Biology subjects

Dessain, Q.

Publications and source records attributed to Dessain, Q..

3 recordsLinked to original sources

bioRxiv2026

Temporal dynamics of cognitive map formation in early- and late-onset blindness

Cognitive maps encode spatial relationships between locations and support flexible navigation. However, how these mental representations form in blindness remains unclear. Here, we introduce a multisensory virtual navigation paradigm that monitors non-visual cognitive map formation over time. Sixteen early blind (EB), 17 late blind (LB), and 29 sighted controls (SC) learned the layout of a tactile maze and, in a virtual version, repeatedly performed pointing (judgment of relative directions) and navigation (reaching locations) tasks. Thus, this experiment tracked both functional and spatio-cognitive components of cognitive map formation across multiple learning stages and showed that EB accumulated knowledge more slowly than SC. In addition, both EB and LB had reduced pointing accuracy under viewpoint changes, indicating difficulty translating cognitive maps into first-person perspectives. Yet, navigation and pointing improved in all groups, and a subset of EB and LB achieved expert-level performance. In sum, this study provides a scalable framework for tracking the temporal dimension of cognitive map formation in blindness and other neurological conditions, informing how spatial knowledge is acquired and translated into navigation behavior. Importantly, it suggests that allocentric cognitive map formation in blindness is an experience-dependent process that varies across time and individuals. Observed spatial disadvantages in both blind groups may result from adaptive strategies that constrain the use of allocentric cognitive maps, independent of prior visual experience.

neuroscience↗

bioRxiv2025

White matter microstructure predicts effort and reward sensitivity

From rodents to humans, animals constantly face a central question: is the reward worth the effort? Effort and reward sensitivity in such situations vary substantially across individuals and ultimately shape goal-directed behavior. Yet, the brain mechanisms underlying this variability across individuals remain unclear. Here, we combined computational modeling of effort and reward sensitivity during decision-making with whole-brain diffusion MRI in 45 healthy participants to identify white matter substrates of individual sensitivity. A data-driven, cluster-based analysis of fractional anisotropy and mean diffusivity revealed 12 clusters: five linked to effort sensitivity, all within tracts connected to major frontal valuation nodes (e.g., supplementary motor area [SMA], dorsal anterior cingulate cortex [dACC], orbitofrontal cortex [OFC]), and seven linked to reward sensitivity, spanning frontal valuation, fronto-parietal, and sensorimotor networks. The strongest associations involved two SMA-connected clusters, one shared across effort and reward sensitivity and another consistent across both microstructural metrics. Critically, microstructural features from the five effort-related and seven reward-related clusters reliably predicted individual effort and reward sensitivity in out-of-sample machine learning analyses, respectively, whereas randomly sampled clusters did not. SMA-connected tracts were the dominant predictors in these decoding analyses, with additional contributions from fronto-parietal and sensorimotor pathways for reward sensitivity. These findings reveal a distributed white matter architecture underlying inter-individual differences in effort and reward sensitivity, with SMA pathways emerging as central hubs. They demonstrate that localized white matter microstructure can robustly predict these individual differences, offering a framework to forecast the impact of lesions or interventions on goal-directed behavior, including apathy and impulsivity. SIGNIFICANCE STATEMENTWhy do some people give up easily when faced with high effort demands, while others persist even when rewards are small? Such differences in effort and reward sensitivity shape goal-directed behavior, yet their neural basis is unclear. Using diffusion MRI and computational modeling, we show that white matter microstructure in specific pathways reliably predicts individual differences in these sensitivities. Tracts connected to the supplementary motor area emerged as central hubs, with additional contributions from fronto-parietal and sensorimotor networks. These results demonstrate that variability in effort and reward sensitivity is rooted not only in brain activity but also in structural connectivity, providing a framework to anticipate how white matter lesions or interventions may alter goal-directed behavior, including apathy and impulsivity.

neuroscience↗

bioRxiv2024

Fronto-motor circuits linked to subclinical apathy

Apathy is a syndrome characterized by a disruption in effort-reward decision-making, accompanied by structural and functional changes in a related fronto-basal ganglia (BG) network. While activity changes in the primary motor cortex (M1) during effort and reward valuation have been repeatedly observed, previous work on apathy has largely overlooked the connections between the fronto-BG network and M1, potentially missing key circuits in the apathy network. This study addresses this gap by investigating structural and effective connectivity in fronto-M1, fronto-BG-M1, and intra-M1 circuits in relation to apathy in 45 healthy subjects. Behavior was assessed using a battery of apathy-related questionnaires and computational modeling of effort and reward valuation in a decision-making task. Fronto-motor circuits were examined through a combination of MRI-derived tractography and paired-pulse transcranial magnetic stimulation, which probed structural and effective connectivity, respectively. The data reveal that apathy scores are associated with both structural and effective connectivity in fronto-M1 and fronto-BG-M1 circuits. Circuits originating from the supplementary motor area primarily index effort valuation, while connectivity in intra-M1 GABAergic circuits correlates exclusively with reward valuation. These findings suggest that distinct fronto-motor circuits are linked to different dimensions of motivated behavior and may constitute specific neuromodulation targets for patients suffering from apathy.

neuroscience↗