Biology subjects

Tosi, M.

Publications and source records attributed to Tosi, M..

3 recordsLinked to original sources

bioRxiv2025

Hemispheric Dissociation Revealed by Attentional Isolation and tRNS

Prolonged sensory imbalance, induced by directing attention to one visual field, can paradoxically enhance performance in the opposite, non-attended visual field. This effect is likely driven by the brains homeostatic mechanisms that regulate excitation and inhibition between hemispheres in homotopic attention processing regions. Here, we employed transcranial random noise stimulation (tRNS) to modulate cortical excitability and probe its role in interhemispheric dynamics controlling visual attention. Specifically, we used a procedure called attentional isolation, where neurotypical participants covertly focused their visual attention in one hemifield (the attended visual field) for 30 minutes. Performance changes in both the unattended (opposite) visual field and the attended visual field were measured following this manipulation. We applied transcranial random noise stimulation (tRNS) over the right or left frontoparietal cortex to modulate the excitability of one hemisphere relative to the other during attention isolation, probing the neural mechanisms underlying the observed contralateral performance shift. Our results showed improved performance in the previously unattended visual field following the attentional isolation period after sham stimulation. However, tRNS revealed a functional dissociation between the hemispheres: right hemisphere active stimulation abolished the performance improvement, while left hemisphere stimulation preserved it. These findings suggest distinct roles for the left and right hemispheres in modulating paradoxical visual performance shifts and may inform the development of novel neurorehabilitation strategies for clinical populations.

neuroscience↗

bioRxiv2024

Complex responses of soil prokaryotes, fungi and protists to prairie restoration on retired agricultural lands

Restoring native ecosystems on marginal croplands has many benefits but the impacts on belowground biodiversity are less clear, in part because the limiting factors regulating soil biota are complex and poorly described. Here, we studied how grassland prairie restoration of marginal croplands affected the diversity and composition of soil microbiota on 5 conventional farms from Ontario, Canada. Soil samples (0-15 cm) were collected from annually cultivated fields and adjacent planted perennial grassland where cultivation and chemical inputs had ceased several years previously. Following DNA extraction, we estimated bacterial and fungal abundance using quantitative PCR, and microbial diversity of prokaryotes, fungi and protists using amplicon high-throughput sequencing. Under both land uses, prokaryotic communities were dominated by Proteobacteria, Actinobacteria and Acidobacteria, fungal communities by Ascomycota, and protist communities by Rhizaria (TSAR), Evosea (Amoebozoa) and Chlorophyta (Archaeplastida). Prairie restoration did not have a consistent effect on soil microbial abundance, richness or evenness, which responses varied across farms. Microbial genetic and taxonomic community composition (i.e., sequence variant and genus level) were affected by land use, farm and the interaction between these two factors. Generally, prairie soils had higher relative abundance of Latescibacterota, Desulfobacterota, Acidobacteriota and Glomeromycota, and lower of Deinococcota, Chytridiomycota and Amoebozoa_X. In terms of differentially abundant fungal genera, prairies promoted more fungal plant symbionts, less saprotrophs and no plant pathogens. Interkingdom networks revealed changes in potential microbe-microbe associations with prairie restoration, with only 8 associations in common between land uses. The relationship between soil microbial diversity and physicochemical properties varied across microbial groups, diversity metrics and land uses. Our results evidence the complexity associated with restoring soils from agricultural land to natural ecosystems, with unspecified farm-specific factors (e.g., soil type, prairie species, management history) strongly modulating the response of different microbial groups and variables.

microbiology↗

bioRxiv2024

When Attention Hurts: The Effect Of rTMS On Neural Correlates Of Time Perception

The parietal lobe plays a crucial role in the attentional networks that help shape our perception, including our perception of time. Based on neuropsychological and neurophysiological evidence, a "when" pathway including the right parietal lobe has been proposed as the critical cortical site for the discrimination of objects across time. When an oddball stimulus is presented in a stream of identical standard stimuli, it is perceived as lasting longer, even when its actual duration is shorter. While attentional capture seems to play a major role in this subjective expansion of time the cortical mechanisms responsible for this effect remain unclear. We therefore set to investigate the direct role of parietal brain areas in time perception using combined repetitive transcranial magnetic stimulation (rTMS) and electroencephalogram (EEG). We measured the perceived duration of an oddball stimulus in each participant before and after inhibitory 1-Hz rTMS stimulation at one of three scalp locations: the right intraparietal sulcus (rIPS), the right inferior parietal lobe (rIPL), or the occipital cortex as a control. EEG was recorded throughout. Stimulation over the rIPL caused a more veridical experience of times subjective expansion towards the oddball, while rTMS over the rIPS and the occipital cortex had no effect. These data provide theoretically challenging notions to the concept of the cortexes role within time perception and the mechanisms involved.

neuroscience↗