Periodic Reporting for period 3 - SPANUMBRA (Number-space associations in the brain)
Reporting period: 2022-11-01 to 2024-04-30
In zebrafish we developed a new habituation/dishabituation test complemented by qPCR of early gene expression and in situ hybridation. In a first paper we showed involvement of thalamus and pallium (Messina et al. (2020) Sci. Rep.). Then we identified for the first time a region of the pallium (dorso-central in the more caudal part) showing population of neurons selectively sensitive to numerosity but not to other quantitative aspects of the stimuli (Messina et al. (2021) Cereb Cortex). We are now proceeding looking at the nuclei in the thalamus and tectum that connect to the pallium (and motoric control areas) using anterograde and retrograde tracers in order to identify the overall circuitry and how spatial extension and numerical aspects of stimuli are represented and interact to each other. A paper is in preparation.
We developed standardized techniques for presentation of numerical stimuli with control of continuous physical variables (Zanon et al. (2022) Behav Res Meth) and recently we used these to prove that fish are capable of ‘pure’ numerical cognition, with accurate controls of all continuous physical variables (Potrich et al. (2022) eLife).
We also investigated in zebrafish the distribution of pallial-expressed genes of relevance to numerical and other aspects of higher cognition, and found striking asymmetries (Messina et al. (2020) Eur. J. Neurosci.). We plan now to look at the possibilities to reveal these asymmetries in our behavioral tasks, looking at IEG expression separately in the two sides of the brain.
QMU developed transgenic lines for candidate genes for dyscalculia, a preliminary report testing numerical abilities in transgenic lines has been just submitted.
With QMU we also tested the ontogeny of numeracy using a group size preference (GSP) task in juvenile zebrafish. We found GSP from 21 days post-fertilization, though the systems involved in quantity representation do not operate separately from other cognitive mechanisms, suggesting that quantity processing in zebrafish may be the result of an interplay between attentional, cognitive and memory-related mechanisms as in humans (Sheardown et al (2022) Proc R Soc London B). Studies with human babies and infants were delayed because the pandemics prevented access to the hospital labs; we have now continued this part studying infants and comparing them with adults. Meanwhile, we completed the study on mental number line a traditional society, the Himba of Namibia, and submitted the paper to a major scientific journal.
Finally, we published several reviews and theoretical papers on topics related to the project, i.e. Miletto-Petrazzini et al. (2020) Front. Neuroanat.; Bortot et al. (2020) Biochem. Biophys. Res. Comm.; Lorenzi et al. (2021) Front. Psychol (Vallortigara et al (2022). Cur Dir Psycho Sci,; Messina et al (2021). Animals, 11: 3072); Messina et al (2022) Front Neuroanat; Kobylkov et al (2023) Bio Systems).
All these findings open the door to subsequent work we plan to carry on to reveal neural circuitry and to perform genetic analyses at a level that would have had no precedent in more traditional models for studies of numerical and association between number and spatial aspects of the stimuli.
We are confident to obtain in the remaining part of the project further results about connectivity of pallial areas with others regions (in particular the thalamus and the tectum) as well as patterns of asymmetry of response, particularly in gene expression that will ensure further progress in our understanding of number and number/space associations. Furthermore, we expect to have indications by transgenic lines of zebrafish about candidate genes involved in numerical cognition and its disturbances (e.g. developmental dyscalculia).