Saccades

Saccades are ballistic eye movements made 2-4 times a second while viewing a visual scene. They change object locations on the retina and visual information relayed to the cortex, yet do not interfere with a stable percept. A mechanism by which the visual cortex accomplishes this visual continuity is predictive remapping of receptive fields (RF) of neurons: neurons across visual and oculomotor areas predictively respond to visual stimuli that will appear in their receptive field after an impending saccade. This update of visual representations is mediated by an efferent motor-to-sensory signal

The diagnosis of Alzheimer's disease (AD) typically occurs after the onset of cognitive symptoms. Consequently, the global challenge around the world is to identify early and easily accessible biomarkers. Intriguingly, certain brainstem structures, such as the Superior Colliculus (SC), which plays a pivotal role in fixation maintenance and saccade programming, exhibit neurofibrillary changes sooner than cortical regions (Uematsu et al., 2018) and is susceptible to tau pathology and neuronal loss in AD patients. Accordingly, eye movement abnormalities associated with AD are often observed durin

To investigate the origins of social cognition, we need to look beyond the human species. Investigations within primates constrain us to a linear understanding of evolution. Dogs have emerged as an alternative animal model because our last common ancestor with them dates back 95-100 million years. They have advanced socio-cognitive skills, even when discounting recent domestication effects, not present in many other mammals, suggestive of convergent rather than linear evolution. Moreover, they can be trained to perform awake and unrestrained functional magnetic resonance imaging. To better und

Distinguishing between sensory experiences elicited by external stimuli and an animal's own actions is critical for accurate perception. However, the diversity of behaviors and their complex influences on the senses make this distinction challenging. Here, we show that a combination of self-motion cues modulates visual processing in the superficial superior colliculus (sSC), the brain's first visual relay. We uncovered a projection from the ventral lateral geniculate nucleus to the sSC in mice that functions as a corollary discharge hub, conveying inhibitory signals about translational optic f

…target blanking or loss of foveation, saccades are performed to catch up with the target. Mathematical models can be used to implement a quantitative description of underlying processes. Thus, models can provide insight by identifying parameters related to the physiological mechanisms (like pursuit gain or retinal delay).Here, we adapted a one-dimensional oculomotor model (Marti et al. 2008) to a two-dimensional pursuit task with target blanking (see f

In a complex and mutable environment, animals continuously face scenarios where behavioral decisions determine their survival. These rely primarily on sensory input and the associated cognitive process is known as perceptual decision-making. The decision-making is typically preceded by the gathering of information across time in a process called evidence accumulation. This has been widely studied on various animals; however, in flies, the emphasis has primarily been centered on the subcellular integration mechanisms, overlooking the behavioral impacts and whole-brain neuronal dynamics.Here, we

…motion of the retinal image during saccades). In this talk, I will present

…attention-driven visual processing and saccades, miniature eye movements influenced by attention. We conduct experiments by analyzing: i) the robustness of different deep neural network (DNN) feature extractors to partially-sensed images for image classification and object detection, and ii) the utility of saccades in masking image patches for image classification and object tracking.

Saccades enable primates to sample their visual environments at high resolution. Yet, even before the saccade occurs, visual discrimination sensitivity increases at the saccade target location. Does this benefit occur in all scenarios? To address this question, we designed a dual-task paradigm involving visual change detection. On each trial, participants (n=10) prepared and executed a saccade to one (cued) of four grating locations while concurrently localizing a change in grating orientation that immediately preceded the saccade. Surprisingly, we found no improvement in orientation change de

Saccades are fast eye movements that change gaze direction in a ballistic fashion. Human saccadic behaviour has been studied extensively in neuroscience and several methods have been proposed to model the saccadic system. For example, John et al. (2021) adopted a model-based approach, based on a physical model of the eye plant (eyeball, extraocular muscles, and surrounding tissues). They used feedforward optimal-control principles to replicate human saccadic behaviour. Here, we adopted a model-free approach to study the question: “How to learn saccadic behaviours without prior knowledge of the

…in V1 and the relation to evoked saccades. In the final part of the talk I will discuss top-down influences in V1 and their re

Human vision relies on rapid eye movements (saccades) 2-3 times every second to bring peripheral targets to central foveal vision for high resolution inspection. This rapid sampling of the world defines the perception-action cycle of natural vision and profoundly impacts our perception. Marmosets have similar visual processing and eye movements as humans, including a fovea that supports high-acuity central vision. Here, I present a novel approach developed in my laboratory for investigating the neural mechanisms of visual processing using naturalistic free viewing and simple target foraging pa

…and action; rapid gaze shifts (saccades) occur 2-3 times every second, separating brief “fixation” intervals in which visual information is acquired and processed. During fixation, however, the eye is not immobile. Small eye movements incessantly shift the image on the retina even when the attended stimulus is already foveated, suggesting a much deeper coupling between visual functions and oculomo