לוח שנה משולב

The orienting response, described by Pavlov as the “what is it?” reflex, aims to describe an individual's reaction to unexpected stimuli in their environment. Many experimental results show that in such an event, the quickest motor response is of a saccadic eye movement, and if the head is free to move, a head-shift follows the eye to meet the event. Studying orienting in different tasks and contexts have uncovered several variations in head-eye coordination, including modulations of the number of saccades during a single orienting motion and modulations of the relative timing between head and eye movements.
In this presentation, I will present my attempt at understanding and modeling the brain-environment loops underlying the visual orienting response. For this aim I have designed and constructed a virtual reality (VR) setting that allows head and eye real-time tracking during visual tasks in different contexts. I will show that, with head-free viewing, the classic eye-leading, fast saccadic gaze-shift response is typical for cases of external visual stimuli. In contrast, multi-saccadic, head-leading gaze-shifts are typical for cases in which the subject orients towards an internal reference position, with no external visual que, regardless of the angle. I demonstrate that the kinematics of the first saccadic eye movement is different between the two conditions, suggesting different motor control mechanisms. My results suggest that the context of orienting, whether it is exogenous (targeting an external stimulus) or endogenous (targeting an internal reference point) affects the balance between the two mechanisms. A comparison of the orienting responses towards visual versus auditory stimuli suggests different modalities (such as auditory and proprioceptive) are treated as endogenous by the visual control system.  Based on these results, I suggest a competitive multiple-closed-loop dynamic model of gaze orienting. Simulations of the model show it can replicate the empirical kinematics and statistics.
My results suggest that the traditional view of the mechanism underlying gaze orienting response should be revisited to take into account the source of the response as well as the subjective context of orienting. I propose that the closed-loop model for orienting presented here can address this aspect. If accepted, this model can facilitate the diagnosis and treatment of several oculomotor impairments.

Zoom: https://weizmann.zoom.us/j/98466393859?pwd=blJkSDUyWkR0L2FhQUFueS9FY2lwZz09
Id: 98466393859
passcode: 059130