The pollutome-connectome axis: a putative mechanism to explain pollution effects on neurodegeneration.

The study of pollutant effects is extremely important to address the epochal challenges we are facing, where world populations are increasingly moving from rural to urban centers, revolutionizing our world into an urban world. These transformations will exacerbate pollution, thus highlighting the necessity to unravel its effect on human health. Epidemiological studies have reported that pollution increases the risk of neurological diseases, with growing evidence on the risk of neurodegenerative disorders. Air pollution and water pollutants are the main chemicals driving this risk. These chemicals can promote inflammation, acting in synergy with genotype vulnerability. However, the biological underpinnings of this association are unknown. In this review, we focus on the link between pollution and brain network connectivity at the macro-scale level. We provide an updated overview of epidemiological findings and studies investigating brain network changes associated with pollution exposure, and discuss the mechanistic insights of pollution-induced brain changes through neural networks. We explain, in detail, the pollutome-connectome axis that might provide the functional substrate for pollution-induced processes leading to cognitive impairment and neurodegeneration. We describe this model within the framework of two pollutants, air pollution, a widely recognized threat, and polyfluoroalkyl substances, a large class of synthetic chemicals which are currently emerging as new neurotoxic source.

Are Rational Numbers Spontaneous? Natural Numbers Suffice all Processing by the Number Sense.

The presence of preverbal numerical abilities in animals and infants is widely established, but an important discussion remains about which cognitive systems support these abilities. In particular, a great amount of research is dedicated to the approximate number system (ANS) for the elaboration of non-symbolic numbers and their possible types of mental numeric representations. In a recently published article, Clarke and Beck (2021) provide a series of evidence that supports its existence (ANS) and argue that the mental referents of this system are both natural and rational numbers. In the current commentary, we introduce the notion of the "whole-entity bias" that permeates perception and cognition and favors an automatic processing of discrete mental magnitudes while hindering the representations of fractional numbers. Further, we argue that a hierarchical structure of the ANS that represents natural numbers and supports the understanding of proportions through a series of computations is a more ecological theorization. To conclude, we believe that such a view is still compatible with the proposal of a single representational system (the ANS) supporting both number kinds but offers a different perspective on the computational level of explanation.