Biology subjects

Vladimirov, N.

Publications and source records attributed to Vladimirov, N..

3 recordsLinked to original sources

bioRxiv2022

Prox2+ and Runx3+ neurons regulate esophageal motility

Sensory neurons of the vagus nerve monitor distention and stretch in the gastrointestinal tract. Major efforts are underway to assign physiological functions to the many distinct subtypes of vagal sensory neurons. Here, we used genetically guided anatomical tracing, optogenetics and electrophysiology to identify and characterize three vagal sensory neuronal subtypes expressing Prox2 and Runx3. We show that these neuronal subtypes innervate the esophagus and stomach where they display regionalized innervation patterns. Their electrophysiological analysis showed that they are all low threshold mechanoreceptors, but possess different adaptation properties. Lastly, genetic ablation of Prox2+ and Runx3+ neurons demonstrated their essential roles for esophageal peristalsis and swallowing in freely behaving animals. Our work reveals the identity and function of the vagal neurons that provide mechanosensory feedback from the esophagus to the brain, and could lead to better understanding and treatment of esophageal motility disorders.

neuroscience↗

bioRxiv2021

A brainstem integrator for self-localization and positional homeostasis

To accurately track self-location, animals need to integrate their movements through space. In amniotes, representations of self-location have been found in regions such as the hippocampus. It is unknown whether more ancient brain regions contain such representations and by which pathways they may drive locomotion. Fish displaced by water currents must prevent uncontrolled drift to potentially dangerous areas. We found that larval zebrafish track such movements and can later swim back to their earlier location. Whole-brain functional imaging revealed the circuit enabling this process of positional homeostasis. Position-encoding brainstem neurons integrate optic flow, then bias future swimming to correct for past displacements by modulating inferior olive and cerebellar activity. Manipulation of position-encoding or olivary neurons abolished positional homeostasis or evoked behavior as if animals had experienced positional shifts. These results reveal a multiregional hindbrain circuit in vertebrates for optic flow integration, memory of self-location, and its neural pathway to behavior.

neuroscience↗

bioRxiv2020

Dual-view light-sheet imaging through tilted glass interface using a deformable mirror

Light-sheet microscopy has become one of the primary tools for imaging live developing organisms because of its high speed, low phototoxicity, and optical sectioning capabilities. Detection from multiple sides (multi-view imaging) additionally allows nearly isotropic resolution via computational merging of the views. However, conventional light-sheet microscopes require that the sample is suspended in a gel to allow optical access from two or more sides. At the same time, the use of microfluidic devices is highly desirable for many experiments, but geometric constrains and strong optical aberrations caused by the coverslip titled relative to objectives make the use of multi-view lightsheet challenging for microfluidics. In this paper we describe the use of adaptive optics (AO) to enable multi-view light-sheet microscopy in such microfluidic setup by correcting optical aberrations introduced by the tilted coverslip. The optimal shape of deformable mirror is computed by an iterative stochastic gradient-descent algorithm that optimizes PSF in two orthogonal planes simultaneously. Simultaneous AO correction in two optical arms is achieved via a knife-edge mirror that splits excitation path and combines the detection path. We characterize the performance of this novel microscope setup and, by dual-view light-sheet imaging of C.elegans inside a microfluidic channel, demonstrate a drastic improvement of image quality due to AO and dual-view reconstruction. Our microscope design allows multi-view light-sheet microscopy with microfluidic devices for precisely controlled experimental conditions and high-content screening.

bioengineering↗