All years
All events, All years
Deciphering non-neuronal cells fate in Alzheimer’s disease by next generation transcriptomics
Lecture
Monday, June 20, 2022
Hour: 11:30 - 12:30
Location:
Deciphering non-neuronal cells fate in Alzheimer’s disease by next generation transcriptomics
Mor Kenigsbuch
Advisors: Prof. Michal Schwartz
& Prof. Ido Amit
For decades, Alzheimer's disease (AD) was perceived as a disease of the neuron alone. However, research advances in recent years have challenged this concept and shed light on the critical roles of other cells within the central nervous system (CNS) and the periphery. Within the CNS, microglia and astrocytes were revealed to be key players in disease progression, while other cell types, such as oligodendrocytes, pericytes, and endothelial cells, remained relatively understudied. In my PhD, I focused on understanding how two non-neuronal cell types, the oligodendroglia in the brain parenchyma and the choroid plexus (CP) epithelium, respond to AD and how they possibly affect pathological processes. My research identified a cellular state of oligodendrocytes that significantly increased in association with brain pathology, which we termed disease-associated oligodendrocytes (DOLs). Oligodendrocytes with DOL signature could also be identified in a mouse model of tauopathy and other neurodegenerative and autoimmune inflammatory conditions, suggesting a common response of oligodendrocytes to severe deviation from homeostasis. In the second part of my PhD, I contributed to a research aiming to investigate the mechanisms underlying the decline of the CP's neuroprotective abilities in the context of AD. We found that exposure of choroid plexus epithelial cultures to 24-hydroxycholesterol (24-OH), the enzymatic product of the brain-specific enzyme cholesterol 24-hydroxylase (CYP46A1), results in downregulation of aging- related transcriptomic signatures-such as Interferon type I (IFN-I) associated inflammation. Moreover, we found that CYP46A1 is constitutively expressed by the CP of humans and mice but is reduced in AD patients and 5xFAD mice. Overexpression of Cyp46a1 at the CP in 5xFAD mice attenuated cognitive loss and brain inflammation. Our results suggest that CP CYP46A1 is an unexpected safeguard against chronic anti-viral-like responses that can be rescued when lost. Overall, my PhD work highlights the significance of studying the fate of non-neuronal cell types in neurodegenerative diseases, in general, and in AD, in particular, and emphasizes the potential of next- generation transcriptomic techniques as a powerful tool to unveil previously unexpected pathways and mechanisms involved in these diseases.
Zoom link-https://weizmann.zoom.us/j/98815291638?pwd=cnZTanhzWkEyYmh4Mjk4OWxHMGE5UT09
Meeting ID:988 1529 1638
Password:880170
Nonoscillatory coding and multiscale representation of ultra-large environments in the bat hippocampus
Lecture
Thursday, June 9, 2022
Hour: 15:00 - 16:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Nonoscillatory coding and multiscale representation of ultra-large environments in the bat hippocampus
Tamir Eliav
Prof. Nachum Ulanovsky Lab
Dept of Brain Sciences WIS
The hippocampus plays a key role in memory and navigation, and forms a cognitive map of the world: hippocampal ‘place cells’ encode the animal’s location by activating whenever the animal passes a particular region in the environment (the neuron’s ‘place field’). Over the last 50 years of hippocampal research, almost all studies have focused on rodents as animal models, using small laboratory experimental setups. In my research, I explored hippocampal representations in a naturalistic settings, in a unique animal model – the bat. My talk will outline two main stories:
(i) In rodents, hippocampal activity exhibits ‘theta oscillations’. These oscillations were proposed to support multiple functions, including memory and sequence formation. However, absence of clear theta in bats and humans has questioned these proposals. Surprisingly, we found that in bats hippocampal neurons exhibited nonoscillatory phase-coding. This highlights the importance of phase-coding, but not oscillations per se, for hippocampal function across species – including humans.
(ii) Real-world navigation requires spatial representation of very large environments. To investigate this, we wirelessly recorded from hippocampal dorsal CA1 neurons of bats flying in a long tunnel (200 meters). Place cells displayed a multifield multiscale code: Individual neurons exhibited multiple place fields of diverse sizes, ranging from 0.6 to 32 meters, and the fields of the same neuron differed up to 20-fold in size. Theoretical analysis showed that the multiscale code allows representing large environments with much better accuracy than other codes. Thus, by increasing the spatial scale, we uncovered a neural code that is radically different from classical spatial codes.
Together, these results highlight the power of the comparative approach, and demonstrate that studying the brain under naturalistic settings and behavior enables discovering new unknown aspects of the neural code.
Molecular mechanisms underlying neural circuit assembly in the mammalian visual system
Lecture
Thursday, June 9, 2022
Hour: 12:30 - 13:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Molecular mechanisms underlying neural circuit assembly in the mammalian visual system
Prof. Alex L. Kolodkin
Deputy Director Institute of Basic Biomedical Sciences
Kavli Neuroscience Discovery Institute
The Johns Hopkins School of Medicine
The assembly of neural circuits critical for visual system function includes the differentiation of select subtypes of amacrine cells (ACs) and retinal ganglion cells (RGCs), the elaboration of precise connections within the retina among ACs and RGCs, and targeting of RGC axons to their appropriate retino-recipient regions within the CNS. I will consider these events in the context of the mammalian accessory optic system (AOS), which is tuned to detect slow directional motion in order to stabilize images on the retina. This work implicates mutations in certain human genes that encode orthologues of proteins critical for assembling murine AOS circuits in phylogenetically conserved aspects of visual system function.
Thalamic regulation of prefrontal dynamics for cognitive control
Lecture
Tuesday, June 7, 2022
Hour: 15:30 - 16:30
Location:
Thalamic regulation of prefrontal dynamics for cognitive control
Prof. Michael Halassa
Dept of Brain and Cognitive Sciences, Massachusetts Institute of Technology
Interactions between the thalamus and cortex are critical for normal cognition. Although classical theories emphasize its role in transmitting signals to or between cortical areas, recent studies show that the thalamus modulates cortical function through additional mechanisms. In this talk, I will discuss findings that highlight the role of the mediodorsal (MD) thalamus in regulating prefrontal excitatory/inhibitory balance and effective connectivity during decision making. I will present recently published data showing that the MD thalamus dynamically adjusts prefrontal evidence integration according to incoming stimulus statistics. I will also present unpublished data showing how the thalamus may be a nexus for handling distinct types of task uncertainty. Given that MD-PFC interactions are known to be perturbed in schizophrenia, these findings may be relevant to suboptimal management of uncertainty that leads to aberrant beliefs. If time allows, I will present early collaborative work in that domain.
Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Architecture and function of small neuronal networks
Lecture
Monday, June 6, 2022
Hour: 13:30 - 15:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Architecture and function of small neuronal networks
Adam Haber
Prof. Elad Schneidman Lab
Neurons in the brain form complex networks of synaptic connections. These elaborate networks define the physical scaffold on which neural activity occurs, and shape the collective dynamics of groups of neurons. In this talk, I will present my work on understanding the structural design principles of neural networks, and the relations between their architecture and their functional properties. First, I will ask what are the structural features that shape the function of neural networks, and show we can learn these features from large ensembles of simulated networks. Second, I will discuss how a strong biological constraint on the structure of neural networks does not incur a computational cost, and may even be functionally beneficial. Third, I will show how we can build connectomes which capture both the structure and the function of real data, using a small number of simple biological features.
Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Fast multimodal imaging of brain dynamics underlying sleep and wakefulness
Lecture
Tuesday, May 17, 2022
Hour: 14:00 - 15:00
Location:
Fast multimodal imaging of brain dynamics underlying sleep and wakefulness
Dr. Laura Lewis
Center for Systems Neuroscience
Boston University
When we fall asleep, brain function and physiology are rapidly transformed. Understanding the neural basis of sleep requires imaging methods that can capture multiple aspects of brain physiology at fast timescales. We develop approaches for analyzing human brain physiology using multimodal neuroimaging, and apply them to investigate the neural origins and consequences of sleep. We found that accelerated methods for fMRI can enable imaging subsecond neural dynamics throughout the human brain. We applied these methods to investigate the neural dynamics that occur at state transitions, and identified temporal sequences within thalamocortical networks that precede the moment of awakening from sleep. In addition, we developed a method to image cerebrospinal fluid flow, and discovered large waves of fluid flow that appear in the sleeping human brain. Together, these studies highlight the new biological information that can be extracted from fast fMRI data, and use this approach to discover neurophysiological dynamics unique to the sleeping brain.
Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Brain plasticity: Regulation and Modulation
Conference
Monday, May 16, 2022
Hour: 08:00 - 18:00
Location:
The David Lopatie Conference Centre
Brain plasticity: Regulation and Modulation
Models of Human Memory
Lecture
Tuesday, May 3, 2022
Hour: 12:30 - 13:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Models of Human Memory
Prof. Misha Tsodyks
Dept of Brain Sciences, WIS
Human memory is a multi-stage process that in real life cannot be easily quantified let alone predicted by any kind of mathematical model. Cognitive psychologists developed experimental paradigms to overcome the first problem by using randomly assembled lists of words or other items for recognition and recall. Results of these experiments can be precisely characterized, and we recently proposed a set of mathematical models that are based on simple assumptions that can be analytically solved and provide surprisingly accurate predictions tested on Amazon Mechanical Turk internet platform. The main innovation of this approach to modeling memory is that (i) it is based on a very small set of basic principles and has little to no free parameters and (ii) assumes deterministic processes underlying memory. In particular, our recall model results in the prediction with not a single free parameter, indicating full universality of this memory component. Our model for forgetting has one free integer parameter, and indeed our experiments show that different types of items exhibit different rate of forgetting. The most ambitious part of this project is to generalize the quantitative approach to memory to more meaningful material such as narratives. We are designing quantitative measures of performance in these experiments. Our preliminary results indicate interesting features of performance for meaningful material, in particular the recall is more structured and uniform across subjects. We believe that better understanding of memory processes with meaningful material will allow the future AI systems to achieve a better and more ‘human’ level of processing of natural language.
Representation of 3D space in the mammalian brain: From 3D grid cells in flying bats to 3D perception in flying humans
Lecture
Wednesday, April 27, 2022
Hour: 12:30 - 13:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Representation of 3D space in the mammalian brain: From 3D grid cells in flying bats to 3D perception in flying humans
Gily Ginosar
Prof. Nachum Ulanovsky Lab
Dept of Brain Sciences, WIS
While our world is three-dimensional (3D), spatial perception is most often studied in animals and humans navigating across 2D surfaces. I will present two cases in which the consideration of the 3D nature of the world has led us to surprising results. The first case regards the neural recording of mammalian grid cells. Grid cells that are recorded over 2D surfaces create a hexagonal-shaped repetitive lattice, which inspired many theoretical studies to investigate the pattern’s mechanism and function. Upon recording in bats flying through 3D space, we found that grid cells did not exhibit a hexagonal global lattice, but rather showed a local order – with grid-fields exhibiting fixed local distances. Our results in 3D strongly argue against most of the prevailing models of grid-cell function, and we suggest a unified model that explains the results in both 2D and 3D. The second case regards the perception of 3D space in humans. Different behavioral studies have shown contradicting evidence of human perception of 3D space being either isotropic or vertically compressed. We addressed this question using human experts in 3D motion and navigation – fighter pilots – studied in a flight simulator. We considered two aspects of the perception of 3D space: surrounding space and travelled space. We show that different aspects of the perception of space are shaped differently with experience: whereas the perception of the 3D surrounding space was vertically compressed in both expert and non-expert subjects, fighter pilots exhibited isotropic perception of travelled space, whereas non-expert subjects retained a distorted perception. Together, our research sheds light on the differences and similarities between the coding of 3D versus 2D space, in both animals and humans.
Dopamine release is inversely related to economic demand
Lecture
Tuesday, April 26, 2022
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dopamine release is inversely related to economic demand
Prof. Neir Eshel
Dept of Psychiatry and Behavioral Sciences
Stanford University
Decision-making requires a consideration of both costs and benefits. Although mesolimbic dopamine (DA) plays an established role in reward-related decisions, there has been longstanding controversy over its sensitivity to costs vs benefits. Manipulations of DA function imply a primary role in mediating cost calculations, while DA recordings suggest a preference for encoding benefit. These studies often confound cost and benefit by varying both simultaneously, and rarely combine correlational and causal tools to explore how encoding relates to behavior. Here we independently varied costs and benefits, studying DA's role using both recording and manipulation. We found that DA release reflects changes in both cost and benefit, although the precise relationship depended on the time within a trial and the site of DA release. Then we used behavioral economics to probe how these patterns of DA release relate to two important behavioral parameters: a mouse's preferred level of reward consumption and the amount of work it is willing to expend to maintain that consumption. We found that DA release in the nucleus accumbens core and dorsolateral striatum does not predict an animal's preferred level of consumption. It does, however, strongly reflect an animal's willingness to work for reward. Surprisingly, the more DA released for each reward, the less demand for that reward. The inverse relationship between DA release and demand held true both for natural rewards and optogenetic stimulation of DA release in both striatal targets. Our findings support an inverted-U model of dopamine and reinforcement, where a minimal level of DA release is critical to motivate behavior, but increments above that level actually reduce demand.
Link to join:
https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Pages
All years
All events, All years
Deciphering non-neuronal cells fate in Alzheimer’s disease by next generation transcriptomics
Lecture
Monday, June 20, 2022
Hour: 11:30 - 12:30
Location:
Deciphering non-neuronal cells fate in Alzheimer’s disease by next generation transcriptomics
Mor Kenigsbuch
Advisors: Prof. Michal Schwartz
& Prof. Ido Amit
For decades, Alzheimer's disease (AD) was perceived as a disease of the neuron alone. However, research advances in recent years have challenged this concept and shed light on the critical roles of other cells within the central nervous system (CNS) and the periphery. Within the CNS, microglia and astrocytes were revealed to be key players in disease progression, while other cell types, such as oligodendrocytes, pericytes, and endothelial cells, remained relatively understudied. In my PhD, I focused on understanding how two non-neuronal cell types, the oligodendroglia in the brain parenchyma and the choroid plexus (CP) epithelium, respond to AD and how they possibly affect pathological processes. My research identified a cellular state of oligodendrocytes that significantly increased in association with brain pathology, which we termed disease-associated oligodendrocytes (DOLs). Oligodendrocytes with DOL signature could also be identified in a mouse model of tauopathy and other neurodegenerative and autoimmune inflammatory conditions, suggesting a common response of oligodendrocytes to severe deviation from homeostasis. In the second part of my PhD, I contributed to a research aiming to investigate the mechanisms underlying the decline of the CP's neuroprotective abilities in the context of AD. We found that exposure of choroid plexus epithelial cultures to 24-hydroxycholesterol (24-OH), the enzymatic product of the brain-specific enzyme cholesterol 24-hydroxylase (CYP46A1), results in downregulation of aging- related transcriptomic signatures-such as Interferon type I (IFN-I) associated inflammation. Moreover, we found that CYP46A1 is constitutively expressed by the CP of humans and mice but is reduced in AD patients and 5xFAD mice. Overexpression of Cyp46a1 at the CP in 5xFAD mice attenuated cognitive loss and brain inflammation. Our results suggest that CP CYP46A1 is an unexpected safeguard against chronic anti-viral-like responses that can be rescued when lost. Overall, my PhD work highlights the significance of studying the fate of non-neuronal cell types in neurodegenerative diseases, in general, and in AD, in particular, and emphasizes the potential of next- generation transcriptomic techniques as a powerful tool to unveil previously unexpected pathways and mechanisms involved in these diseases.
Zoom link-https://weizmann.zoom.us/j/98815291638?pwd=cnZTanhzWkEyYmh4Mjk4OWxHMGE5UT09
Meeting ID:988 1529 1638
Password:880170
Nonoscillatory coding and multiscale representation of ultra-large environments in the bat hippocampus
Lecture
Thursday, June 9, 2022
Hour: 15:00 - 16:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Nonoscillatory coding and multiscale representation of ultra-large environments in the bat hippocampus
Tamir Eliav
Prof. Nachum Ulanovsky Lab
Dept of Brain Sciences WIS
The hippocampus plays a key role in memory and navigation, and forms a cognitive map of the world: hippocampal ‘place cells’ encode the animal’s location by activating whenever the animal passes a particular region in the environment (the neuron’s ‘place field’). Over the last 50 years of hippocampal research, almost all studies have focused on rodents as animal models, using small laboratory experimental setups. In my research, I explored hippocampal representations in a naturalistic settings, in a unique animal model – the bat. My talk will outline two main stories:
(i) In rodents, hippocampal activity exhibits ‘theta oscillations’. These oscillations were proposed to support multiple functions, including memory and sequence formation. However, absence of clear theta in bats and humans has questioned these proposals. Surprisingly, we found that in bats hippocampal neurons exhibited nonoscillatory phase-coding. This highlights the importance of phase-coding, but not oscillations per se, for hippocampal function across species – including humans.
(ii) Real-world navigation requires spatial representation of very large environments. To investigate this, we wirelessly recorded from hippocampal dorsal CA1 neurons of bats flying in a long tunnel (200 meters). Place cells displayed a multifield multiscale code: Individual neurons exhibited multiple place fields of diverse sizes, ranging from 0.6 to 32 meters, and the fields of the same neuron differed up to 20-fold in size. Theoretical analysis showed that the multiscale code allows representing large environments with much better accuracy than other codes. Thus, by increasing the spatial scale, we uncovered a neural code that is radically different from classical spatial codes.
Together, these results highlight the power of the comparative approach, and demonstrate that studying the brain under naturalistic settings and behavior enables discovering new unknown aspects of the neural code.
Molecular mechanisms underlying neural circuit assembly in the mammalian visual system
Lecture
Thursday, June 9, 2022
Hour: 12:30 - 13:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Molecular mechanisms underlying neural circuit assembly in the mammalian visual system
Prof. Alex L. Kolodkin
Deputy Director Institute of Basic Biomedical Sciences
Kavli Neuroscience Discovery Institute
The Johns Hopkins School of Medicine
The assembly of neural circuits critical for visual system function includes the differentiation of select subtypes of amacrine cells (ACs) and retinal ganglion cells (RGCs), the elaboration of precise connections within the retina among ACs and RGCs, and targeting of RGC axons to their appropriate retino-recipient regions within the CNS. I will consider these events in the context of the mammalian accessory optic system (AOS), which is tuned to detect slow directional motion in order to stabilize images on the retina. This work implicates mutations in certain human genes that encode orthologues of proteins critical for assembling murine AOS circuits in phylogenetically conserved aspects of visual system function.
Thalamic regulation of prefrontal dynamics for cognitive control
Lecture
Tuesday, June 7, 2022
Hour: 15:30 - 16:30
Location:
Thalamic regulation of prefrontal dynamics for cognitive control
Prof. Michael Halassa
Dept of Brain and Cognitive Sciences, Massachusetts Institute of Technology
Interactions between the thalamus and cortex are critical for normal cognition. Although classical theories emphasize its role in transmitting signals to or between cortical areas, recent studies show that the thalamus modulates cortical function through additional mechanisms. In this talk, I will discuss findings that highlight the role of the mediodorsal (MD) thalamus in regulating prefrontal excitatory/inhibitory balance and effective connectivity during decision making. I will present recently published data showing that the MD thalamus dynamically adjusts prefrontal evidence integration according to incoming stimulus statistics. I will also present unpublished data showing how the thalamus may be a nexus for handling distinct types of task uncertainty. Given that MD-PFC interactions are known to be perturbed in schizophrenia, these findings may be relevant to suboptimal management of uncertainty that leads to aberrant beliefs. If time allows, I will present early collaborative work in that domain.
Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Architecture and function of small neuronal networks
Lecture
Monday, June 6, 2022
Hour: 13:30 - 15:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Architecture and function of small neuronal networks
Adam Haber
Prof. Elad Schneidman Lab
Neurons in the brain form complex networks of synaptic connections. These elaborate networks define the physical scaffold on which neural activity occurs, and shape the collective dynamics of groups of neurons. In this talk, I will present my work on understanding the structural design principles of neural networks, and the relations between their architecture and their functional properties. First, I will ask what are the structural features that shape the function of neural networks, and show we can learn these features from large ensembles of simulated networks. Second, I will discuss how a strong biological constraint on the structure of neural networks does not incur a computational cost, and may even be functionally beneficial. Third, I will show how we can build connectomes which capture both the structure and the function of real data, using a small number of simple biological features.
Zoom Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Fast multimodal imaging of brain dynamics underlying sleep and wakefulness
Lecture
Tuesday, May 17, 2022
Hour: 14:00 - 15:00
Location:
Fast multimodal imaging of brain dynamics underlying sleep and wakefulness
Dr. Laura Lewis
Center for Systems Neuroscience
Boston University
When we fall asleep, brain function and physiology are rapidly transformed. Understanding the neural basis of sleep requires imaging methods that can capture multiple aspects of brain physiology at fast timescales. We develop approaches for analyzing human brain physiology using multimodal neuroimaging, and apply them to investigate the neural origins and consequences of sleep. We found that accelerated methods for fMRI can enable imaging subsecond neural dynamics throughout the human brain. We applied these methods to investigate the neural dynamics that occur at state transitions, and identified temporal sequences within thalamocortical networks that precede the moment of awakening from sleep. In addition, we developed a method to image cerebrospinal fluid flow, and discovered large waves of fluid flow that appear in the sleeping human brain. Together, these studies highlight the new biological information that can be extracted from fast fMRI data, and use this approach to discover neurophysiological dynamics unique to the sleeping brain.
Link: https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
Models of Human Memory
Lecture
Tuesday, May 3, 2022
Hour: 12:30 - 13:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Models of Human Memory
Prof. Misha Tsodyks
Dept of Brain Sciences, WIS
Human memory is a multi-stage process that in real life cannot be easily quantified let alone predicted by any kind of mathematical model. Cognitive psychologists developed experimental paradigms to overcome the first problem by using randomly assembled lists of words or other items for recognition and recall. Results of these experiments can be precisely characterized, and we recently proposed a set of mathematical models that are based on simple assumptions that can be analytically solved and provide surprisingly accurate predictions tested on Amazon Mechanical Turk internet platform. The main innovation of this approach to modeling memory is that (i) it is based on a very small set of basic principles and has little to no free parameters and (ii) assumes deterministic processes underlying memory. In particular, our recall model results in the prediction with not a single free parameter, indicating full universality of this memory component. Our model for forgetting has one free integer parameter, and indeed our experiments show that different types of items exhibit different rate of forgetting. The most ambitious part of this project is to generalize the quantitative approach to memory to more meaningful material such as narratives. We are designing quantitative measures of performance in these experiments. Our preliminary results indicate interesting features of performance for meaningful material, in particular the recall is more structured and uniform across subjects. We believe that better understanding of memory processes with meaningful material will allow the future AI systems to achieve a better and more ‘human’ level of processing of natural language.
Representation of 3D space in the mammalian brain: From 3D grid cells in flying bats to 3D perception in flying humans
Lecture
Wednesday, April 27, 2022
Hour: 12:30 - 13:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Representation of 3D space in the mammalian brain: From 3D grid cells in flying bats to 3D perception in flying humans
Gily Ginosar
Prof. Nachum Ulanovsky Lab
Dept of Brain Sciences, WIS
While our world is three-dimensional (3D), spatial perception is most often studied in animals and humans navigating across 2D surfaces. I will present two cases in which the consideration of the 3D nature of the world has led us to surprising results. The first case regards the neural recording of mammalian grid cells. Grid cells that are recorded over 2D surfaces create a hexagonal-shaped repetitive lattice, which inspired many theoretical studies to investigate the pattern’s mechanism and function. Upon recording in bats flying through 3D space, we found that grid cells did not exhibit a hexagonal global lattice, but rather showed a local order – with grid-fields exhibiting fixed local distances. Our results in 3D strongly argue against most of the prevailing models of grid-cell function, and we suggest a unified model that explains the results in both 2D and 3D. The second case regards the perception of 3D space in humans. Different behavioral studies have shown contradicting evidence of human perception of 3D space being either isotropic or vertically compressed. We addressed this question using human experts in 3D motion and navigation – fighter pilots – studied in a flight simulator. We considered two aspects of the perception of 3D space: surrounding space and travelled space. We show that different aspects of the perception of space are shaped differently with experience: whereas the perception of the 3D surrounding space was vertically compressed in both expert and non-expert subjects, fighter pilots exhibited isotropic perception of travelled space, whereas non-expert subjects retained a distorted perception. Together, our research sheds light on the differences and similarities between the coding of 3D versus 2D space, in both animals and humans.
Dopamine release is inversely related to economic demand
Lecture
Tuesday, April 26, 2022
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dopamine release is inversely related to economic demand
Prof. Neir Eshel
Dept of Psychiatry and Behavioral Sciences
Stanford University
Decision-making requires a consideration of both costs and benefits. Although mesolimbic dopamine (DA) plays an established role in reward-related decisions, there has been longstanding controversy over its sensitivity to costs vs benefits. Manipulations of DA function imply a primary role in mediating cost calculations, while DA recordings suggest a preference for encoding benefit. These studies often confound cost and benefit by varying both simultaneously, and rarely combine correlational and causal tools to explore how encoding relates to behavior. Here we independently varied costs and benefits, studying DA's role using both recording and manipulation. We found that DA release reflects changes in both cost and benefit, although the precise relationship depended on the time within a trial and the site of DA release. Then we used behavioral economics to probe how these patterns of DA release relate to two important behavioral parameters: a mouse's preferred level of reward consumption and the amount of work it is willing to expend to maintain that consumption. We found that DA release in the nucleus accumbens core and dorsolateral striatum does not predict an animal's preferred level of consumption. It does, however, strongly reflect an animal's willingness to work for reward. Surprisingly, the more DA released for each reward, the less demand for that reward. The inverse relationship between DA release and demand held true both for natural rewards and optogenetic stimulation of DA release in both striatal targets. Our findings support an inverted-U model of dopamine and reinforcement, where a minimal level of DA release is critical to motivate behavior, but increments above that level actually reduce demand.
Link to join:
https://weizmann.zoom.us/j/95406893197?pwd=REt5L1g3SmprMUhrK3dpUDJVeHlrZz09
Meeting ID: 954 0689 3197
Password: 750421
An attempt to account for multiple perceptual memory behaviors in a single framework
Lecture
Wednesday, April 13, 2022
Hour: 15:00 - 16:00
Location:
Gerhard M.J. Schmidt Lecture Hall
An attempt to account for multiple perceptual memory behaviors in a single framework
Prof. Mathew Diamond
Cognitive Neuroscience SISSA Trieste Italy
Rats (if trained appropriately) can apply to some set of tactile stimuli a multitude of different perceptual and memory capacities. For instance, they can express working memory, where the most recent stimulus has to be stored and retrieved to support a comparison to the ongoing stimulus. They can express reference memory, where the ongoing stimulus has to be compared to some stable, internal boundary. They can change that internal boundary as a function of stimulus statistics. They can learn to ignore stimuli of the same sensory modality, if untagged by an acoustic cue. While it might seem easiest to draw up computational/functional frameworks tailor-made to each behavior, we are trying to explain several different behaviors by common algorithms. This informal discussion will mainly present ongoing psychophysical studies, with a few preliminary physiological added here and there.
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