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Lesley J Rogers

Publications and source records attributed to Lesley J Rogers.

18 recordsLinked to original sources
PubMed2006

Complementary and lateralized forms of processing in Bufo marinus for novel and familiar prey.

Amphibian vision is one of the most comprehensively studied of all vertebrate sensory systems. However, the processes of object recognition and memory in anuran amphibians have resisted satisfactory explanation. Our research shows that insight to the issue of visual discrimination and recognition in toads may be gained by investigation of the specialized and complementary functions carried out by the left and right brain hemispheres. We report that specialized processes associated with the left eye (right hemisphere) of the Bufo marinus toad carry out decisions to view and strike at complex prey stimuli recognized as 'novel.' This was demonstrated in the toads' preferences when provided a choice between identical novel insect models presented simultaneously into the left and right lateral, monocular visual fields. In a second experiment, videotaped trials of toad groups competing in an open field for live crickets were analysed for lateralized prey-catching behaviour. Concomitant with a preference for directing agonistic strikes at conspecifics within the left visual hemifield, toads were found to possess a significant preference for directing predatory responses at the familiar prey viewed in the right visual hemifield. The preference for directing prey-catching responses at freely moving crickets in the right visual hemifield supports the earlier findings drawn from automated and familiar model insect prey. We present a hypothesis explaining differences in hemispheric processing in toads responding to 'novel' and 'familiar' prey types, utilizing a range of long-term memories found to be lateralized in other vertebrates.

Animals↗
PubMed2006

Head-cocking as a form of exploration in the common marmoset and its development.

Head-cocking of 15 infant marmosets (Callithrix jacchus) was scored from Day 1 to 60 of postnatal life, the growth period with overproduction of interneuronal synapses. Head-cocking was scored during four 30 min intervals daily, including angle of head-cocking and objects being fixated. Mean age of onset of head-cocking was Day 13 (+/-1.3) and frequency increased to a fixed rate by Day 24-29, at the time of maturation of the foveal representation in layer 6 of the visual cortex, thus lending further support to the importance of head-cocking to visual processing. The most common distance of objects fixated during head-cocking was up to .5 m. Angle of head-cocking increased with age, and some asymmetry of direction was noted. Fewer head-cocking events occurred in the morning than in the afternoon. We also scored anogenital licking of offspring. Head-cocking occurred at higher levels in marmosets receiving more anogenital licking. As this was associated positively with increased exploration, head-cocking may be regarded as an exploratory behavior.

Age Factors↗
PubMed2006

Laterality of horses associated with emotionality in novel situations.

We have established that lateral biases are characteristic of visual behaviour in 65 horses. Two breeds, Trotters and French Saddlebreds aged 2 to 3, were tested on a novel object test. The main finding was a significant correlation between emotionality index and the eye preferred to view the novel stimulus: the higher the emotionality, the more likely that the horse looked with its left eye. The less emotive French Saddlebreds, however, tended to glance at the object using the right eye, a tendency that was not found in the Trotters, although the emotive index was the same for both breeds. The youngest French Saddlebreds did not show this trend. These results are discussed in relation to the different training practices for the breeds and broader findings on lateralisation in different species.

Affect↗
PubMed2005

Effects of light stimulation of embryos on the use of position-specific and object-specific cues in binocular and monocular domestic chicks (Gallus gallus).

Chicks hatched from eggs incubated in the dark (D-chicks) or from eggs exposed to light during the last 3 days before hatching (L-chicks) were trained on day 4 to peck at small cones for food reinforcement. The cones had different patterns (checked or striped) and were located in different positions (either on the left or on the right of a rectangular arena) so as both object-specific (pattern) and position-specific cues could be used to discriminate cones that contained or that did not contain food. After learning, the position of the cones was reversed so that object- and position-specific cues provided contradictory information. No effect of light incubation was observed in binocular chicks that chose cones on the basis of object-specific cues. Monocular D-chicks also tended to approach and peck the cones with the correct pattern in the wrong position, whereas monocular L-chicks did not show any clear choice. Initial choices for one side or other of the arena were mostly determined by the first side visible through the non-occluded eye in D-chicks, particularly when using their left eye. These results suggest that light exposure of the embryo makes neural mechanisms that do not receive direct visual input (i.e., those of the occluded side) more available to be used in assessment of novelty.

Analysis of Variance↗
PubMed2005

Survival with an asymmetrical brain: advantages and disadvantages of cerebral lateralization.

Recent evidence in natural and semi-natural settings has revealed a variety of left-right perceptual asymmetries among vertebrates. These include preferential use of the left or right visual hemifield during activities such as searching for food, agonistic responses, or escape from predators in animals as different as fish, amphibians, reptiles, birds, and mammals. There are obvious disadvantages in showing such directional asymmetries because relevant stimuli may be located to the animal's left or right at random; there is no a priori association between the meaning of a stimulus (e.g., its being a predator or a food item) and its being located to the animal's left or right. Moreover, other organisms (e.g., predators) could exploit the predictability of behavior that arises from population-level lateral biases. It might be argued that lateralization of function enhances cognitive capacity and efficiency of the brain, thus counteracting the ecological disadvantages of lateral biases in behavior. However, such an increase in brain efficiency could be obtained by each individual being lateralized without any need to align the direction of the asymmetry in the majority of the individuals of the population. Here we argue that the alignment of the direction of behavioral asymmetries at the population level arises as an "evolutionarily stable strategy" under "social" pressures occurring when individually asymmetrical organisms must coordinate their behavior with the behavior of other asymmetrical organisms of the same or different species.

Animals↗
PubMed2005

Lateralisation of escape responses in the stripe-faced dunnart, Sminthopsis macroura (Dasyuridae: Marsupialia).

Although lateralisation has been observed in many vertebrate species, marsupials have been neglected in the study of lateralisation. We investigated the behavioural responses of the stripe-faced dunnart (Sminthopsis macroura) to a mechanical model of a snake approaching into the monocular (left and right) or the binocular visual field. The snake model was presented to 30 adult subjects. The behavioural responses and the latency to react to the stimulus were scored. Reactivity was calculated by pooling scores for retreat, startle, ears back, and orientation. Retreat tended to be the most common of these responses. Approach of the snake into the dunnarts' left monocular visual field elicited a significantly higher reactivity compared to approach into the right or binocular visual field. Half of the animals did not respond in the 60 seconds allocated when the stimulus approached on their right side, whereas only seven did not respond when the stimulus approached on the left, and ten when the stimulus was presented binocularly. These results are consistent with the right hemisphere's known specialisation for controlling fear and escape responses. Our results suggest that marsupials are lateralised in a way similar to other vertebrates.

Animals↗
PubMed2004

Advantages of having a lateralized brain.

Brain lateralization is common among vertebrates. However, despite its implications for higher-order cognitive functions, almost no empirical evidence has been provided to show that it may confer any advantage to the functioning of the brain. Here, we show in the domestic chick (Gallus gallus domesticus) that cerebral lateralization is associated with an enhanced ability to perform two tasks simultaneously: finding food and being vigilant for predators. This finding suggests that cerebral lateralization enhances brain efficiency in cognitive tasks that demand the simultaneous but different use of both hemispheres.

Animals↗
PubMed2004

Light experience and the development of behavioural lateralisation in chicks. II. Choice of familiar versus unfamiliar model social partner.

In late-stage embryos of domestic fowl, exposure of the right eye to light entering through the shell induces asymmetry of the thalamofugal visual pathway, together with differences in performance according to whether the right or left eye (RE, LE) is in use (Behav. Brain Res. 38 (1990) 211). Nevertheless, at least some of the main specialisations of the right and left eye systems (RES, LES) are not dependent on such exposure. Higher ability of LES to assess and respond to novelty is present in dark-incubated (Da) chicks. This is probably also true of RES ability to control response, and specifically to inhibit shift to an alternative response (i.e. to a novel stimulus). We imprinted chicks on red table-tennis balls with a horizontal, white strip on their equator. At test, they chose between this and a ball with a vertical, white strip. Da chicks showed clear choice with the LE, but not with the RE. Unexpectedly, light-incubated (Li) chicks failed to show LE/RE differences in choice. Exploratory pecks at a novel feature were greatly reduced in Li. Two effects of light exposure on RES are likely. The first is greater use of RES in the home-cage, affecting what is learned about the companion ball. This may make RES more competent in assessing ball properties, and so explain the enhanced choice by RE, that abolished the RE/LE difference in Li. Secondly, the ability of RES to inhibit shift to an alternative response is enhanced. Light exposure and being female similarly opposed shift to the novel feature, but probably via different mechanisms. The effects of exposure are discussed as an example of the generation of a range of behavioural phenotypes, which are sustained within a single population by varying or frequency-dependent selection.

Age Factors↗
PubMed2004

Diurnal cycle in salivary cortisol levels in common marmosets.

A noninvasive method of saliva sampling was used to assess the diurnal cortisol rhythm from 0900 to 1700 hr in the common marmoset (Callithrix jacchus). The levels of cortisol were highest in the morning and declined significantly over the day. Individual marmosets varied in the magnitude of the cycle, and the greatest individual variability occurred in the morning levels. The decrease in cortisol levels was more rapid after than before the midday feeding period in subordinate marmosets (aged 53-63 months) compared to dominant marmosets (aged 79-80 months), and overall, the levels of cortisol were higher in the subordinate marmosets. We found no effect of sex on cortisol levels across the cycle.

Animals↗
PubMed2003

Light-dependent development of asymmetry in the ipsilateral and contralateral thalamofugal visual projections of the chick.

Light-exposure of the chick embryo induces development of asymmetry in the thalamofugal visual projections to the Wulst regions of the forebrain since the embryo is turned so that it occludes its left and not its right eye. This asymmetry can be reversed by occluding the embryo's right eye and exposing its left eye to light. Here we show that three sub-regions of the thalamus (two in the dorsolateral anterior thalami (DLA) and one more caudal) have differing asymmetries of contralateral and/or ipsilateral projections. Hence the effect of asymmetrical light stimulation is regionally specific within the thalamus. Lateralised light stimulation appears to promote the development of ipsilateral projections from DLA pars dorsolateralis pars anterioris and contralateral projections from the caudal regions (the nucleus superficialis parvocellularis especially) but it may suppress the development of contralateral projections from the nucleus dorsolateralis anterior thalami pars lateralis rostralis. We also show that the light stimulation causes lateralised expression of c-fos and receptors for neurotransmitters.

Animals↗
PubMed2002

Prehatching visual experience and lateralization in the visual Wulst of the chick.

We revealed functional lateralization of the chick visual system by placing injections of monosodium glutamate (0.5 microl, 100 mM) into the left or right Wulst regions of the hemispheres, and examined the effects of light experience before hatching on this lateralization. Following exposure of the left or right eye to light for 24 h beginning on day 18 of incubation, the chick's ability to categorize grain as distinct from pebbles was impaired by glutamate treatment of the Wulst contralateral to the exposed eye. Attack and copulation scores were also elevated. Following incubation of the eggs in darkness or with both eyes exposed to light, treatment of neither the left or right Wulst affected performance on the pebble-grain task: showing that either the left and right Wulst can assume control of this function. Treatment of either the left or right Wulst of these chicks elevates attack and copulation. However, examination of the distribution of attack scores revealed a bimodality in the attack scores of the chicks treated with glutamate in the right Wulst and not those treated in the left Wulst. In summary, light stimulation of one eye during a critical period of embryonic development causes the visual Wulst contralateral to the light exposed eye to develop dominance over its equivalent region in the other hemisphere. Without this lateralized stimulation of light both the left and right Wulst regions are largely but not exactly equivalent.

Aggression↗
PubMed2002

Chemosensory input and lateralization of brain function in the domestic chick.

One-day old domestic chicks (Gallus gallus domesticus) show concentration-dependent behavioural responses to olfactory cues. In the present study we investigated the lateralized olfactory responses of 1-day-old chicks to the odours of eugenol and iso-amyl acetate. In experiment 1 different concentrations of each odour were presented in repeated trials to chicks housed individually. The odours were presented together with a small coloured bead at which the chick pecked. When tested with the highest concentration of eugenol (100% v/v), the chicks demonstrated more head shaking when their left nostril was occluded (RN; right nostril in use) than when their right nostril was occluded (LN; left nostril in use). No such lateralization occurred in response to iso-amyl acetate. This result was confirmed in a second experiment in which the chicks were tested with unscented stimuli, 100% eugenol and 100% isoamyl acetate. In experiment 3 we found that occluding both the chicks' nostrils abolished the head shaking response to eugenol and to iso-amyl acetate. Thus, the chicks' head shaking responses to the odorants eugenol and iso-amyl acetate are mediated primarily by inputs from within the nasal cavity, and not by oral or occular inputs. The present results are consistent with the hypothesis that there is lateralization to olfactory cues and that it is dependent on the involvement of receptors inside the nasal cavity. We suggest that differences in lateralized olfactory responses to different odours are affected by the relative involvement of intranasal olfactory and trigeminal chemoreceptors.

Animals↗
PubMed2002

Lateralisation of predator avoidance responses in three species of toads.

Lateralisation of responses to presentation of a simulated predator was investigated in three species of toads: two European species (the common toad, Bufo bufo, and the green toad, Bufo viridis) and one species introduced to Australia from South America, the cane toad Bufo marinus . First a simulated snake was presented moving rapidly towards the toad in the frontal field of vision and the toad's escape responses, including jumps to the right and to the left, were recorded. No significant bias in left or right side jumping was apparent in this test. Next the simulated snake was presented in the left or right lateral field of vision in random order. Escape and defensive responses were elicited more strongly, in all three species, when the stimulus was on the toad's left side compared to its right side. Reaction times scored in the experiments with B. marinus, alone, did not differ from left to right. There were, however, species differences in the types of escape responses with respect to the laterality: B. viridis and B. marinus showed similar patterns of more sideways jumps with left presentation and more frontal jumps with right presentation. Sideways jumps were not lateralised in B. bufo, but this species showed more frontal jumps when the presentation was on the left side. These findings suggest that the selective involvement of structures located in the right side of the brain (left monocular visual field) in emotional responses (particularly fear responses) could be a phylogenetic ancient trait.

Journal Article↗
PubMed2002

Lateralised brain function in anurans: comparison to lateralisation in other vertebrates.

In recent years researchers have begun to investigate lateralisation of behaviour in amphibians. Given the mounting evidence of lateralisation in birds and mammals, and even reptiles, over the past two or more decades, it is not surprising that amphibians have attracted attention in this context. In particular, the evidence for lateralisation in fish has provided a strong basis for this research. This paper summarises the currently available information on lateralisation in anuran amphibians and discusses it in comparison to lateralisation in other vertebrate species, beginning with examples of motor lateralisation and then discussing functional asymmetries that occur between the left and right sides of the brain. The latter are manifested as side biases in responding to different stimuli or, in a number of non-amphibian species, revealed by monocular testing. Most of the examples discussed refer to lateralisation present at the level of the forebrain hemispheres, and so represent hemispheric specialisation. Lateralisation usually refers to examples in which there is a population bias for the majority of individuals in a population to be lateralised in the same direction. In other words, there is a significant skew in the frequency distribution. Such population biases in lateralisation are now known to be widespread among the vertebrates and, as shown, there are some surprisingly similar patterns of lateralisation in those species of fish, amphibians, reptiles, birds, and mammals that have been studied so far. It is also noted that, despite their ubiquity in vertebrates, far from all forms of lateralisation develop solely, or even largely, according to genetic determinants. In fact, the clear and powerful influences of environmental stimulation on development of some kinds of lateralisation in birds provide a basis for similar investigations in anurans.

Journal Article↗
PubMed2002

Limb preference and skeletal asymmetry in the cane toad, Bufo marinus (Anura: Bufonidae).

Two forms of skeletal asymmetry were identified in a population of cane toads, Bufo marinus, an exotic species in Australia. Fluctuating asymmetry characterised the lengths and weights of the long bones of the forelimbs and hindlimbs. Directional asymmetry was observed in the structure of the pectoral girdle of the toads, with the right epicoracoid positioned ventral to the left epicoracoid in 88% of the skeletons examined. Morphological data from a cohort of individuals were correlated with limb preferences determined from 10 consecutive trials in which the toads were inverted and briefly submerged in water while bilaterally clasping the experimenter's fingers. The toad's left forelimb was released first to enable the right forelimb to exert force against the experimenter's fingers and so control righting the body of the toad in 90% of trials. Asymmetries in the long bones of the forelimbs and pectoral girdles of the toads did not correlate significantly with the strength of preference for the right forelimb, although asymmetry of the weight of the tibiafibulae did correlate significantly with percent right forelimb preference. Age, or nutritional status, was a factor in the right forelimb preference: the preference for the use of the right forelimb was strongest in toads possessing longer and heavier long bones of both the forelimbs and hindlimbs. These results provide insight into the interaction between skeletal development and lateralised motor behaviour in an anuran species.

Journal Article↗