Past events

: I’ll describe two projects: In the first, we examined the circuitry that underlies olfaction in a mouse model with severe developmental degeneration of the OB. The olfactory bulb (OB) is a critical component of mammalian olfactory neuroanatomy. Beyond being the first and sole relay station for olfactory information to the rest of the brain, it also contains elaborate stereotypical circuitry that is considered essential for olfaction. In our mouse model, a developmental collapse of local blood vessels leads to degeneration of the OB. Mice with degenerated OBs could perform odor-guided tasks and even responded normally to innate olfactory cues. I will describe the aberrant circuitry that supports functional olfaction in these mice. The second project focusses on the nucleus of the lateral olfactory tract. This amygdaloid nucleus is typically considered part of the olfactory cortex, yet almost nothing is known about its function, connectivity, and physiology. I will describe our approach to studying this intriguing structure and will present some of its cellular and synaptic properties that may guide hypotheses about its function.

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

Neural circuits in the brain must be plastic enough to allow an animal to adapt to and learn from new experiences yet they must also remain functionally stable such that previously learned skills and information are retained. Thus, fundamental questions in neuroscience concern the molecular, cellular, and circuit mechanisms that balance the plasticity and stability of neural circuits. During my studies, I investigated these mechanisms in three studies that focused on sensory- and behavioral state-dependent changes in transcription and GABAergic inhibition in the visual cortex of adult mice. In my Ph.D. defense, I will elaborate on the novel molecular-cellular mechanisms that I discovered in these studies and discuss their role in conveying both plasticity and stability to visual processing and perception.