Biology subjects

Prsa, M.

Publications and source records attributed to Prsa, M..

8 recordsLinked to original sources

bioRxiv2026

Developmental enrichment enhances a topographically structured proprioceptive cortical code

The organization of proprioceptive cortex emerges from experience-dependent patterns of limb use during development, rather than merely reflecting peripheral innervation. However, the degree and specifics of these developmental changes remain poorly understood. To address this question, we investigated how early environmental enrichment (EE) reshapes the topography and functional properties of the mouse forelimb proprioceptive cortex. Using wide-field calcium imaging, we found that EE did not induce major reorganization of the mesoscale activation map. To resolve cellular level topology, we developed a large-field fluorescence macroscope enabling unbiased single neuron imaging across the entire activation area. We identified a topographically organized preference in directional tuning in which somatosensory and motor regions of the map encode distinct movement axes within the peripersonal space. Developmental enrichment reshaped this anisotropic representation at the cellular level. Rather than reducing the directional bias by homogenizing tuning across movement directions, EE strengthened the anisotropy by sharpening its topographic segregation and concentrating neuronal tuning around a common peripersonal axis. Our findings therefore reveal that enriched limb use and sensorimotor exploration reinforce an ecologically relevant specialization of the mouse proprioceptive cortex for movements directed toward the body.

neuroscience↗

bioRxiv2026

Proprioceptive Neurons in Somatosensory Cortex Implement Optimal State Estimation

While the primary somatosensory cortex (S1) is known to be essential for skilled limb movements, it remains unclear how distinct functional ensembles within its network uniquely contribute to motor control. By isolating a stable population of proprioceptive S1 neurons in layer 2/3, we demonstrate how their selective removal impacts goal-directed reaching. We found that following their microablation global reach kinematics remained stable, yet natural movement variability was reorganized. Trajectories became more spatially dispersed while simultaneously becoming more geometrically stereotyped. Through computational modeling, we show that this seemingly paradoxical increase in one form of variability alongside a reduction in another reflects a failure in optimal state estimation. In contrast, broad S1 lesions mask the unique contribution of this ensemble, revealing instead that cortical feedback is temporally phased, engaging during high-precision grasping and retrieval rather than initial reaching. These findings identify a functionally defined subset of cortical neurons as the biological substrate for a core postulate of optimal control theory, operating within a broader S1 circuit specialized for fine motor refinement.

neuroscience↗

bioRxiv2025

Translating Music to Touch: Exploring Tactile Perception of Pitch, Roughness, and Pleasantness

Music is a rich multisensory experience, yet individuals with hearing impairments often lack access to this important aspect of culture. As tactile technologies advance, there is growing interest in whether musical information can be conveyed through vibration. This study investigates how core dimensions of auditory music perception, pitch, roughness, and pleasantness, can be translated into the tactile domain. Participants were asked to rate these perceptual dimensions in response to sinusoidal and complex waveforms, including amplitude-modulated signals, sawtooth, and missing fundamental stimuli. Perceived pitch showed a systematic relationship with stimulus frequency for most participants, suggesting that tactile devices could at least partially convey some form of simple melodic patterns. The sawtooth waveform emerged as particularly effective for representing pitch changes, underscoring the role of rapid temporal transitions in tactile pitch encoding. Roughness ratings were negatively correlated with pleasantness, mirroring well-established findings in auditory perception. Waveforms with sudden temporal changes or rapid amplitude modulations were consistently judged as less pleasant. Taken together, these findings in normal hearing participants may inform the design of vibrotactile displays that could support access to selected music relevant perceptual dimensions, although generalization to people with hearing loss remains to be tested. Importantly, our results highlight the crucial role of the fast temporal envelope rather than the temporal fine structure, in shaping vibrotactile perception. Consistent with this interpretation, our data provide evidence for a tactile analog of the auditory missing fundamental phenomenon, reinforcing the idea that tactile pitch perception primarily relies on envelope periodicity rather than the presence of specific frequency components.

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bioRxiv2025

The olivocerebellar system differentially encodes the effect sensory events exert on behavior

Inferior olive neurons convey information about sensorimotor events via climbing fibers to the cerebellum, but their functional significance remains unclear. We directly imaged, with two-photon microscopy, climbing fiber axonal terminals in the cerebellum during a task that successively exposed mice to a force perturbation, a movement instruction and reward; each followed by multiple modes of motor activity. Climbing fiber activations by the sensory events were either generic or informative about the consequences the encoded event has on behavior. The number of informative cells and the information strength are regulated by event modality and functional complexity of the cells activity. We observed an additional, previously unreported activation of climbing fibers: they carried probabilistic information on the behavioral context during idle waiting periods preceding stimulus presentation. Our findings reveal properties of olivary neurons that are key for defining their function in the cerebellum-dependent control of behavior. They suggest that the inferior olive flexibly instructs the cerebellum of any process that may shape an animals action.

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bioRxiv2023

Transformation of neural coding for vibrotactile stimuli along the ascending somatosensory pathway

Perceiving substrate vibrations is a fundamental component of somatosensation. In mammals, action potentials fired by rapidly adapting mechanosensitive afferents are known to reliably time lock to the cycles of a vibration. This stands in contrast to coding in the higher-order somatosensory cortices, where neurons generally encode vibrations in their firing rates, which are tuned to a preferred vibration frequency. How and where along the ascending neuraxis is the peripheral afferent temporal code of cyclically entrained action potentials transformed into a rate code is currently not clear. To answer this question, we probed the encoding of vibrotactile stimuli with electrophysiological recordings along major stages of the ascending somatosensory pathway in mice. Recordings from individual primary sensory neurons in lightly anesthetized mice revealed that rapidly adapting mechanosensitive afferents innervating Pacinian corpuscles display phase-locked spiking for vibrations up to 2000 Hz. This precise temporal code was reliably preserved through the brainstem dorsal column nuclei. The main transformation step was identified at the level of the thalamus, where we observed a significant loss of phase-locked spike timing information accompanied by a further narrowing of tuning curve widths. Using optogenetic manipulation of thalamic inhibitory circuits, we found that parvalbumin-positive interneurons in thalamic reticular nucleus participate in sharpening frequency selectivity and disrupting the precise spike timing of ascending neural signals encoding vibrotactile stimuli. To test the functional implications of these different neural coding mechanisms, we applied frequency-specific microstimulation within the brainstem, which generated frequency selectivity reminiscent of real vibration responses in the somatosensory cortex, whereas microstimulation within thalamus did not. Finally, we applied microstimulation in the brainstem of behaving mice and demonstrated that frequency-specific stimulation could provide informative and robust signals for learning. Taken together, these findings not only reveal novel features of the computational circuits underlying vibrotactile sensation, but could also guide biomimetic stimulus strategies to activate specific nuclei along the ascending somatosensory pathway for sensory neural prostheses.

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bioRxiv2022

Spatial encoding of forelimb proprioception in the mouse somatosensory cortex

Conscious perception of limb movements depends on proprioceptive neural responses in the somatosensory cortex. In contrast to tactile sensations, proprioceptive cortical coding is barely studied in the mammalian brain and practically non-existent in rodent research. To understand the cortical representation of this important sensory modality we developed a passive forelimb displacement paradigm in behaving mice and also trained them to perceptually discriminate where their limb is moved in space. We delineated, for the first time, the rodent proprioceptive cortex with wide-field calcium imaging and optogenetic silencing experiments during awake behavior. Our results reveal that proprioception is represented in both sensory and motor cortical areas. In addition, behavioral measurements and responses of layer 2/3 neurons imaged with two-photon microscopy reveal that passive limb movements are both perceived and encoded in the mouse cortex as a spatial direction vector that interfaces the limb with the bodys peripersonal space.

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bioRxiv2020

Common computational principle for vibro-tactile pitch perception in mouse and human

We live surrounded by vibrations generated by moving objects. These oscillatory stimuli can produce sound (i.e. airborne waves) and propagate through solid substrates. Pitch is the main perceptual characteristic of sound, and a similar perceptual attribute seems to exist in the case of substrate vibrations: vibro-tactile pitch. Here, we establish a mechanistic relationship between vibro-tactile pitch perception and the actual physical properties of vibrations using behavioral tasks, in which vibratory stimuli were delivered to the human fingertip or the mouse forelimb. The resulting perceptual reports were analyzed with a model demonstrating that physically different combinations of vibration frequencies and amplitudes can produce equal pitch perception. We found that the perceptually indistinguishable but physically different stimuli follow a common computational principle in mouse and human. It dictates that vibro-tactile pitch perception is shifted with increases in amplitude toward the frequency of highest vibrotactile sensitivity. These findings suggest the existence of a fundamental relationship between the seemingly unrelated concepts of spectral sensitivity and pitch perception.

neuroscience↗

bioRxiv2018

Frequency selective encoding of substrate vibrations in the somatosensory cortex

Sensing vibrations that propagate through solid substrates conveys fundamental information about moving objects and other nearby dynamic events. Here we report that neurons responsive to substrate vibrations applied to the mouse forelimb reveal a new way of representing frequency information in the primary somatosensory cortex (S1). In contrast to vibrotactile stimulation of primate glabrous skin, which produces temporally entrained spiking and frequency independent firing rates, we found that mouse S1 neurons rely on a different coding scheme: their spike rates are conspicuously tuned to a preferred frequency of the stimulus. Histology, peripheral nerve block and optogenetic tagging experiments furthermore reveal that these responses are associated with the activation of mechanoreceptors located in deep subdermal tissue of the distal forelimb. We conclude that the encoding of frequency information of substrate-borne vibrations in the mouse S1 might be analogous to the representation of pitch of airborne sound in auditory cortex.

neuroscience↗