Biology subjects

Pasini, A.

Publications and source records attributed to Pasini, A..

4 recordsLinked to original sources

bioRxiv2026

The confidence code: parietal alpha oscillations turn expectations into beliefs

Metacognition, the ability to evaluate whether ones decisions are correct, is crucial for adaptive behavior. However, confidence judgments are not bias-free: they can be systematically modulated by predictive cues and beliefs, favoring expectation-consistent judgments, while leaving metacognitive precision unchanged. Here, we identify parietal alpha activity as the causal mechanism linking expectations to metacognitive bias. In Study 1, EEG was recorded while 75 participants performed a visual detection task with symbolic cues signaling target probability. Cues induced a metacognitive bias in confidence without altering metacognitive sensitivity, and cue-driven alpha modulation over the right parietal cortex predicted the magnitude of this bias. In Study 2 (N = 88), continuous theta-burst stimulation (cTBS) over the right parietal cortex abolished cue-induced alpha modulation, thereby selectively reducing metacognitive bias, while sham stimulation had no effect. Together, these findings demonstrate that parietal alpha-mediated gain control causally shapes metacognitive judgments, revealing an oscillatory code for predictive metacognition.

neuroscience↗

bioRxiv2025

Fast calcium-dependent reorientation of motile cilia basal bodies in the simple metazoan, Trichoplax.

Ciliary-based animal locomotion relies on the spatially coordinated beating of motile cilia to displace the body in liquid environments or across solid surfaces. The orientation of ciliary beating largely depends on the rotational polarity of the basal body, which in most animals is fixed and controlled by cues linked to the main body axes. The small marine animal Trichoplax exploits the beating of motile cilia in its lower epithelium to crawl on substrates. However, Trichoplax lacks defined body axes and exhibits rapid changes in body shape and direction of movement, thus raising the question of what controls the orientation and reorientation of ciliary beating. We show here that the basal bodies of the cilia in the lower epithelium of Trichoplax are oriented along the direction of the animal movements, and that they change their orientation throughout the lower epithelium in a few seconds time when the animal modifies its shape or changes direction following external mechanical stimuli. We also show that Ca2+ is required for fast basal body reorientation. Such rapid ciliary basal body reorientation has never been observed in metazoans before. Thus, our results identify a previously undescribed mechanism underlying directional motility in a metazoan and shed light on its subcellular determinants, bridging the scale between intra-cellular ciliary machinery and animal movement.

cell biology↗

bioRxiv2020

The SCF/KIT pathway implements self-organised epithelial patterning by cell movement

How individual cell behaviours lead to the emergence of global patterns is poorly understood. In the Xenopus embryonic epidermis, multiciliated cells (MCCs) are born in a random pattern within an inner mesenchymal layer, and subsequently intercalate at regular intervals into an outer epithelial layer. Using both experiments and mathematical modelling, we show that this transition from chaotic to ordered distribution relies on mutual repulsion among motile immature MCCs, and affinity towards outer-layer intercellular junctions. Consistently, ARP2/3-mediated actin remodelling is required for MCC pattern emergence. Using multiple functional approaches, we show that the Kit tyrosine kinase receptor, expressed in MCCs, and its ligand Scf, expressed in outer-layer cells, are both required for regular MCC distribution. While Scf behaves as a potent adhesive cue for MCCs, Kit expression is sufficient to confer order to a disordered heterologous cell population. Our work reveals how a single signalling system can implement self-organised large-scale patterning. Highlights- Immature multiciliated cells transit from a disordered to an ordered pattern - The transition is a self-organising process based on repulsive and affinity movements - ARP2/3-dependent actin remodelling is required for pattern emergence - The SCF/KIT pathway promotes both repulsion and affinity movements eTOC blurbIn developing Xenopus epidermis, immature multiciliated cells (MCCs), initially chaotically distributed within an inner layer, emerge in an orderly pattern among cells of the outer layer. This process involves MCC mutual repulsion and affinity towards outer-layer intercellular junctions. The SCF/KIT signalling pathway promotes both properties to allow regular MCC distribution.

developmental biology↗

bioRxiv2019

Anthropogenic Soils Promote Biodiversity in Amazonian Rainforests

Amazonian Dark Earths (ADEs) are fertile anthropic soils found throughout Amazonia, resulting from long-term occupation by pre-Columbian societies. Although the chemistry of these soils is well known, their biodiversity, particularly soil invertebrate communities have been neglected. To address this, we characterised soil macroinvertebrate communities and their activities in ADEs, comparing them with adjacent reference soils under forests and agriculture, at nine archaeological sites. We found 667 morphospecies and a tenacious pre-Columbian biodiversity footprint, with 40% of species found exclusively in ADEs. Soil biological activity was higher in ADEs than in adjacent soils, and associated with higher biomass and richness of organisms known to engineer the ecosystem. We show that these habitats have unique species pools, but that contemporary land-use causes nutrient loss and threatens their diversity. Both past and present human activities alter biodiversity and its distribution in Amazonia, and further efforts are needed to recognize and preserve these ADEs and their biodiversity.

zoology↗