Biology subjects

Beraneck, M.

Publications and source records attributed to Beraneck, M..

8 recordsLinked to original sources

bioRxiv2026

Deficits in tail-lift and air-righting reflexes in rats after ototoxicity associate with loss of vestibular type I hair cells

The rat vestibular system plays a critical role in anti-gravity responses such as the tail-lift reflex and the air-righting reflex. In a previous study in male rats, we obtained evidence that these two reflexes depend on the function of non-identical populations of vestibular sensory hair cells (HC). Here, we caused graded lesions in the vestibular system of female rats by exposing the animals to several different doses of an ototoxic chemical, 3,3-iminodipropionitrile (IDPN). After exposure, we assessed the anti-gravity responses of the rats and then assessed the loss of type I HC (HCI) and type II HC (HCII) in the central and peripheral regions of the crista, utricle and saccule. As expected, we recorded a dose-dependent loss of vestibular function and loss of HCs. The relationship between hair cell loss and functional loss was examined using non-linear models fitted by orthogonal distance regression. The results indicated that both the tail-lift reflex and the air-righting reflexes mostly depend on HCI function. However, a different dependency was found on the epithelium triggering the reflex: while the tail-lift response is sensitive to loss of crista and/or utricle HCIs, the air-righting response rather depends on utricular and/or saccular integrity.

neuroscience↗

bioRxiv2025

Hair cell population integrity necessary to preserve vestibular function

Vestibular dysfunction constitutes a major medical concern, and regeneration of hair cells (HC) is a primary target of gene therapy aimed at restoring vestibular functions. Thus far, therapeutic trials in animal models targeting vestibular loss associated with genetic diseases have yielded variable and partial results, and the functional identity and quantity of HCs required to restore minimal or normal vestibular function remain undefined. Indeed, direct comparisons between structural pathology and quantitative assessments of vestibular dysfunctions are lacking in humans and are rather limited in animal models, representing a significant gap in current knowledge. Here, we present an innovative methodology to bridge the gap between HC integrity and functional vestibular loss in individuals. Gradual vestibular deficits were induced through a dose-dependent ototoxic lesion, quantified with canal or utricular-specific vestibulo-ocular reflex tests, and were then correlated in all individuals with the loss of type I and type II HCs in different regions of ampulla and macula. Our findings reveal that the structure-function relationship is nonlinear, with lower bound of approximately 50% of HCs necessary to retain minimal vestibular function, and threshold exceeding 80% to preserve normal function, thus shedding light on population coding mechanisms for vestibular response. Our data further support the decisive role of type I, rather than type II, HC in the tested VOR functions.

neuroscience↗

bioRxiv2023

Subchronic alteration of vestibular hair cells in mice: implications for multisensory gaze stabilization

The functional complementarity of the vestibulo-ocular reflex (VOR) and optokinetic reflex (OKR) allows for optimal combined gaze stabilization responses (CGR) in light. While sensory substitution has been reported following complete vestibular loss, the capacity of the central vestibular system to compensate for partial peripheral vestibular loss remains to be determined. Here, we first demonstrate the efficacy of a 6-week subchronic ototoxic protocol in inducing transient and partial vestibular loss which equally affects the canal- and otolith-dependent VORs. Immunostaining of hair cells in the vestibular sensory epithelia revealed that organ-specific alteration of type I, but not type II, hair cells correlates with functional impairments. The decrease in VOR performance is paralleled with an increase in the gain of the OKR occurring in a specific range of frequencies where VOR normally dominates gaze stabilization, compatible with a sensory substitution process. Comparison of unimodal OKR or VOR versus bimodal CGR revealed that visuo-vestibular interactions remain reduced despite a significant recovery in the VOR. Modeling and sweep-based analysis revealed that the differential capacity to optimally combine OKR and VOR correlates with the reproducibility of the VOR responses. Overall, these results shed light on the multisensory reweighting occurring in pathologies with fluctuating peripheral vestibular malfunction.

neuroscience↗

bioRxiv2021

Conservation of locomotion-induced oculomotor activity through evolution in higher tetrapods

Efference copies are neural replicas of motor outputs used to anticipate the sensory consequences of a self-generated motor action or to coordinate neural networks involved in distinct motor behaviors1. An established example of this motor-to-motor coupling is the efference copy of the propulsive motor command that supplements classical visuo-vestibular reflexes to ensure gaze stabilization during amphibian larval locomotion2. Such feedforward replica from spinal pattern-generating circuits produces a spino-extraocular motor coupled activity that evokes eye movements, spatio-temporally coordinated to tail undulation independently of any sensory signal3,4. Exploiting the evolutionary-development characteristic of the frog1, studies in metamorphing Xenopus demonstrated the persistence of this spino-extraocular motor command in adults, and its developmental adaptation to tetrapodal locomotion5,6. Here, we demonstrate for the first time the existence of a comparable locomotor-to-ocular motor coupling in the mouse. In neonates, ex vivo nerve recordings from brainstem-spinal cord preparation reveals a spino-extraocular motor coupled activity similar to the one described in Xenopus. In adult mice, trans-synaptic rabies injection in lateral rectus eye muscle labels cervical spinal cord neurons projecting directly to abducens motor neurons. Finally, treadmill-elicited locomotion in decerebrated preparations7 evokes rhythmic eye movements in synchrony with the limb gait pattern. Overall, our data are evidence for the conservation of locomotor-induced eye movements in higher tetrapods. Thus, in mammals as in amphibians, during locomotion CPG-efference copy feedforward signals might interact with sensory feedback to ensure efficient gaze control. HighlightsO_LISpino-extraocular motor coupling is evidenced from newborn mice ex vivo preparations C_LIO_LIAdult decerebrated mice exhibit conjugated rhythmic eye movements during treadmill locomotion C_LIO_LILocomotor-induced oculomotor activity occurs in absence of visuo-vestibular inputs C_LIO_LIConserved CPG-based efference copy signal in vertebrates with common features. C_LI eTOC blurbWe report a functional coupling between spinal locomotor and oculomotor networks in the mouse, similar to the one previously described in Amphibians. This is the first evidence for the direct contribution of locomotor networks to gaze control in mammals, suggesting a conservation of the spino-extraocular coupling in higher tetrapods during sustained locomotion.

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bioRxiv2021

Locomotion-induced ocular motor behavior in larval Xenopus is developmentally tuned by visuo-vestibular reflexes

Locomotion requires neural computations to maintain stable perception of the world despite disturbing consequences of the motor behavior on sensory stability. The developmental establishment of locomotor proficiency is therefore accompanied by a concurrent maturation of gaze-stabilizing motor behaviors. Using developing larval Xenopus, we demonstrate mutual plasticity of predictive spinal locomotor efference copies and multi-sensory motion signals with the aim to constantly ensure dynamically adequate eye movements during swimming. Following simultaneous ontogenetic onsets of locomotion, spino-ocular, optokinetic and otolith-ocular motor behaviors, locomotor efference copy-driven eye movements improve through gradually augmenting influences of semicircular canal signals. Accordingly, neuronal computations change from a predominating cancelation of angular vestibulo-ocular reflexes by locomotor efference copies in young larvae to a summation of these signals in older larvae. The developmental switch occurs in synchrony with a reduced efficacy of the tail-undulatory locomotor pattern generator causing gradually decaying influences on the ocular motor output.

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bioRxiv2020

Does gravity shape internal representations of space for human 3D perception?

Human 3D perception of visual objects is flawed by distortions, which are influenced by non-visual factors, such as gravitational vestibular signals. Whether gravity acts specifically on the visual system or at a higher, modality-independent, level of information processing remains unknown. To test these modality-specific vs modality-independent hypotheses, we performed experiments comparing visual versus haptic 3D shape perception in normo-gravity and microgravity. The results obtained for upright and supine posture in 1g show that visual and haptic perceptual anisotropies are systematically in opposing ego-centered, but not gravity-centered, directions suggesting they share a common origin. On the other hand, microgravity significantly modulates both visual and haptic perceptual distortion in the same direction. Overall, our results show a clear link between the visual and haptic perceptual distortions and demonstrate a role of gravity-related signals on a modality-independent internal representation of 3D space used to interpret incoming sensory inputs.

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bioRxiv2018

Optogenetic stimulation of long-range inputs and functional characterization of connectivity in patch-clamp recordings in mouse brain slices

Knowledge of cell type specific synaptic connectivity is a crucial prerequisite for understanding brain wide neuronal circuits. The functional investigation of long-range connections requires targeted recordings of single neurons combined with the specific stimulation of identified distant inputs. This is often difficult to achieve with conventional, electrical stimulation techniques, because axons from converging upstream brain areas may intermingle in the target region. The stereotaxic targeting of a specific brain region for virus-mediated expression of light sensitive ion channels allows to selectively stimulate axons coming from that region with light. Intracerebral stereotaxic injections can be used in well-delimited structures, such as the anterodorsal thalamic nuclei, and also in other subcortical or cortical areas throughout the brain.\n\nHere we describe a set of techniques for precise stereotaxic injection of viral vectors expressing channelrhodopsin in the anterodorsal thalamus, followed by photostimulation of their axon terminals in hippocampal slices. In combination with whole-cell patch clamp recording from a postsynaptically connected presubicular neuron, photostimulation of thalamic axons allows the detection of functional synaptic connections, their pharmacological characterization, and the evaluation of their strength in the brain slice preparation. We demonstrate that axons originating in the anterodorsal thalamus ramify densely in presubicular layers 1 and 3. The photostimulation of Chronos expressing thalamic axon terminals in presubiculum initiates short latency postsynaptic responses in a presubicular layer3 neuron, indicating a monosynaptic connection. In addition, biocytin filling of the recorded neuron and posthoc revelation confirms the layer localization and pyramidal morphology of the postsynaptic neuron. Taken together, the optogenetic stimulation of long-range inputs in ex vivo brain slices is a useful method to determine the cell-type specific functional connectivity from distant brain regions.

neuroscience↗

bioRxiv2018

Anterior thalamic excitation and feed-forward inhibition of presubicular neurons projecting to medial entorhinal cortex

The presubiculum contains head direction cells that are crucial for spatial navigation. Here, we examined the connectivity and strengths of thalamic inputs to presubicular layer 3 neurons projecting to the medial entorhinal cortex in the mouse. We recorded pairs of projection neurons and interneurons while optogenetically stimulating afferent fibers from the anterior thalamic nuclei (ATN). Thalamic input differentially affects presubicular neurons: layer 3 pyramidal neurons and fast-spiking parvalbumin expressing (PV) interneurons are directly and monosynaptically activated, with depressing dynamics, while somatostatin (SST) expressing interneurons are indirectly excited, during repetitive ATN activity. This arrangement ensures that the thalamic excitation of layer 3 cells is often followed by disynaptic inhibition. Feed-forward inhibition is largely mediated by PV interneurons which have a high probability of connection to presubicular pyramidal cells. Our data point to a specific role of presubicular microcircuits in shaping thalamic head-direction signals transmitted to medial entorhinal cortex: Short-latency PV cell activation may enforce temporally precise head direction tuning during fast turns. However, depression at ATN-PV synapses during repeated activation tends to facilitate pyramidal cell firing when head direction is maintained. Operations performed in presubicular layer 3 circuits seem well-adapted for spatial fine-tuning of head direction signals sent to the medial entorhinal cortex.\n\nSIGNIFICANCE STATEMENTHow microcircuits participate in shaping neural inputs is crucial to understanding information processing in the brain. Here, we show how the presubiculum may process thalamic head directional information before transmitting it to the medial entorhinal cortex. Synaptic inputs from the anterior thalamic nuclei (ATN) excite layer 3 pyramidal cells (PC) and parvalbumin (PV) interneurons, which mediate disynaptic feed-forward inhibition. Somatostatin (SST) interneurons are excited indirectly. Presubicular circuits may switch between two regimes according to the angular velocity of head movements. During immobility, SST-PC interactions support maintained head directional firing with attractor-like dynamics. During rapid head turns, in contrast, PV mediated feed-forward inhibition acts to tune the head direction signal transmitted to medial entorhinal cortex.

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