Biomedical subjects

G Vallortigara

Publications and source records attributed to G Vallortigara.

At least 19 recordsLinked to original sources

PubMed2006

Spatial cognition based on geometry and landmarks in the domestic chick (Gallus gallus).

Recent evidence suggest that encoding of spatial information based on extended surfaces may differ from encoding based on discrete arrays of local elements. Here we investigated the use of these different frames of reference in domestic chicks. Chicks were trained to search for food hidden under sawdust in the center of the floor of a square-shaped landmark array, with its center in coincidence with the center of a square-shaped enclosure. Displacement of the array to a corner caused a shift of searching behavior toward the array, the search activity spanning between the center of the arena and the center of the array. After changing distances between landmarks, chicks still searched in the central area. Asymmetries were apparent in chicks tested in monocular conditions, with left-eyed chicks being more affected by the overall enclosure and right-eyed chicks by local landmarks. These results suggest that chicks can use both distances from extended surfaces and local information provided by the landmarks of the array to orient in space. However, chicks do not seem to perceive the array as a whole configuration, rather they tend to rely only on single landmarks to locate the goal.

Animals↗

PubMed2006

Multiple landmarks, the encoding of environmental geometry and the spatial logics of a dual brain.

A series of place learning experiments was carried out in young chicks (Gallus gallus) in order to investigate how the geometry of a landmark array and that of a walled enclosure compete when disoriented animals could rely on both of them to re-orient towards the centre of the enclosure. A square-shaped array (four wooden sticks) was placed in the middle of a square-shaped enclosure, the two structures being concentric. Chicks were trained to ground-scratch to search for food hidden in the centre of the enclosure (and the array). To check for effects of array degradation, one, two, three or all landmarks were removed during test trials. Chicks concentrated their searching activity in the central area of the enclosure, but their accuracy was inversely contingent on the number of landmarks removed; moreover, the landmarks still present within the enclosure appeared to influence the shape of the searching patterns. The reduction in the number of landmarks affected the searching strategy of chicks, suggesting that they had focussed mainly on local cues when landmarks were present within the enclosure. When all the landmarks were removed, chicks searched over a larger area, suggesting an absolute encoding of distances from the local cues and less reliance on the relationships provided by the geometry of the enclosure. Under conditions of monocular vision, chicks tended to rely on different strategies to localize the centre on the basis of the eye (and thus the hemisphere) in use, the left hemisphere attending to details of the environment and the right hemisphere attending to the global shape.

Animals↗

PubMed2005

Lateralised behaviour and immune response in dogs: relations between paw preference and interferon-gamma, interleukin-10 and IgG antibodies production.

The production of specific antibodies (IgG), interleukin-10 (IL-10) and interferon-gamma (IFN-gamma) was evaluated in dogs in relation to behavioural lateralisation as assessed by paw preference. Left-handed, right-handed and ambidextrous dogs of mixed breed were selected on the basis of their performance in a task consisting of the removal of a piece of adhesive paper from the snout. All dogs were immunised with rabies vaccine. IgG anti-rabies antibody response was evaluated by indirect immunofluorescence (IIF) test. Serum IFN-gamma and IL-10 levels were measured by ELISA in animals showing significant individual left-, right- or no-paw preferences in the behavioural test. The results showed that the direction of behavioural lateralisation influenced the immune response in dogs. The titers of anti-rabies antibodies were lower in left-pawed dogs than in right-pawed and ambidextrous dogs. Similarly, the IFN-gamma serum levels were lower in left-pawed dogs than in right-pawed and ambidextrous dogs. IL-10, on the contrary, seemed to be an immune parameter, which was not affected by lateralisation. These findings suggest that immunomodulation can be correlated with brain laterality in canine species by the regulation of the production of antibodies and some cytokines like IFN-gamma, which are molecules involved in the immune-neurohumoral crosstalk.

Animals↗

PubMed2004

Paw preference in dogs: relations between lateralised behaviour and immunity.

Paw use in a task consisting of the removal of a piece of adhesive paper from the snout was investigated in 80 mongrel and pure-bred domestic dogs (Canis familiaris). Population lateralisation was observed, but in opposite directions in the two sexes (animals were not desexed): males preferentially used their left paw, females their right paw. The relationship between immune function and paw preference was then investigated. Some immune parameters (total number of white blood cells including lymphocytes, granulocytes and monocytes; leukocyte formula; total proteins; gamma-globulins) were investigated in a sample of left-pawed (n = 6), right-pawed (n = 6) and ambidextrous (n = 6) dogs. The results showed that the percentage of lymphocytes was higher in left-pawed than in right-pawed and ambidextrous dogs, whereas granulocytes percentage was lower in left-pawed than in right-pawed and ambidextrous dogs. Moreover, total number of lymphocytes cells was higher in left-pawed than in right-pawed and ambidextrous dogs, whereas the number of gamma-globulins was lower in left-pawed than in right-pawed and ambidextrous dogs. These findings represent the first evidence that brain asymmetry modulates immune responses in dogs.

Animals↗

PubMed2001

Why do birds sleep with one eye open? Light exposure of the chick embryo as a determinant of monocular sleep.

Together with some aquatic mammals, birds exhibit a unique behavioral and electrophysiological state called "unihemispheric sleep," in which one cerebral hemisphere is awake and the other is sleeping. Slow-wave sleep in one hemisphere is associated with closure of the contralateral eye, while the eye contralateral to the awake hemisphere is open; closure of both eyes, in contrast, is associated with bihemispheric slow-wave sleep or with REM sleep. During the last few days of incubation, the chick's embryo is turned in the egg so that it occludes its left eye, whereas light entering through the shell can stimulate the right eye. Here we show that in the first two days after hatching, chicks coming from eggs incubated in the light prevalently slept with their right eye open, whereas those coming from eggs incubated in the dark prevalently slept with their left eye open. Thus, asymmetric light stimulation in the embryo can modulate the left-right direction of eye opening during post-hatching monocular sleep.

Aging↗

PubMed2001

How birds use their eyes: Opposite left-right specialization for the lateral and frontal visual hemifield in the domestic chick.

Recent evidence has demonstrated that, in animals with laterally placed eyes, functional cerebral asymmetry is revealed by preferential use of either the left or right eye in a range of behaviors (birds: [1, 2, 3]; fish: [4, 5]; reptiles: [6, 7]). These findings pose a theoretical problem. It seems that there would be disadvantages in having a substantial degree of asymmetry in the use of the two eyes; a deficit on one side would leave the organism vulnerable to attack on that side or unable to exploit resources appearing on one side. We here report a possible solution to the problem. We have found that domestic chicks show selective use of the lateral visual field of the left eye and of the right hemifield in the binocular, frontal visual field when they peck at strangers but not at cagemates. Thus, during social recognition, there seems to be opposite and complementary left-right specialization for the lateral and frontal visual fields of the two eyes. These findings can reconcile the computational advantages associated with asymmetry of the left and right sides of the brain with the ecological demands for an animal to perceive and respond equally well to the left and right sides of its midline.

Animals↗

PubMed2001

Illusory smoke and dazzling fog.

It is well known that a flat ellipse rotating in the frontoparallel plane appears, after brief inspection, as a rigid circular disc tilting back and forth in a 3-D space. We here report that rotation of a grey-shaded ellipse on a white or on a black background produces the compelling illusion of a dark smoke or a dazzling fog (depending on the conditions of the background) moving in front of a completely white or completely black tilting disc. The fog effect disappears when there is a luminance contrast all along the perimeter of the ellipse. An experiment is reported showing that the effect can be experienced in static conditions only to a limited extent and mostly in the 'dazzling' version, and that relative movement between the contours of the figure and the shaded area is crucial to the occurrence of the effect, while the occurrence of a depth effect is not.

Humans↗

PubMed2001

Consistency among different tasks of left-right asymmetries in lines of fish originally selected for opposite direction of lateralization in a detour task.

Lines of fish, Girardinus falcatus preferentially turning rightward (RD) or leftward (LD) when facing a dummy predator visible behind a barrier have been obtained through selective breeding. To check whether lateralization was maintained in other behavioral responses, five different tests were carried out. They comprised measures of (1) turning direction in a T-maze; (2) proportion of clockwise and anticlockwise direction of rotation in a circular arena; (3) preferential eye use by females during shoaling behavior (i.e. while looking at their own mirror image reflection); (4) preferential eye use by males during sexual behavior (i.e. while turning around a barrier to join a group of females); and (5) preferential eye use by males during agonistic behavior (i.e. while attacking a rival visible in a mirror). In all five tests the two selected lines showed opposite direction of lateralization. Results thus indicate that behavioral asymmetries in the detour test are predictive of lateralization in other types of behavioral tests. Moreover, results show that RD and LD fish have a similar but left-right reversed pattern of subdivision of cognitive/ behavioral functions, which is suggestive of a similarly left-right reversed (mirror image) brain organization.

Agonistic Behavior↗

PubMed2001

Lateralization of ventral fins use during object exploration in the blue gourami (Trichogaster trichopterus).

Blue gourami fish have a pair of modified ventral fins that are used to obtain tactile information about surrounding objects. Use of ventral fins by blue gourami was investigated during initial exploration of novel objects. When exposed to a sequence of novel plastic objects, varying in shape and colour, the blue gourami showed preferential use of the left fin during initial contacts. Laterality apparently depends on the nature of the stimulus: Fish exposed to a randomized series of natural objects showed preferential use of the left fin for inanimate mineral objects, but no asymmetry was apparent for investigating animate objects. This would suggest that some form of 'handedness' may have been present prior to the appearance of tetrapods. On the other hand, measurements of fish monocular viewing revealed that the fin use was strongly associated with preferential use of the ipsilateral eye before the touching of the stimulus took place, thus, suggesting that the asymmetry in fin use may also be related to lateralization of the visual system.

Animals↗

PubMed2001

Hemispheric memories for the content and position of food caches in the domestic chick.

From Day 2 to Day 4 of life, chicks were fed daily in a large enclosure with 2 identical food caches, each filled with a different type of seed. On Day 5, binocular and monocular chicks were fed in their home cages 1 type of seed exclusively for 30 min. At test, soon after this devaluation phase, both binocular and right-eyed chicks chose the food caches containing the seeds that had not been devalued; in contrast, left-eyed chicks did not show a clear choice. Experiments revealed that the asymmetry was not due to lack of motivation, worse spatial memory, or inability to remember the consequences of devaluation by left-eyed chicks. Results suggest that young chicks can form declarative-like memories of the content of food caches. However, chicks using their left eye (which provides a supply mainly to the right hemisphere) failed to integrate memory of the content of food caches with memory of the consequences of devaluation.

Age Factors↗

PubMed2001

Hippocampus and homing in pigeons: left and right hemispheric differences in navigational map learning.

One-month-old, inexperienced homing pigeons, prior to any opportunity to learn a navigational map, were subjected to either right or left unilateral ablation of the hippocampal formation (HF). These pigeons were then held together with a group of age-matched control birds in an outdoor aviary, where they were kept for about 3 months with the opportunity to learn a navigational map. When subsequently tested for navigational map learning at about 4 months of age posthatching, control and right HF-ablated pigeons were equally good at orienting homeward from distant, unfamiliar locations, indicating successful navigational map learning. By contrast, left HF-ablated pigeons were impaired in orienting homeward, indicating a failure to learn a navigational map. Interestingly, both right and left HF-ablated pigeons displayed impaired homing performance relative to controls. These results suggest that different aspects of homing pigeon navigation may be lateralized to different hemispheres, and in particular, the HF of the different hemispheres. The left HF appears critical for navigational map learning, i.e. determining an approximate direction home from distant, unfamiliar locations. The right HF, and possibly the left HF as well, appear to play an important role in local navigation near the loft, which is likely based on familiar landmarks.

Animals↗

PubMed2001

Encoding of geometric and landmark information in the left and right hemispheres of the Avian Brain.

Chicks were trained binocularly to find food buried under sawdust in the center of a square enclosure. When tested in an enclosure made larger or smaller in size, binocular and left-eyed chicks searched mainly on the basis of relative distance of the food from the enclosure walls, whereas right-eyed chicks searched on the basis of absolute distance. Moreover, binocular and left-eyed chicks relied mainly on global spatial information (i.e., distances from the walls), whereas right-eyed chicks also used information provided by visual landmarks. These results suggest that the right hemisphere of the avian brain (fed mostly by the left eye) is primarily concerned with encoding of relational spatial information, whereas the left hemisphere (fed mainly by the right eye) is concerned with absolute metric information, possibly as part of an encoding strategy based primarily on local (both spatial and nonspatial) cues.

Animals↗

PubMed2000

Comparative neuropsychology of the dual brain: a stroll through animals' left and right perceptual worlds.

Perceptual asymmetries in humans typically manifest themselves under quite unnatural settings (e.g., tachistoscopic viewing and dichotic listening) and this has put into question their real biological significance. In animals with laterally placed eyes, however, perceptual asymmetries are ubiquitous in the normal, everyday behavior, as revealed by the differential use of the lateral visual field of the left and right eye in a variety of tasks. Data are presented showing how preferential use of the left and right eyes influences visual discrimination learning and detour behavior in chicks; similarities with detour tests performed in fish and evidence for asymmetries in eye use in animals with larger binocular overlap (e.g., anuran amphibians) are discussed. Implications of these perceptual asymmetries on the formation and fate of memory traces are put forward, with examples from unihemispheric sleep and lateralization of spatial memory in chicks. Finally, speculations about the evolutionary origins and possible adaptive advantages of perceptual asymmetries in vertebrates are presented.

Animals↗

PubMed2000

Heritability of lateralization in fish: concordance of right-left asymmetry between parents and offspring.

The poeciliid fish Girardinus falcatus shows a consistent population bias to detour a vertical-bar barrier preferentially leftwise when approaching a dummy predator to inspect it; the asymmetry seems to be due to a preferential use of the lateral field of the right eye during fixation of biologically relevant stimuli such as a predator. In order to unravel the origins of this lateral bias, we took advantage of the individual variability present in the natural population to perform artificial selection experiments. Males and females that scored similarly at the detour test were mated together and their progeny were tested in the same task. Results showed that there was a striking similarity in the strength and in the direction of the asymmetries between parents and offspring. Correlation was highly significant and the estimate of heritability was greater than 0.5. This represents the first demonstration of heritability of the direction of a behavioural asymmetry outside the primate order. The finding paves the way to the use of a novel and suitable animal model for the neuro-genetics of lateralization and to the possible identification of homologous and/or analogous genes underlying brain asymmetry among vertebrates.

Animals↗

PubMed2000

Eye use in search is determined by the nature of task in the domestic chick (Gallus gallus).

In Experiments 1-3 chicks were trained to find, using both eyes, food covered by a cap, using wide-angle search so as to involve lateral and frontal visual fields, with either local or positional cues, or both, identifying the baited site. At test they used right, left or both eyes (RE, LE, Bin). When both types of cue were relevant, LE made greater use of positional cues than the other two groups, as has been previously found, whereas RE made greater use of local (colour) cues. However, when only one type of cue was relevant, RE and LE were equally able to use positional or local cues. Right/left differences emerge when RE and LE can be used in different ways during training. In Experiments 4-5 Bin chicks were shown to turn preferentially to the right during wide-angle search, when relying on local, and to the left when relying on positional cues. In search, parallel processing of RE and LE inputs appears to allow competition which is usually won by the eye system more suited to the task, which then initiates targeting to objects which are visible to its eye.

Analysis of Variance↗

PubMed2000

Searching for the center: spatial cognition in the domestic chick (Gallus gallus).

Chicks learned to find food hidden under sawdust by ground-scratching in the central position of the floor of a closed arena. When tested inan arena of identical shape but a larger area, chicks searched at 2 different locations, one corresponding to the correct distance (i.e., center) in the smaller (training) arena and the other to the actual center of the test arena. When tested in an arena of the same shape but a smaller area, chicks searched in the center of it. These results suggest that chicks are able to encode information on the absolute and relative distance of the food from the walls of the arena. After training in the presence of a landmark located at the center of the arena, animals searched at the center even after the removal of the landmark. Marked changes in the height of the walls of the arena produced some displacement in searching behavior, suggesting that chicks used the angular size of the walls to estimate distances.

Animals↗

PubMed2000

Population lateralisation and social behaviour: a study with 16 species of fish.

We investigated turning responses in 16 species of fish faced with a vertical-bar barrier through which a learned dummy predator was visible. Ten of these species showed a consistent lateral bias to turn preferentially to the right or to the left. Species belonging to the same family showed similar directions of lateral biases. We performed an independent test of shoaling tendency and found that all gregarious species showed population lateralisation, whereas only 40% of the non-gregarious species did so. The results provide some support to the Rogers (1989) hypothesis that population lateralisation might have been developed in relation to the need to maintain coordination among individuals in behaviours associated with social life.

Journal Article↗

PubMed1999

Laterality and cooperation: mosquitofish move closer to a predator when the companion is on their left side.

Mirror images simulating social partners that cooperated or defected have been used as an experimental method to test the hypothesis that, while inspecting a predator, pairs of fish play a conditional strategy, Tit for Tat, in an iterated version of the Prisoner's Dilemma game. Using this method, we found that predator inspection was more likely to occur when the mirror image was visible on the left rather than on the right side of mosquitofish, Gambusia holbrooki. The same occurred even when a videorecorded stimulus presentation was used, in which sequences of the predator were mixed with their mirror-image equivalents, thus showing that the asymmetry was not due to behavioural or morphological asymmetries of the predator itself. Moreover, irrespective of whether they were tested with a cooperative (parallel mirror) or a defecting (angled mirror) partner, mosquitofish drew closer to the predator when the mirror was on their left side. These findings suggest that the images seen on the right and left sides by a fish may evoke different types of social behaviour, probably because of differing modes of analysis of perceptual information carried out by the left and right sides of the brain; accurate control and balancing of the side of presentation of visual stimuli during behavioural experiments thus appears to be crucial. Copyright 1999 The Association for the Study of Animal Behaviour.

Journal Article↗