Biology subjects

Chamberland, V.

Publications and source records attributed to Chamberland, V..

3 recordsLinked to original sources

bioRxiv2025

Online HD-tRNS over the right temporoparietal junction modulates social inference but not motor coordination

Social interactions are fundamental to human cognition, with the right temporoparietal junction (rTPJ) playing a key role in integrating motor coordination and social inference. Transcranial random noise stimulation (tRNS) is a promising technique for modulating cortical excitability, yet its effect on dynamic social processes remains unexplored. This study aimed to establish a causal link between rTPJ and real-time social interaction by applying high-definition transcranial random noise stimulation (HD-tRNS) during the Human Dynamic Clamp (HDC) paradigm. Specifically, we investigated whether online HD-tRNS modulates motor coordination and social inference when interacting with an adaptive virtual partner (VP). Eighty right-handed participants were assigned to one of two experiments: (Exp1) a block design with active HD-tRNS and sham blocks or (Exp2) a trial-by-trial design with intermixed active and sham conditions. Participants engaged in an interactive coordination task with a covert VP that could behave cooperatively or competitively. Kinematic data and self-reported measures of perceived cooperativeness and humanness were analyzed. HD-tRNS over the rTPJ did not influence motor coordination or task performance. However, in Exp1, participants receiving active stimulation progressively attributed lower cooperativeness and humanness to the competitive VP, suggesting improved detection of competitive intent. This effect was absent in Exp2, indicating that repeated stimulation was necessary for cumulative neuromodulatory effects. Online HD-tRNS over the rTPJ does not acutely impact motor coordination but progressively modulates social inference, particularly in competitive interactions. The findings highlight the rTPJs role in self-other distinction and suggest that repeated short neuromodulation sessions can shape social perception. Significant statementSocial interactions rely on distinguishing between cooperative and competitive behaviors, a process involving the right temporoparietal junction (rTPJ). Using high-definition transcranial random noise stimulation (HD-tRNS), we tested the rTPJs causal role in real-time social inference. While HD-tRNS did not affect motor coordination, repeated stimulation progressively reduced perceived cooperativeness and humanness of a competitive virtual partner, suggesting enhanced sensitivity to competitive intent. Our findings provide insights into social perception mechanisms and suggest HD-tRNS as a potential tool for studying and modulating social cognition, with implications for conditions affecting social inference, such as autism and schizophrenia.

neuroscience↗

bioRxiv2025

Mosaic accumulation of somatic genetic variation and estimates of age in the long-lived reef-building coral Acropora palmata

Somatic genetic variation (SOGV), accumulating during an organisms lifetime, was traditionally viewed as detrimental rather than adaptive due to links with cancer and senescence. However, in modular organisms like corals, deleterious mutations can be purged at the cellular or polyp level, while adaptive mutations may rise in frequency as polyps create genetically distinct modules. Quantifying the somatic genetic landscape in corals is necessary to understand the role these mutations may have in coral and clonal animal development and evolution. Here, we catalog somatic genetic variation in eight Acropora palmata colonies from Curacao. Whole genomes were sequenced (70-100x depth), documenting mutation variant allele frequency shifts as genets aged. Large numbers of SOGVs were observed in six- to ten-year-old colonies, and inferred mutation rates were used to age a genet of uncertain age to almost a century old. Although mutations were not fixed at the polyp or branch levels, i.e. they always displayed frequencies <0.5 as expected at mutating homozygous sites, their allele frequencies followed a power-law distribution, similar to aging human tissues. No signs of positive selection were found; instead SOGVs in the colony of uncertain age were under purifying selection. In one colony, mutations in 28 samples from along a branch were analyzed using a SNP microarray. Contrary to expectations, genetic and physical distances were unrelated. This observation together with the observed lack of fixation may be explained by a large stem cell population, the de-differentiation or dormancy of stem cells, the contribution of strong purifying selection, or a combination of the previously mentioned. Our findings provide a neutral framework against which to test for module-level selection of genetic variation in corals, explore the relationship between physical and genetic distance within a colony, and apply a somatic genetic clock to colonies of Acropora palmata. This work provides necessary fundamental insights into the landscape of somatic mutations in reef-building coral, highlighting the importance of studying these mutations as they may contribute to genetic diversity and adaptability in colonial animals.

genomics↗

bioRxiv2023

Registered report: Age-preserved semantic memory and the CRUNCH effect manifested as differential semantic control networks: an fMRI study

Semantic memory representations are generally well maintained in aging, whereas semantic control is thought to be more affected. To explain this phenomenon, this study tested the predictions of the Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH), focusing on task demands in aging as a possible framework. The CRUNCH effect would manifest itself in semantic tasks through a compensatory increase in neural activation in semantic control network regions but only up to a certain threshold of task demands. This study compares 39 younger (20-35 years old) with 39 older participants (60-75 years old) in a triad-based semantic judgment task performed in an fMRI scanner while manipulating task demand levels (low versus high) through semantic distance. In line with the CRUNCH predictions, differences in neurofunctional activation and behavioral performance (accuracy and response times) were expected in younger versus older participants in the low-versus high-demand conditions, which should be manifested in semantic control Regions of Interest (ROIs). Our older participants had intact behavioral performance, as proposed in the literature for semantic memory tasks (maintained accuracy and slower response times (RTs)). Age-invariant behavioral performance in the older group compared to the younger one is necessary to test the CRUNCH predictions. The older adults were also characterized by high cognitive reserve, as our neuropsychological tests showed. Our behavioral results confirmed that our task successfully manipulated task demands: error rates, RTs and perceived difficulty increased with increasing task demands in both age groups. We did not find an interaction between age group and task demand, or a statistically significant difference in activation between the low- and high-demand conditions for either RTs or accuracy. As for brain activation, we did not find the expected age group by task demand interaction, or a significant main effect of task demand. Overall, our results are compatible with neural activation in the semantic network and the semantic control network, largely in frontotemporoparietal regions. ROI analyses demonstrated significant effects (but no interactions) of task demand in the left and right inferior frontal gyrus, the left posterior middle temporal gyrus, the posterior inferior temporal gyrus and the prefrontal gyrus. Overall, our test did not confirm the CRUNCH predictions.

neuroscience↗