Beiza-Canelo, N. | Search bioRxiv

bioRxiv2024

Distinct and Asymmetric Neuronal Responses to Pitch- and Roll-Axis Vestibular Stimulation in larval zebrafish

SO_SCPLOWUMMARYC_SCPLOWThe vestibular apparatus plays a pivotal role in maintaining postural equilibrium and processing movement signals, underscoring its importance in studying certain neurological disorders. Here, we present a rotating light-sheet microscope, enabling brain-wide functional recordings during dynamic vestibular stimulation along the pitch axes in addition to the roll axis in head-restrained zebrafish larvae. The system incorporates a double galvanometer mirror configuration, is amenable to 3D printing, and enhances scanning efficiency. Employing this apparatus, we have successfully conducted the first comprehensive mapping of zebrafish brain responses to dynamic pitch-tilt vestibular stimulation. Through Fourier and regression analyses, we report an asymmetry in neuronal recruitment during nose-up versus nose-down pitch tilts within critical regions, including the cerebellum, oculomotor nucleus, caudal hindbrain, and vestibular nucleus, highlighting physiological adaptations to downward motion. We identified specific brain regions, notably the cerebellum and medial-rostral rhombencephalon, that respond to roll-but not pitch-tilt vestibular stimuli. Furthermore, we have identified a transgenic line that closely correlates with our functional mappings and demonstrates a significant response to vestibular stimulation. The elucidation of brain-wide neuronal circuits involved in vestibular processing establishes a foundational framework for subsequent detailed investigations into the molecular and genetic mechanisms underlying postural control and motion perception.

neuroscience↗

bioRxiv2023

Magnetic actuation of otoliths allows behavioral and brain-wide neuronal exploration of vestibulo-motor processing in larval zebrafish.

The vestibular system in the inner ear plays a central role in sensorimotor control by informing the brain about the orientation and acceleration of the head. However, most experiments in neurophysiology are performed using head-fixed configurations, depriving animals of vestibular inputs. To overcome this limitation, we decorated the utricular otolith of the vestibular system in larval zebrafish with paramagnetic nanoparticles. This procedure effectively endowed the animal with magneto-sensitive capacities: applied magnetic field gradients induced forces on the otoliths resulting in robust behavioral responses comparable to that evoked by rotating the animal by up to 25{degrees}. We recorded the whole-brain neuronal response to this fictive motion stimulation using light-sheet functional imaging. Experiments performed in unilaterally injected fish revealed the activation of a commissural inhibition between the brain hemispheres. This magnetic-based stimulation technique for larval zebrafish opens new perspectives to functionally dissect the neural circuits underlying vestibular processing and to develop multisensory virtual environments, including vestibular feedback. HighlightsO_LIAfter injecting a ferrofluid into the inner ear of a larval zebrafish, the ear-stones can be actuated via magnetic forces. C_LIO_LIThis method allows one to elicit vestibular-like behavioral responses without impairing physiological inner ear functions. C_LIO_LIIt is compatible with brain-scale functional imaging and thus offers a promising avenue to investigate the neural underpinnings of vestibular-driven behaviors. C_LI eTOCFerrofluid injection into zebrafish inner ear allows magnetic manipulation of ear-stones to evoke vestibular responses in static animals. This in vivo method is compatible with brain-scale imaging, offering a promising approach to investigate neural mechanisms underlying vestibular-driven behaviors.

neuroscience↗