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Biomedical subjects

Lucia Regolin

Publications and source records attributed to Lucia Regolin.

15 recordsLinked to original sources
PubMed2007

Preference for symmetry is experience dependent in newborn chicks (Gallus gallus).

Spontaneous pecking preferences toward symmetric or asymmetric stimuli were tested in newborn chicks (Gallus gallus). A preference for asymmetric patterns was found in naïve chicks (either 24 or 48 hours old), although a preference for symmetry appeared at retest after chicks had experienced standard rearing conditions (Experiments 1 and 2). Only food-experienced chicks preferred symmetric patterns; food-deprived and hand-fed chicks did not show any preference (Experiment 3). A key factor that allowed for the emergence of a preference for symmetry may relate to the improving of pecking sensorimotor skills occurring during active food manipulation. Possible explanations are discussed for the late emergence of the preference for symmetry and for the preference for asymmetry found in naïve chicks.

Age Factors↗
PubMed2007

Rudimental numerical competence in 5-day-old domestic chicks (Gallus gallus): identification of ordinal position.

Numerical competencies were investigated for the 1st time in very young nonhuman animals. Chicks (Gallus gallus) learned to identify the 3rd, 4th, or 6th positions in a series of 10 identical positions (Experiment 1). Use of spatial information (i.e., distances) was ruled out in Experiment 2 (chicks generalized the reinforced response to an array of stimuli rotated by 90 degrees as compared with training) and Experiment 3 (chicks generalized their response to a series in which distances between the single positions had been manipulated). Chicks found the correct position even when both identity and distance of each position changed from trial to trial (Experiment 4). Overall, young chicks seemed to use ordinality when required to identify a target by its numerical serial position.

Age Factors↗
PubMed2006

Chicks discriminate human gaze with their right hemisphere.

Domestic chicks were tested for eye use while feeding on the floor in the presence of a dummy mask which could either look at the location where the chicks were feeding or in the opposite direction. Animals completely naïve of visual experience of human eyes and gaze showed a more intense fear response when directly looked at (as shown by higher latency to approach the food) and a preferential use of the left eye (mainly feeding structures in their right hemisphere) to monitor the dummy mask. This response, seemingly predisposed, could be reversed in chicks with experience of human eyes and gaze directed toward them, which showed higher latency to approach the food and preferential left eye use when the dummy mask looked away from them. The results are discussed in relation to evidence for a right hemisphere involvement in fear responses and detection of predators in the vertebrate brain.

Analysis of Variance↗
PubMed2006

Spatial reorientation: the effects of space size on the encoding of landmark and geometry information.

The effects of the size of the environment on animals' spatial reorientation was investigated. Domestic chicks were trained to find food in a corner of either a small or a large rectangular enclosure. A distinctive panel was located at each of the four corners of the enclosures. After removal of the panels, chicks tested in the small enclosure showed better retention of geometrical information than chicks tested in the large enclosure. In contrast, after changing the enclosure from a rectangular-shaped to a square-shaped one, chicks tested in the large enclosure showed better retention of landmark (panels) information than chicks tested in the small enclosure. No differences in the encoding of the overall arrangement of landmarks were apparent when chicks were tested for generalisation in an enclosure differing from that of training in size together with a transformation (affine transformation) that altered the geometric relations between the target and the shape of the environment. These findings suggest that primacy of geometric or landmark information in reorientation tasks depends on the size of the experimental space, likely reflecting a preferential use of the most reliable source of information available during visual exploration of the environment.

Animals↗
PubMed2006

Perception of the stereokinetic illusion by the common marmoset (Callithrix jacchus).

Stereokinetic illusions have never been investigated in non-human primates, nor in other mammalian species. These illusions consist in the perception of a 3D solid object when certain 2D stimuli are rotated slowly in the plane perpendicular to the line of sight. The ability to perceive the stereokinetic illusion was investigated in the common marmoset (Callithrix jacchus). Four adult marmosets were trained to discriminate between a solid cylinder and a solid cone for food reward. Once learning criterion was reached, the marmosets were tested in sets of eight probe trials in which the two solid objects used at training were replaced by two rotating 2D stimuli. Only one of these stimuli produced, at least to the human observer, the stereokinetic illusion corresponding to the solid object previously reinforced. At test, the general behaviour and the total time spent by the marmosets observing each stimulus were recorded. The subjects stayed longer near the stimulus producing the stereokinetic illusion corresponding to the solid object reinforced at training than they did near the illusion corresponding to the previously non-rewarded stimulus. Hence, the common marmosets behaved as if they could perceive stereokinetic illusions.

Animals↗
PubMed2006

Lateralized righting behavior in the tortoise (Testudo hermanni).

Lateralization of brain and behaviour at the population level has been documented in all vertebrate classes. Research was mostly carried out on mammalian and avian species, the least investigated class with this regards being the Reptilia, with studies concentrating on lateralized aggressive behaviour in lizards. No research has been carried out on lateralization in the Chelonian order. We investigated the presence of motor asymmetries in the tortoise Testudo hermanni, using the righting response (i.e. the animal is positioned upside-down and the left/right side to which it uprights is observed), a procedure already employed to assess behavioural lateralization in amphibians. The ability of righting has a particularly high adaptive value in tortoises, as in case of overturning, and consequent exposure to sunrays, changes in body temperature and difficulties in respiration could occur leading to serious conditions. Thirty-four tortoises underwent a series of righting tests in a standardized apparatus, 15 tortoises were also retested 10 months later. A bias at the individual as well as at the population level was found for preferentially turning on the right side. Consistency of responses at retest was also observed. The results are discussed with reference to the implications for the evolution of brain lateralization in vertebrates.

Age Factors↗
PubMed2006

Domestic chicks perceive stereokinetic illusions.

Stereokinetic illusions occur when certain 2-D patterns are set in slow rotation in a plane perpendicular to the line of sight. Such phenomena have never been investigated in animal species other than our own. We used the domestic chick (Gallus gallus) to check whether these illusions are experienced by non-human species, taking advantage of filial imprinting. Newly hatched visually naive chicks were individually exposed for 4 h to 2-D stimuli producing, to a human observer, the perception of a stereokinetic cone (experiment 1) or of a stereokinetic cylinder (experiment 2). Thereafter, each chick underwent a free-choice test between a solid 3-D cone and a solid 3-D cylinder. A control group of newly hatched but not imprinted chicks underwent the same testing procedure, to check for the presence of any spontaneous preference for one or other of the two solid objects. Imprinted chicks approached the 3-D stimulus closely resembling the stimulus they had been exposed to during imprinting (the cone in experiment 1 and the cylinder in experiment 2). Non-imprinted chicks did not show any preference. These results suggest that domestic chicks experience stereokinetic illusions.

Animals↗
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

Visually inexperienced chicks exhibit spontaneous preference for biological motion patterns.

When only a small number of points of light attached to the torso and limbs of a moving organism are visible, the animation correctly conveys the animal's activity. Here we report that newly hatched chicks, reared and hatched in darkness, at their first exposure to point-light animation sequences, exhibit a spontaneous preference to approach biological motion patterns. Intriguingly, this predisposition is not specific for the motion of a hen, but extends to the pattern of motion of other vertebrates, even to that of a potential predator such as a cat. The predisposition seems to reflect the existence of a mechanism in the brain aimed at orienting the young animal towards objects that move semi-rigidly (as vertebrate animals do), thus facilitating learning, i.e., through imprinting, about their more specific features of motion.

Animals↗
PubMed2005

Working memory in the chick: parallel and lateralized mechanisms for encoding of object- and position-specific information.

Working memory of chicks was probed in a delayed-response task, with either object- or position-specific information available in order to locate a goal that had disappeared behind one of two screens in a test arena. When the position of the correct screen was the only available cue (i.e., the two screens were identical) binocular and monocular chicks could easily locate the goal, and the same occurred when the visual characteristics of the screens (no matter what their spatial position) were the only relevant information available and when object- and position-specific cues were both available and in agreement (i.e., the two screens were different and maintained fixed spatial locations). In contrast, when object- and position-specific cues were available but were put in conflict (the two screens were different and were swapped during the delay time) left-eyed and binocular chicks went to the correct position, whereas right-eyed chicks seemed to choose both the correct spatial position and the correct object cue to the same degree. When during the delay the correct screen was substituted by an entirely novel screen, no left-right asymmetry associated with response to novelty was observed; monocular chicks preferentially approached the novel screen in the correct position, whereas binocular chicks did not show any clear choice. The results suggest that both object- and position-specific information is available to the two cerebral hemispheres in working memory tasks; however, when a conflict between cues arises, the right hemisphere preferentially attends to position-specific cues, whereas the left hemisphere tends to attend to object-specific cues.

Animals↗
PubMed2005

Visual lateralisation, form preferences, and secondary imprinting in the domestic chick.

Newly hatched chicks (Exp. 1) were exposed to an imprinting object of a certain shape (sphere/cylinder) on Day 1 (primary imprinting) and then to a different-shaped object (cylinder/sphere) on Day 2 (secondary imprinting). They were tested on Day 3 for preferences between primary and secondary imprinting objects in binocular and monocular conditions. Right-eyed males, but not females, showed relatively stronger preferences for the primary imprinting object than left-eyed males; however, the asymmetry was modulated by a spontaneous preference for the sphere. In Experiment 2, a more traditional imprinting paradigm was used: chicks were exposed to the same object for the first 2 days, and on Day 3 underwent a free-choice test between the imprinting object (sphere/cylinder) and a novel one (cylinder/sphere). Results showed that no asymmetries in the use of eyes were apparent, only a general preference for the sphere. In Experiment 3 chicks were exposed, as in Experiment 1, to a primary (Day 1) and a secondary (Day 2) imprinting object; on Day 3 they were exposed to both objects simultaneously; they were also tested for preferences for the two stimuli on Day 4. Left- and right-eyed chicks showed different choice, with the latter preferring the cylinder, thus showing that the eye-asymmetry was in some way peculiar to the secondary imprinting procedure.

Animals↗
PubMed2004

Hemispheric differences in the recognition of partly occluded objects by newly hatched domestic chicks (Gallus gallus).

Domestic chicks are capable of perceiving as a whole objects partly concealed by occluders ("amodal completion"). In previous studies chicks were imprinted on a certain configuration and at test they were required to choose between two alternative versions of it. Using the same paradigm we now investigated the presence of hemispheric differences in amodal completion by testing newborn chicks with one eye temporarily patched. Separate groups of newly hatched chicks were imprinted binocularly: (1) on a square partly occluded by a superimposed bar, (2) on a whole or (3) on an amputated version of the square. At test, in monocular conditions, each chick was presented with a free choice between a complete and an amputated square. In the crucial condition 1, chicks tested with only their left eye in use chose the complete square (like binocular chicks would do); right-eyed chicks, in contrast, tended to choose the amputated square. Similar results were obtained in another group of chicks imprinted binocularly onto a cross (either occluded or amputated in its central part) and required to choose between a complete or an amputated cross. Left-eyed and binocular chicks chose the complete cross, whereas right-eyed chicks did not choose the amputated cross significantly more often. These findings suggest that neural structures fed by the left eye (mainly located in the right hemisphere) are, in the chick, more inclined to a "global" analysis of visual scenes, whereas those fed by the right eye seem to be more inclined to a "featural" analysis of visual scenes.

Animals↗