Biology subjects

Vallortigara, G.

Publications and source records attributed to Vallortigara, G..

At least 19 recordsLinked to original sources

bioRxiv2026

The Brain Encodes Pure Logic Beyond Natural Language And At The Boundaries With Mathematics

You are not not reading this sentence. True, because you are. It's the law of double negation, a logical rule that states that a statement that is not not true is itself true. The development of pure logic - the study of the properties of formal systems, irrespective of their content - represents one of the most abstract intellectual achievements of human culture. Yet its neural correlates remain vastly unexplored. Is pure logic represented in a linguistic format like natural language, in an abstract symbolic format like other formal systems such as mathematics, or as a fully distinct domain of knowledge? To address this question, we monitored the brain activity of professional logicians and matched controls while they evaluated the truth of spoken statements of pure logic, and compared these activations to those elicited by language and mental arithmetic. We show that pure logic recruits left-lateralized brain circuits that are completely distinct from those involved in language processing. Those circuits only partially overlap with those involved in mathematics. These findings highlight an independent neural pathway for abstract thought and indicate that the brain's capacity to process structured rules of formal systems is implemented beyond language and at the boundaries with mathematics.

neuroscience↗

bioRxiv2026

Neural evidence for an abstract sense of number in humans at birth

One of the most astonishing abilities documented in human newborns is that they can abstract numerosity - the number of items in sets - across sensory modalities. Its underlying neural mechanisms remain unknown. Using high-density EEG and a frequency-tagging paradigm, we measured neural entrainment to periodically presented visual arrays that were either numerically congruent or incongruent with previously familiarized and concurrently presented auditory sequences in 21 newborns (0-3 days old). The amplitude of neural entrainment to the visual arrays provided a robust index of cross-modal numerical congruency: it was significantly reduced for numerically congruent relative to incongruent stimuli, consistent with a cross-modal numerosity repetition-suppression mechanism. These findings identify a candidate neural mechanism supporting newborns ability to encode numerosity in an abstract supramodal format, and reinforce the view that number constitutes a foundational dimension of human perception since birth.

neuroscience↗

bioRxiv2026

Early Emergence of Auditory Quantity Discrimination in Domestic Chicks

Numerical abilities are widespread in the animal kingdom and are not exclusive to humans. Domestic chicks (Gallus gallus) have been shown to discriminate numerosities spontaneously, but prior research has focused exclusively on the visual modality. Whether chicks can discriminate numerical information in the auditory domain remains unknown, despite evidence that they can perceive other auditory features such as tone and rhythm. In this study, we investigated spontaneous numerical discrimination in the auditory modality in naive domestic chicks. In Experiment 1, newly-hatched chicks were tested for their ability to discriminate between two auditory sequences differing in numerosity (4 vs. 12 identical sounds), with and without controlling for continuous variables such as duration and total sound amount. Experiment 2 examined chicks filial imprinting responses to familiar or unfamiliar numerosities. Experiment 3 controlled for potential spontaneous preferences for a single longer sound versus a shorter one. Our results showed a preference for the 12-sound sequence only when duration and total sound amount were not matched. When these continuous variables were controlled, no spontaneous numerical preference emerged. Experiment 2 revealed an overall preference for the 12-sound sequence regardless of imprinting conditions, while Experiment 3 confirmed that chicks do not have an inherent preference for longer sounds. These findings suggest that chicks are sensitive to overall magnitude in the auditory domain but do not spontaneously discriminate numerical differences when other continuous variables are held constant. Future studies will explore how specific stimulus features, such as heterogeneity of sounds, influence these preferences.

animal behavior and cognition↗

bioRxiv2026

Visual detection of cryptic displays in jumping spiders

Most animals can segment camouflaged targets via static cues, such as luminance or contrast differences against a background. However, targets can be cryptic and merge with background clutter, making static cues unavailable until the camouflaged object starts moving: the target can then be segmented by identifying spatially coherent luminance changes over time. Jumping spiders represent a unique model for the study of spatiotemporal segmentation, as they process moving signals and static figures separately through distinct pathways associated with different pairs of eyes: the secondary eyes detect moving objects and trigger full body pivot responses, bringing the target within focused view of the principal eyes for subsequent figure processing. While secondary eyes can be selective for specific stimulus characteristics that cause the animal to pivot, it remains unclear whether their selectivity requires full motion segmentation or relies on simpler stimulus characteristics. Here, we tested whether the pivoting response triggered by secondary eyes is specifically linked to motion segmentation, or whether it is also elicited by less specific stimulus characteristics. We presented jumping spiders with several moving and non-moving stimuli, including clearly delineated objects, cryptic objects visible only through motion, and non-segmentable spatio-temporal luminance patterns. Based on the measured responses, we developed a computational model that captured all salient features of the pivoting behavior produced by the animal. We found that jumping spiders do not require a discrete, segmented object to trigger a pivoting response. Instead, they attend to luminance patterns that change across both time and space, while disregarding changes that repeat over the same spatial location. This mechanism constitutes an effective solution in terms of neural simplification: it offloads the task of complex motion segmentation from the secondary eyes, thus maximizing the efficiency of visual modularity--a unique evolutionary solution to the problem of brain miniaturization.

neuroscience↗

bioRxiv2026

Number-Space Association in Macaques

Humans order numbers in space from left to right, with smaller quantities represented preferentially in the left hemispace and larger ones in the right hemispace. The direction of this mental number line (MNL), or more generally of number-space associations (NSA), is influenced by cultural habits such as reading and writing direction. However, a growing body of evidence from pre-verbal infants and non-human animals suggests that number-space mappings may also have biological foundations. In non-human primates, evidence for a directional MNL remains mixed, partly due to small sample sizes and methodological heterogeneity. Here, we tested samples of rhesus (Macaca mulatta) and crab-eating macaques (Macaca fascicularis) across two experiments using spontaneous food-related tasks. In Experiment 1, monkeys chose between identical food quantities (1x1 to 24x24) presented on the left and right. No systematic spatial choice bias emerged as a function of numerical magnitude, and hand use did not differ across exact numerical pairs, although exploratory analyses revealed magnitude-related modulations of manual responses. In Experiment 2, monkeys were habituated to small (4x4) or large (16x16) quantities and subsequently tested with the alternative quantity. Result showed significantly more leftward choices following numerical decreases (16[->]4) and more rightward choices following numerical increases (4[->]16), indicating that relative numerical context, rather than absolute magnitude, elicited directional spatial biases. These findings suggest that in macaques, number-space associations emerge most robustly in comparative contexts involving expectancy violations of magnitude.

animal behavior and cognition↗

bioRxiv2026

Space-number association in zebrafish

Spatial-numerical associations reflect the tendency to map small numerosities to the left and larger numerosities to the right. Although widely documented in humans and some non-human species, its presence in teleost fish has remained unclear. Here, we investigated whether zebrafish exhibit a spatial-numerical association by presenting fish with a left-right numerical discrimination task in a controlled behavioral assay. Zebrafish showed a reliable leftward preference when selecting smaller numerosities and a rightward preference when selecting larger ones, indicating a systematic coupling between numerical magnitude and spatial direction. These results provide the first evidence of a number-space association in zebrafish and demonstrate that number-space mapping extends to a basal vertebrate lineage. This establishes zebrafish as a tractable model for probing the neurobiological foundations of number-space associations. HighlightsO_LIZebrafish map numerical magnitudes onto left-right spatial positions. C_LIO_LISpatial biases are more robust for small numerosities but still present for larger ones. C_LIO_LIContinuous physical controls disproportionately affect the strength of spatial mapping for large sets. C_LI

animal behavior and cognition↗

bioRxiv2025

Antlion larvae follow optimality rules in body orientation during sand-tossing

Pit-building antlion larvae (Myrmeleon spp.) throw sand at prey that approach their pit using their head and mandibles as a backward-directed "biological catapult". This mechanism restricts effective sand-tossing to a defined angular range behind the larva. When prey-like vibrations come from outside this range, antlions are known to reorient, but the consistency and rules behind this behaviour remain unclear. We tested whether larvae follow optimal turning strategies when reorienting toward a vibrating artificial stimulus placed in disadvantageous positions along the pit. Most larvae responded and often ended in an optimal sand-throwing position. Initial orientation strongly predicted turning direction: larvae rotated along the shortest angular path to reach the optimal sand-throwing orientation. Our results show that antlion larvae do not rely on rigid reflexes during prey capture but appear to integrate vibrational cues with spatial rules to minimize angular displacement. This reveals unexpected behavioural flexibility in a sit-and-wait predator with highly limited mobility.

animal behavior and cognition↗

bioRxiv2025

Neural encoding of innate preference to gravity-defying motion

The ability to detect animate objects is a fundamental property of the animal visual system. Among the cues used to infer animacy, gravity provides an important reference for identifying animate motion. Earlier work has demonstrated that upward-moving objects, which violate gravitational constraints, elicit spontaneous attention in newborn humans and domestic chicks. However, the neural mechanisms underlying this innate predisposition remain unclear. We recorded neural activity in the nidopallium of one-week-old domestic chicks as they observed stimuli moving upward or downward. In parallel, we analyzed spontaneous behavioral responses with video-based tracking and high-speed accelerometer data. This analysis revealed a robust attentional bias toward upward-moving, gravity-defying stimuli. We identified neurons in the NCL that encode the direction of motion, most of which responded preferentially to upward movement. Moreover, the population activity of direction-sensitive neurons successfully predicted the spontaneous behavioral response to upward-moving objects.

animal behavior and cognition↗

bioRxiv2025

A left-to-right bias in spatial numerical associations with dots and symbols

Number and space are intertwined in human and non-human cognition. A substantial body of research has shown that numerical magnitudes are mentally represented along a spatially oriented continuum, akin to a "mental number line". Some suggested that its directionality is determined by culture and context, an idea that was recently challenged by a study that showed that an implicit association between "left" and "small" emerges not only in literate adults, but also in unschooled indigenous adult populations and preschool Western children. This finding suggests that SNAs may originate from universal innate mechanisms rather than being solely a by-product of cultural learning. However, while the study reported a strong association between "left" and "decreasing" numerosity, there was only a very weak association between "right" and "increasing" numerosity. This asymmetry was not predicted and needs further investigation to be understood. Here, we investigated the number/space association in implicit tasks in educated Western adults in greater depth by using more variable and better-controlled stimuli compared to the ones used in the previous study, and also manipulating stimulus format, using both dot patterns and symbolic numbers. Fifty-one adult participants performed a numerical comparison task within a Go-No-Go paradigm on subsequent pairs of visual stimuli (with ratios spanning from 0.75 to 0.94) that could appear on the left or on the right of a fixation point and completed two different tasks: "press when more" and "press when less". Results revealed distinct response patterns depending on the symbolic/non-symbolic nature of the stimuli. When non-symbolic stimuli were used, a consistent association between small numerosities and the left side and large numerosities and the right side was observed. When symbolic stimuli were used, only an association between large numerosities and the right side was observed. These findings support the hypothesis that SNAs may reflect a biological predisposition associated with brain asymmetry and that task demands may interact with the underlying hemispheric specialisations.

neuroscience↗

bioRxiv2025

Odor sequence learning in honeybees: insights from olfactory classical conditioning paradigm

The ability to extract regularities from the sensory input is important for adaptation to a complex environment and to support behavioral flexibility. Honeybees have sophisticated cognitive and learning capacities, including categorization of stimuli on the basis of perceptual (e.g., symmetry) and abstract (e.g., sameness/difference) concepts. Here we investigated whether bees could extrapolate the temporal regularity of a sequence. By exploiting the olfactory conditioning of the proboscis extension response (PER), we investigated whether honeybees could learn and generalize a particular sequence structure composed of different odors presented in a specific temporal order. Different conditioning paradigms (i.e., absolute, differential, generalization) were employed. Bees used different strategies, such as an early tendency to encode the single odor properties, instead of learning the entire sequence pattern. The use of a generalization paradigm potentially uncovered a spontaneous tendency to transfer over similar structures one hour after the training irrespective of the single-element properties, though this finding is not yet conclusive. These results shed light on the strategies used by bees to solve an odor abstraction task, highlighting the crucial role of the type of conditioning to let them emerge.

animal behavior and cognition↗

bioRxiv2025

Predisposed and learned preferences for multipoint visual statistics in visually naïve newly hatched chicks

Significance statementWe show that visually naive chicks spontaneously prefer specific multipoint correlation patterns, mirroring preferences seen in humans and rats, and reflecting the most informative structures in natural scenes. This provides evidence that efficient coding mechanisms may be innately driven by evolutionary predispositions. Notably, early visual experience through imprinting can alter these preferences, highlighting a role for learning in shaping visual processing. Recent studies have revealed that human and non-human animals (rats) can detect luminance distribution and correlations between pixels in an image (ranging from 2-point to 4-point). This sensitivity is believed to stem from optimization processes in the visual system that operate through efficient coding mechanisms to extract the most informative image statistics from the environment. However, it is yet to be determined whether this optimization is evolutionarily given by inborn mechanisms or shaped by visual experience. Here we report that newly-hatched visually naive domestic chicks spontaneously prefer to approach luminance, 2-point and 4-point correlation patterns (respectively, horizontal lines and rectangular patterns), while showing no preference for 3-point correlation over white noise controls. This parallels the ranking observed in adult humans and rats, thus suggesting that evolutionarily given biological predispositions largely drive efficient coding of natural images. We also found that learning by exposure to visual stimuli, as occurs naturally during visual imprinting, induced a preference for white noise over point correlation patterns in chicks exposed to 3- and 4-point patterns. We hypothesize that this behavior could reflect chicks preference for stimuli of lower statistical complexity.

animal behavior and cognition↗

bioRxiv2024

Jumping spiders are not fooled by the peripheral drift illusion

In the peripheral drift illusion, a static circular sawtooth pattern is perceived as if it were rotating. It is believed that this effect is a byproduct of how the neural substrate responsible for motion perception is organized. The structure of the motion perception circuitry is widespread across the animal kingdom, vertebrates and invertebrates alike, which in turn causes the illusion effect to be experienced by virtually all animals. Among invertebrates, jumping spiders possess a unique visual system. For them, the tasks of visual computation are split across 4 pairs of eyes, with motion detection, target recognition, and shape discrimination computed in completely segregated brain areas and visual field sections. In such an organization, it is unlikely that the circuitry for motion perception common to other animals is shared by jumping spiders. Consequently, jumping spiders should be immune to the peripheral drift illusion. To test this hypothesis, we placed jumping spiders on top of an omnidirectional treadmill and presented them with circular visual stimuli in their visual periphery. These were either composed of a sawtooth pattern, and therefore inducing the illusion, or of a sine-wave pattern of equal luminance and spatial frequency but not illusion-inducing. The stimuli could either be static or rotate around their center, either clockwise or counterclockwise. As jumping spiders perform distinctive full-body pivots when detecting a moving object in their visual periphery, we registered the frequency of this behavior to assess the illusory percept. We found that the spiders responded consistently to all moving stimuli, but did not react to the static illusion, therefore it was not perceived as in motion. The absence of the illusory percept in spiders opens many questions about the nature of their motion perception circuitry and casts doubts on how the illusion is widespread in the animal kingdom outside the common model species usually inquired about.

animal behavior and cognition↗

bioRxiv2024

Neural Basis of Number Sense in Larval Zebrafish

Number sense, the ability to discriminate discrete quantity, is widespread across animals, yet how this capacity develops remains unknown. Using two-photon light-sheet imaging, we recorded whole-brain activity at single-cell resolution in larval zebrafish (Danio rerio) exposed to controlled visual numerosity stimuli. We discovered that number-selective neurons emerge in a striking developmental sequence: cells tuned to numerosity 1 are already present at 3 days post-fertilization (dpf), and neurons selective for 2, 3, and higher quantities appear in increasing abundance later, at 5 and 7 dpf, accompanied by a relative reduction in 1-tuned cells. The proportion of number-selective cells, summed over all tested numerosities, relative to all identified neurons in the brain, was found to decrease over time. We further showed that a machine-learning decoder based on the activity of the number-selective neurons can predict the number stimulus seen by the animals with accuracies at better than twice chance level. These results reveal how neuronal circuits develop structured numerical codes and provide a framework for studying the emergence of cognitive primitives at cellular resolution.

neuroscience↗

bioRxiv2024

Innate face detectors in the nidopallium of young domestic chicks

Soon after birth, naive animals and newborn babies show spontaneous attraction towards faces and face-like stimuli with three dark features representing eyes and a mouth/beak. While neurons selectively responding to faces have been found in the inferotemporal cortex of adult primates, face-selective domains in the brains of young monkeys seem to develop only later in life after exposure to faces. This has fueled a debate on the role of experience in the development of face-detector mechanisms, since face preferences are well documented in naive animals, such as domestic chicks reared without exposure to faces. Here we demonstrate that neurons in a cortex-homologue area of one-week-old face-naive domestic chicks selectively respond to a face-like configuration. Our single-cell recordings show that these face detectors do not respond to alternative configurations or isolated facial features. Moreover, the population activity of face-selective neurons accurately encoded the face-like stimulus as a unique category. Thus, our findings show that face detectors are present in the brains of very young animals without pre-existing experience.

animal behavior and cognition↗

bioRxiv2023

A Kaspar Hauser experiment for innateness of numerical cognition

Whether non-symbolic encoding of quantity is predisposed at birth with dedicated hard-wired neural circuits is debated. Here we presented newly-hatched visually naive chicks with stimuli (flashing dots) of either identical or different numerousness (with a ratio 1:3) with their continuous physical appearance (size, contour length, density, convex hull) randomly changing. Chicks spontaneously tell apart the stimuli on the basis of the number of elements. Upon presentation of either fixed or changing numerousness chicks also showed different expression of early gene c-fos in the visual Wulst, the hippocampal formation, the intermediate medial mesopallium, and the caudal part of the nidopallium caudolaterale. The results support the hypothesis that the ability to discriminate quantities does not require any specific instructive experience. Evidence for innateness of non-symbolic numerical cognition have implications for both neurobiology and philosophy of mathematics.

neuroscience↗

bioRxiv2023

Manganese Enhanced Magnetic Resonance Imaging reveals light-induced brain asymmetry in embryo

The idea that sensory stimulation to the embryo (in utero or in ovo) may be crucial for brain development is widespread. Unfortunately, up to now evidence was only indirect because imaging of embryonic brain activity in vivo was not viable. Here we applied for the first time Manganese Enhanced Magnetic Resonance Imaging (MEMRI) to the eggs of domestic chicks. We revealed light-induced brain asymmetry by comparing embryonic brain activity in vivo of eggs that were stimulated by light or maintained in the darkness. Our protocol paves the way to investigation of the effects of a variety of sensory stimulations on brain activity in embryo. SignificanceSensory stimulation in embryo may be crucial for many aspects of brain and behavioral development (e.g., mother language in humans). However, direct evidence of this is lacking because imaging of embryonic brain activity in vivo is not viable. Here we established a new protocol for measuring embryonic brain activity in vivo in domestic chick eggs. We were able to visualize in vivo the effect of light stimulation on the development of structural brain asymmetries of the embryo. The protocol established paves the way for collecting further evidence on the effects of sensory stimulation on embryonic brain activity.

neuroscience↗

bioRxiv2022

Impaired Epigenesis of Imprinting Predispositions Causes Autism-like Behavioral Phenotypes in Domestic Chicks

Several environmental chemicals are suspected as risk factors for autism spectrum disorder (ASD), including valproic acid (VPA) and pesticides acting on nicotinic acetylcholine receptor (nAChR) if exposed during pregnancy. However, their target processes in fetal neuro-development are unspecified. We report that fetal injection of VPA impaired the imprinting of an artifact object in hatchlings, while the predisposed preference to biological motion (BM) remained intact. Blockade of nAChR acted oppositely, namely, spared imprinting and impaired BM in chicks. Beside ketamine and tubocurarine, significant effects of imidacloprid (a neonicotinoid insecticide) appeared at dose [≤]1ppm. Despite the distinct processes, both VPA and nAChR blockade similarly impaired imprinting of biological image composed of point-light animation. Furthermore, both impairments were rescued by post-natal bumetanide treatment, suggesting common pathology underlying the social attachment malformation. Ambient neonicotinoid could hinder adaptive socialization through impaired development of visual perception in early neonates.

animal behavior and cognition↗

bioRxiv2022

Functional MRI reveals memories of mother in newborn chicks

Filial imprinting has been used as a powerful ethological paradigm to investigate the neurobiology of early learning that affects lifelong behaviours. When a visually naive chick is exposed to one of a wide range of conspicuous objects, it may learn its characteristics and subsequently recognises and selectively approaches this stimulus (usually the mother hen and siblings). While the initial phases of memory acquisition have been unravelled, the long-term storage and retrieval components of imprinting memories are still unknown. Here, we used functional MRI in awake newly hatched chicks to identify the long-term storage of imprinting memories in a wide network comprising the hippocampal formation, the medial striatum, the arcopallium, and the prefrontal-like nidopallium caudolaterale. These results provide the first example of non-invasive imaging of the brain in a newborn vertebrate.

neuroscience↗