Biology subjects

Whitney, D.

Publications and source records attributed to Whitney, D..

6 recordsLinked to original sources

bioRxiv2026

Statistical factorization in motor control: Opposing biases from statistics on different timescales enable fast and accurate behavior

Motor planning is fundamentally constrained by the speed-accuracy tradeoff: a single optimization that balances time and error costs, such that longer preparation yields more accurate movements while faster ones incur greater error. Here we propose that the motor system exploits environmental statistics to reshape this relationship, using two complementary computations that rely on distinct statistical information. The first leverages the marginal statistics of the target distribution, learned by integrating slowly over many trials, to modify the initial preparation state, accelerating planning for frequently encountered targets; this simultaneously speeds decisions and reduces planning variability, but introduces an attractive bias toward the mean of the target distribution. Strikingly, a second process tracks the sequential statistics of the environment over only the last few trials, producing a repulsive sequential bias whose persistence is tuned to the temporal autocorrelation and selectively counteracting the attractive bias introduced by the first. These results reveal that the motor system applies statistical factorization, estimating marginal and sequential statistics on their own timescales to shape movement preparation, thereby escaping the speed-accuracy tradeoff and producing movements that are both faster and more accurate.

neuroscience↗

bioRxiv2025

Slow change blindness from serial dependence

Slow change blindness, when attentive observers fail to notice large changes that happen gradually, raises questions about how visual information is combined across time. One plausible integration strategy is serial dependence: blending information from the recent past into current perception. Here, we investigate serial dependencies in perception of a cartoon object that slowly changes hue. In a one-shot experiment, observers each viewed a single trial with a random degree of hue change and provided one hue judgement response. Across participants, the entire morph was probed. Observers hue reports revealed an overall bias towards the past that increased in magnitude as more of the morph was experienced. In three follow-up experiments, we verified that observers experienced slow change blindness, confirmed that the bias was serial dependence, and replicated the results with a repeated-trials design. Overall, we provide evidence that serial dependence actively biases perception during gradual changes, producing slow change blindness. TeaserBy strategically integrating recent and current visual information, observers experience a slowly changing stimulus as stable.

neuroscience↗

bioRxiv2024

Efficient Coding in Motor Planning

The nervous system utilizes prior information to enhance the accuracy of perception and action. Prevailing models of motor control emphasize Bayesian models, which suggest that the system adjusts the current motor plan by integrating information from previous observations. While Bayesian integration has been extensively examined, those studies usually applied a highly stable and predictable environment. In contrast, in many real-life situations, motor goals change rapidly over time in a relatively unpredictable way, leaving it unclear whether Bayesian integration is useful in those natural environments. An alternative model that leverages prior information to improve performance is efficient coding, which suggests that the motor system maximizes the accuracy by dynamically tuning the allocation of the encoding resources based on environmental statistics. To investigate whether this adaptive mechanism operates in motor planning, we employed center-out reaching tasks with motor goals changing in a relatively unpredictable way, where Bayesian and efficient coding models predict opposite sequential effects. Consistent with the efficient coding model, we found that current movements were biased in the opposite direction of previous movements. These repulsive biases were amplified by intrinsic motor variability. Moreover, movement variability decreased when successive reaches were similar to each other. Together, these effects support the presence of efficient coding in motor planning, a novel mechanism with which the motor system maintains flexibility and high accuracy in dynamic environments.

neuroscience↗

bioRxiv2022

High-throughput discovery of TRAF6-interacting peptides identifies determinants of positive and negative design and shows known and candidate human interaction partner motifs are not optimized for affinity

TRAF6 is an adapter protein and E3 ubiquitin ligase involved in signaling downstream of cell receptors essential for development and the immune system. TRAF6 participates in many protein-protein interactions, some of which are mediated by a C-terminal MATH domain that recruits TRAF6 to cell-surface receptors and associated proteins. The TRAF6 MATH domain binds to short peptide segments containing the motif PxExx[FYWHDE], where x is any amino acid. Blocking TRAF6 interactions is associated with favorable effects in various disease models. To better define the TRAF6 MATH domain binding preferences, we generated a bacterial cell-surface peptide display library to sample the TRAF6 motif sequence space. We performed sorting experiments and identified 236 of the best TRAF6-interacting peptides and a set of 1,200 peptides that match the sequence PxE but do not bind TRAF6. Selected binders, tested by single-clone bacterial display titrations and bio-layer interferometry, bound TRAF6 tighter than previously measured native peptides. To elucidate the structural basis for TRAF6 interaction preferences, we built all-atom structural models of the TRAF6 MATH domain in complex with high-affinity binders and motif-matching nonbinders that were identified in the screen. We identified motif features that favor binding to TRAF6 as well as negative design elements distributed across the motif that can disfavor or preclude binding. Searching the human proteome for matches to the library screening-defined binding motif revealed that most known, biologically relevant TRAF6 motif matches occupy a different sequence space from the most enriched hits discovered in combinatorial library screening. Our experimentally determined binding preferences and structural models can support the design of peptide-based interaction inhibitors with higher affinities than endogenous TRAF6 ligands.

biochemistry↗

bioRxiv2020

Idiosyncratic Perception: A Link Between Acuity, Perceived Position, and Apparent Size

Perceiving the positions of objects is a prerequisite for most other visual and visuomotor functions, but human perception of object position varies from one individual to the next. The source of these individual differences in perceived position and their perceptual consequences are unknown. Here, we tested whether idiosyncratic biases in the underlying representation of visual space propagate across different levels of visual processing. In Experiment 1, using a position matching task, we found stable, observer-specific compressions and expansions within local regions throughout the visual field. We then measured Vernier acuity (Experiment 2) and perceived size of objects (Experiment 3) across the visual field and found that individualized spatial distortions were closely associated with variations in both visual acuity and apparent object size. Our results reveal idiosyncratic biases in perceived position and size, originating from a heterogeneous spatial resolution that carries across the visual hierarchy.

neuroscience↗

bioRxiv2018

Serial Dependence in Position Perception Occurs at the Time of Perception

Observers perceive objects in the world as stable over space and time, even though the visual experience of those objects is often discontinuous and distorted due to masking, occlusion, camouflage, noise, etc. How are we able to easily and quickly achieve stable perception in spite of this constantly changing visual input? It was previously shown that observers experience serial dependence in the perception of features and objects, an effect that extends up to 15 seconds back in time. Here, we asked whether the visual system utilizes an objects prior physical location to inform future position assignments in order to maximize location stability of an object over time. To test this, we presented subjects with small targets at random angular locations relative to central fixation in the peripheral visual field. Subjects reported the perceived location of the target on each trial by adjusting a cursors position to match its location. Subjects made consistent errors when reporting the perceived position of the target on the current trial, mislocalizing it toward the position of the target in the preceding two trials (Experiment 1). This pull in position perception occurred even when a response was not required on the previous trial (Experiment 2). In addition, we show that serial dependence in perceived position occurs immediately after stimulus presentation, and is a fast stabilization mechanism that does not require a delay (Experiment 3). This indicates that serial dependence occurs for position representations and facilitates the stable perception of objects in space. Taken together with previous work, our results show that serial dependence occurs at many stages of visual processing, from initial position assignment to object categorization.

neuroscience↗