Mechanisms of 3-Dimensional visual constancy in primates

• Applicant: Baptiste Caziot, Ph.D.
• Subject Area: Cognitive, Systems and Behavioural Neurobiology
• Term: since 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 524696675

When moving our eyes, we generally experience a clear sense of stability in the visual scene surrounding us. How our visual system maintains that sense of space constancy despite constantly varying retinal inputs has been investigated but remains far from being understood. Surprisingly, previous studies have almost entirely focused on 2D (flat) visual scenes, which disregards depth information. We argue that a theory of space constancy must extend to 3D scenes as we evolve in a 3D world. One prominent such hypothesis is through the remapping of attentional pointers. However, as the orienting of attention in depth has also been largely neglected so far, we will start this research program by investigating the orienting of attention in depth, with the long-term goal to understand the perceptual stability of 3-dimensional scenes. In a series of psychophysical experiments in human observers, we will systematically test the orienting of attention in 3D. Attention is often described as a spotlight, which disregards depth information. In successive experiments we will investigate the orienting of attention in depth in absence of eye-movements; then during eye-movements and finally the remapping of 3-dimensional information across eye-movements. These psychophysical experiments in human observers will be matched by a series of physiological experiments in Non-Human Primates (Awake, behaving macaque monkeys) to investigate the potential physiological underpinnings of these behavioral effects. We will aim for neural recordings in the lateral and ventral intraparietal areas (areas LIP and VIP) of the Posterior Parietal Cortex (PPC). Importantly, functional equivalents of both areas have been identified in humans. In order to tightly link physiological experiments with psychological experiments, we will use stimuli and tasks as similar as possible to tasks in human participants. We expect to show that the attentional effects revealed in human observers are reflected in the activity of neurons in the PPC. Overall, in this series of experiments we aim at demonstrating that attention operates on a 3-dimensional representation of the environment and could, therefore, play a role in 3D space constancy as it has been hypothesized for 2D (flat) scenes. We further expect to demonstrate that these effects are reflected at a neural level in the targeted areas of the PPC.

• DFG Programme: Research Grants
• International Connection: France
• Co-Investigator: Professor Dr. Frank Bremmer
• Cooperation Partners: Professor Guillaume Masson, Ph.D.; Martin Szinte, Ph.D.