Biology subjects

Watson, M. F.

Publications and source records attributed to Watson, M. F..

3 recordsLinked to original sources

bioRxiv2026

Modeling the journey as well as the destination: a control theory account of rotational navigation

Navigation requires estimating heading and transforming these estimates into actions. Prior models explain how self-motion and landmark cues are combined into heading estimates, but less is known about how these estimates are iteratively transformed into motor commands to reach a goal. Here, we hypothesized that navigation operates as a closed-loop process in which ongoing movement is updated by sensory prediction errors. To test this hypothesis, participants performed a goal-directed rotation task in virtual reality. On select trials, visual landmarks were shifted during movement, inducing a prediction error between the heading expected from self-motion estimates and the heading observed from the shifted landmarks. In parallel, we developed a closed-loop model of turning behavior that represents heading and angular velocity as jointly estimated states over time. This model accounts not only for final position--the destination--but also for the movement dynamics that produce it--the journey. The model predicts that landmark-induced visual prediction errors should produce rapid corrective changes in movement. Participant turning behavior qualitatively paralleled these model dynamics: acceleration changed after visual feedback, with larger landmark mismatches producing larger corrective responses. Together, these findings suggest that naturalistic movement depends on continuously transforming heading estimates into motor command through closed-loop control.

neuroscience↗

bioRxiv2026

Illusory path configurations reveal age-related differences in egocentric pointing variability

A consistent finding across studies with older adults is that they typically perform worse at spatial memory tasks, particularly those conducted in virtual reality and involving novel environments, compared to young adults. While the underlying reasons for this difference remain unclear, some proposed hypotheses include differences in sensory cue integration and cue conflict resolution. Here, we tested older (n = 29) and young adults (n = 28) in immersive and walkable virtual reality using both correctly rendered and illusory hallways to test how visual cues (i.e., an intersection) and self-motion cues are integrated. In the illusory or false-intersection condition, we hypothesized that participants who walked an uncrossed path would merge two disconnected intersections, creating the illusion of a crossed path. The overall accuracy and pointing patterns were similar between young and older adults in both true- and false-intersection conditions. We did find, however, a significant age by condition interaction effect in egocentric pointing variability where older adults showed lower variability in the illusory condition and higher variability in the control condition. At the same time, older adults also drew worse maps for the control condition compared to young adults. However, the pointing error correlated with the accuracy of maps drawn regardless of age, suggesting that the pointing patterns shown by both age groups related to their underlying representations of the paths. Our findings are inconsistent with a global deficit in allocentric navigation or path integration and instead suggest that more subtle differences in strategy use might manifest with age.

neuroscience↗

bioRxiv2019

Forest canopy resists plant invasions: a case study of Chromolaena odorata in sub-tropical Sal (Shorea robusta) forests of Nepal

Invasive Alien Species cause tremendous ecological and economic damage in agriculture, forestry, aquatic ecosystems, and pastoral resources. They are one of the major threats to biodiversity conservation. Understanding the spatial pattern of invasive species and disentangling the biophysical drivers of invasion at forest stand level is essential for managing invasive species in forest ecosystems and the wider landscape. However, forest-level and species-specific information on invasive species abundance and area of extent is largely lacking. In this context, we analysed the cover of one of the worlds worst invasive plant species Chromolaena odorata in Sal (Shorea robusta Gaertn.) forest in central Nepal. Vegetation was sampled in four community-managed forests using 0.01 ha square quadrats, covering forest edge to the interior. Chromolaena cover, floral richness, tree density, forest canopy cover, shrub cover, and tree basal area were measured in each plot. We also estimated the level of disturbance in plots, and calculated distance from the plot to the nearest road. We also explored forest and invasive species management practices in community forests.\n\nChromolaena cover was found to be negatively correlated with forest canopy cover, distance to the nearest road, angle of slope and shrub cover. Canopy cover had the greatest effect on the Chromolaena cover. Chromolaena cover did not show any pattern along native species richness gradients. In conclusion, forest canopy cover is the overriding biotic covariate affecting Chromolaena cover in Sal forests. The practical application of our results in managing Chromolaena in forest ecosystems is discussed.

ecology↗