Past events | The department of Brain Sciences

All events, event

The evolution and development of critical periods of cortical plasticity

Lecture

Date:

Tuesday, May 7, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Department of Neurobiology, David Geffen School of Medicine at UCLA

Consciousness and the brain: comparing and testing neuroscientific theories of consciousness

Lecture

Date:

Tuesday, April 16, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Liad Mudrik

|

Sagol School of Neuroscience, School of Psychological Sciences, Tel Aviv University

For centuries, consciousness was considered to be outside the reach of scientific investigation. Yet in recent decades, more and more studies have tried to probe the neural correlates of conscious experience, and several neuronally-inspired theories for consciousness have emerged. In this talk, I will focus on four leading theories of consciousness: Global Neuronal Workspace (GNW), integrated Information Theory (IIT), Recurrent Processing Theory (RPT) and Higher Order Theory (HOT). I will first shortly present the guiding principles of these theories. Then, I will provide a bird's-eye view of the field, using the results of a large-scale quantitative and analytic review we conducted, examining all studies that either empirically tested these theories or interpreted their findings with respect to at least one of them. Finally, I will describe the first results of the Cogitate consortium - an adversarial collaboration aimed at testing GNW and IIT.

Beyond Touch: Exploring Audible Aspects of Rodent Whisking

Lecture

Date:

Tuesday, April 9, 2024

Hour: 14:00 - 15:00

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Ben Efron PhD Thesis Defense

|

Advisor: Prof. Ilan Lampl

Sensory processing is fundamental for animal adaptation and survival, linking them to their environments. Understanding the nervous system's integration of sensory information is crucial for comprehending behavior and cognition. This process involves integrating external cues across modalities, along with internal states, cognitive processes, and motor control, leading to complex behaviors and a nuanced understanding of the world. To facilitate research on these processes, we aimed to identify natural behaviors that produce both auditory and somatosensory stimuli, steering clear of artificial stimulus sources. We discovered that whisking, previously considered a unimodal behavior associated solely with tactile sensations, also produces sounds with distinctive acoustic features within the auditory frequency range of mice. We explored the auditory neuronal representation of sounds generated by whisking and their implications for behavioral performance. We demonstrate that sounds produced by whisking elicit diverse neuronal responses in the auditory cortex, encoding the object's identity and the mouse's whisking state, even in the absence of tactile sensations. Furthermore, we show that mice are capable of completing behavioral tasks relying solely on auditory cues generated by whisking against objects.

Information processing in spiking networks: Converging assemblies

Lecture

Date:

Tuesday, April 9, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Eran Stark

|

Sagol Department of Neurobiology Haifa University

How information is processed within the brain is a key question in systems neuroscience. We address the issue in spiking neuronal networks of freely moving mice. I will describe our recent findings and conclusions pertaining to three specific information processing steps: transmission, representation, and storage. First, using feedforward optogenetic injection of white noise input to a small group of adjacent neocortical excitatory cells, we find that spike transmission to a postsynaptic cell exhibits error correction, improved precision, and temporal coding. The results are consistent with a nonlinear coincidence detection model in the postsynaptic neuron. Second, by triggering input on animal kinematics, we create an artificial place field in an otherwise-silent pyramidal cell. In hippocampal region CA1 but not in the neocortex, artificial fields exhibit synthetic phase precession that persists for a full cycle. The local conversion of an induced rate code into an emerging phase code is compatible with a dual-oscillator interference model. Third, by triggering input on spontaneous spiking, we impose self-terminating spike patterns in a group of presynaptic excitatory neurons and a postsynaptic cell. The precise timing of all pre- and postsynaptic spikes has a more substantial impact on long-lasting effective connectivity than that of individual cell pairs, revealing an unexpected plasticity mechanism. We conclude that intrinsic properties of single neurons support millisecond-timescale operations, and that cortical networks are organized in functional modules which we refer to as “converging assemblies”.

Studying Ageing and Neurodegenerative Brain with Quantitative MRI

Lecture

Date:

Tuesday, April 2, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Aviv Mezer

|

ELSC for Brain Sciences The Hebrew University of Jerusalem

Aging and neurodegeneration are associated with changes in brain tissue at the molecular level, affecting its organization, density, and composition. These changes can be detected using quantitative MRI (qMRI), which provides physical measures that are sensitive to structural alterations. However, a major challenge in brain research is to relate physical estimates to their underlying biological sources. In this talk, I will discuss the community's efforts to use qMRI to identify biological processes that underlie changes in brain tissue. Specifically, I will highlight approaches for differentiating between changes in the concentration and composition of myelin and iron during aging. By exploring the molecular landscape of the aging and neurodegenerative brain using qMRI, we aim to gain a better understanding of these processes and potentially provide new metrics for evaluating them.

Hippocampal pathology and pathophysiology in the development of temporal lobe epileptogenesis

Lecture

Date:

Sunday, March 24, 2024

Hour: 11:00 - 12:00

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Robert S. Sloviter

|

The Neuroscience Institute MRC 245 Morehouse School of Medicine, Atlanta GA

In families with febrile seizures and temporal lobe epilepsy, mutations affecting different GABAergic mechanisms suggest that failure of chloride conductance to limit depolarization may be directly epileptogenic. This “GABAergic disinhibition” hypothesis has been discounted historically for two reasons. First, early attempts to produce hippocampal sclerosis and epilepsy simply by eliminating hippocampal GABA neurons consistently failed to do so. Second, the notion persists that because clinical epilepsy diagnosis is typically delayed for years or decades after brain injury, temporal lobe epileptogenesis should be presumed to involve a complex pathological transformation process that reaches completion during this “latent period.” Recent advances clarify both issues. Although spatially limited hippocampal GABA neuron ablation causes only submaximal granule cell hyperexcitability, more spatially extensive ablation maximizes granule cell hyperexcitability and triggers nonconvulsive granule cell status epilepticus, hippocampal sclerosis, and epilepsy. Recent studies also show that disinhibited granule cells begin to generate clinically subtle seizures immediately post-injury, and these seizures then gradually increase in duration to become clinically obvious. Therefore, rather than being a seizure-free “gestational” state of potentially interruptible epileptogenesis, the “latent period” is more likely an active epileptic state when barriers to seizure spread and clinical expression are gradually overcome by a kindling process. The likelihood that an epileptic brain state exists long before clinical diagnosis has significant implications for anti-epileptogenesis studies. The location, magnitude, and spatial extent of inherited, autoimmune, and injury-induced disinhibition may determine the latency to clinical diagnosis and establish the continuum between the benign, treatable, and refractory forms of temporal lobe epilepsy.

Dimensionality bottleneck uncovers simple action selection rules in hunting zebrafish

Lecture

Date:

Tuesday, March 19, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Lilach Avitan

|

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

Animal movements are complex, high-dimensional, and lead to many different consequences. Thus, efficiently quantifying the behavior and uncovering the underlying representation used by the animal pose a great challenge. Tracking freely behaving zebrafish larvae using a high-speed camera and analyzing their movements, we reveal that zebrafish movements can be described using exactly two parameters. Mapping all possible two-dimensional movement representations, we identified the representation used by the fish. We show that fish do not trivially represent distance and angles as separate parameters, but rather mix them nonlinearly. Moreover, when hunting, this specific nonlinear relation depends on the prey angle and further dictates a particular set of potential movements. These results uncover, for the first time, the underlying action selection principles of hunting behavior, suggesting that behind this seemingly complex behavior there is a simple and low-dimensional process.

A brain-computer interface for studying long-term changes of hippocampal neural codes

Lecture

Date:

Wednesday, March 13, 2024

Hour: 15:30 - 16:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Linor Baliti Turgeman-PhD Thesis Defense

|

Prof. Yaniv Ziv Lab

Brain-computer interfaces (BCI), have important applications both in medicine and as a research tool. Typically, BCIs rely on electrode arrays to capture electrical signals, which are then processed by algorithms to translate neural activity into actions of an external device. However, these electrophysiological techniques are often inadequate for tracking large populations of the same neurons over timescales longer than ~1 day. To address this, we developed calcium imaging-based BCI for freely behaving mice, facilitating continuous recording and analysis of specific neuronal populations over extended periods. This BCI allowed investigating the long-term neuronal coding dynamics in the hippocampus, revealing changes in neuronal population activity both within and across days. I am hopeful that this BCI will advance studies on spatial cognition and long-term memory.

Travelling waves or sequentially activated modules: mapping the granularity of cortical propagation

Lecture

Date:

Tuesday, March 12, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Mark Shein-Idelson

|

Dept of Neurobiology, Faculty of Life Sciences Tel Aviv University

: Numerous studies have identified travelling waves in the cortex and suggested they play important roles in brain processing. These waves are most often measured using macroscopic methods that do not allow assessing wave dynamics at the single neuron scale and analyzed using techniques that smear neuronal excitability boundaries. In my talk, I will present a new approach for discriminating travelling waves from modular activation. Using this approach I will show that Calcium dynamics in mouse cortex and spiking activity in turtle cortex are dominated by modular activation rather than by propagating waves. I will then show how sequentially activating two discrete brain areas can appear as travelling waves in EEG simulations and present an analytical model in which modular activation generates wave-like activity with variable directions, velocities, and spatial patterns. I will end by illustrating why a careful distinction between modular and wave excitability profiles across scales will be critical for understanding the nature of cortical computations.

Mapping the world around us: A topology-preserved schema of space that supports goal-directed navigation

Lecture

Date:

Tuesday, February 20, 2024

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Raunak Basu

|

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

Successful goal-directed navigation requires estimating one’s current position in the environment, representing the future goal location, and maintaining a map that preserves the topological relationship between positions. In addition, we often need to implement similar navigational strategies in a continuously changing environment, thereby necessitating certain invariance in the underlying spatial maps. Previous research has identified neurons in the hippocampus and parahippocampal cortices that fire specifically when an animal visits a particular location, implying the presence of a spatial map in the brain. However, this map largely encodes the current position of an animal and is context-dependent, whereby changing the room or shape of the arena results in a new map orthogonal to the previous one. These observations raise the question, are there other spatial maps that fulfill the cognitive requirements necessary for goal-directed navigation? Using a goal-directed navigation task with multiple reward locations, we observed that neurons in the orbitofrontal cortex (OFC) exhibit distinct firing patterns depending on the goal location, and this goal-specific OFC activity originates even before the onset of the journey. Further, the difference in the ensemble firing patterns representing two target locations is proportional to the physical distance between these locations, implying the preservation of spatial topology. Finally, carrying out the task across different spatial contexts revealed that the mapping of target locations in the OFC is largely preserved and that the maps formed in two different contexts occupy similar neural subspaces and could be aligned by a linear transformation. Taken together, the OFC forms a topology-preserved schema of spatial locations that is used to represent the future spatial goal, making it a potentially crucial brain region for planning context-invariant goal-directed navigational strategies.

Pages

All events, event

The evolution and development of critical periods of cortical plasticity

Lecture

Date:

Tuesday, May 7, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Department of Neurobiology, David Geffen School of Medicine at UCLA

Consciousness and the brain: comparing and testing neuroscientific theories of consciousness

Lecture

Date:

Tuesday, April 16, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Liad Mudrik

|

Sagol School of Neuroscience, School of Psychological Sciences, Tel Aviv University

For centuries, consciousness was considered to be outside the reach of scientific investigation. Yet in recent decades, more and more studies have tried to probe the neural correlates of conscious experience, and several neuronally-inspired theories for consciousness have emerged. In this talk, I will focus on four leading theories of consciousness: Global Neuronal Workspace (GNW), integrated Information Theory (IIT), Recurrent Processing Theory (RPT) and Higher Order Theory (HOT). I will first shortly present the guiding principles of these theories. Then, I will provide a bird's-eye view of the field, using the results of a large-scale quantitative and analytic review we conducted, examining all studies that either empirically tested these theories or interpreted their findings with respect to at least one of them. Finally, I will describe the first results of the Cogitate consortium - an adversarial collaboration aimed at testing GNW and IIT.

Beyond Touch: Exploring Audible Aspects of Rodent Whisking

Lecture

Date:

Tuesday, April 9, 2024

Hour: 14:00 - 15:00

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Ben Efron PhD Thesis Defense

|

Advisor: Prof. Ilan Lampl

Sensory processing is fundamental for animal adaptation and survival, linking them to their environments. Understanding the nervous system's integration of sensory information is crucial for comprehending behavior and cognition. This process involves integrating external cues across modalities, along with internal states, cognitive processes, and motor control, leading to complex behaviors and a nuanced understanding of the world. To facilitate research on these processes, we aimed to identify natural behaviors that produce both auditory and somatosensory stimuli, steering clear of artificial stimulus sources. We discovered that whisking, previously considered a unimodal behavior associated solely with tactile sensations, also produces sounds with distinctive acoustic features within the auditory frequency range of mice. We explored the auditory neuronal representation of sounds generated by whisking and their implications for behavioral performance. We demonstrate that sounds produced by whisking elicit diverse neuronal responses in the auditory cortex, encoding the object's identity and the mouse's whisking state, even in the absence of tactile sensations. Furthermore, we show that mice are capable of completing behavioral tasks relying solely on auditory cues generated by whisking against objects.

Information processing in spiking networks: Converging assemblies

Lecture

Date:

Tuesday, April 9, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Eran Stark

|

Sagol Department of Neurobiology Haifa University

How information is processed within the brain is a key question in systems neuroscience. We address the issue in spiking neuronal networks of freely moving mice. I will describe our recent findings and conclusions pertaining to three specific information processing steps: transmission, representation, and storage. First, using feedforward optogenetic injection of white noise input to a small group of adjacent neocortical excitatory cells, we find that spike transmission to a postsynaptic cell exhibits error correction, improved precision, and temporal coding. The results are consistent with a nonlinear coincidence detection model in the postsynaptic neuron. Second, by triggering input on animal kinematics, we create an artificial place field in an otherwise-silent pyramidal cell. In hippocampal region CA1 but not in the neocortex, artificial fields exhibit synthetic phase precession that persists for a full cycle. The local conversion of an induced rate code into an emerging phase code is compatible with a dual-oscillator interference model. Third, by triggering input on spontaneous spiking, we impose self-terminating spike patterns in a group of presynaptic excitatory neurons and a postsynaptic cell. The precise timing of all pre- and postsynaptic spikes has a more substantial impact on long-lasting effective connectivity than that of individual cell pairs, revealing an unexpected plasticity mechanism. We conclude that intrinsic properties of single neurons support millisecond-timescale operations, and that cortical networks are organized in functional modules which we refer to as “converging assemblies”.

Studying Ageing and Neurodegenerative Brain with Quantitative MRI

Lecture

Date:

Tuesday, April 2, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Aviv Mezer

|

ELSC for Brain Sciences The Hebrew University of Jerusalem

Aging and neurodegeneration are associated with changes in brain tissue at the molecular level, affecting its organization, density, and composition. These changes can be detected using quantitative MRI (qMRI), which provides physical measures that are sensitive to structural alterations. However, a major challenge in brain research is to relate physical estimates to their underlying biological sources. In this talk, I will discuss the community's efforts to use qMRI to identify biological processes that underlie changes in brain tissue. Specifically, I will highlight approaches for differentiating between changes in the concentration and composition of myelin and iron during aging. By exploring the molecular landscape of the aging and neurodegenerative brain using qMRI, we aim to gain a better understanding of these processes and potentially provide new metrics for evaluating them.

Hippocampal pathology and pathophysiology in the development of temporal lobe epileptogenesis

Lecture

Date:

Sunday, March 24, 2024

Hour: 11:00 - 12:00

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Robert S. Sloviter

|

The Neuroscience Institute MRC 245 Morehouse School of Medicine, Atlanta GA

In families with febrile seizures and temporal lobe epilepsy, mutations affecting different GABAergic mechanisms suggest that failure of chloride conductance to limit depolarization may be directly epileptogenic. This “GABAergic disinhibition” hypothesis has been discounted historically for two reasons. First, early attempts to produce hippocampal sclerosis and epilepsy simply by eliminating hippocampal GABA neurons consistently failed to do so. Second, the notion persists that because clinical epilepsy diagnosis is typically delayed for years or decades after brain injury, temporal lobe epileptogenesis should be presumed to involve a complex pathological transformation process that reaches completion during this “latent period.” Recent advances clarify both issues. Although spatially limited hippocampal GABA neuron ablation causes only submaximal granule cell hyperexcitability, more spatially extensive ablation maximizes granule cell hyperexcitability and triggers nonconvulsive granule cell status epilepticus, hippocampal sclerosis, and epilepsy. Recent studies also show that disinhibited granule cells begin to generate clinically subtle seizures immediately post-injury, and these seizures then gradually increase in duration to become clinically obvious. Therefore, rather than being a seizure-free “gestational” state of potentially interruptible epileptogenesis, the “latent period” is more likely an active epileptic state when barriers to seizure spread and clinical expression are gradually overcome by a kindling process. The likelihood that an epileptic brain state exists long before clinical diagnosis has significant implications for anti-epileptogenesis studies. The location, magnitude, and spatial extent of inherited, autoimmune, and injury-induced disinhibition may determine the latency to clinical diagnosis and establish the continuum between the benign, treatable, and refractory forms of temporal lobe epilepsy.

Dimensionality bottleneck uncovers simple action selection rules in hunting zebrafish

Lecture

Date:

Tuesday, March 19, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Lilach Avitan

|

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

Animal movements are complex, high-dimensional, and lead to many different consequences. Thus, efficiently quantifying the behavior and uncovering the underlying representation used by the animal pose a great challenge. Tracking freely behaving zebrafish larvae using a high-speed camera and analyzing their movements, we reveal that zebrafish movements can be described using exactly two parameters. Mapping all possible two-dimensional movement representations, we identified the representation used by the fish. We show that fish do not trivially represent distance and angles as separate parameters, but rather mix them nonlinearly. Moreover, when hunting, this specific nonlinear relation depends on the prey angle and further dictates a particular set of potential movements. These results uncover, for the first time, the underlying action selection principles of hunting behavior, suggesting that behind this seemingly complex behavior there is a simple and low-dimensional process.

A brain-computer interface for studying long-term changes of hippocampal neural codes

Lecture

Date:

Wednesday, March 13, 2024

Hour: 15:30 - 16:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Linor Baliti Turgeman-PhD Thesis Defense

|

Prof. Yaniv Ziv Lab

Brain-computer interfaces (BCI), have important applications both in medicine and as a research tool. Typically, BCIs rely on electrode arrays to capture electrical signals, which are then processed by algorithms to translate neural activity into actions of an external device. However, these electrophysiological techniques are often inadequate for tracking large populations of the same neurons over timescales longer than ~1 day. To address this, we developed calcium imaging-based BCI for freely behaving mice, facilitating continuous recording and analysis of specific neuronal populations over extended periods. This BCI allowed investigating the long-term neuronal coding dynamics in the hippocampus, revealing changes in neuronal population activity both within and across days. I am hopeful that this BCI will advance studies on spatial cognition and long-term memory.

Travelling waves or sequentially activated modules: mapping the granularity of cortical propagation

Lecture

Date:

Tuesday, March 12, 2024

Hour: 12:30 - 13:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Mark Shein-Idelson

|

Dept of Neurobiology, Faculty of Life Sciences Tel Aviv University

: Numerous studies have identified travelling waves in the cortex and suggested they play important roles in brain processing. These waves are most often measured using macroscopic methods that do not allow assessing wave dynamics at the single neuron scale and analyzed using techniques that smear neuronal excitability boundaries. In my talk, I will present a new approach for discriminating travelling waves from modular activation. Using this approach I will show that Calcium dynamics in mouse cortex and spiking activity in turtle cortex are dominated by modular activation rather than by propagating waves. I will then show how sequentially activating two discrete brain areas can appear as travelling waves in EEG simulations and present an analytical model in which modular activation generates wave-like activity with variable directions, velocities, and spatial patterns. I will end by illustrating why a careful distinction between modular and wave excitability profiles across scales will be critical for understanding the nature of cortical computations.

Mapping the world around us: A topology-preserved schema of space that supports goal-directed navigation

Lecture

Date:

Tuesday, February 20, 2024

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Raunak Basu

|

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

Successful goal-directed navigation requires estimating one’s current position in the environment, representing the future goal location, and maintaining a map that preserves the topological relationship between positions. In addition, we often need to implement similar navigational strategies in a continuously changing environment, thereby necessitating certain invariance in the underlying spatial maps. Previous research has identified neurons in the hippocampus and parahippocampal cortices that fire specifically when an animal visits a particular location, implying the presence of a spatial map in the brain. However, this map largely encodes the current position of an animal and is context-dependent, whereby changing the room or shape of the arena results in a new map orthogonal to the previous one. These observations raise the question, are there other spatial maps that fulfill the cognitive requirements necessary for goal-directed navigation? Using a goal-directed navigation task with multiple reward locations, we observed that neurons in the orbitofrontal cortex (OFC) exhibit distinct firing patterns depending on the goal location, and this goal-specific OFC activity originates even before the onset of the journey. Further, the difference in the ensemble firing patterns representing two target locations is proportional to the physical distance between these locations, implying the preservation of spatial topology. Finally, carrying out the task across different spatial contexts revealed that the mapping of target locations in the OFC is largely preserved and that the maps formed in two different contexts occupy similar neural subspaces and could be aligned by a linear transformation. Taken together, the OFC forms a topology-preserved schema of spatial locations that is used to represent the future spatial goal, making it a potentially crucial brain region for planning context-invariant goal-directed navigational strategies.