Biology subjects

Pilacinski, A.

Publications and source records attributed to Pilacinski, A..

8 recordsLinked to original sources

bioRxiv2025

Pupillary oscillations accompany hand movement planning in naturalistic scenes

Pupil diameter changes may be a useful signal source for noninvasive studies of motion planning. However, the pupil is also sensitive to luminance changes, making it difficult to study pupillary signals under natural conditions. Here we used pupillary hippus, a luminance-insensitive measure of high-frequency pupil dynamics while human participants planned naturalistic reaches in virtual reality. We found that hippus is significantly increased during planning compared to both rest and movement execution epoch. This finding shows pupillary dynamics change during motion planning reflecting preparatory processes. Most importantly, we demonstrate the potential of a new pupillometric method to study motion planning in natural conditions.

neuroscience↗

bioRxiv2025

Network dynamics for sensory prioritization: Functional connectivity related to individual sensory weighting of vision versus proprioception during upper limb control

Precise control of the hand requires the dynamic integration of visual and proprioceptive (body position sense) sensory cues with internal models, task goals, and motor plans. Individual differences in how visual and proprioceptive cues are weighted have been related to neural substrates, such as posterior parietal regions, yet the underlying neural dynamics are unclear. This study investigated the relationship between visuo-proprioceptive perception during a bimanual pointing task and the whole-brain network dynamics using resting-state functional magnetic resonance imaging (rsfMRI) with both atlas-based and individually-localized ROI seeds. Our results confirm the existence of individual sensory biases, and find they have systematic influences on functional connectivity. Activity between sensorimotor regions and default mode network (DMN) nodes was related to sensory weighting (e.g. individual degree of reliance on vision versus proprioception) and may reflect updating of internal models. The ventral premotor cortex (PMv) emerged as an important node with functional connections suggesting its role for integrating motor plans, internal models, and sensory percepts. Connections from multisensory integration regions like the middle temporal gyrus (MTG) and the superior parietal lobule (SPL), and motor coordination regions in the cerebellum, were related to increased reliance on visual versus proprioceptive information. These findings suggest that individual sensory biases during sensorimotor behavior may be characterized by specific and specialized patterns of neural activity. This research establishes a foundational exploration of the neural systems underlying sensorimotor processing, supporting theories suggesting that learning in either the sensory or motor system may also cause plasticity in the other.

neuroscience↗

bioRxiv2025

Spontaneous eye movements reveal that premotor cortex is involved in human thinking

Non-visual saccades (NVS) are spontaneous eye movements humans make while thinking. Their role is puzzling and there is no framework to explain them in terms of underlying neural systems. Here we studied neural activity preceding NVS when subjects performed standardized abstract thinking tasks. We used high-density EEG and focused on frontal and parietal channels representing oculomotor cortical areas. We found that NVS are distinctively preceded by neural activity changes in frontal and parietal EEG channels qualitatively different to that for voluntary saccades. However, only the ERP amplitude changes in frontal channels, but not in parietal channels, were different from saccadic preparation. A source reconstruction analysis additionally revealed that presaccadic neural activity originated mainly in the premotor cortex. Frequency spectrum analyses showed increased synchronization in alpha to low gamma bands suggesting complex top-down and bottom-up processing. We propose that this presaccadic activity while thinking represents evidence accumulation and attentional shifts, as shown before in the premotor cortex during sensorimotor tasks. Our findings suggest that human thinking appears to function similarly to human actions and engages premotor areas responsible for evaluating and manipulating objects also when evaluating and manipulating concepts.

neuroscience↗

bioRxiv2023

Neural representations of economic decision variables in human posterior parietal cortex

Decision making has been intensively studied in the posterior parietal cortex in non-human primates on a single neuron level. In humans decision making has mainly been studied with psychophysical tools or with fMRI. Here, we investigated how single neurons from human posterior parietal cortex represent numeric values informing future decisions during a complex two-player game. The tetraplegic study participant was implanted with a Utah electrode array in the anterior intraparietal area (AIP). We played a simplified variant of Black Jack with the participant while neuronal data was recorded. During the game two players are presented with numbers which are added up. Each time a number is presented the player has to decide to proceed or to stop. Once the first player stops or the score reaches a limit the turn passes on to the second player who tries to beat the score of the first player. Whoever is closer to the limit (without overshooting) wins the game. We found that many AIP neurons selectively responded to the face value of the presented number. Other neurons tracked the cumulative score or were selectively active for the upcoming decision of the study participant. Interestingly, some cells also kept track of the opponents score. Our findings show that parietal regions engaged in hand action control also represent numbers and their complex transformations. This is also the first demonstration of complex economic decisions being possible to track in single neuron activity in human AIP. Our findings show how tight are the links between parietal neural circuits underlying hand control, numerical cognition and complex decision-making.

neuroscience↗

bioRxiv2023

Phantom touch illusion: Unexpected phenomenological effects of tactile gating in the absence of tactile stimulation

We report the presence of a tingling sensation perceived during self touch without physical stimulation. We used immersive virtual reality scenarios in which subjects touched their body using a virtual object. This touch resulted in a tingling sensation corresponding to the location touched on the virtual body. We called it "phantom touch illusion" (PTI). Interestingly the illusion was also present when subjects touched invisible (inferred) parts of their limb. We reason that this PTI results from tactile gating process during self-touch. The reported PTI when touching invisible body parts indicates that tactile gating is not exclusively based on vision, but rather on multi-sensory, top-down input involving body schema. This finding shows that representations of own body are defined top-down, beyond the available sensory information.

neuroscience↗

bioRxiv2019

Effector-dependent modulation of working memory maintenance in posterior parietal cortex

Working memory (WM) is the key process linking perception to action. Several lines of research have, accordingly, highlighted WMs engagement in sensori-motor associations between retrospective stimuli and future behavior. Using human fMRI we investigated whether prior information about the effector used to report in a WM task would have an impact on the way the same sensory stimulus is maintained in memory - even if a behavioral response could not be readily planned. Specifically, we focused on WM-related activity in posterior parietal cortex during the maintenance of spatial items for a subsequent match-to-sample comparison, which was reported either with a verbal or with a manual response. We expected WM activity to be higher for manual response trials, because of posterior parietal cortexs engagement in both spatial WM and hand movement preparation. Increased fMRI activity for manual response trials in bilateral anterior intraparietal sulcus confirmed our expectations. These results imply that the maintenance of sensory material in WM is optimized for motor context of the upcoming behavioral responses.

neuroscience↗

bioRxiv2018

How will it look like? Human posterior parietal and dorsal premotor cortex encode the visual properties of an upcoming action

Behavioral studies show that motor actions are planned by adapting motor programs to produce desired visual consequences. Does this mean that the brain plans these visual consequences independent of the motor actions required to obtain them? Here we addressed this question by investigating planning-related fMRI activity in human posterior parietal (PPC) and dorsal premotor (PMd) cortex. By manipulating visual movement of a virtual end-effector controlled via button presses we could dissociate motor actions from their sensory outcome. A clear representation of the visual consequences was visible in both PPC and PMd activity during early planning stages. Our findings suggest that in both PPC and PMd action plans are initially represented on the basis of the desired sensory outcomes while later activity shifts towards representing motor programs.

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bioRxiv2017

Distinct representations of planned reach trajectories in human premotor and posterior parietal cortex

Goal-directed movements of the hand are often directed straight at the target, e.g. when swatting a fly; but when drawing or avoiding obstacles, hand trajectories can also become quite complex. Studies on movement planning have largely neglected the latter case and the question of whether the same neural machinery is planning straight, saccade-like vs. complex hand trajectories. Using time-resolved fMRI during delayed response tasks we examined planning activity in human superior parietal lobule (SPL) and dorsal premotor cortex (PMd). We show that the recruitment of both areas in trajectory planning differs significantly: PMd represented both straight and complex hand trajectories while SPL only those that led straight to the target. This implies that complex and computationally demanding reach planning is governed by a frontal pathway while a parietal route could warrant an alternative and faster way to put simple plans into action.

neuroscience↗