Biology subjects

Sirigu, A.

Publications and source records attributed to Sirigu, A..

5 recordsLinked to original sources

bioRxiv2026

Chemogenetic activation of hypothalamic oxytocin neurons reorients face exploration toward the eyes in macaques

Oxytocin (OT) shapes social behavior across species. However, in humans and non-human primates, its effects have been studied mainly through exogenous administration, despite uncertainty about the extent to which peripherally administered OT reaches the brain and limited control over the neural pathways it engages. To overcome these limitations, we developed a chemogenetic approach targeting the endogenous OT system by selectively activating OT neurons in the paraventricular nucleus (PVN) and supraoptic nucleus (SON) of macaques using excitatory DREADDs. We combined this approach with digit-tracking, a non-invasive, calibration-free assay of face exploration in freely moving animals. In this task, subjects explored blurred face images through a finger-controlled viewing window, providing a proxy for gaze exploration and enabling behavioral assessment of OT neuron activation. DREADD-mediated activation redirected ongoing face exploration toward the eyes at the expense of non-face regions, increasing the consistency of eye-directed exploration and the time spent inspecting the eyes once reached. Immunohistochemical analysis confirmed selective DREADD expression in OT neurons of the PVN and SON. These findings provide the first causal evidence in primates that hypothalamic OT neurons regulate social visual orienting by increasing exploration of the eyes, thereby linking a hallmark effect of intranasal OT administration to defined central OT pathways and establishing chemogenetic access to this system in freely behaving macaques.

neuroscience↗

bioRxiv2025

Digit-Tracking Reveals Curiosity-Driven Visual Attention in Macaque Monkeys

We used digit-tracking, a touch-based method for assessing visual attention, to investigate spontaneous exploration in macaque monkeys. By engaging with degraded images on a touch-sensitive display, monkeys could uncover high-resolution portions through finger movements, allowing for natural and unrestricted interaction. Monkeys received juice rewards after touching a predetermined number of pixels, but no specific regions were targeted. Attention maps were generated from their interactions, along with data from human digit-tracking and monkey eye-tracking experiments. We applied a saliency model and a Convolutional Neural Network (CNN) model to predict the empirical explorations. The correlation between model prediction maps and empirical attention maps indicated that monkeys focused non-randomly on information-rich regions, with the CNN model providing the most accurate predictions. These findings suggest that exploration was driven by intrinsic curiosity, beyond the extrinsic rewards for interaction. Digit-tracking offers a minimally invasive, portable alternative to eye-tracking, expanding research opportunities in visual cognition within ecologically valid settings.

animal behavior and cognition↗

bioRxiv2025

Spatio-temporal dynamics of ingroup interactions in macaques

When sharing a space with others, many species including humans evolved a compromise regulating occupancy influenced by social determinants. For example, students in a classroom tend to sit close to their friends, keeping the same spots across days, revealing the social structure in the classroom. This place preference suggests that factors such as social hierarchy and affiliation can shape space utilization; contrasting with random walk models of agents moving at random in any given direction. Here, we asked whether spatial occupancy of macaques (Macaca fascicularis and M. mulatta) within a unisex group, reveals a structured space utilization beyond simple spatial affordance within the finite space. To this end, in two groups of four animals, we analyzed the simultaneously recorded positions of each individual while the group roamed in an enclosure. The data was gathered using automated devices that allow measuring accurate concomitant positions and calculate precise inter-individual distance, which is impossible in classical ethology even using GPS devices. Thus, our setup opens new possibilities using modelling approach, to characterize social interaction dynamics in small enclosures. We found that (1) The identity of each animal could be decoded from its individual pattern of spatial occupancy, revealing that each animal sustained a spatial footprint across multiple days. (2) Average distance between monkeys was a proxy of their social hierarchy, confirming that interpersonal distance is correlated to affiliation and dominance hierarchy. (3) Alternating the social context by removing one of the monkeys revealed that only removing the closest social partner influenced occupancy. (4) Finally, the distribution of distance between pairs of monkeys was bimodal and was modeled using random walk approach with an additional parameter reflecting propensity to stay in close proximity, which was again related to dominance hierarchy. These analyses reveal that space utilization is structured as a function of social determinants in macaques and simple modeling approach to further study group organization in neuro-ethological settings.

animal behavior and cognition↗

bioRxiv2021

Dissociation of early and late face-related processes in Autism Spectrum Disorder and Williams syndrome

Williams syndrome (WS) and Autism Spectrum Disorders (ASD) are psychiatric conditions associated with atypical but opposite face-to-face interactions patterns: WS patients overly stare at others, ASD individuals escape eye contact. Whether these behaviors result from dissociable visual processes within the occipito-temporal pathways is unknown. Using high-density electroencephalography, multivariate signal processing algorithms and a protocol designed to identify and extract evoked activities sensitive to facial cues, we investigated how WS (N=14), ASD (N=14) and neurotypical subjects (N=14) decode the information content of a face stimulus. We found two neural components in neurotypical participants, both strongest when the eye region was projected onto the subjects fovea, simulating a direct eye contact situation, and weakest over more distant regions, reaching a minimum when the focused region was outside the stimulus face. The first component peaks at 170ms, an early signal known to be implicated in low-level face features. The second is identified later, 260ms post-stimulus onset and is implicated in decoding salient face social cues. Remarkably, both components were found distinctly impaired and preserved in WS and ASD. In WS, we could weakly decode the 170ms signal based on our regressor relative to facial features, probably due to their relatively poor ability to process faces morphology, while the late 260ms component was highly significant. The reverse pattern was observed in ASD participants who showed neurotypical like early 170ms evoked activity but impaired late evoked 260ms signal. Our study reveals a dissociation between WS and ASD patients and point at different neural origins for their social impairments.

neuroscience↗

bioRxiv2021

An eye gaze-modulated neural source highly impaired in autism spectrum disorder

Attention to faces and eye contact are key behaviors for establishing social bonds in humans. In Autism Spectrum Disorders (ASD) a neurodevelopmental disturbance characterized by poor communication skills, impaired face processing and gaze avoidance are critical clinical features for its diagnosis. The biological alterations underlying these impairments are not clear yet. Using high-density electroencephalography coupled with multi-variate pattern classification and group blind source separation methods we searched for face- and face components-related neural signals that could best discriminate neurotypical and ASD visual processing. First, we isolated a face-specific neural signal in the superior temporal sulcus peaking at 240ms after stimulus onset. A machine learning algorithm applied on the extracted neural component reached 74% decoding accuracy at the same latencies, dissociating the neurotypical population from ASD subjects in whom this signal was weak. Further, by manipulating attention to face parts we found that the signal-evoked power in neurotypical subjects varied as a function of the distance of the eyes in the face stimulus with respect to the viewers fovea, i.e. it was strongest when the eyes were projected on the fovea and weakest when projected in the retinal periphery. Such selective face and face-components neural modulations were not found in ASD individuals although they showed typical early face related P100 and the N170 signals. These findings show that dedicated cortical mechanisms related to face perception set neural priority for attention to eyes and that these mechanisms are altered in individuals with ASD.

neuroscience↗