Biology subjects

Seegelke, C.

Publications and source records attributed to Seegelke, C..

6 recordsLinked to original sources

bioRxiv2026

Toward naturalistic reaching: Intermediate reaches under uncertainty generalize to walking, but are not obligatory

Highly-constrained laboratory-based experiments have provided important insights into movement planning. When people reach toward one of several stimuli before knowing which to target, their hand trajectories are situated intermediate to direct reaches to each stimulus. Real-world reaching, however, involves a greater decision landscape than typical laboratory tasks. We extended the go-before-you-know paradigm to a walk-to-reach task resembling unconstrained natural behavior. Participants walked three steps toward a touchscreen before reaching for one of two stimuli, marked as the target either at walk onset or after reach onset. Under uncertainty, intermediate reaches occurred, but only for some stimulus layouts and participants. Individual reaches varied considerably; many directly targeted one stimulus and corrected late. Body position at reach onset was anchored to the screen more than the stimuli and was partly intermediate. Thus, intermediate movements generalize beyond the laboratory, but as one flexible strategy among several, not as obligatory motor plan averaging.

neuroscience↗

bioRxiv2026

Motor planning and execution establish distinct feedforward and feedback motor histories

Movements are systematically affected by the recent motor history. These history effects may be induced either by reused motor plans or from lingering tuning of the previous movements' execution. We dissociated planning and execution using four experimental manipulations across two complementary motor paradigms. We isolated planning by preventing execution with stop signals and mechanical blocks, and execution by moving participants' hand passively using a robot manipulandum. History effects emerged in feedforward movement aspects - reaction time and early movement kinematics - following isolated planning. In contrast, they were absent or markedly reduced for isolated execution. History effects emerged also in late movement aspect that involves sensory feedback during execution - movement accuracy and precision - but only when movements were both planned and executed. Feedforward effects generalized across hands, whereas feedback effects were effector specific. Thus, prior motor planning and execution make distinct and complementary contributions in shaping future motor behavior.

neuroscience↗

bioRxiv2026

Distinct contributions of motor imagery and execution to history-dependent biases in reaching

The recent movement history shapes motor performance, that is, previous movements can affect current movement characteristics such as trajectory shape. History effects are commonly attributed to carryover of motor-related activity. However, action execution entails sensory feedback; therefore, an alternative is that history effects stem from the sensory information produced by previous movements. To dissociate motor and sensory contributions, we assessed whether history effects emerge from imagined movements, which involve movement planning but not sensory feedback. Overt reaches around an obstacle led to systematic adjustment of the initial reach direction of following reaches - a hallmark of motor history. Imagined reaches around obstacles induced similar biases, albeit with smaller magnitude, presumably due to the need to inhibit overt execution during imagery. By contrast, execution but not imagery induced biases in late, feedback-related measures, suggesting that these history effects depended on sensory rather than motor aspects of the movement history. Thus, motor and sensory signals make distinct and complementary contributions to movement history: recent motor states shape feedforward planning, whereas recent sensory states shape feedback-related movement refinement.

neuroscience↗

bioRxiv2024

Effector selection precedes movement specification: evidence from repetition effects in motor planning

Motor performance is influenced by movements that were performed shortly prior. For example, reaction times (RTs) for successive movements are reduced when executed with the same effector, even if the specifics of the consecutive movements differ. These findings have been taken to support the notion that repetition effects in motor planning reflect the involvement of effector-specific motor plans. However, previous studies have confounded motor and visual aspects of repetition: movements have typically been instructed via visual cues, and movement repetition, therefore, implied repeating also the visual cue, so that the latter may be (at least partly) responsible for the observed RT effects. In the present study, participants performed two movements in succession, a prime and a probe action, either with their left or right hand and in one of two directions, inward or outward relative to the body midline. We used different cues for prime and probe actions, so that movement repetitions did not involve repetition of the visual cue. Participants initiated successive same-limb movements faster than different-limb movements, but this RT advantage was smaller than observed in previous work. Moreover, repeating movement direction also led to a decrease in RT, though only in combination with hand repetition. Whereas these findings imply that visual cue repetition can contribute to accelerated RTs in movement repetition, they confirm that the recent motor history affects motor planning. Furthermore, they support the idea of a hierarchical framework of motor planning in which effector selection precedes specification of motor parameters.

neuroscience↗

bioRxiv2022

Allocation of visuospatial attention indexes evidence accumulation for reach decisions

Visuospatial attention is a prerequisite for the performance of visually guided movements: Perceptual discrimination is regularly enhanced at target locations prior to movement initiation. It is known that this attentional prioritization evolves over the time of movement preparation; however, it is not clear whether this build-up simply reflects a time requirement of attention formation or whether, instead, attention build-up reflects the emergence of the movement decision. To address this question, we combined behavioral experiments, psychophysics, and computational decision-making models to characterize the time course of attention build-up during motor preparation. Participants (n = 46, 29 female) executed center-out reaches to one of two potential target locations and reported the identity of a visual discrimination target that occurred concurrently at one of various time-points during movement preparation and execution. Visual discrimination increased simultaneously at the two potential target locations but was modulated by the experiment-wide probability that a given location would become the final goal. Attention increased further for the location that was then designated as the final goal location, with a time course closely related to movement initiation. A sequential sampling model of decision-making predicted key temporal characteristics of attentional allocation. Together, these findings provide evidence that visuospatial attentional prioritization during motor preparation does not simply reflect that a spatial location has been selected as movement goal, but rather indexes the time-extended, cumulative decision that leads to selection, hence constituting a link between perceptual and motor aspects of sensorimotor decisions. Significance statementWhen humans perform a goal-directed movement such as a reach, attention shifts towards the goal location already before movement initiation, indicating that motor goal selection relies on the use of attention. Here, we demonstrate that key temporal aspects of visuospatial attention are predicted by a well-known computational model of decision-making. These findings suggest that visual attention signals much more than simply that a motor goal has been selected: instead, the time-course of emergent, visuospatial attention reflects the time-extended, cumulative decision that leads to goal selection, offering a window onto the tight link of perceptual and motor aspects in sensorimotor decision-making.

neuroscience↗

bioRxiv2021

Repetition effects in action selection reflect effector- but not hemisphere-specific coding

Action choices are influenced by future and recent past action states. For example, when performing two actions in succession, response times (RT) to initiate the second action are reduced when the same hand is used. These findings suggest the existence of effector-specific processing for action planning. However, given that each hand is primarily controlled by the contralateral hemisphere, the RT benefit might actually reflect effector-independent, hemisphere-specific rather than effector-specific repetition effects. Here, participants performed two consecutive movements, each with a hand or a foot, in one of two directions. Direction was specified in an egocentric reference frame (inward, outward) or in an allocentric reference frame (left, right). Successive actions were initiated faster when the same limb (e.g., left hand - left hand), but not when the other limb of the same body side (e.g., left foot - left hand) executed the second action. The same-limb advantage was evident even when the two movements involved different directions, whether specified egocentrically or allocentrically. Corroborating evidence from computational modeling lends support to the claim that repetition effects in action planning reflect persistent changes in baseline activity within neural populations that encode effector-specific action plans.

neuroscience↗