The work performed and the main achievement in the project can be summarized as follows. First, we used our animal model systems to identify brain regions involved in the processing of discrete (countable) and continuous (spatial) quantities or magnitudes, as well as the circuitry by which associations between numerosities and space may occur. We were successful in this enterprise for we have identified specific brain regions that show selective activities to the different kind of magnitudes (e.g. the caudal nidopallium and the Wullst in the chick and the caudal part of the dorso-central division and habenula of the zebrafish pallium; see Messina et al 2021 Cereb Cortex; Lorenzi et al Heliyon 2024).
We also conducted work at the level of single neurons, discovering by single cell recording in chicks number neurons in the caudal nidopallium (Kobylkov et al PNAS 2022) and at the level of whole brain using light-sheet microscopy in the larval zebrafish in the midbrain and forebrain (Luu et al 2024, bioRxiv). Most interestingly we found an orderly appearance of number neurons during development in the zebrafish larvae, a finding linking SNA with the ordinal representation of numerosity as occuring during development. Second, we explored in work with chicks, zebrafish, pre-scholar babies and human adults the role of learning (and culture in humans) and of biological mechanisms in the development of the mental number line. The main findings (mostly already published - e.g. Eccher et al Nature Comm 2025; Potrick et al 2024 Heliyon; Sheardown et al Proc R Soc B, 2022) revealed a major role of biological mechanisms, that we also explored with our UK partner Caroline Brennan of Queen Mary Univ. London in transgenic lines of fish showing deficits mimicking discalculya, Torres et al, subm). Furthermore, our theory that explain SNA in terms of a valence hypothesis for division of function in the left and right side of the brain has been successfully tested in zebrafish (Potrich et al in prep) and also, in collaboration with another lab, in monkeys (Annichiarico et al in prep). Our interest for the societal and applied aspects of neurodevelopmental disorders of number cognition prompted us to develop novel tests for larval zebrafish, both wildtype (Adam et al, Anim Cogn 2024) and transgenic lines (Adam et al in prep), as well as the development of a screening and rehabilitation method for the early detection and treatment of developmental dyscalculia in children, in the form of an entertaining, tablet-based gaming environment. New theoretical work on brain asymmetry has been also generated thanks to the impetus provided by the empirical work done in the project (Vallortigara and Vitiello, 2024 R Soc Open Sci).
With more than fifty published papers on major scientific journals I believe the aims of the project have been fully and successfully accomplished. Exploitation and dissemination has been also intense, with participation of PI and group members to several conferences, science festival, and television events and newspapers pieces.
