ELSC Seminar: May 28th, 2019

ELSC cordially invites you to the lecture given by:

 

Dr. Yuval Nir

Sagol School of Neuroscience
Department of Physiology and Pharmacology

 

On the topic of:

“Sensory disconnection across sleep, anesthesia, and cognitive lapses: The role of reduced noradrenaline signaling”

 

 

"Sensory disconnection" – when a sensory stimulus does not reliably affect behavior or subjective experience - is a defining feature of sleep, and similar processes may occur during light anesthesia or during cognitive lapses. What are the changes in brain activity that mediate sensory disconnection? In a series of studies in humans and rodents, we investigate how "disconnected" states affect sensory processing. The first set of studies reveals differences in neuronal responses to identical sensory stimuli across states. In humans, cognitive lapses after sleep deprivation involve attenuated and delayed single-neuron responses in MTL co-occurring with local slow/theta waves. In the auditory domain, in both rodents and humans responses in sleep and light anesthesia are preserved up to A1, challenging the classic "thalamic gating" notion. Instead, robust attenuation occurs later in high-level cortical regions. In addition, sleep affects more strongly responses that require integration over long time intervals, and responses to high-frequency content. The second set of studies investigates the underlying mechanisms, testing the potential role of locus coeruleus-noradrenaline (LC-NE) neuromodulation. In rats, we test how NE signaling affects the probability of sound-evoked awakening from sleep. We establish selective in-vivo LC optogenetics by showing effects on spiking activity, evoked sleep-wake transitions, and pupil dilation. Auditory stimulation on a background of weak LC-NE modulation synergistically increases the probability of awakenings beyond independent effects of sound and laser alone, supporting a role for LC-NE activity in mediating sensory responses. We also tested the effects of NE levels on perception and sensory-evoked activity (EEG, fMRI) in awake humans. Pharmacologically manipulating NE levels in double-blind placebo-controlled experiments, we find that NE modulates visual perception and boosts late visual responses, suggesting that NE is a key factor causally linking sensory awareness to external world events. In the final minutes I will share some ongoing studies investigating sleep and memory consolidation in humans.

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