Direction-Selective Retinal Cells Encode Motion Uniformly Despite Cardinal Preferences

Populations of On-Off direction-selective retinal ganglion cells encode motion direction uniformly across all directions of movement despite having discrete cardinal preferences, according to an investigation by Carlo Paris, Félix Hubert, Felix Franke, Olivier Marre, Matthew Chalk, and Ulisse Ferrari. The research team evaluated how small groups of these specialized retinal neurons process directional information when responding to moving visual stimuli, addressing how the visual system reliably tracks movement that does not align with cardinal axes.

On-Off direction-selective retinal ganglion cells are characterized by broad tuning curves, which allow them to respond robustly to motion aligned with or close to their preferred directions. These neural populations are divided into four primary subtypes, with each subtype selectively tuned along one of four cardinal axes: nasal, superior, temporal, or inferior. Because natural stimuli routinely move in arbitrary directions rather than strictly along cardinal pathways, scientists have sought to determine whether intermediate directions are encoded less effectively or whether this cardinal architecture successfully maintains uniform direction encoding.

To resolve this question, the researchers combined previous electrophysiological recordings of direction-selective retinal ganglion cells stimulated with a moving light bar with an information-theoretic analytical measure known as Stimulus Specific Information. By applying this quantitative framework, the authors estimated the directional sensitivity of small populations of the recorded neurons. The resulting analysis demonstrated that populations of direction-selective retinal ganglion cells maintain uniform sensitivity across all directions of motion, showing that directional encoding remains homogeneous across intermediate angles.

Following this observation, the investigators asked whether the homogeneous sensitivity was driven by direction-selective retinal ganglion cells maximizing average stimulus information. The authors performed computational simulations using artificially modified tuning curve widths to explore alternative neural configurations. These simulations revealed that direction-selective cells prioritize avoiding pronounced drops in sensitivity over maximizing the average transmitted information across stimulus conditions.

This prioritization directly reduces large deficits in directional sensitivity for specific motion angles, thereby limiting potential blind spots in the neural encoding of motion. More broadly, the researchers noted that their results raise the possibility that maintaining a high minimum sensitivity across stimulus space could be one factor influencing the organization of sensory representations.

Subject of Research: Directional motion encoding by retinal ganglion cells

Article Title: Direction-selective retinal ganglion cells encode motion direction uniformly, despite having discretely distributed cardinal preferences

Article References: Paris, C., Hubert, F., Franke, F., Marre, O., Chalk, M., & Ferrari, U. (2026). Direction-selective retinal ganglion cells encode motion direction uniformly, despite having discretely distributed cardinal preferences. PLOS Computational Biology, 22(11), e1014872. https://doi.org/10.1371/journal.pcbi.1014872

Image Credits: AI Generated

DOI: 10.1371/journal.pcbi.1014872

Keywords: retinal ganglion cells, motion encoding, direction selectivity, computational biology, sensory representations, electrophysiology, stimulus specific information, neural sensitivity, Direction-selective, retinal, ganglion, cells