Biology subjects

Vallortigara, G.

Publications and source records attributed to Vallortigara, G..

36 records · Page 2Linked to original sources

bioRxiv2022

Behavioural analysis of loss of function zebrafish supports baz1b as master regulator of domestication

Domestication is associated with both morphological and behavioural phenotypic changes that differentiate domesticated species from their wild counterparts. Some of the traits are those purposely targeted by the selection process, whilst others co-occur as a result of selection. The combination of traits is referred to as the domestication syndrome and their shared characteristics has given rise to the neural crest domestication syndrome (NCDS) hypothesis. According to this hypothesis, the phenotypic changes are a consequence of a selection towards animals with mild underdevelopment of the neural crest. A similar mechanism is suggested to affect some species of "self-domesticated" animals, including humans. Recent research supports a role for BAZ1B, one of the haplo-insufficient genes in Williams syndrome (WS), in the evolution of craniofacial features of modern humans. Interestingly, WS recapitulates some of the traits observed in the domestication syndrome, including hypersociability and reduced facial bones. However, the evidence linking BAZ1B to behavioural phenotypes associated with domestication is presumptive. Here, we use zebrafish as a model to test the hypothesis that baz1b loss-of-function leads to both morphological and behavioural phenotypes associated with the domestication syndrome by influencing the development of the neural crest. Our research provides further evidence supporting the NCDS hypothesis and bazlbs role in this process.

animal behavior and cognition↗

bioRxiv2022

Number neurons in the nidopallium of young domestic chicks

Numerical cognition is ubiquitous in the animal kingdom. Domestic chicks are a widely used developmental model for studying numerical cognition. Soon after hatching, chicks can perform sophisticated numerical tasks. Nevertheless, the neural basis of their numerical abilities has remained unknown. Here, we describe for the first time number neurons in the caudal nidopallium (functionally equivalent to the mammalian prefrontal cortex) of young domestic chicks. Number neurons that we found in young chicks showed remarkable similarities to those in the prefrontal cortex and caudal nidopallium of adult animals. Thus, our results suggest that numerosity perception based on the labeled-line code provided by number neurons might be an inborn feature of the vertebrate brain. SignificanceNumerosity, i.e. the number of items in a set, is a significant aspect in the perception of the environment. Behavioural and in silico experiments suggest that number sense belongs to a core knowledge system and can be present already at birth. However, neurons sensitive to the number of visual items have been so far described only in the brain of adult animals. Therefore, it remained unknown to what extent their selectivity would depend on visual learning and experience. We found number neurons in the caudal nidopallium (a higher associative area with functional similarities to the mammalian prefrontal cortex) of very young, numerically naive domestic chicks. This result suggests that numerosity perception is possibly an inborn feature of the vertebrate brain.

neuroscience↗

bioRxiv2021

Light-induced asymmetries in the embryonic retina are mediated by the vascular system and extracellular matrix

Left-right asymmetries in the nervous system (lateralisation) influence a broad range of behaviours, from social responses to navigation and language. The role and pathways of endogenous and environmental mechanisms in the ontogeny of lateralisation remains to be established. The domestic chick is a model of both endogenous and experience-induced lateralisation driven by light exposure. Following the endogenous rightward rotation of the embryo, the asymmetrical position in the egg results in a greater exposure of the right eye to environmental light. To identify the genetic pathways activated by asymmetric light stimulation, and their time course, we exposed embryos to different light regimes: darkness, 6 hours of light and 24 hours of light. We used RNA-seq to compare gene expression in the right and left retinas and telencephalon. As expected, no differential expression between left and right was present in darkness. We detected differential gene expression in right vs left retina after 6 hours of light exposure. This difference disappeared before 24 hours of light exposure, suggesting that light-induced activation is a self-terminating phenomenon. This transient effect of light exposure was associated with a downregulation of the sensitive-period mediator gene DIO2 (iodothyronine deiodinase 2) in the right retina. No differences between genes expressed in the right vs. left telencephalon were detected. Gene networks associated with lateralisation were connected to vascularisation, cell motility, and the extracellular matrix. Interestingly, we know that the extracellular matrix- including the differentially expressed PDGFRB (platelet-derived growth factor receptor {beta}) gene - is involved in both sensitive periods and in the endogenous chiral mechanism of primary cilia, that drives lateralisation. Our data show a similarity between endogenous and experience-driven lateralisation, identifying functional gene networks that affect lateralisation in a specific time window.

neuroscience↗

bioRxiv2021

Archerfish number discrimination

Debates have arisen as to whether non-human animals actually can learn astract non-symbolic numerousness or whether they always rely on some continuous physical aspect of the stimuli covarying with number. Here we investigated archerfish (Toxotes jaculatrix) non-symbolic numerical discrimination with accurate control for co-varying continuous physical stimulus attributes. Archerfish were trained to select one of two groups of black dots (Exp. 1: 3 vs. 6 elements; Exp. 2: 2 vs. 3 elements); these were controlled for several combinations of physical variables (elements size, overall area, overall perimeter, density and sparsity), ensuring that only numerical information was available. Generalization tests with novel numerical comparisons (2 vs. 3, 5 vs. 8 and 6 vs. 9 in Exp. 1; 3 vs. 4, 3 vs. 6 in Exp. 2) revealed choice for the largest or smallest numerical group according to the relative number that was rewarded at training. None of the continuous physical variables, including spatial frequency, were affecting archerfish performance. Results provide evidence of the spontaneous use of abstract relative numerical information in archerfish for both small and large numbers.

animal behavior and cognition↗

bioRxiv2021

Towards a standardization of non-symbolic numerical experiments: GeNEsIS, a flexible and user-friendly tool to generate controlled stimuli

Several studies have suggested that vertebrate and invertebrate species may possess a number sense, i.e. an ability to process in a non-symbolic and non-verbal way the numerousness of a set of items. However, this hypothesis has been challenged by the presence of other non-numerical continuous physical variables, that vary along with numerosity (e.g. any change in the number of visual physical elements in a set naturally involves a related change in visual features such as area, density, contour length and convex hull of the stimulus). It is therefore necessary to control and manipulate the continuous physical information when investigating the ability of humans and other animals to perceive numerousness. During decades of research, different methods have been implemented in order to address this issue, which has implications for experiments replicability and inter-species comparisons, since no general standardized procedure is currently being used. Here we present the "Generation of Numerical Elements Images Software" (GeNEsIS) for the creation of non-symbolic numerical arrays in a standardized and user-friendly environment. The main aim of this tool would be to provide researchers in the field of numerical cognition with a manageable and precise instrument to produce visual numerical arrays controlled for all the continuous variables; additionally, we implemented the possibility to actively guide stimuli presentation during habituation/dishabituation and dual-choice comparison tasks used in human and comparative research.

animal behavior and cognition↗

bioRxiv2021

Characterising ontogeny of numerosity discrimination in zebrafish reveals multiple, numerical and non- numerical mechanisms.

A sense of non-symbolic numerical magnitudes is widespread in the animal kingdom and has been documented in adult zebrafish. Here we investigated the ontogeny of this ability using a group size preference task in juvenile zebrafish. Fish showed group size preference from 21 days post fertilization (dpf) and reliably chose the larger group when presented with discriminations of between 1 vs. 3, 2 vs. 5 and 2 vs. 3 conspecifics but not 2 vs. 4 conspecifics. When the ratio between the number of conspecifics in each group was maintained at 1:2, fish could discriminate between 1 vs. 2 individuals and 3 vs. 6, but again, not when given a choice between 2 vs. 4 individuals. These findings are in agreement with studies in other species suggesting the systems involved in quantity representation do not operate separately from other cognitive mechanisms. Rather they suggest quantity processing in fish may be the result of an interplay between attentional, cognitive and memory-related mechanisms as in humans and other animals. Our results emphasise the potential of the use of zebrafish to explore the genetic and neural processes underlying the ontogeny and function of number cognition.

animal behavior and cognition↗

bioRxiv2021

Young domestic chicks spontaneously represent the absence of objects

Absence is a notion that is usually captured by language-related concepts like zero or negation. Whether non-linguistic creatures encode similar thoughts is an open question, as everyday behavior marked by absence (of food, of social partners) can be explained solely by expecting presence somewhere else. We investigated 8-day-old chicks looking behavior in response to events violating expectations about the presence or absence of an object. We found different behavioral responses to violations of presence and absence, suggesting distinct underlying mechanisms. Importantly, chicks displayed an avian signature of novelty detection to violations of absence, namely a sex-dependent left-eye-bias. Follow-up experiments excluded accounts that would explain this bias by perceptual mismatch or by representing the object at different locations. These results suggest that the ability to spontaneously form thoughts about the absence of objects likely belongs to the initial cognitive repertoire of vertebrate species.

animal behavior and cognition↗

bioRxiv2020

Resurgence of a perinatal attraction for animate objects via thyroid hormone T3

For inexperienced brains, some stimuli are more attractive than others. Human neonates and newly-hatched chicks preferentially orient towards face-like stimuli, biological motion, and objects changing speed. In chicks, this enhances exposure to social partners, and subsequent attachment trough filial imprinting. Early preferences are not steady. The preference for stimuli changing speed fades away after three days in chicks. To understand the physiological mechanisms underlying these transient responses, we tested whether the early preferences for objects changing speed can be promoted by thyroid hormone 3,5,3-triiodothyronine (T3). This hormone determines the start of imprintings sensitive period. We found that the preference for objects changing speed can be re-established in female chicks treated with T3. Moreover, day-one chicks treated with an inhibitor of endogenous T3 did not show any preference. These results suggest that the time windows of early predispositions and of high plasticity are controlled by the same molecular mechanisms.

animal behavior and cognition↗

bioRxiv2020

Newborns' sensitivity to speed changes as a building block for animacy perception

The human visual system can discriminate between animate beings vs. inanimate objects on the basis of some kinematic cues, such as starting from rest and speed changes by self-propulsion. The ontogenetic origin of such capability is still under debate. Here we investigate for the first time whether newborns manifest an attentional bias toward objects that abruptly change their speed along a trajectory as contrasted with objects that move at a constant speed. To this end, we systematically manipulated the motion speed of two objects. An object that moves with a constant speed was contrasted with an object that suddenly increases (Experiment 1) or with one that suddenly decreases its speed (Experiment 2). When presented with a single speed change, newborns did not show any visual preference. However, newborns preferred an object that abruptly increases and then decreases its speed (Experiment 3), but they did not show any visual preference for the reverse sequence pattern (Experiment 4). Overall, results are discussed in line with the hypothesis of the existence of attentional biases in newborns that trigger their attention towards some visual cues of motion that characterized animate perception in adults.

neuroscience↗

bioRxiv2020

Neurons in the dorso-central division of zebrafish pallium respond to change in visual numerosity

Non-symbolic number cognition based on an approximate sense of magnitude has been documented in zebrafish. Here we investigated for the first time its neural bases. Zebrafish were habituated to a set of three or nine small dots associated with food reward. During habituation trials, the dots changed in their individual size, position and density maintaining their numerousness and overall surface area. In the dishabituation test, zebrafish faced a change (i) in number (from three to nine or vice versa with the same overall surface), (ii) in shape (with the same overall surface and number), or (iii) in size (with the same shape and number); in a control group (iv) zebrafish faced the same familiar stimuli as during the habituation. Using qPCR to measure modulation of the expression of the immediate early genes c-fos and egr-1 and in-situ hybridization to count egr1-positive cells we found a specific and selective activation of the caudal part of the dorso-central (Dc) division of the zebrafish pallium upon change in numerosity. As pallial regions are implicated in number cognition in mammals and birds, these findings support the existence of an evolutionarily conserved mechanism for approximate magnitude and provide an avenue for exploring the underlying molecular correlates.

neuroscience↗

bioRxiv2020

Stability and individual variability of social attachment in imprinting

Filial imprinting has become a model for understanding memory, learning and social behaviour in neonate animals. This fast attachment mechanism allows the young of precocial bird species to learn the characteristics of conspicuous visual stimuli and display affiliative response to them. Although more prolonged exposure to an object produces a stronger preference for it afterwards, this relation is not linear. Chicks can even prefer to approach novel rather than familiar objects at some stages of imprinting. The time course and stability of imprinting has just started to be investigated. To date, little is known about how filial preferences develop across time, due to the challenges in assessing individual performance. This study aimed to investigate filial preferences for familiar and novel imprinting objects over time. We have used an automated setup to track the behaviour of chicks continuously for subsequent days. After hatching, chicks were individually placed in an arena where stimuli were displayed on two opposite screens. The duration of exposure and the type of stimuli were manipulated while the time spent at the imprinting stimulus was monitored across six days. We showed that prolonged exposure (3 days vs 1 day) to a stimulus produced robust filial imprinting preferences. Interestingly, with a shorter exposure (1 day), animals re-evaluated their filial preferences in functions of their innate preferences and past experiences. Our study suggests that predispositions influence learning when the imprinting memories are not fully consolidated, driving animal preferences toward more predisposed stimuli.

animal behavior and cognition↗

bioRxiv2019

Transfer from number to size reveals abstract coding of magnitude in honeybees

Number discrimination has been documented in honeybees. It is not known, however, whether it reflects, as in vertebrates, the operating of an underlying general magnitude system that estimates quantities irrespective of dimensions (e.g., number, space, time) and format (discrete, continuous). We investigated whether bees spontaneously transfer discrete discrimination of number to continuous discrimination of size. Bees were trained to discriminate between different numerical comparisons having either a 0.5 (2 vs. 4 and 4 vs. 8) or 0.67 ratio (2 vs. 3 and 4 vs. 6). Half of the subjects learnt to choose the smaller quantity and the other half the larger quantity. Bees were then tested for spontaneous choice (in the absence of reward) using comparisons with identical numbers but different sizes. Irrespective of the ratio of the stimuli, bees trained to select the smaller numerical quantity chose the congruent smaller size; bees trained to choose the larger numerical quantity chose the congruent larger size. This finding provides the first evidence for a cross-dimensional transfer between discrete (numerical) and continuous (spatial) dimensions in an invertebrate species and supports the hypothesis of a cognitive universality of a coding for general magnitude.

animal behavior and cognition↗

bioRxiv2019

A transient time window for early predispositions in newborn chicks

Neonates of different species are born with a set of predispositions that influence their early orienting responses toward the first stimuli encountered in their life. Human neonates and domestic chicks exhibit several similarities in the predisposition for attending to objects that move with speed changes, face-like stimuli and biological motion. Although early predispositions are connected to physiological development, little is known on the temporal course of early predispositions (whether they are stable or change in time) and on their genetic basis. To address these issues, we tested the preference for objects that change in speed vs. linear motion in three chicken breeds (Padovana, Polverara and Robusta maculata) within one day after hatching and three days after hatching. We found that the predisposition to preferentially attend to changes in speed is fixed at the species level on the first day of life and that it disappears by day three. These results indicate the existence of a short and transient time window of early predispositions that does not depend on visual experience.

animal behavior and cognition↗

bioRxiv2018

Continuous and discrete quantity discrimination in tortoises

The ability to estimate quantity, which is crucially important in several aspects of animal behaviour (e.g., foraging), has been extensively investigated in most taxa, with the exception of reptiles. The few studies available, in lizards, report lack of spontaneous discrimination of quantity, which may suggest that reptiles could represent an exception in numerical abilities among vertebrates. We investigated the spontaneous ability of Hermanns tortoises (Testudo hermanni) to select the larger quantity of food items. Tortoises showed able to choose the larger food item when exposed with two options differing in size (0.25, 0.50, 0.67 and 0.75 ratio) and when presented with two groups differing in numerousness (1 versus 4, 2 versus 4, 2 versus 3 and 3 versus 4 items). The tortoises succeeded in both size and numerousness discrimination, and their performance appeared to depend on the ratio of items to be discriminated (thus following Webers Law). These findings in chelonians provide evidence of an ancient system for the extrapolation of numerical magnitudes from given sets of elements, shared among vertebrates.

animal behavior and cognition↗

bioRxiv2018

A cortical route for face-like pattern processing in human newborns

Humans are endowed with an exceptional ability for detecting faces, a competence that in adults is supported by a set of face-specific cortical patches. Human newborns already shortly after birth preferentially orient to faces even when they are presented in the form of highly schematic geometrical patterns, over perceptually equivalent non-face-like stimuli. The neural substrates underlying this early preference are still largely unexplored. Is the adult face-specific cortical circuit already active at birth, or does its specialization develop slowly as a function of experience and/or maturation? We measured EEG responses in 1-4 days old awake, attentive human newborns to schematic face-like patterns and non-face-like control stimuli, visually presented with a slow oscillatory \"peekaboo\" dynamics (0.8 Hz) in a frequency-tagging design. Despite the limited duration of newborns attention, reliable frequency-tagged responses could be estimated for each stimulus from the peak of the EEG power spectrum at the stimulation frequency. Upright face-like stimuli elicited a significantly stronger frequency-tagged response than inverted face-like controls in a large set of electrodes. Source reconstruction of the underlying cortical activity revealed the recruitment of a partially right-lateralized network comprising lateral occipito-temporal and medial parietal areas largely overlapping with the adult face-processing circuit. This result suggests that the cortical route specialized in face processing is already functional at birth.\n\nSignificance statementNewborns show a remarkable ability to detect faces even minutes after birth, an ecologically fundamental skill that is instrumental for interacting with their conspecifics. What are the neural bases of this expertise? Using EEG and a slow oscillatory visual stimulation, we identified a reliable response specific to face-like patterns in newborns, which underlying cortical sources largely overlap with the adult face-specific cortical circuit. This suggests that the development of face perception in infants might rely on an early cortical route specialized in face processing already shortly after birth.

neuroscience↗

bioRxiv2018

Embryonic Exposure to Valproic Acid impairs Social Predispositions for Dynamic Cues of Animate Motion in Newly-Hatched Chicks

Predispositions to preferentially orient towards cues associated with social partners, such as face-like stimuli or biological and animate motion, appear to guide social behavior from the onset of life. These predispositions have been documented in several vertebrate species including human neonates, young monkeys and newly-hatched domestic chicks. Human newborns at high familiar risk of Autism Spectrum Disorder (ASD) show a remarkable deficit in their attention toward these predisposed stimuli, either static and dynamic, compared to newborns at low risk. A previous study showed that prenatal exposure to valproic acid (VPA) (that in humans increases the risk of developing ASD) impairs the chicks predisposition to approach naturalistic social stimuli that convey static configurations of features (a stuffed hen), without impairing general cognitive and learning abilities. Here we investigated the effect of VPA exposure on another class of social predispositions, i.e. the spontaneous preference to approach self-propelled objects, namely objects that display autonomous changes in speed. We observed that the preference for stimuli displaying autonomous changes in speed was impaired in VPA-compared to vehicle-injected chicks. Our results indicate an effect of VPA on the development of predisposed orienting mechanisms towards dynamic stimuli, that could be used to investigate the molecular and neurobiological mechanisms underlying ASD early symptoms.

neuroscience↗

bioRxiv2017

A mental number line in human newborns

In the 19th century Francis Galton first reported that humans represent numbers on a mental number line with smaller numbers on the left and larger numbers on the right. It has been suggested that this orientation emerges as a result of reading/writing habits for both words or numbers. Recent evidence in animals and infants in the first months of life has challenged the primary role of language in determining the left-to-right direction of spatial-numerical association, SNA. However, the possibility that SNA is learnt by early exposure to caregivers directional biases is still open. Here we show that 55-hour-old newborns, once habituated to a number (i.e., 12), spontaneously associated a smaller number (i.e., 4) with the left side and a larger number (i.e., 36) with the right side of space. Moreover, SNA in neonates was not absolute but relative. The same number (i.e., 12) was associated with the left side whenever the previously experienced number was larger (i.e., 36), but with the right side whenever the number was smaller (i.e., 4). Control on continuous physical variables showed that the effect was specific of discrete magnitudes. Hence, soon after birth humans associate smaller numbers with the left space and larger numbers with the right space. These results constitute strong evidence that in our species SNA originates from pre-linguistic and biologically precursors in the brain.\n\nSIGNIFICANCE STATEMENTFor human adults, the representation of number and space is profoundly intertwined. Humans represent numbers on a left to right oriented Mental Number Line (MNL), with small numbers located on the left and larger ones on the right. How do these connections arise? Do we learn to associate numbers with space throughout cultural learning and social interactions or is this association rooted in the biology of the human brain? We showed that neonates spontaneously associate numbers with space. After being habituated to a certain number, neonates associated a smaller number with the left and a larger number with the right side. This evidence demonstrates that a predisposition to map numbers onto space is rooted in human neural systems.

neuroscience↗

bioRxiv2017

Embryonic Exposure to Valproic Acid Disrupts Social Predispositions in Newly-Hatched Chicks

Biological predispositions to attend to visual cues, such as those associated with face-like stimuli or with biological motion, guide social behavior from the first moments of life and have been documented in human neonates, infant monkeys and newly-hatched domestic chicks. In human neonates at high familial risk of Autism Spectrum Disorder (ASD), a lack of such predispositions has been recently reported. Prompted by these observations, we modeled ASD behavioral deficit in newborn chicks, using embryonic exposure to valproic acid (VPA), the histone deacetylases (HDACs) inhibitor that in humans is associated with an increased risk for developing ASD. We assessed spontaneous predispositions in newly-hatched, visually-naive chicks, by comparing responses to a stuffed hen vs. a scrambled version of it. We found that social predispositions were abolished in VPAtreated chicks. In contrast, experience-dependent learning mechanisms associated with filial imprinting were not affected. Our results indicate a specific effect of VPA on the development of biologically-predisposed social orienting mechanisms, opening new perspectives to investigate the molecular and neurobiological mechanisms involved in early ASD symptoms.

neuroscience↗