to deposit their excrement on the dung pile which was already present. They were attracted not only by their own dung pile but also by that of strange conspecifics. However, raccoon dogs could olfactorily recognize and memorize both their own feces and that of strange conspecifics individually. These results indicate that, in the raccoon dog, latrines serve as a place of information exchange about conspecific individuals, and olfactory memorization of the feces adjusts their social behaviour when they acutually encounter each other.     

Social Awareness in Monkeys

Tests of self-awareness in nonhuman primates have to date beenconcerned almost entirely with the recognition of an animal'sreflection in a mirror. By contrast, we know much less aboutnon-human primates' perception of their place within a socialnetwork, or of their understanding of themselves as individualswith unique sets of social relationships. Here we review evidencethat monkeys who fail the mirror test may nonetheless behaveas if they recognize themselves as distinct individuals, eachof whom occupies a unique place in society and has a specificset of relations with others. A free-ranging vervet monkey,baboon, or macaque recognizes other members of his group asindividuals. He also recognizes matrilineal kin groups, lineardominance rank orders, and behaves as if he recognizes his ownunique place within them. This sense of "social self" in monkeys,however, is markedly different from self-awareness in humans.Although monkeys may behave in ways that accurately place themselveswithin a social network, they are unaware of the knowledge thatallows them to do so: they do not know what they know, cannotreflect on what they know, and cannot become the object of theirown attention.     

The ranging and nesting behaviour of Wood mice, Apodemus sylvaticus (Rodentia: Muridae), as revealed by radio-tracking

The social organization, nightly movements and nesting behaviour of Wood mice. Apodemus sylvaticus (L.), were studied by radio-tracking 35 individuals in a deciduous wood in north-east Scotland. The radios, which were mounted on collars and weighed 2·4 g, were only attached to mice weighing more than 20 g. During the breeding season (mid-March to December), when all the mice tracked were reproductively active, male ranges were on average 3·6 times as big (5110 m²) as those of females (1424 m²); male ranges overlapped considerably whilst females probably maintained ranges largely exclusive of one another. The ranges of males overlapped those of females apparently at random, each male's range encompassing parts of about five to ten females' ranges. Individuals' ranges changed position with time, although no total displacements were noted. No long-term bisexual associations were recorded. Nests appeared to be located at random within ranges, and nest sites were changed frequently. In summer, mice nested solitarily, whilst in winter they nested in groups of up to at least three. Typically, mice moved extensively over their ranges each night, males moving further between successive radio-fixes than females, and having fewer activity loci. Throughout the year, mice occasionally left their normal home ranges on excursions, sometimes over 100 m in length.     

Dispersal behaviour of individuals in metapopulations of two British butterflies

Dispersal patterns are important in metapopulation ecology because they affect the dynamics and survival of populations. However, because little empirical information exists on dispersal behaviour of individuals, theoretical models usually assume random dispersal. Recent empirical evidence, by contrast, suggests that the butterfly Maniola jurtina uses a non‐random, systematic dispersal strategy, can detect and orient towards habitat from distances of 100–150 m, and prefers a familiar habitat patch over a non‐familiar one (‘homing behaviour’). The present study (1) investigated whether these results generalise to another butterfly species, Pyronia tithonus; and (2) examined the cause of the observed ‘homing behaviour’ in M. jurtina. P. tithonus used a similar non‐random, systematic dispersal strategy to M. jurtina, had a similar perceptual range for habitat detection and preferred a familiar habitat patch over a non‐familiar one. The ‘homing behaviour’ of M. jurtina was found to be context‐dependent: individual M. jurtina translocated within habitat did not return towards their capture point, whereas individuals translocated similar distances out of habitat did return to their ‘home’ patch. We conclude that butterfly ‘homing behaviour’ is not based on an inherent preference for a familiar location, but that familiarity with an area facilitates the recognition of suitable habitat, towards which individuals orient if they find themselves in unsuitable habitat. Contrary to conventional wisdom, we suggest that frequent, short ‘excursions’ over habitat patch boundaries are evolutionarily advantageous to individuals, because increased familiarity with the surrounding environment is likely to increase the ability of a straying animal to return to its natural habitat, and to reduce the rate of mortality experienced by individuals attempting to disperse between habitat patches. We discuss the implications of the non‐random dispersal for existing metapopulation models, including models of the evolution of dispersal rates.     

Axonal Dynamics of Excitatory and Inhibitory Neurons in Somatosensory Cortex

Cortical topography can be remapped as a consequence of sensory deprivation, suggesting that cortical circuits are continually modified by experience. To see the effect of altered sensory experience on specific components of cortical circuits, we imaged neurons, labeled with a genetically modified adeno-associated virus, in the intact mouse somatosensory cortex before and after whisker plucking. Following whisker plucking we observed massive and rapid reorganization of the axons of both excitatory and inhibitory neurons, accompanied by a transient increase in bouton density. For horizontally projecting axons of excitatory neurons there was a net increase in axonal projections from the non-deprived whisker barrel columns into the deprived barrel columns. The axon collaterals of inhibitory neurons located in the deprived whisker barrel columns retracted in the vicinity of their somata and sprouted long-range projections beyond their normal reach towards the non-deprived whisker barrel columns. These results suggest that alterations in the balance of excitation and inhibition in deprived and non-deprived barrel columns underlie the topographic remapping associated with sensory deprivation.     

Foraging navigation of hornets studied in natural habitats and laboratory experiments

Foraging flights have been studied in three species of hornets (Vespa mandarinia, V. simillima and V. analis) in the field and the laboratory. Hornets seem to use multiple navigational cues for visiting a familiar feeding place. They could orient towards the feeding place immediately after they rose in air from the nest without directly viewing the feeder. They could visit the feeding place after dark at a luminosity 8 lux. These data suggest that they can navigate for some distance with few external cues. Hornets also seem to rely on visual cues for their mid-range navigation. They used some structures on their way as navigational landmarks to negotiate. Individual hornets are supposed to have their own landmarks. Olfactory cues seem to be used to find a new feeding place or to recruit other member. In the approach flight hornets seemed to use multiple visual cues such as the visual characteristics of the feeder and the wider scenery around the feeder. Even if the feeder in training was removed during the test, they flew with a smooth course as if they were pin-pointing the missing feeder, but without sitting on the ground. Hornets learnt how to fly to reach the feeder without external cues after passing by the last visual landmark under conditions with extremely poor visual cues. The present work suggests that hornets retain multiple navigational cues during repeated foraging behavior, and which cues they use seems to depend upon environmental conditions.     

Alarm calls of wintering great tits Parus major: warning of mate,reciprocal altruism or a message to the predator?

When a predator is not an immediate threat, a prey may produce relatively loud alarm calls because the risk is low. Since such calls could nevertheless attract acoustically oriented predators, the cost of predator attraction must be outweighed by factors beneficial to the caller. In this field study we elicited low-risk alarm calls by temporarily catching wintering adult male great tits Parus major at feeders both within and outside their territories. We tested whether the alarm calls of dominant males can be explained in terms of mate warning, reciprocal altruism or notifying the predator of detection. If alarms are intended to warn mates, males accompanied by their mates should give alarm calls both within and outside home range, even if other permanent flock members are absent. If alarms are to be explained by reciprocal altruism, male great tits should give low-risk alarm calls when accompanied by permanent flock members other than mate within and not outside of the home-range. If alarm calling is a message to a predator, males should call when foraging alone. We found that male great tits gave low-risk alarm calls when accompanied by their mates, independent of feeder location. They also gave low-risk alarm calls within home ranges in the presence of other permanent flock members when mates were absent. In contrast, only a few males gave calls when foraging alone within their home ranges, or when in the company of unfamiliar great tits outside their usual home-range. The results suggest that the utterance of alarm calls may be explained as mate protection and reciprocal altruism among familiar individuals.     

Behavioural conflict in two strains of rat: Home cage preference versus dark preference

When confronted with a novel situation rats show a tendency either to stay in a dark place or to retreat to a familiar place, if available. To produce a conflict between these two tendencies the rat's home cage was connected by a runway to a dark but unfamiliar compartment. Three groups of rats were tested in this apparatus with different levels of illumination in the home cage. Tryon Maze Bright rats showed a strong preference for the home cage which was independent of the illumination level. This preference was also found in Wistar rats. With a very high level of illumination in the home cage, however, Wistar rats showed a preference for the home cage only in the first few trials or a series of repeated trials. In later trials they spent more time in the dark part of the apparatus. The results were regarded as an indication that in a novel situation rats primarily search for a familiar place. When such a place is available they tolerate aversive stimulation present in this place.     

A quantitative study of visual cortex synapses during the postnatal development of dark-reared rats

The method of Aghajanian and Bloom (1967) was applied to the visual cortex of normal and neonatally visually deprived rats. The rats were kept with their mothers in total darkness since birth, in a ventilated and temperature-controlled animal quarter. Controls were rats from the same stock, maintained in a regular 12-h-light/12-h-dark rhythm. The animals were killed at 15, 23, 40, and 65 days of age, and the visual cortices fixed in 4% glutaraldehyde and processed for electron micrography with ethanol-phosphotungstic acid. A total of 6249 synaptic profiles were counted and their numerical density (DS) determined in both conditions. Features of the presynaptic grid were used for classifying the synaptic profiles in: type A [with one presynaptic dense projection (PsDP)]; type B (with two or three PsDPS); and type C (with four or more PsDPS). In the visually deprived rats the DS increases with a rate similar to controls, but the values for each age are slightly lower (P > 0.01). Type B synapses predominate in the visually deprived group while types A and C are scarcer. The differences found between types were maximal at 65 days of age and the results were highly significant (P > 0.001). It is concluded that major effects of dark-rearing are manifested when the individual features of the presynaptic grid are considered. It seems that a selected population of synapses is affected by the alteration of the normal epigenetic influence of early visual experience.     

Dynamic spatial partitioning and coexistence among tall grass grazers in an African savanna

Competitive relationships among mobile animals may be expressed through dynamically changing spatial relationships over different time frames. Less common species that are apparently inferior competitors may be able to coexist with more abundant species by concentrating in regions of the landscape little utilized by the former at spatio‐temporal scales from annual or seasonal ranges to the specific foraging localities exploited at different stages of the annual cycle. Spatial relationships may be influenced further by dependencies on other resources, predation risks and facilitatory interactions under certain conditions. Our study aimed to determine whether competition with more abundant zebra and buffalo restricted the abundance of sable antelope in a region where these three tall‐grass grazers overlapped in their herd distributions. We tracked the simultaneous movements of animals representing herds of these species over two dry seasons and one wet season using GPS‐GSM collars, and estimated seasonal or monthly range extents and their overlap. We also compared daily separation distances between these animals against the null pattern expected if their movements had been independent, and assessed how prior grazing by buffalo influenced the subsequent use of these localities by sable. The range of the sable herd was mostly separated from the seasonal range of the buffalo herd during the late dry season of 2006 and throughout the dry season of 2007. Seasonal home ranges of zebra herds overlapped partially with the range of the sable herd during most of the year. Even during times when their ranges overlapped, sable were rarely recorded within <1 km of the buffalo herd. Prior grazing by buffalo beyond a threshold level inhibited later use of these localities by sable, but the sable were nevertheless able to exploit places that were little utilized by buffalo at that time. Sable were less able to evade overlap with the small, mobile zebra herds, and hence more vulnerable to competitive exclusion by zebra than by buffalo. Our findings demonstrate how less abundant species can restrict competition from more abundant competitors through dynamic spatial partitioning in regions where their home ranges overlap.     

Neuronal connections of ocular dominance columns in the cortex of monocularly deprived cats

We have investigated the developmental changes of intrahemispheric neuronal connections of the areas 17 & 18 ocular dominance columns in monocularly deprived cats. Single cortical columns were microiontophoretically injected with horseradish peroxidase and 3D reconstruction of retrogradely labelled cells' region was done. Ocular dominance of injected columns and their coordinates in the visual field map were determined. In area 17 it was shown that for non-deprived eye the connections of columns that are driven via the crossed pathways were longer than connections of columns driven via uncrossed ones, and in both cases they were longer than connections in intact cats. The connections of deprived eye columns are significantly reduced. We have observed some changes in the spatial organization of long-range connections in area 17 for columns driven by the non-deprived eye (more rounded shape of regions of labeled cells, non-uniform distribution of cells within it). Maximal length of such connections did not exceed the length of connections in strabismic cats. We speculate that the length of cell axons providing for the horizontal connections of cortical columns has some intrinsic limit that does not depend on visual stimulation during the critical period of development.     

Reducing Mouse Anxiety during Handling: Effect of Experience with Handling Tunnels

Handling stress is a well-recognised source of variation in animal studies that can also compromise the welfare of research animals. To reduce background variation and maximise welfare, methods that minimise handling stress should be developed and used wherever possible. Recent evidence has shown that handling mice by a familiar tunnel that is present in their home cage can minimise anxiety compared with standard tail handling. As yet, it is unclear whether a tunnel is required in each home cage to improve response to handling. We investigated the influence of prior experience with home tunnels among two common strains of laboratory mice: ICR(CD-1) and C57BL/6. We compared willingness to approach the handler and anxiety in an elevated plus maze test among mice picked up by the tail, by a home cage tunnel or by an external tunnel shared between cages. Willingness to interact with the handler was much greater for mice handled by a tunnel, even when this was unfamiliar, compared to mice picked up by the tail. Once habituated to handling, C57BL/6 mice were most interactive towards a familiar home tunnel, whereas the ICR strain showed strong interaction with all tunnel handling regardless of any experience of a home cage tunnel. Mice handled by a home cage or external tunnel showed less anxiety in an elevated plus maze than those picked up by the tail. This study shows that using a tunnel for routine handling reduces anxiety among mice compared to tail handling regardless of prior familiarity with tunnels. However, as home cage tunnels can further improve response to handling in some mice, we recommend that mice are handled with a tunnel provided in their home cage where possible as a simple practical method to minimise handling stress.     

Site fidelity and homing in juvenile rabbitfishes (Siganidae)

The behaviour of juvenile fishes is critical in establishing the link between recruitment and subsequent adult populations. If juvenile fishes move, they can respond to variation in local conditions before adult home ranges are established. Alternatively, if juveniles establish fixed home ranges at settlement, their decisions may determine future population densities at small spatial scales. Field observations and translocations revealed that juvenile rabbitfishes (Siganus corallinus and S. doliatus) have small home ranges and strong homing abilities (covering 6 m in 1 h or 36 m within 24 h). Only four of 22 individuals failed to return; all were transferred up-current, suggesting that olfaction is important in homing. Small home ranges and strong homing tendencies in juvenile herbivores suggest that decisions made by recruits will impact the spatial extent of both adult fishes and the functional roles they play within ecosystems.     

Social recognition in wild fish populations

The ability of animals to gather information about their social and physical environment is essential for their ecological function. Odour cues are an important component of this information gathering across taxa. Recent laboratory studies have revealed the importance of flexible chemical cues in facilitating social recognition of fishes. These cues are known to be mediated by recent habitat experience and fishes are attracted to individuals that smell like themselves. However, to be relevant to wild populations, where animals may move and forage freely, these cues would have to be temporally flexible and allow spatial resolution. Here, we present data from a study of social recognition in wild populations of three-spined sticklebacks (Gasterosteus aculeatus). Focal fish preferentially associated with conspecifics from the same habitat as themselves. These preferences were changed and updated following translocation of the focal fish to a different site. Further investigation revealed that association preferences changed after 3 h of exposure to different habitat cues. In addition to temporal flexibility, the cues also allowed a high degree of spatial resolution: fish taken from sites 200 m apart produced cues that were sufficiently different to enable the focal fish to discriminate and associate with fish captured near their own home site. The adaptive benefits of this social recognition mechanism remain unclear, though they may allow fish to orient within their social environment and gain current local information.     

The Role of Olfactory Cues in Short-Range Mate Finding by the Emerald Ash Borer, Agrilus planipennis Fairmaire (Coleoptera: Buprestidae)

We investigated the relative importance of olfaction versus vision in the mate-finding behavior of Agrilus planipennis. When coupled in male–female, male–male and female–female pairs, attempts to mate occurred only in the male–female pairs, suggesting that beetles can identify the opposite sex before attempting to mate. In a set of sensory deprivation experiments with male–female pairs, we evaluated whether males could find females when deprived of their sense of olfaction, vision or both. Males whose antennae were blocked with model paint took significantly longer to find females and spent less time in copula compared to untreated males. Males whose eyes were similarly blocked did not differ in their mate finding capacity compared to untreated males. In a third experiment that compared both olfaction and vision, olfactorily impaired beetles never mated whereas the mate finding potential of visually impaired beetles did not differ from that of untreated beetles. Our results indicate that males can identify females before coming into physical contact with them, and that at short range (≤5 cm), volatile cues detected by olfaction are involved in mate finding by A. planipennis.