Biology subjects

Orlowska-Feuer, P.

Publications and source records attributed to Orlowska-Feuer, P..

6 recordsLinked to original sources

bioRxiv2026

Parallel visual processing in the suprachiasmatic region of a diurnal mammal.

Light shapes mammalian physiology and behaviour through hypothalamic pathways, yet how these pathways process visual information in day-active species remains poorly understood. Based largely on work in nocturnal rodents, the suprachiasmatic nucleus (SCN) is classically viewed as a retinal target that encodes ambient illumination for circadian entrainment. We combine anatomical tracing, light-evoked c-Fos mapping and high-density silicon-probe electrophysiology to define visual processing in the suprachiasmatic region of the diurnal murid Rhabdomys pumilio. We find that retinal input and light-evoked activity extend beyond the SCN into rostral and lateral peri-SCN hypothalamus. Within the SCN, neurons encode irradiance with graded changes in maintained firing broadly similar to those observed in parallel recordings of nocturnal Mus domesticus. Across the wider suprachiasmatic region, Rhabdomys neurons show selectivity for more dynamic visual stimuli, including luminance transitions, contrast and temporal structure. Unsupervised clustering identifies five functionally distinct hypothalamic visual response classes with different anatomical distributions. These findings reveal an expanded hypothalamic visual network in a diurnal mammal, placing SCN irradiance coding within a broader system for processing dynamic visual features.

neuroscience↗

bioRxiv2024

Embodied processing in whisker somatosensory cortex during exploratory behaviour in freely moving mice

Sensory systems have evolved to solve computational challenges that animals face during behaviour in their natural environments. To illuminate how sensory cortex operates under such conditions, we investigated the function of neurons in whisker-related Somatosensory Cortex (wS1) of freely moving mice, engaged in tactile exploratory behaviour. By recording neural activity from wS1 whilst tracking the mouse body in 3D, we found that wS1 neurons are substantially modulated by body state (configuration of individual body-parts and their derivatives), even in the absence of whisker afferent input. Most neurons were modulated by multiple dimensions of body state, with the most prominently encoded being the angle of the head to the body and locomotion speed. Overall, our data suggest that sensory cortex functions as an embodied representation, which integrates signals from its associated sense organ within a body schema.

neuroscience↗

bioRxiv2024

Reconfiguration of the visual code and retinal cell type complement in closely related diurnal and nocturnal mice

How does evolution act on neuronal populations to match computational characteristics to functional demands? We address this problem by comparing visual code and retinal cell composition in closely related murid species with different behaviours. Rhabdomys pumilio are diurnal and have substantially thicker inner retina and larger visual thalamus than nocturnal Mus musculus. High-density electrophysiological recordings of visual response features in the dorsal lateral geniculate nucleus (dLGN) reveals that Rhabdomys attains higher spatiotemporal acuity both by denser coverage of the visual scene and a selective expansion of elements of the code characterised by non-linear spatiotemporal summation. Comparative analysis of single cell transcriptomic cell atlases reveals that realignment of the visual code is associated with increased relative abundance of bipolar and ganglion cell types supporting OFF and ON-OFF responses. These findings demonstrate how changes in retinal cell complement can reconfigure the coding of visual information to match changes in visual needs.

neuroscience↗

bioRxiv2022

Look-up and look-down neurons in the mouse visual thalamus during freely moving exploration

The traditional view that visuomotor integration is a property of higher brain centres has recently been challenged by the discovery in head-fixed rodents that locomotion increases neuronal activity throughout the early visual system (including the retina). Any appreciation of the importance of this behavioural modulation of visual inputs must encompass a comprehensive understanding of the range of behaviours engaged by this mechanism. This information is unavailable from head-fixed preparations in which head and body postures are fundamentally constrained and dissociated from their natural coupling with visual experience. We addressed this deficit by recording spiking activity from the primary visual thalamus during freely moving exploration, while simultaneously applying frame-by-frame quantification of postures and movements to robust 3D reconstructions of head and body. We found that postures associated with the animal looking up/down affected activity in >50% neurons. The extent of this effect was comparable to that induced by locomotion. Moreover, the two effects were largely independent and jointly modulated neuronal activity. Thus, while most units were excited by locomotion, some expressed highest firing when the animal was looking up ("look up" neurons) while others when the animal was looking down ("look-down" neurons). These results were observed in the dark, thus representing a genuine behavioural modulation, and were amplified in a lit arena. These findings define the influence of natural exploratory behaviour on activity in the early visual system and reveal the importance of up/down postures in gating neuronal activity in the primary visual thalamus.

neuroscience↗

bioRxiv2020

Using a bistable animal opsin for switchable and scalable optogenetic inhibition of neurons

There is no consensus on the best optogenetic tool for neuronal inhibition. Lamprey parapinopsin ( Lamplight) is a Gi/o-coupled bistable animal opsin that can be activated and deactivated by short and long wavelength light, respectively. Since native mechanisms of neuronal inhibition frequently employ Gi/o signalling, we asked here whether Lamplight could be used for optogenetic silencing. We show that short (405nm) and long (525nm) wavelength pulses repeatedly switch Lamplight between stable signalling active and inactive states, and that combining these wavelengths can be used to achieve intermediate levels of activity. We demonstrate that these properties can be applied to produce switchable and scalable neuronal hyperpolarisation, and suppression of spontaneous spike firing in the mouse hypothalamic suprachiasmatic nucleus. We show that expressing Lamplight in (predominantly) ON bipolar cells can photosensitise retinas following advanced photoreceptor degeneration, and that 405 and 525nm stimuli can produce responses of opposite sign in output neurons of the retina. Lamplight-driven responses to both activating (405nm) and deactivating (525nm) light can occur within 500ms and be elicited by intensities at least 10x below threshold for available inhibitory optogenetic tools. We conclude that Lamplight can co-opt endogenous signalling mechanisms to allow optogenetic inhibition that is scalable, sustained and rapidly reversible.

neuroscience↗

bioRxiv2020

Infra-slow modulation of fast beta/gamma oscillations in the mouse visual system.

Infra-slow (<0.02 Hz) and fast beta/gamma (20 - 100 Hz) oscillations in neurophysiological activity have been widely found in the subcortical visual system. While it is well established that fast beta/gamma oscillations are involved in visual processing, the role (if any) of infra-slow oscillations is currently unknown. One possibility is that infra-slow oscillations exert influence by modulating the amplitude of fast oscillations, yet the extent to which these different oscillations arise independently and interact remains unknown. We addressed these questions by recording in vivo spontaneous activity from subcortical visual system of visually intact mice, and animals whose retinal network was disrupted by advanced rod/cone degeneration (rd/rd cl) or melanopsin loss (Opn4-/- We found many neurons expressing only one type of oscillation, and indeed fast oscillations were absent in rd/rd cl. Conversely, neurons co-expressing the two oscillations were also common, and were encountered more often than expected by chance in visually intact but not Opn4-/- mice. Finally, where they co-occurred we found that beta/gamma amplitude was modulated by the infra-slow rhythm. Our data thus reveal that: 1.) infra-slow and beta-gamma oscillations are separable phenomena; and 2.) that they actively co-occur in a subset of neurones in which the phase of infra-slow oscillations define beta-gamma oscillation amplitude. These findings suggest that infra-slow oscillations could influence vision by modulating beta-gamma oscillations, and raise the possibility that disruptions in these oscillatory behaviours contribute to vision dysfunction in retinal dystrophy. KEY POINTS SUMMARYO_LINeurophysiological activity in the subcortical visual system fluctuates in both infra-slow and fast oscillatory ranges, however the level of co-occurrence and potential functional interaction of these rhythms is unknown. C_LIO_LIAnalyzing dark-adapted spontaneous activity in the mouse subcortical visual system, we find that these two types of oscillation interact uniquely through a population of neurons expressing both rhythms. C_LIO_LIGenetic ablation of rod/cone signaling potentiates infra-slow and abolishes fast beta/gamma oscillations while genetic ablation of melanopsin substantially diminishes the interaction between these two rhythms. C_LIO_LIOur results indicate that in an intact visual system the phase of infra-slow modulates fast beta/gamma oscillations. C_LIO_LIThus one possible impact of infra-slow oscillations in vision is to guide visual processing by interacting with fast narrowband oscillations. C_LI

neuroscience↗