Biology subjects

Oostwoud Wijdenes, L.

Publications and source records attributed to Oostwoud Wijdenes, L..

8 recordsLinked to original sources

bioRxiv2025

Movement Effort does not alter the Planning Horizon of Sequential Reaching Movements

Everyday tasks often involve multiple reaching movements in a sequence, where the choices made for one movement also affect the conditions for subsequent movements. Previous research indicates that humans are capable of planning ahead to optimize such sequences. Here, we ask whether increasing the resistance to movement prompts participants to plan even further ahead to reduce overall movement effort. Participants (n=28) were shown 14 targets that varied in size, value and location, and were instructed to accumulate as many points as possible. To collect each target, they reached while holding the handle of a robotic manipandulum that applied a resistive force. We analyzed their target choices using a planning model that takes into account the size, value and distance of several future targets. We expected that, as resistance - and therefore the effort required to move between two targets - increased, participants would plan further ahead to minimize total movement distance. Results show that participants typically planned 2-4 targets ahead. However, increasing resistance did not significantly affect the planning horizon. We conclude that movement effort is not a primary constraint on the planning horizon in sequential reaching movements. NEW AND NOTEWORTHYHumans are capable of planning ahead in sequential reaching movements, but whether they adjust their planning horizon according to task demands is unknown. To manipulate task demands, we increased movement effort during a free target collection task. This makes planning more beneficial. However, we found no adjustment in planning horizon, suggesting that movement effort might not be a critical factor for planning in sequential reaching movements.

neuroscience↗

bioRxiv2025

Does stimulus order affect central tendency and serial dependence in vestibular path integration?

The reproduction of a perceived stimulus, such as a distance or a duration, is often influenced by two biases. Central tendency indicates that reproductions are biased toward the mean of the stimulus distribution. Serial dependence reflects that the reproduction of the current stimulus is influenced by the previous stimulus. Although these biases are well-documented, their origins remain to be determined. Studies on duration reproduction suggest that autocorrelation within a stimulus sequence may play a role. In this study, we explored whether the level of autocorrelation in a stimulus sequence affects central tendency and serial dependence in vestibular path integration. Participants (n = 24) performed a vestibular distance reproduction task in total darkness by actively replicating a passively moved stimulus distance with a linear motion platform. We compared two conditions: a high-autocorrelation condition, where stimulus distances followed a random walk, and a no-autocorrelation condition, where the same distances were presented in a randomly shuffled order. We quantified both biases using two approaches: separate simple linear regressions and a joint multiple linear regression model that accounts for the autocorrelation in the stimulus sequence. Simple linear regressions revealed that central tendency was weaker and serial dependence reversed in the high-autocorrelation condition compared to the no-autocorrelation condition. However, these differences were no longer observed in the multiple linear regression analysis, indicating that these biases were independent of the specific stimulus sequence protocol. We conclude that these perceptual biases in vestibular path integration persist regardless of stimulus autocorrelation, suggesting that they reflect robust strategies of the brain to process vestibular information in self-motion perception. Author summaryHow are we able to successfully navigate our surroundings? An essential part of navigation is distance estimation based on self-motion signals. We previously found that distance reproductions based on vestibular self-motion signals were affected by stimulus history. Reproductions showed a central tendency toward the mean of the stimulus distribution and an attractive serial dependence toward the immediately preceding stimulus distance. The stimulus distances were presented in a low-autocorrelation, randomized order. Here we ask whether reproductions show the same central tendency and serial dependence when consecutive stimulus distances are similar (i.e., in a high-autocorrelation, random-walk order). Participants performed a distance reproduction task in the dark: a linear motion platform first passively moved the participant over a stimulus distance, after which they actively reproduced this distance by steering the platform back to the estimated start position. We found that the reproductions showed similar central tendency and attractive serial dependence in both a no- and high-autocorrelation condition, but only if the analysis accounted for the covariation of the two effects in the high-autocorrelation condition. In conclusion, our findings indicate that central tendency and serial dependence of vestibular distance reproductions are not a result of the stimulus sequence protocol, but have neurocognitive origins.

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bioRxiv2024

Central tendency and serial dependence in vestibular path integration

Path integration, the process of updating ones position using successive self-motion signals, has previously been studied using visual distance reproduction tasks in which optic flow patterns provide information about traveled distance. These studies have reported that reproduced distances show two types of systematic biases: central tendency and serial dependence. In the present study, we investigated whether these biases are also present in vestibular path integration. Participants were seated on a linear motion platform and performed a distance reproduction task in total darkness. The platform first passively moved the participant a pre-defined stimulus distance which they then actively reproduced by steering the platform back the same distance. Stimulus distances were sampled from short- and long-distance probability distributions and presented in either a randomized order or in separate blocks to study the effect of presentation context. Similar to the effects observed in visual path integration, we found that reproduced distances showed an overall positive central tendency effect as well as a positive, attractive serial dependence effect. Furthermore, reproduction behavior was affected by presentation context. These results were mostly consistent with predictions of a Bayesian Kalman-filter model, originally proposed for visual path integration. New & NoteworthyDistance reproduction tasks based on visual information about the traveled distance have shown that reproductions are biased by central tendency and serial dependence effects. Here, we show that distance reproductions based on vestibular signals show similar biases and that the reproductions are affected by the presentation order of the stimulus distances.

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bioRxiv2024

Does early-stage Alzheimer's disease affect the dynamics of motor adaptation?

Alzheimers disease (AD) is characterized by an initial decline in declarative memory, while non-declarative memory processing remains relatively intact. Error-based motor adaptation is traditionally seen as a form of non-declarative memory, but recent findings suggest that it involves both fast, declarative and slow, non-declarative adaptive processes. If the declarative memory system shares resources with the fast process in motor adaptation, it can be hypothesized that the fast, but not the slow, process is disturbed in AD patients. To test this, we studied 20 early-stage AD patients and 21 age-matched controls of both sexes using a reach adaptation paradigm that relies on spontaneous recovery after sequential exposure to opposing force fields. Adaptation was measured using error clamps and expressed as an adaptation index (AI). Although patients with AD showed slightly lower adaptation to the force field than the controls, both groups demonstrated effects of spontaneous recovery. The time course of the AI was fitted by a hierarchical Bayesian two-state model in which each dynamic state is characterized by a retention and learning rate. Compared to controls, the retention rate of the fast process was the only parameter that was significantly different (lower) in the AD patients, confirming that the memory of the declarative, fast process is disturbed by AD. The slow adaptive process was virtually unaffected. Since the slow process learns only weakly from error, our results provide neurocomputational evidence for the clinical practice of errorless learning of everyday tasks in people with dementia.

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bioRxiv2022

Natural statistics of head roll: implications for Bayesian inference in spatial orientation

We previously proposed a Bayesian model of multisensory integration in spatial orientation (1). Using a Gaussian prior, centered on an upright head orientation, this model could explain various perceptual observations in roll-tilted participants, such as the subjective visual vertical, the subjective body tilt (1), the rod-and-frame effect (2), as well as their clinical (3) and age-related deficits (4). Because it is generally assumed that the prior reflects an accumulated history of previous head orientations, and recent work on natural head motion suggests non-Gaussian statistics, we examined how the model would perform with a non-Gaussian prior. In the present study, we first experimentally generalized the previous observations in showing that also the natural statistics of head orientation are characterized by long tails, best quantified as a t-location-scale distribution. Next, we compared the performance of the Bayesian model and various model variants using such a t-distributed prior to the original model with the Gaussian prior on their accounts of previously published data of the subjective visual vertical and subjective body tilt tasks. All of these variants performed substantially worse than the original model, suggesting a special value of the Gaussian prior. We provide computational and neurophysiological reasons for the implementation of such a prior, in terms of its associated precision-accuracy trade-off in vertical perception across the tilt range. New & NoteworthyIt has been argued that the brain uses Bayesian computations to process multiple sensory cues in vertical perception, including a prior centered on upright head orientation which is usually taken to be Gaussian. Here, we show that non-Gaussian prior distributions, although more akin to the statistics of head orientation during natural activities, provide a much worse explanation of such perceptual observations than a Gaussian prior.

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bioRxiv2021

Even well-practiced movements benefit from repetition

Professional golf players spend years practicing, but will still perform one or two practice swings without a ball before executing the actual swing. Why do they do this? In this study we tested the hypothesis that repeating a well-practiced movement leads to a reduction of movement variability. To operationalize this hypothesis, participants were tested in a center- out reaching task with four different targets, on four different days. To probe the effect of repetition they performed random sequences from one to six movements to the same target. Our findings show that, with repetition, movements are not only initiated earlier but their variability is reduced across the entire movement trajectory. Furthermore, this effect is present within and across the four sessions. Together, our results suggest that movement repetition changes the tradeoff between movement initiation and movement precision. New & NoteworthyProfessional athletes practice movements that they have performed thousands of times in training just before it is their turn in a game. Why do they do this? Our results indicate that both initial and endpoint variability reduce with repetition in a short sequence of reaching movements. This means that even well-practiced movements benefit from practice.

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bioRxiv2021

Beta-band desynchronization reflects uncertainty in effector selection during motor planning

While beta-band activity during motor planning is known to be modulated by uncertainty about where to act, less is known about its modulations to uncertainty about how to act. To investigate this issue, we recorded oscillatory brain activity with EEG while human participants (n = 17) performed a hand choice reaching task. The reaching hand was either predetermined or of participants choice, and the target was close to one of the two hands or at about equal distance from both. To measure neural activity in a motion-artifact-free time window, the location of the upcoming target was cued 1000-1500 ms before the presentation of the target, whereby the cue was valid in 50% of trials. As evidence for motor planning during the cueing phase, behavioral observations showed that the cue affected later hand choice. Furthermore, reaction times were longer in the choice than in the predetermined trials, supporting the notion of a competitive process for hand selection. Modulations of beta-band power over central cortical regions, but not alpha-band or theta-band power, were in line with these observations. During the cueing period, reaches in predetermined trials were preceded by larger decreases in beta-band power than reaches in choice trials. Cue direction did not affect reaction times or beta-band power, which may be due to the cue being invalid in 50% of trials, retaining effector uncertainty during motor planning. Our findings suggest that effector uncertainty, similar to target uncertainty, selectively modulates beta-band power during motor planning. New & NoteworthyWhile reach-related beta-band power in central cortical areas is known to modulate with the number of potential targets, here we show, using a cueing paradigm, that the power in this frequency band, but not in the alpha or theta-band, is also modulated by the uncertainty of which hand to use. This finding supports the notion that multiple possible effector-specific actions can be specified in parallel up to the level of motor preparation.

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bioRxiv2021

Corticospinal correlates of hand preference for reaching during whole-body motion

Behavioral studies have shown that humans account for inertial acceleration in their decisions of hand choice when reaching during body motion. Physiologically, it is unclear at what stage of movement preparation information about body motion is integrated in the process of hand selection. Here, we addressed this question by applying transcranial magnetic stimulation over motor cortex (M1) of human participants who performed a preferential reach task while they were sinusoidally translated on a linear motion platform. If M1 only represents a read-out of the final hand choice, we expect the body motion not to affect the MEP amplitude. If body motion biases the hand selection process prior to target onset, we expect corticospinal excitability to modulate with the phase of the motion, with larger MEP amplitudes for phases that show a bias to using the right hand. Behavioral results replicate our earlier findings of a sinusoidal modulation of hand choice bias with motion phase. MEP amplitudes also show a sinusoidal modulation with motion phase, suggesting that body motion influences corticospinal excitability which may ultimately reflect changes of hand preference. The modulation being present prior to target onset suggests that competition between hands is represented throughout the corticospinal tract. Its phase relationship with the motion profile suggests that other processes after target onset take up time until the hand selection process has been completely resolved, and the reach is initiated. We conclude that the corticospinal correlates of hand preference are modulated by body motion.

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