All events, All years

Coding in the ever-changing world: a mechanistic view of retinal dynamic computation of motion

Lecture
Date:
Wednesday, December 16, 2020
Hour: 14:00 - 15:00
Location:
Lea Ankri (PhD Thesis Defense)
|
Dr. Michal Rivlin Lab, Dept of Neurobiology WIS

The world around us is barely stable. To maintain constancy of perception, neuronal circuits adopt multiple mechanisms, each carefully tailored to grant the system with computational fidelity in the face of variable stimuli, yet to enable flexibility of computation in certain contexts. During my PhD I investigated the mechanisms that underlie retinal direction-selectivity. Using electrophysiology and modelling approaches, I will show how several mechanisms cooperate to maintain stability in the circuit’s response to moving objects carrying distinct characteristics. This stability is compromised when the retina is confronted by a repetitive light-adapting stimulus that changes the receptive field of cells in several layers of the circuit. Intriguingly, these changes in the cells’ receptive field expose antagonistic center-surround organization of direction coding: the center receptive field supports response to one direction, while the surround supports response to the opposite direction. Center-surround antagonism is thought to enhance spatial discrimination, but this is the first evidence for its contribution to retinal direction selectivity. This provides an example of how the retina elegantly implements computational motifs that are reminiscent of those found in higher brain regions, using just a handful of cell types, already at the first station of the visual system. (If you are not from the neuroscience field, please check out THIS). Zoom link to join: https://weizmann.zoom.us/j/91058452206?pwd=UFpBZkVrM1luUSttSGZUTHRiNUg5dz09 Meeting ID: 910 5845 2206 Password: 229240

Short and prolonged dynamics of taste processing in health and disease

Lecture
Date:
Tuesday, December 8, 2020
Hour: 12:30 - 13:30
Location:
Dr. Anan Moran
|
Neurobiology Dept Sagol School of Neuroscience Faculty of Life Sciences Tel Aviv University

The brain is rife with feedback connections within and between its regions, which almost inevitably should give rise to dynamic activity in the underlying neuronal populations. In the taste system of awake rats, neurons sequentially transition between activity states that correlate with taste perceptions such as identity, palatability, and novelty. In my talk I will present the current knowledge regarding taste information processing in the taste system and will add our recent description of sub-second novelty information transmission through a new circuit. Next, I will present unpublished data showing the dynamic changes in neuronal activity as taste memory is acquired and consolidated across 12 hours in behaving rats. Last, I will show how taste learning helps us investigating the early, pre-pathological, stages of Alzheimer’s disease. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Understanding the distinctive neuronal epigenome

Lecture
Date:
Tuesday, December 1, 2020
Hour: 14:00
Location:
Prof. Harrison Gabel
|
Dept of Neuroscience, Washington University School of Medicine, USA

Recent discoveries indicate that the genomes of mammalian neurons are enriched for unique epigenetic modifications, including exceptionally high levels of non-CG DNA methylation. In my seminar, I will present our studies defining how a distinctive DNA methylation landscape is established in neurons and exploring how this methylation is read out to control critical gene expression programs. I will discuss the role of gene expression and genome architecture in shaping genomic profiles of non-CG methylation and highlight emerging mechanistic insights into how non-CG methylation and the Rett syndrome protein, MeCP2, work together to control transcription. Finally, I will outline growing evidence that disruption of this regulatory pathway contributes to neurodevelopmental disorders. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Seeing the big picture - time scales of automatic prediction in temporal and frontal cortex

Lecture
Date:
Tuesday, November 10, 2020
Hour: 12:30
Location:
Prof. Leon Y. Deouell
|
Edmond and Lily Safra Center for Brain Research and Dept of Psychology The Hebrew University of Jerusalem, Israel

According to the hierarchical predictive-coding framework, regularities in the environment are used by the nervous system for predicting the input, and deviations from this prediction are transmitted as ‘prediction errors’. However, regularities may be based on more than one dimension and may be based on different time windows. Multiple predictions, sometimes contradicting, may be formed simultaneously and it is not clear how the brain deals with this situation. I will present evidence from scalp and intracranial EEG (in humans) showing that different parts of auditory cortex and frontal cortices are involved in predictions in multiple time scales for the same events. These predictions do not obey a simple hierarchy.

Immune therapy for Alzheimer’s disease and Dementia: From the bench to the bedside

Lecture
Date:
Tuesday, November 3, 2020
Hour: 12:30
Location:
Prof. Michal Schwartz
|
Department of Neurobiology, WIS

With increased life expectancy, the incidence of patients suffering from Alzheimer’s disease (AD) and dementia has been steadily increasing. Currently, there is not a single treatment that can change the diseases course. Our team, over more than two decades, has demonstrated that the brain needs support from the immune system for its life-long functional plasticity and repair. Furthermore, using immunological and immunogenomic tools, we demonstrated that in AD, the immune system dysfunctions and perpetuates the pathology. Based on these observations and numerous others, we proposed that boosting the systemic immune system might facilitate mobilization of immune cells to help the brain. We found that the optimal way to activate such a reparative immune response is by reducing the restraints on the immune system, by blocking the PD-1/PD-L1 inhibitory immune checkpoint pathway. This therapy facilitates translocation of phagocytic cells to the brain; based on their transcriptomic profile, we demonstrated that these cells express molecules that can uniquely remove the toxic forms of misfolded proteins plaques, dead cells, and cell debris, and can thereby rescue synapses, change the disease course and improve brain function. Overall, our results indicate that targeting systemic and local immune cells rather than brain-specific disease-escalating factors provides a multi-dimensional disease-modifying therapy for AD and dementia, regardless of the primary disease etiology. Our approach is under an expedited development process towards clinical trial.

High-dimensional geometry of visual cortex

Lecture
Date:
Thursday, June 25, 2020
Hour: 16:00
Location:
Dr. Carsen Stringer
|
Janelia Research Campus

Interpreting high-dimensional datasets requires new computational and analytical methods. We developed such methods to extract and analyze neural activity from 20,000 neurons recorded simultaneously in awake, behaving mice. The neural activity was not low-dimensional as commonly thought, but instead was high-dimensional and obeyed a power-law scaling across its eigenvalues. We developed a theory that proposes that neural responses to external stimuli maximize information capacity while maintaining a smooth neural code. We then observed power-law eigenvalue scaling in many real-world datasets, and therefore developed a nonlinear manifold embedding algorithm called Rastermap that can capture such high-dimensional structure.

Mean-field models for finite-size populations of spiking neurons

Lecture
Date:
Monday, June 8, 2020
Hour: 10:00
Location:
Dr. Tilo Schwalger
|
Institute for Mathematics Technical University of Berlin

Firing-rate (FR) or neural-mass models are widely used for studying computations performed by neural populations. Despite their success, classical firing-rate models do not capture spike timing effects on the microscopic level such as spike synchronization and are difficult to link to spiking data in experimental recordings. For large neuronal populations, the gap between the spiking neuron dynamics on the microscopic level and coarse-grained FR models on the population level can be bridged by mean-field theory formally valid for infinitely many neurons. It remains however challenging to extend the resulting mean-field models to finite-size populations with biologically realistic neuron numbers per cell type (mesoscopic scale). In this talk, I present a mathematical framework for mesoscopic populations of generalized integrate-and-fire neuron models that accounts for fluctuations caused by the finite number of neurons. To this end, I will introduce the refractory density method for quasi-renewal processes and show how this method can be generalized to finite-size populations. To demonstrate the flexibility of this approach, I will show how synaptic short-term plasticity can be incorporated in the mesoscopic mean-field framework. On the other hand, the framework permits a systematic reduction to low-dimensional FR equations using the eigenfunction method. Our modeling framework enables a re-examination of classical FR models in computational neuroscience under biophysically more realistic conditions.

Individual differences in decision-making under uncertainty: a neuroeconomic approach

Lecture
Date:
Tuesday, May 19, 2020
Hour: 12:30
Location:
Prof. Ifat Levy
|
Decision Neuroscience Lab Yale School of Medicine

Individuals differ substantially in their attitudes to uncertainty: some avoid is at all costs, while others are tolerant of, or even seek, uncertainty. These differences are important, because uncertainty is everywhere – how we cope with uncertainty can have significant implications for our mental health and quality of life. I will describe a series of studies in which we characterize individual differences in decision-making under uncertainty, and use these characterizations to study the neural mechanisms of decision-making under uncertainty and variations in these mechanisms in mental illness.

From sensory perception to decision making in bats

Lecture
Date:
Tuesday, May 12, 2020
Hour: 12:30
Location:
Prof. Yossi Yovel
|
Faculty of Life Sciences Tel Aviv University

From Cognition to Depression: Using Magnetic Resonance Spectroscopy to Study In-vivo Neurochemistry

Lecture
Date:
Tuesday, March 3, 2020
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dr. Assaf Tal
|
Dept of Chemical & Biological Physics Faculty of Chemistry, WIS

Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concentrations of several metabolites in the brain non-invasively. I will present our work using MRS to study two aspects of brain metabolism. First, I'll talk about our work on functional MRS, whereby we look at neurochemical changes during or after learning or function. In the second half of the talk, I will focus on new methods we're developing in the lab, and in particular on our ability to measure the thermal relaxation times of metabolites, which probe specific cellular and subcellular microenvironments. I will present some preliminary data showing where and how this could be useful.

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All events, All years

Short and prolonged dynamics of taste processing in health and disease

Lecture
Date:
Tuesday, December 8, 2020
Hour: 12:30 - 13:30
Location:
Dr. Anan Moran
|
Neurobiology Dept Sagol School of Neuroscience Faculty of Life Sciences Tel Aviv University

The brain is rife with feedback connections within and between its regions, which almost inevitably should give rise to dynamic activity in the underlying neuronal populations. In the taste system of awake rats, neurons sequentially transition between activity states that correlate with taste perceptions such as identity, palatability, and novelty. In my talk I will present the current knowledge regarding taste information processing in the taste system and will add our recent description of sub-second novelty information transmission through a new circuit. Next, I will present unpublished data showing the dynamic changes in neuronal activity as taste memory is acquired and consolidated across 12 hours in behaving rats. Last, I will show how taste learning helps us investigating the early, pre-pathological, stages of Alzheimer’s disease. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Understanding the distinctive neuronal epigenome

Lecture
Date:
Tuesday, December 1, 2020
Hour: 14:00
Location:
Prof. Harrison Gabel
|
Dept of Neuroscience, Washington University School of Medicine, USA

Recent discoveries indicate that the genomes of mammalian neurons are enriched for unique epigenetic modifications, including exceptionally high levels of non-CG DNA methylation. In my seminar, I will present our studies defining how a distinctive DNA methylation landscape is established in neurons and exploring how this methylation is read out to control critical gene expression programs. I will discuss the role of gene expression and genome architecture in shaping genomic profiles of non-CG methylation and highlight emerging mechanistic insights into how non-CG methylation and the Rett syndrome protein, MeCP2, work together to control transcription. Finally, I will outline growing evidence that disruption of this regulatory pathway contributes to neurodevelopmental disorders. Zoom link to join: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068 Host: Dr. Rita Schmidt rita.schmidt@weizmann.ac.il tel: 9070

Seeing the big picture - time scales of automatic prediction in temporal and frontal cortex

Lecture
Date:
Tuesday, November 10, 2020
Hour: 12:30
Location:
Prof. Leon Y. Deouell
|
Edmond and Lily Safra Center for Brain Research and Dept of Psychology The Hebrew University of Jerusalem, Israel

According to the hierarchical predictive-coding framework, regularities in the environment are used by the nervous system for predicting the input, and deviations from this prediction are transmitted as ‘prediction errors’. However, regularities may be based on more than one dimension and may be based on different time windows. Multiple predictions, sometimes contradicting, may be formed simultaneously and it is not clear how the brain deals with this situation. I will present evidence from scalp and intracranial EEG (in humans) showing that different parts of auditory cortex and frontal cortices are involved in predictions in multiple time scales for the same events. These predictions do not obey a simple hierarchy.

Immune therapy for Alzheimer’s disease and Dementia: From the bench to the bedside

Lecture
Date:
Tuesday, November 3, 2020
Hour: 12:30
Location:
Prof. Michal Schwartz
|
Department of Neurobiology, WIS

With increased life expectancy, the incidence of patients suffering from Alzheimer’s disease (AD) and dementia has been steadily increasing. Currently, there is not a single treatment that can change the diseases course. Our team, over more than two decades, has demonstrated that the brain needs support from the immune system for its life-long functional plasticity and repair. Furthermore, using immunological and immunogenomic tools, we demonstrated that in AD, the immune system dysfunctions and perpetuates the pathology. Based on these observations and numerous others, we proposed that boosting the systemic immune system might facilitate mobilization of immune cells to help the brain. We found that the optimal way to activate such a reparative immune response is by reducing the restraints on the immune system, by blocking the PD-1/PD-L1 inhibitory immune checkpoint pathway. This therapy facilitates translocation of phagocytic cells to the brain; based on their transcriptomic profile, we demonstrated that these cells express molecules that can uniquely remove the toxic forms of misfolded proteins plaques, dead cells, and cell debris, and can thereby rescue synapses, change the disease course and improve brain function. Overall, our results indicate that targeting systemic and local immune cells rather than brain-specific disease-escalating factors provides a multi-dimensional disease-modifying therapy for AD and dementia, regardless of the primary disease etiology. Our approach is under an expedited development process towards clinical trial.

High-dimensional geometry of visual cortex

Lecture
Date:
Thursday, June 25, 2020
Hour: 16:00
Location:
Dr. Carsen Stringer
|
Janelia Research Campus

Interpreting high-dimensional datasets requires new computational and analytical methods. We developed such methods to extract and analyze neural activity from 20,000 neurons recorded simultaneously in awake, behaving mice. The neural activity was not low-dimensional as commonly thought, but instead was high-dimensional and obeyed a power-law scaling across its eigenvalues. We developed a theory that proposes that neural responses to external stimuli maximize information capacity while maintaining a smooth neural code. We then observed power-law eigenvalue scaling in many real-world datasets, and therefore developed a nonlinear manifold embedding algorithm called Rastermap that can capture such high-dimensional structure.

Mean-field models for finite-size populations of spiking neurons

Lecture
Date:
Monday, June 8, 2020
Hour: 10:00
Location:
Dr. Tilo Schwalger
|
Institute for Mathematics Technical University of Berlin

Firing-rate (FR) or neural-mass models are widely used for studying computations performed by neural populations. Despite their success, classical firing-rate models do not capture spike timing effects on the microscopic level such as spike synchronization and are difficult to link to spiking data in experimental recordings. For large neuronal populations, the gap between the spiking neuron dynamics on the microscopic level and coarse-grained FR models on the population level can be bridged by mean-field theory formally valid for infinitely many neurons. It remains however challenging to extend the resulting mean-field models to finite-size populations with biologically realistic neuron numbers per cell type (mesoscopic scale). In this talk, I present a mathematical framework for mesoscopic populations of generalized integrate-and-fire neuron models that accounts for fluctuations caused by the finite number of neurons. To this end, I will introduce the refractory density method for quasi-renewal processes and show how this method can be generalized to finite-size populations. To demonstrate the flexibility of this approach, I will show how synaptic short-term plasticity can be incorporated in the mesoscopic mean-field framework. On the other hand, the framework permits a systematic reduction to low-dimensional FR equations using the eigenfunction method. Our modeling framework enables a re-examination of classical FR models in computational neuroscience under biophysically more realistic conditions.

Individual differences in decision-making under uncertainty: a neuroeconomic approach

Lecture
Date:
Tuesday, May 19, 2020
Hour: 12:30
Location:
Prof. Ifat Levy
|
Decision Neuroscience Lab Yale School of Medicine

Individuals differ substantially in their attitudes to uncertainty: some avoid is at all costs, while others are tolerant of, or even seek, uncertainty. These differences are important, because uncertainty is everywhere – how we cope with uncertainty can have significant implications for our mental health and quality of life. I will describe a series of studies in which we characterize individual differences in decision-making under uncertainty, and use these characterizations to study the neural mechanisms of decision-making under uncertainty and variations in these mechanisms in mental illness.

From sensory perception to decision making in bats

Lecture
Date:
Tuesday, May 12, 2020
Hour: 12:30
Location:
Prof. Yossi Yovel
|
Faculty of Life Sciences Tel Aviv University

From Cognition to Depression: Using Magnetic Resonance Spectroscopy to Study In-vivo Neurochemistry

Lecture
Date:
Tuesday, March 3, 2020
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dr. Assaf Tal
|
Dept of Chemical & Biological Physics Faculty of Chemistry, WIS

Magnetic Resonance Spectroscopy (MRS) can be used to measure the in-vivo concentrations of several metabolites in the brain non-invasively. I will present our work using MRS to study two aspects of brain metabolism. First, I'll talk about our work on functional MRS, whereby we look at neurochemical changes during or after learning or function. In the second half of the talk, I will focus on new methods we're developing in the lab, and in particular on our ability to measure the thermal relaxation times of metabolites, which probe specific cellular and subcellular microenvironments. I will present some preliminary data showing where and how this could be useful.

Synaptic markers in the reward system for the predisposition to overeat

Lecture
Date:
Tuesday, February 25, 2020
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dr. Yonatan Kupchik
|
Dept of Medical Neurobiology Faculty of Medicine The Institute for Medical Research Israel-Canada (IMRIC), The Hebrew University of Jerusalem

Obesity is a complex disease with its roots in the physiology of various brain circuits. Although much progress has been made in understanding the disease, the most fundamental question remains unanswered – why do we overeat? As Clifford Saper (Harvard) points out, “if feeding were controlled solely by homeostatic mechanisms, most of us would be at our ideal body weight, and people would consider feeding like breathing or elimination, a necessary but unexciting part of existence”. Clearly this is not the case; hedonic eating has come increasing under the spotlight in recent years as a main driver of obesity. As food becomes more and more rewarding, could overeating be driven by a pathological search for reward? In my talk I will demonstrate that chronic diet of highly-palatable food changes the physiology of the reward system and that mice that gained the most weight differ from those that gained the least weight in the physiology of two regions of the reward system – the nucleus accumbens and the ventral pallidum. Furthermore, I will show that long term plasticity in the ventral pallidum may be an innate marker for the predisposition to overeat palatable food.

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