Biology subjects

Fransen, A.

Publications and source records attributed to Fransen, A..

4 recordsLinked to original sources

bioRxiv2026

Choice-driven remapping of action- and stimulus-anchored value in human single neurons

Whether stimulus- and action-based choices rely on a shared neural architecture remains intensely debated. While lesion and fMRI studies show conflicting regional dissociation and overlap, the underlying single neuron substrates remain unknown. We recorded single neuron activity from the human ventromedial prefrontal cortex (vmPFC), anterior cingulate cortex (ACC), pre-supplementary motor area (preSMA), and amygdala during distinct action- and stimulus-based reward tasks. Prior to decision-making, neurons across all regions broadly encode value for both choice domains. However, choice commitment triggers domain segregation across the prefrontal cortex. While ACC and vmPFC neurons flexibly track both chosen actions and stimuli, they exhibit a double dissociation for chosen valuation: ACC neurons selectively maintain action-based values, whereas vmPFC neurons selectively maintain stimulus-based values. Conversely, preSMA neurons invariant to task domain track chosen action identity and value. These findings reveal how prefrontal networks transition from domain-general evaluation to domain-segregated choice execution.

neuroscience↗

bioRxiv2025

Distributed activity in the human posterior putamen distinguishes goal-directed from habitual control in humans

How do some individuals rapidly form habits while others maintain flexible, goal-directed control? Using multivariate fMRI decoding in 199 participants, we show that distributed neural activity patterns in the left posterior putamen during initial learning predict individual behavioral strategy on a subsequent outcome devaluation test. This prediction generalized across two independent cohorts of healthy adults and psychiatric patients with heterogeneous diagnoses and was anatomically specific to the posterior putamen. Critically, predictive neural signatures were present during training, before strategy expression after devaluation, enabling prospective classification of habitual versus goal-directed behavior. These findings demonstrate that stable individual differences in behavioral control are reflected in circumscribed brain activity during learning, highlighting the posterior putamen as a candidate neural marker of habit propensity with potential clinical relevance.

neuroscience↗

bioRxiv2025

Lignin degradation and valorization by Pseudomonas putida KT2440: a new role for glutathione peroxidase

Lignin, a complex natural aromatic polymer, poses significant challenges to its efficient degradation, hindering the utilization of biomass for many industrial applications. Bacterial degradation of lignin may offer a promising solution to this challenge. This project aimed at elucidating the function of secreted oxidative enzymes from Pseudomonas putida involved in lignin degradation and utilization. Using CRISPR-Cas9 and CRISPR-Cas3 systems, the putative lignin-degrading versatile peroxidase gene (VP; PP_1686, originally annotated as glutathione peroxidase GPx) and dye-decolorizing peroxidase gene (PP_3248) were individually knocked out from P. putida KT2440. The {Delta}PP_1686 mutant exhibited impaired growth and utilization of lignin-derived compounds. This correlated with reduced expression of p-hydroxybenzoate hydroxylase pobA and of DNA repair modules, alongside compensatory upregulation of energy and redox supply pathways. This work expands our knowledge on bacterial glutathione peroxidase by presenting a role beyond ROS scavenging. This work revealed the importance of P. putida VP/GPx in maintaining redox balance while supporting lignin-derived aromatic metabolism, offering new targets for future investigation into stress-metabolism crosstalk and lignin valorization strategies.

microbiology↗

bioRxiv2025

The neural computations underlying context dependent attribute-based valuation of complex stimuli.

Adaptive decision making requires value computations to be flexible because we often need to value a stimulus differently as the context changes. A stimulus might be highly desirable in one context but completely unappealing in another. However, it is not known how the brain can support such flexible modulation of overall stimulus value. Here we test a model of flexible value construction whereby individual attributes of a stimulus are converted into contextually dependent attribute-specific value representations before being combined into an overall integrated stimulus value. To test this framework, human participants (online n=95, MRI n=35) provided ratings for 75 unique high-dimensional clothing stimuli under three instructed goal-contexts designed to elicit differences in overall value judgments for the items. Integrated value ratings for each stimulus were found to be goal-context dependent, while individual stimulus-attributes varied markedly in how they contributed to value ratings across goal contexts. In the fMRI data, representations of the absolute levels of particular attributes were revealed in visual areas. In contrast, encoding of individual attributes in value space, alongside integrated overall stimulus value, was present within distinct regions of prefrontal cortex. More specifically, behaviorally relevant attributes in value space and integrated stimulus value were found in vmPFC and dmPFC respectively. These findings indicate that the construction of value for high-dimensional stimuli is achieved through the computation of goal-context-dependent attributes in value space, providing mechanistic insight into how the brain can flexibly modulate stimulus-values as context changes.

neuroscience↗