From Branch to Branch: Unravelling Primate Vision in Arboreal Leaping and Navigation

Fred Wolf – Universität Göttingen, MPI for Dynamics and Self-Organization
Claudia Fichtel – Universität Göttingen, German Primate Center
Daniel Huber – Université de Genève

Primates, including humans and their non-human relatives, possess a highly derived sense of vision for tasks such as object recognition, spatial vision, and detecting and processing of social clues. The early visual cortex underwent a significant transformation at the origin of crown group primates, with the emergence of a near invariant form of vision circuitry in the primary visual cortex (V1). This architectural design has been conserved throughout primate brain evolution and was accompanied by an expansion of neocortex dedicated to vision. In the mouse lemur (Microcebus murinus), a basal primate resembling the primate last common ancestor, V1 covers 20% of the neocortex. However, the visual capabilities and behaviors served by this architecture differ greatly from those in humans, apes, and Old World monkeys. Here we propose a research program to investigate key features of early primate vision. Using the EthoLoop platform, we will study behavior, cognition, and perception in free-ranging mouse lemurs in a controlled naturalistic laboratory setting resembling their arboreal habitat. This platform enables quantitative studies of visually guided navigation, foraging behaviors, and neuronal recording during complex tasks. By adjusting environmental conditions, we can explore visual parameters and infer computational principles. The project combines expertise in quantifying ecological behaviors, theoretical neuroscience and computer vision, and neural recording in free-ranging mouse lemurs. The research aims to understand visual processing and cognition during arboreal navigation and foraging. Aim 1: Understanding the strategies of active vision during arboreal leaping: To characterize the different modalities and strategies involved in visually guided leaping, we will design a novel, parameterizable behavioral leaping task, constrained by physical features actually observed in natural settings in Madagascar. Aim 2: Characterizing large scale navigation strategies under varying visual conditions: To gain a better understanding of how the visual conditions affect navigational strategies we will observe freely moving mouse lemurs in the wild, model their behavior and test our predictions under controlled conditions in the laboratory settings. Aim 3: Revealing the neuronal codes for vision, gaze, posture and space in the mouse lemur brain: To characterize the coding of visual and non-visual features (including motor and posture parameters) we will record the activity of individual neurons under freely moving conditions using electrophysiologyy and portable miniature microscope imaging. Taken together, our studies will open a new perspective on primate vision in action that defined much of the form of vision circuitry still used in the human brain and address several major open questions about potential differences between visual information processing in the primate brain and in that of closely related rodents.