Past events | The department of Brain Sciences

All events, All years

New insights on continuous attractor neural networks

Lecture

Date:

Tuesday, April 20, 2021

Hour: 12:30

Location:

Prof. Yoram Burak

|

Racah Institute of Physics and Edmond and Lily Safra Center for Brain Sciences The Hebrew University of Jerusalem

One of the most fundamental concepts in theoretical neuroscience is that of an attractor neural network, in which recurrent synaptic connectivity constraints the joint activity of neurons into a highly restricted repertoire of population activity patterns. In continuous attractor networks, these activity patterns span a continuous, low-dimensional manifold. I will survey two recent works from my group that are related to this concept. The first work is concerned with fixational eye drifts, a form of eye motion that occurs between saccades and is characterized by smooth, yet random, diffusive-like motion. This motion is tiny compared to saccadic eye motion, yet it is highly consequential for high-acuity vision. Even though fixational drift has been identified at least as early as the 19th century, its mechanistic origins have remained completely unknown. We hypothesize that the main drive for fixational drifts arises in diffusive motion along a line-attractor memory network - the oculomotor network, which is responsible for maintaining a fixed activation of the ocular muscles between saccades. I will present evidence in support of this hypothesis, coming from electrophysiology in monkeys and from theoretical modeling. The second work is concerned with the ability of a single recurrent neural network to express activity patterns that span multiple yet distinct continuous manifolds, a question that has been of interest in the context of spatial coding, across multiple environments, in area CA3 of the hippocampus. 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

Uncovering the Boundaries of Olfactory Perception

Lecture

Date:

Monday, April 19, 2021

Hour: 15:00 - 16:00

Location:

Aharon Ravia (PhD Thesis Defense)

|

Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics WIS

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

Dissecting the functional organization of sensory neurons in gut-brain communication

Lecture

Date:

Tuesday, April 13, 2021

Hour: 12:30

Location:

Dr. Henning Fenselau

|

Max Planck Institute for Metabolism Research, Cologne, Germany

Sensory neurons relay gut-derived signals to the brain, and thereby contribute to systemic energy and glucose homeostasis regulation. However, the relevant sensory neuronal populations innervating the gut along with the pertaining underlying functional neurocircuits remain poorly understood. Advances in this field have been impeded by the challenges associated with targeting distinct sensory neurons of vagal and spinal origin in a cell-type-specific manner, thereby making the accurate determination of their function highly difficult. We employ a combinatorial set of modern molecular systems neuroscience tools and novel mouse genetic approaches to elucidate the role of molecularly defined sensory neurons in feeding behavior and glucose metabolism, and map their downstream neurocircuits in the brain. The overarching goal of our studies is to gain greater insights into the integral components of sensory neurons as gut-to-brain connectors in controlling metabolism. 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

Cellular and circuit basis of distinct memory formation in the hippocampus

Lecture

Date:

Tuesday, April 6, 2021

Hour: 12:30

Location:

Dr. Christoph Schmidt-Hieber

|

Department of Neuroscience, Institut Pasteur, Paris

Formation and retrieval of distinct memories are complementary processes that put conflicting requirements on neuronal computations in the hippocampus, especially when memories closely resemble each other. How this challenge is resolved in hippocampal circuits to guide memory-based decisions is unclear. To address this question, our group uses in vivo 2-photon calcium imaging and whole-cell recordings from hippocampal subregions in head-fixed mice trained to distinguish between novel and familiar virtual-reality environments. We find that granule cells consistently show a small transient depolarization of their membrane potential upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the observed transient synaptic response to novel environments leads to a bias in the granule cell population activity, which can in turn drive the downstream attractor networks to a new state, thereby favoring the switch from generalization to discrimination when faced with novelty. Such a novelty-driven cholinergic switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones. 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

Uncovering Olfactory Perception Boundaries

Lecture

Date:

Thursday, March 25, 2021

Hour: 15:00 - 16:00

Location:

Aharon Ravia (PhD Thesis Defense)

|

Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

Re-rendering Reality

Lecture

Date:

Thursday, March 25, 2021

Hour: 12:30 - 13:30

Location:

Prof. Tali Dekel

|

Department of Computer Science and Applied Mathematics Weizmann Institute of Science

We all capture the world around us through digital data such as images, videos and sound. However, in many cases, we are interested in certain properties of the data that are either not available or difficult to perceive directly from the input signal. My goal is to “Re-render Reality”, i.e., develop algorithms that analyze digital signals and then create a new version of it that allows us to see and hear better. In this talk, I’ll present a variety of methodologies aimed at enhancing the way we perceive our world through modified, re-rendered output. These works combine ideas from signal processing, optimization, computer graphics, and machine learning, and address a wide range of applications. More specifically, I’ll demonstrate how we can automatically reveal subtle geometric imperfection in images, visualize human motion in 3D, and use visual signals to help us separate and mute interference sound in a video. 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

Cortical Layer 1 – The Memory Layer?

Lecture

Date:

Tuesday, March 16, 2021

Hour: 12:30

Location:

Dr. Guy Doron

|

Humboldt University of Berlin Neurocure Cluster of Excellence, Berlin

The hippocampus and related medial temporal lobe structures (entorhinal cortex, perirhinal cortex, etc.) play a vital role in transforming experience into long-term memories that are then stored in the cortex, however the cellular mechanisms which designate single neurons to be part of a memory trace remain unknown. Part of the difficulty in addressing the mechanisms of transformation of short-term to long-term memories is the distributed nature of the resulting “engram” at synapses throughout the cortex. We therefore used a behavioral paradigm dependent on both the hippocampus and neocortex that enabled us to generate memory traces rapidly and reliably in a specific cortical location, by training rodents to associate the direct electrical microstimulation of the primary sensory neocortex with a reward. We found that medial-temporal input to neocortical Layer 1 (L1) gated the emergence of specific firing responses in subpopulations of Layer 5 pyramidal neurons marked by increased burstiness related to apical dendritic activity. Following learning and during memory retrieval, these neocortical responses became independent of the medial-temporal influence but continued to evoke behaviour with single bursts sufficient to elicit a correct response. These findings suggest that L1 is the locus for hippocampal-dependent associative learning in the neocortex, where memory engrams are established in subsets of pyramidal neurons by enhancing the sensitivity of tuft dendrites to contextual inputs and driving burst firing. 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

Dissecting the Alzheimer’s brain: from disease single cells to cellular communities

Lecture

Date:

Tuesday, March 9, 2021

Hour: 12:30 - 13:30

Location:

Prof. Naomi Habib

|

Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem

Alzheimer’s disease (AD) is one of the most pressing global medical issues to date with no effective therapeutic strategies. Despite extensive research much remains unknown regarding the crosstalk between brain cells and the role of non-neuronal cells in the progression of Alzheimer’s disease (AD). We use single nucleus RNA-sequencing and machine learning algorithms to build detailed cellular maps of mice and human brain and to follow molecular changes in each cell type along disease progression. Our maps revealed new disease associated states in glia cells as well as unique multi-cellular communities linked to AD. Specifically, we found a link between populations of disease-associated astrocytes (DAAs), microglia, oligodendrocytes and GABAergic neurons to AD related traits in mouse models and in post-mortem human brains. Expanding the data analysis across multiple cell types, we found co-occurrences of cellular populations across individuals, which we define as multi-cellular communities. Among these communities we discovered a unique cellular community linked to cognitive decline and Alzheimer’s disease pathology. These new insights are shaping our understanding of the unique cellular environment of the Alzheimer’s disease brains. 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

How People Decide What They Want to Know: Information-Seeking and the Human Brain

Lecture

Date:

Tuesday, March 2, 2021

Hour: 14:30 - 15:30

Location:

Prof. Tali Sharot

|

Cognitive Neuroscience, Max Planck UCL Centre for Computational Psychiatry and Ageing Research & Department of Experimental Psychology, University College London

The ability to use information to adaptively guide behavior is central to intelligence. A vital research challenge is to establish how people decide what they want to know. In this talk I will present our recent research characterizing three key motives of information seeking. We find that participants automatically assess (i) how useful information is in directing action, (ii) how it will make them feel, and (iii) how it will influence their ability to predict and understand the world around them. They then integrate these assessments into a calculation of the value of information that guides information-seeking or its avoidance. These diverse influences are captured by separate brain regions along the dopamine reward pathway and are differentially modulated by pharmacological manipulation of dopamine function. The findings yield predictions about how information-seeking behavior will alter in disorders in which the reward system malfunctions. We test these predictions using a linguistic analysis of participants’ web searches ‘in the wild’ to quantify their motives for seeking information and relate those to reported psychiatric symptoms. Finally, using controlled behavioral experiments we show that the three motives for seeking information follow different developmental trajectories that are consistent with what would be predicted from our neuroimaging data. 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

Memristors in the Neuromorphic Era

Lecture

Date:

Tuesday, February 23, 2021

Hour: 12:30 - 13:30

Location:

Prof. Shahar Kvatinsky

|

Faculty of Electrical Engineering, Technion, Haifa

Memristive technologies are attractive candidates to replace conventional memory technologies and can also be used to combine data storage and computing to enable novel non-von Neumann computer architecture. One such non-von Neumann computer architecture is neuromorphic computing, where brain-inspired circuits are built for massive parallelism and in-place computing. This talk focuses on neuromorphic computing with memristors. I will show how we can get inspiration from the brain to build electronic circuits that are energy efficient and perform both inference and training extremely fast and efficient. We will see that this approach can be used not only to accelerate machine learning applications, but also for novel mixed-signal circuits and for near-sensor processing. 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

Pages

All events, All years

Uncovering the Boundaries of Olfactory Perception

Lecture

Date:

Monday, April 19, 2021

Hour: 15:00 - 16:00

Location:

Aharon Ravia (PhD Thesis Defense)

|

Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics WIS

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

Dissecting the functional organization of sensory neurons in gut-brain communication

Lecture

Date:

Tuesday, April 13, 2021

Hour: 12:30

Location:

Dr. Henning Fenselau

|

Max Planck Institute for Metabolism Research, Cologne, Germany

Sensory neurons relay gut-derived signals to the brain, and thereby contribute to systemic energy and glucose homeostasis regulation. However, the relevant sensory neuronal populations innervating the gut along with the pertaining underlying functional neurocircuits remain poorly understood. Advances in this field have been impeded by the challenges associated with targeting distinct sensory neurons of vagal and spinal origin in a cell-type-specific manner, thereby making the accurate determination of their function highly difficult. We employ a combinatorial set of modern molecular systems neuroscience tools and novel mouse genetic approaches to elucidate the role of molecularly defined sensory neurons in feeding behavior and glucose metabolism, and map their downstream neurocircuits in the brain. The overarching goal of our studies is to gain greater insights into the integral components of sensory neurons as gut-to-brain connectors in controlling metabolism. 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

Cellular and circuit basis of distinct memory formation in the hippocampus

Lecture

Date:

Tuesday, April 6, 2021

Hour: 12:30

Location:

Dr. Christoph Schmidt-Hieber

|

Department of Neuroscience, Institut Pasteur, Paris

Formation and retrieval of distinct memories are complementary processes that put conflicting requirements on neuronal computations in the hippocampus, especially when memories closely resemble each other. How this challenge is resolved in hippocampal circuits to guide memory-based decisions is unclear. To address this question, our group uses in vivo 2-photon calcium imaging and whole-cell recordings from hippocampal subregions in head-fixed mice trained to distinguish between novel and familiar virtual-reality environments. We find that granule cells consistently show a small transient depolarization of their membrane potential upon transition to a novel environment. This synaptic novelty signal is sensitive to local application of atropine, indicating that it depends on metabotropic acetylcholine receptors. A computational model suggests that the observed transient synaptic response to novel environments leads to a bias in the granule cell population activity, which can in turn drive the downstream attractor networks to a new state, thereby favoring the switch from generalization to discrimination when faced with novelty. Such a novelty-driven cholinergic switch may enable flexible encoding of new memories while preserving stable retrieval of familiar ones. 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

Uncovering Olfactory Perception Boundaries

Lecture

Date:

Thursday, March 25, 2021

Hour: 15:00 - 16:00

Location:

Aharon Ravia (PhD Thesis Defense)

|

Prof. Noam Sobel Lab, Dept of Neurobiology Prof. David Harel Lab, Dept of Computer Science and Applied Mathematics

The question of how to measure a smell has troubled scientists for over a century. It was none other than Alexander Graham Bell that raised the challenge: "we have very many different kinds of smells, all the way from the odor of violets and roses up to asafoetida. But until you can measure their likenesses and differences you can have no science of odor”. Such a measure of smell can be naturally derived from a model of olfactory perceptual quality space, and several such models have recently been put forth. These typically rely on finding mathematical rules that link odorant structure to aspects of odor perception. Here, I collected 49,788 perceptual odor estimates from 199 participants, and built such a model, finalizing a physicochemical measure of smell. This measure, expressed in radians, predicts real-world odorant pairwise perceptual similarity from odorant structure alone. Using this measure, I met Bell's challenge by accurately predicting the perceptual similarity of rose, violet and asafoetida, from their physicochemical structure. Next, based on thousands of comparisons, I identified a cutoff in this measure, below 0.05 radians, where discrimination between pairs of mixtures becomes highly challenging. To assess the usefulness of this measure, I investigated whether it can be used to create olfactory metamers, namely non-overlapping molecular compositions that share a common percept. Characterizing the link between physical structure and ensuing perception in vision and audition, and the creation of perceptual entities such as metamers, was important towards understanding their underlying dimensionality, brain mechanisms, and towards their ultimate digitization. I suggest that olfactory metamers can similarly aid these goals in olfaction. Zoom link to join: https://weizmann.zoom.us/j/93360836031?pwd=dDZEdTQ1QUkxUVVONVErVm9CcUJWQT09 Meeting ID: 933 6083 6031 Password: 591230

Re-rendering Reality

Lecture

Date:

Thursday, March 25, 2021

Hour: 12:30 - 13:30

Location:

Prof. Tali Dekel

|

Department of Computer Science and Applied Mathematics Weizmann Institute of Science

We all capture the world around us through digital data such as images, videos and sound. However, in many cases, we are interested in certain properties of the data that are either not available or difficult to perceive directly from the input signal. My goal is to “Re-render Reality”, i.e., develop algorithms that analyze digital signals and then create a new version of it that allows us to see and hear better. In this talk, I’ll present a variety of methodologies aimed at enhancing the way we perceive our world through modified, re-rendered output. These works combine ideas from signal processing, optimization, computer graphics, and machine learning, and address a wide range of applications. More specifically, I’ll demonstrate how we can automatically reveal subtle geometric imperfection in images, visualize human motion in 3D, and use visual signals to help us separate and mute interference sound in a video. 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

Cortical Layer 1 – The Memory Layer?

Lecture

Date:

Tuesday, March 16, 2021

Hour: 12:30

Location:

Dr. Guy Doron

|

Humboldt University of Berlin Neurocure Cluster of Excellence, Berlin

The hippocampus and related medial temporal lobe structures (entorhinal cortex, perirhinal cortex, etc.) play a vital role in transforming experience into long-term memories that are then stored in the cortex, however the cellular mechanisms which designate single neurons to be part of a memory trace remain unknown. Part of the difficulty in addressing the mechanisms of transformation of short-term to long-term memories is the distributed nature of the resulting “engram” at synapses throughout the cortex. We therefore used a behavioral paradigm dependent on both the hippocampus and neocortex that enabled us to generate memory traces rapidly and reliably in a specific cortical location, by training rodents to associate the direct electrical microstimulation of the primary sensory neocortex with a reward. We found that medial-temporal input to neocortical Layer 1 (L1) gated the emergence of specific firing responses in subpopulations of Layer 5 pyramidal neurons marked by increased burstiness related to apical dendritic activity. Following learning and during memory retrieval, these neocortical responses became independent of the medial-temporal influence but continued to evoke behaviour with single bursts sufficient to elicit a correct response. These findings suggest that L1 is the locus for hippocampal-dependent associative learning in the neocortex, where memory engrams are established in subsets of pyramidal neurons by enhancing the sensitivity of tuft dendrites to contextual inputs and driving burst firing. 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

Dissecting the Alzheimer’s brain: from disease single cells to cellular communities

Lecture

Date:

Tuesday, March 9, 2021

Hour: 12:30 - 13:30

Location:

Prof. Naomi Habib

|

Edmond & Lily Safra Center for Brain Sciences, The Hebrew University of Jerusalem

Alzheimer’s disease (AD) is one of the most pressing global medical issues to date with no effective therapeutic strategies. Despite extensive research much remains unknown regarding the crosstalk between brain cells and the role of non-neuronal cells in the progression of Alzheimer’s disease (AD). We use single nucleus RNA-sequencing and machine learning algorithms to build detailed cellular maps of mice and human brain and to follow molecular changes in each cell type along disease progression. Our maps revealed new disease associated states in glia cells as well as unique multi-cellular communities linked to AD. Specifically, we found a link between populations of disease-associated astrocytes (DAAs), microglia, oligodendrocytes and GABAergic neurons to AD related traits in mouse models and in post-mortem human brains. Expanding the data analysis across multiple cell types, we found co-occurrences of cellular populations across individuals, which we define as multi-cellular communities. Among these communities we discovered a unique cellular community linked to cognitive decline and Alzheimer’s disease pathology. These new insights are shaping our understanding of the unique cellular environment of the Alzheimer’s disease brains. 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

How People Decide What They Want to Know: Information-Seeking and the Human Brain

Lecture

Date:

Tuesday, March 2, 2021

Hour: 14:30 - 15:30

Location:

Prof. Tali Sharot

|

Cognitive Neuroscience, Max Planck UCL Centre for Computational Psychiatry and Ageing Research & Department of Experimental Psychology, University College London

The ability to use information to adaptively guide behavior is central to intelligence. A vital research challenge is to establish how people decide what they want to know. In this talk I will present our recent research characterizing three key motives of information seeking. We find that participants automatically assess (i) how useful information is in directing action, (ii) how it will make them feel, and (iii) how it will influence their ability to predict and understand the world around them. They then integrate these assessments into a calculation of the value of information that guides information-seeking or its avoidance. These diverse influences are captured by separate brain regions along the dopamine reward pathway and are differentially modulated by pharmacological manipulation of dopamine function. The findings yield predictions about how information-seeking behavior will alter in disorders in which the reward system malfunctions. We test these predictions using a linguistic analysis of participants’ web searches ‘in the wild’ to quantify their motives for seeking information and relate those to reported psychiatric symptoms. Finally, using controlled behavioral experiments we show that the three motives for seeking information follow different developmental trajectories that are consistent with what would be predicted from our neuroimaging data. 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

Memristors in the Neuromorphic Era

Lecture

Date:

Tuesday, February 23, 2021

Hour: 12:30 - 13:30

Location:

Prof. Shahar Kvatinsky

|

Faculty of Electrical Engineering, Technion, Haifa

Memristive technologies are attractive candidates to replace conventional memory technologies and can also be used to combine data storage and computing to enable novel non-von Neumann computer architecture. One such non-von Neumann computer architecture is neuromorphic computing, where brain-inspired circuits are built for massive parallelism and in-place computing. This talk focuses on neuromorphic computing with memristors. I will show how we can get inspiration from the brain to build electronic circuits that are energy efficient and perform both inference and training extremely fast and efficient. We will see that this approach can be used not only to accelerate machine learning applications, but also for novel mixed-signal circuits and for near-sensor processing. 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

Sleep: sensory disconnection and memory consolidation

Lecture

Date:

Tuesday, February 16, 2021

Hour: 12:30 - 13:30

Location:

Prof. Yuval Nir

|

Dept of Physiology and Pharmacology Sackler School of Medicine Tel Aviv University

A fundamental feature of sleep is that a sensory stimulus does not reliably affect behavior or subjective experience. What mediates such “sensory disconnection”? Do similar processes occur during anesthesia, cognitive lapses, and some neuropsychiatric disorders? In a series of studies in humans and rodents, we compared neuronal responses to identical auditory stimuli across wakefulness and sleep. In A1, early single-neuron spiking responses are largely comparable across wakefulness, natural sleep, and light anesthesia. However, robust differences emerge in downstream high-level regions and late-responding neurons, and in top-down response signatures, suggesting that sleep impairs effective cortical connectivity. We reconcile the apparent discrepancy with the classic “thalamic gating” notion by showing that in contrast to natural sleep, deep anesthesia does lead to attenuation already in A1. Next, we show that reduced locus coeruleus-noradrenaline (LC-NE) activity during sleep mediates sensory disconnection. We find that in freely behaving rats, LC-NE activity is a key mechanism that determines the likelihood of sensory-evoked awakenings (SEA): the level of ongoing tonic LC activity during sleep anticipates SEAs, while minimal optogenetic LC activation or silencing increases and decreases SEA, respectively. In humans, pharmacological manipulation of NE levels modulates sensory perception and late sensory responses, suggesting that NE links sensory awareness to external world events. We are exploring novel methods such as transcutaneous vagal nerve stimulation to modulate LC-NE non-invasively in humans. In the last part of the talk I will present recent results on sleep and memory consolidation. Using unilateral olfactory stimulation during sleep we find that ‘local’ targeted memory reactivation (TMR) in human sleep selectively promotes specific memories associated with regional sleep oscillations. In epilepsy patients implanted with depth electrodes we investigate the effects of intracranial electrical closed loop stimulation during sleep on memory and hippocampal-neocortical dialogue at single-neuron resolution. 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