All events, All years

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

On places and borders in the brain

Lecture
Date:
Tuesday, February 9, 2021
Hour: 12:00 - 13:00
Location:
Prof. Dori Derdikman
|
Faculty of Medicine, Technion, Haifa

While various forms of cells have been found in relation to the hippocampus cognitive map and navigation system, how these cells are formed and what is read from them is still a mystery. In the current lecture I will talk about several projects which tackle these issues. First, I will show how the formation of border cells in the cognitive map is related to a coordinate transformation, second I will discuss the interaction between the reward system (VTA) and the hippocampus. Finally, I will describe a project using place cells as a proxy for associative memory for assessing deficits in 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

Layers of primary visual cortex as a window into internal models about predicted and simulated environments

Lecture
Date:
Tuesday, January 26, 2021
Hour: 12:30 - 13:30
Location:
Prof. Lars Muckli
|
Visual and Cognitive Neurosciences, Director of fMRI at the Centre for Cognitive Neuroimaging, Glasgow, Scotland

Normal brain function involves the interaction of internal processes with incoming sensory stimuli. We have created a series of brain imaging experiments (using 7T fMRI) that sample internal models and feedback mechanisms in early visual cortex. Primary visual cortex (V1) is the entry-stage for cortical processing of visual information. We can show that there are 3 information counter-streams concerned with: (1) retinotopic visual input, (2) top-down predictions of internal models generated by the brain, and (3) top-down imagery acting independently of the perception and prediction loop. Internal models amplify and disamplify incoming information, but there is also mental imagery not interfering with visual perception. Our results speak to the conceptual framework of predictive coding. Healthy brain function will strike a balance between the precision of prediction and prediction update based on prediction error. Our results incorporate state of the art, layer-specific ultra-high field fMRI and other imaging techniques. We argue that fMRI with its capability of measuring dendritic energy consumption is sensitive to activity in different parts of layer spanning neurons, enriching our computational understanding of counter stream brain mechanisms. 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

What can fishes teach us about the brain?

Lecture
Date:
Tuesday, January 19, 2021
Hour: 12:30
Location:
Prof. Ronen Segev
|
Life Sciences Department Ben Gurion University of the Negev

Fishes have diverged in evolution from the mammalian linage some 450 million years ago and as a result fishes’ brain structure is different from the fundamental design of the mammalian, reptilian and avian brains. This raises the question what can we learn from the ability of fishes to solve different tasks. I will discuss how aspects navigation is implemented in the goldfish brain. Zoom link: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068

The Cortical-Hippocampal Interplay during Episodic Memory Retrieval in Humans

Lecture
Date:
Tuesday, January 19, 2021
Hour: 10:00 - 11:00
Location:
Yitzhak Norman (PhD Thesis Defense)
|
Prof. Rafi Malach Lab, Department of Neurobiology

One of the most remarkable functions of the human brain is the ability to recall a personal experience from the past and reenact it vividly in our mind, in a way that allows us to reflect upon the memory and derive from it relevant information that can guide our future behavior. My doctoral research explored the neuronal mechanisms that enable this core cognitive function in the human brain. Using rare electrophysiological recordings obtained from neurosurgical patients for clinical purposes I investigated and characterized the complex bidirectional interactions that occur between the hippocampus and the cerebral cortex during retrieval of conscious, reportable memories. My results are twofold. I first show that 1-2 seconds before the onset of individual recollections the hippocampus elicits transient electrical oscillations known as Sharp Wave Ripples (SWRs). Such oscillatory events have been extensively studied in animal models in recent years and were shown to reflect massive synchronization events during which millions of pyramidal neurons on the hippocampus output pathway fire simultaneously. My results demonstrate that the SWR events are selective to memory contents and play a major role in coordinating the re-activation of hippocampal-neocortical memory representations during retrieval. I show a tight coupling between SWR events and visual cortex activation, and reveal a massive peri-ripple activation of the default mode network. Second, I show that the cortex uses a flexible, goal-directed, "baseline shift" mechanism that allows the imposition of predefined boundaries on spontaneous recollections. Specifically, the results demonstrate that when free recall is limited to a particular category, the average neuronal activity level in cortical sites that represent the targeted category is steadily and significantly enhanced throughout the free recall period. Such steady-state excitatory enhancement is likely to introduce a category-specific bias in the cortical input arriving at the hippocampus, which may facilitate the reactivation of memory traces belonging to the targeted category and not others. Altogether, the results place hippocampal SWRs firmly as a central mechanism in the retrieval of human declarative memory. They demonstrate a central role for SWRs in coordinating the hippocampus-cortical dialogue during recollection and point to a flexible "baseline shift" mechanism that can account for the remarkable ease and precision by which we can constrain this dialogue to support retrieval goals. Zoom link to join: https://weizmann.zoom.us/j/92146113977?pwd=VmhuMEhBcTRYZDNWMVJ4bGJrR0lIdz09 Meeting ID: 92146113977 Password: 803220

Diffusion properties of intracellular metabolites: compartment specific probes for cell structure and physiology

Lecture
Date:
Tuesday, January 5, 2021
Hour: 12:30 - 13:30
Location:
Prof. Itamar Ronen
|
C.J. Gorter Center for High field MRI, Leiden University Medical Center, Leiden, The Netherlands

Diffusion weighted MRI (DWI) is the main neuroimaging modality used in non-invasive investigations of tissue microstructure, and provides quantitative cytomorphological information on a spatial scale well below the nominal resolution of MRI. The main limitation of DWI is its lack of compartmental specificity, as its “reporter molecule” is water, ubiquitous in all tissue compartments and cell types. Brain metabolites are mostly confined to the intracellular space, and their concentrations vary across cell types. Several metabolites give rise to quantifiable magnetic resonance spectroscopy (MRS) signatures, and are thus considered as compartment-specific and sometimes cell-specific markers. Sensitization of MRS to diffusion results in a set of diffusion properties for a variety of intracellular metabolites, from which microstructural information specific to the intracellular space can be obtained. A proper choice of experimental settings can be used to investigate properties that range from cytoplasmic viscosity and tortuosity of the intracellular space, to overall cell morphological features. The specificity of some metabolites to different cell types such as neurons and astrocytes opens the way to studying morphological properties of different cell populations and monitoring their modulation by physiological changes in health and disease. The presentation will introduce methodological concepts of diffusion-weighted MRS, followed by simple examples that demonstrate the unique ability of diffusion-weighted MRS to characterize cell-type specific structural features. Special emphasis will be bestowed on experimental and modelling frameworks that merge the specificity of diffusion-weighted MRS with the sensitivity of DWI to gain insights on tissue microstructure beyond what each method can separately provide. 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

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

On places and borders in the brain

Lecture
Date:
Tuesday, February 9, 2021
Hour: 12:00 - 13:00
Location:
Prof. Dori Derdikman
|
Faculty of Medicine, Technion, Haifa

While various forms of cells have been found in relation to the hippocampus cognitive map and navigation system, how these cells are formed and what is read from them is still a mystery. In the current lecture I will talk about several projects which tackle these issues. First, I will show how the formation of border cells in the cognitive map is related to a coordinate transformation, second I will discuss the interaction between the reward system (VTA) and the hippocampus. Finally, I will describe a project using place cells as a proxy for associative memory for assessing deficits in 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

Layers of primary visual cortex as a window into internal models about predicted and simulated environments

Lecture
Date:
Tuesday, January 26, 2021
Hour: 12:30 - 13:30
Location:
Prof. Lars Muckli
|
Visual and Cognitive Neurosciences, Director of fMRI at the Centre for Cognitive Neuroimaging, Glasgow, Scotland

Normal brain function involves the interaction of internal processes with incoming sensory stimuli. We have created a series of brain imaging experiments (using 7T fMRI) that sample internal models and feedback mechanisms in early visual cortex. Primary visual cortex (V1) is the entry-stage for cortical processing of visual information. We can show that there are 3 information counter-streams concerned with: (1) retinotopic visual input, (2) top-down predictions of internal models generated by the brain, and (3) top-down imagery acting independently of the perception and prediction loop. Internal models amplify and disamplify incoming information, but there is also mental imagery not interfering with visual perception. Our results speak to the conceptual framework of predictive coding. Healthy brain function will strike a balance between the precision of prediction and prediction update based on prediction error. Our results incorporate state of the art, layer-specific ultra-high field fMRI and other imaging techniques. We argue that fMRI with its capability of measuring dendritic energy consumption is sensitive to activity in different parts of layer spanning neurons, enriching our computational understanding of counter stream brain mechanisms. 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

What can fishes teach us about the brain?

Lecture
Date:
Tuesday, January 19, 2021
Hour: 12:30
Location:
Prof. Ronen Segev
|
Life Sciences Department Ben Gurion University of the Negev

Fishes have diverged in evolution from the mammalian linage some 450 million years ago and as a result fishes’ brain structure is different from the fundamental design of the mammalian, reptilian and avian brains. This raises the question what can we learn from the ability of fishes to solve different tasks. I will discuss how aspects navigation is implemented in the goldfish brain. Zoom link: https://weizmann.zoom.us/j/96608033618?pwd=SEdJUkR2ZzRBZ3laUUdGbWR1VFJTdz09 Meeting ID: 966 0803 3618 Password: 564068

The Cortical-Hippocampal Interplay during Episodic Memory Retrieval in Humans

Lecture
Date:
Tuesday, January 19, 2021
Hour: 10:00 - 11:00
Location:
Yitzhak Norman (PhD Thesis Defense)
|
Prof. Rafi Malach Lab, Department of Neurobiology

One of the most remarkable functions of the human brain is the ability to recall a personal experience from the past and reenact it vividly in our mind, in a way that allows us to reflect upon the memory and derive from it relevant information that can guide our future behavior. My doctoral research explored the neuronal mechanisms that enable this core cognitive function in the human brain. Using rare electrophysiological recordings obtained from neurosurgical patients for clinical purposes I investigated and characterized the complex bidirectional interactions that occur between the hippocampus and the cerebral cortex during retrieval of conscious, reportable memories. My results are twofold. I first show that 1-2 seconds before the onset of individual recollections the hippocampus elicits transient electrical oscillations known as Sharp Wave Ripples (SWRs). Such oscillatory events have been extensively studied in animal models in recent years and were shown to reflect massive synchronization events during which millions of pyramidal neurons on the hippocampus output pathway fire simultaneously. My results demonstrate that the SWR events are selective to memory contents and play a major role in coordinating the re-activation of hippocampal-neocortical memory representations during retrieval. I show a tight coupling between SWR events and visual cortex activation, and reveal a massive peri-ripple activation of the default mode network. Second, I show that the cortex uses a flexible, goal-directed, "baseline shift" mechanism that allows the imposition of predefined boundaries on spontaneous recollections. Specifically, the results demonstrate that when free recall is limited to a particular category, the average neuronal activity level in cortical sites that represent the targeted category is steadily and significantly enhanced throughout the free recall period. Such steady-state excitatory enhancement is likely to introduce a category-specific bias in the cortical input arriving at the hippocampus, which may facilitate the reactivation of memory traces belonging to the targeted category and not others. Altogether, the results place hippocampal SWRs firmly as a central mechanism in the retrieval of human declarative memory. They demonstrate a central role for SWRs in coordinating the hippocampus-cortical dialogue during recollection and point to a flexible "baseline shift" mechanism that can account for the remarkable ease and precision by which we can constrain this dialogue to support retrieval goals. Zoom link to join: https://weizmann.zoom.us/j/92146113977?pwd=VmhuMEhBcTRYZDNWMVJ4bGJrR0lIdz09 Meeting ID: 92146113977 Password: 803220

Diffusion properties of intracellular metabolites: compartment specific probes for cell structure and physiology

Lecture
Date:
Tuesday, January 5, 2021
Hour: 12:30 - 13:30
Location:
Prof. Itamar Ronen
|
C.J. Gorter Center for High field MRI, Leiden University Medical Center, Leiden, The Netherlands

Diffusion weighted MRI (DWI) is the main neuroimaging modality used in non-invasive investigations of tissue microstructure, and provides quantitative cytomorphological information on a spatial scale well below the nominal resolution of MRI. The main limitation of DWI is its lack of compartmental specificity, as its “reporter molecule” is water, ubiquitous in all tissue compartments and cell types. Brain metabolites are mostly confined to the intracellular space, and their concentrations vary across cell types. Several metabolites give rise to quantifiable magnetic resonance spectroscopy (MRS) signatures, and are thus considered as compartment-specific and sometimes cell-specific markers. Sensitization of MRS to diffusion results in a set of diffusion properties for a variety of intracellular metabolites, from which microstructural information specific to the intracellular space can be obtained. A proper choice of experimental settings can be used to investigate properties that range from cytoplasmic viscosity and tortuosity of the intracellular space, to overall cell morphological features. The specificity of some metabolites to different cell types such as neurons and astrocytes opens the way to studying morphological properties of different cell populations and monitoring their modulation by physiological changes in health and disease. The presentation will introduce methodological concepts of diffusion-weighted MRS, followed by simple examples that demonstrate the unique ability of diffusion-weighted MRS to characterize cell-type specific structural features. Special emphasis will be bestowed on experimental and modelling frameworks that merge the specificity of diffusion-weighted MRS with the sensitivity of DWI to gain insights on tissue microstructure beyond what each method can separately provide. 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

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Optogenetics: from cells to circuits and behavior

Conference
Date:
Sunday, July 14, 2013
Hour: 08:00 - 18:00
Location:
David Lopatie Conference Centre

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WIS-Australia Symposium on Metabolic Syndroms

Conference
Date:
Sunday, May 12, 2013
Hour: 08:00 - 16:45
Location:
David Lopatie Conference Centre

Emotional memories and stress: from normal physiology to psychopathology

Conference
Date:
Thursday, April 25, 2013
Hour:
Location:
David Lopatie Conference Centre

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Brain Sciences open day

Conference
Date:
Thursday, February 7, 2013
Hour: 12:30 - 16:00
Location:
David Lopatie Conference Centre

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Inflammation: A friend & a foe

Conference
Date:
Sunday, February 3, 2013
Hour: 08:00 - 20:00
Location:
David Lopatie Conference Centre

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Aging of the Mind:Immunity in the middle of mind/body relationship

Conference
Date:
Monday, December 3, 2012
Hour:
Location:
David Lopatie Conference Centre

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Optogenetics symposium

Conference
Date:
Saturday, July 14, 2012
Hour:
Location:
David Lopatie Conference Centre

90th Birthday Meeting for Prof. David Samuel

Conference
Date:
Thursday, June 28, 2012
Hour:
Location:
Michael Sela Adutitorium

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Brain Sciences Open Day

Conference
Date:
Wednesday, March 7, 2012
Hour:
Location:
David Lopatie Conference Centre

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Mini-Symposium-Windows into the Mind:New Approaches to Brain and Cognition

Conference
Date:
Tuesday, January 3, 2012
Hour:
Location:
Arthur and Rochelle Belfer Building for Biomedical Research

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