Biology subjects

Kiraly, J. K.

Publications and source records attributed to Kiraly, J. K..

3 recordsLinked to original sources

bioRxiv2026

The mechanotransduction channel Piezo2 refines axonal projections to the accessory optic system and regulates the optokinetic reflex

The optokinetic reflex (OKR) is an evolutionarily conserved reflexive behavior that ensures image stabilization on the retina during global motion. It consists of smooth eye tracking movements in the direction of the moving stimulus interspersed with rapid resetting saccades. This reflex is driven by retinal ON direction-selective ganglion cells (oDSGCs), which comprise distinct subtypes tuned either to vertical or horizontal motion. oDSGCs convey directional signals to the brain via precise axonal projections to specific accessory optic system (AOS) nuclei. However, the mechanisms that establish and maintain the specificity of these circuits remain poorly understood. Here, we identify a critical role for the mechanosensitive ion channel Piezo2 in refining AOS circuitry to ensure appropriate eye movement responses. Single-cell transcriptomic profiling revealed selective enrichment of Piezo2 in horizontally-tuned oDSGCs. We show that both loss and hyperactivation of Piezo2 in retinal neurons leads to cross-coupling of horizontal and vertical OKR responses, producing aberrant diagonal eye tracking movements during horizontal optokinetic stimulation. Mechanistically, Piezo2 regulates the developmental refinement of oDSGC axonal projections within the AOS, and disruption of this process results in persistent ectopic innervation that enables aberrant crosstalk between horizontal and vertical motion pathways. These findings reveal a channel activity-dependent mechanism that ensures the functional segregation of directional motion circuits underlying gaze stabilization. HIGHLIGHTSO_LIPiezo2 is selectively expressed in forward-tuned ON and ON-OFF DSGCs that innervate the accessory optic system C_LIO_LIBoth loss and overactivation of Piezo2 induce cross-coupling of horizontal and vertical optokinetic reflexes C_LIO_LIPiezo2 function in ON-OFF DSGCs is dispensable for normal optokinetic reflex responses C_LIO_LIRetinal Piezo2 refines axonal targeting to the accessory optic system nuclei, ensuring proper optokinetic reflex function C_LI

neuroscience↗

bioRxiv2026

Protein tyrosine phosphatase receptor type kappa (PTPRκ) regulates Superior ON-Direction Selective Ganglion Cell development, facilitating image stabilization

In vertebrates, gaze stabilization during global visual motion requires ON direction-selective ganglion cells (oDSGCs) in the Accessory Optic System (AOS) to drive the optokinetic reflex (OKR). Three types of oDSGCs form independent mosaics; however, the mechanisms that specify and maintain their numbers to create these mosaics during development remain unknown. Here, we identify protein tyrosine phosphatase receptor type kappa (Ptprk) as a key regulator of Superior oDSGC density, the subtype tuned to upward motion. High-depth single-cell RNA sequencing (scRNAseq) reveals that Ptprk is selectively enriched in Superior oDSGCs compared to Inferior oDSGCs, which detect downward motion. Genetic deletion of Ptprk selectively halves the number of Superior oDSGCs while preserving the number of Inferior oDSGCs. Anatomically, Superior oDSGCs in Ptprk mutants exhibit compensatory neurite remodeling to preserve mosaics. Physiologically, oDSGCs have broader tuning curves, and a subset of Superior oDSGCS have aberrant preferred directions in Ptprk mutants. Postsynaptically, loss of Ptprk reduces oDSGC connectivity to central targets. Behaviorally, the OKR responses to upward motion are attenuated in both global and pan-retinal Ptprk mutants, confirming a retinal role for Ptprk in upward image stabilization. Together, these findings demonstrate that the density of a retinal ganglion cell type is under molecular control, and that reducing density drives neurite remodeling, alters circuit computation, and ultimately impairs visually-guided behavior.

neuroscience↗

bioRxiv2023

A semi-automated method for quantifying optokinetic reflex tracking acuity

The study of murine behavioral responses to visual stimuli is a key component of understanding mammalian visual circuitry. One notable response is the optokinetic reflex (OKR), a highly conserved innate behavior necessary for image stabilization on the retina. The OKR provides a robust readout of image tracking ability and has been extensively studied to understand the logic of visual system circuitry and function in mice from different genetic backgrounds. The OKR consists of two phases: a slow tracking phase as the eye follows a stimulus to the edge of the visual plane, and a compensatory fast phase saccade that maintains the image within the visual field. Assessment of the OKR has previously relied on counting individual compensatory eye saccades to estimate tracking speed. To obtain a more direct quantification of tracking ability, we have developed a novel, semi-automated analysis program that allows for rapid and reproducible quantification of unidirectional tracking gains, in addition to being adaptable to any video-oculography equipment. Our analysis program allows for the selection of slow tracking phases, modeling of the vertical and horizontal eye vectors, quantification of eye movement relative to the stimulus, and organization of resultant data into a usable spreadsheet for statistical and graphical comparisons. This quantitative and streamlined analysis pipeline provides a faster and more direct measurement of OKR responses, thereby facilitating further study of visual behavior responses. SUMMARYWe describe here a semi-automated quantitative analysis method that directly measures eye tracking resulting from murine visual system responses to two-dimensional image motion. A Python-based user interface and analysis algorithm allows for higher throughput and more quantitative measurements of eye tracking parameters than previous methods.

neuroscience↗