Past events | The department of Brain Sciences

All events, All years

A mechanistic model of Macaque V1 cortex

Lecture

Date:

Monday, April 4, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Lai-Sang Young

|

Courant Institute of Mathematical Sciences New York University

I will report on some recent computational modeling work on the Macaque visual cortex. My co-authors Bob Shapley, Logan Chariker and I have constructed a semi-realistic model of LGN-to-4Ca, the input layer to V1 in the magnocellular pathway. As with most modeling work, our aim was to understand how cortex responds to stimuli. To do that, many authors have postulated transducer functions for specific sets of stimuli. We have chosen to take a fundamentally different route: we have chosen to simulate how cortex works, by simulating cortical dynamics on the level of neuron-to-neuron interactions. Using a single network model, we have been able to reproduce as emergent phenomena a fairly comprehensive set of experimental observations, including orientation selectivity, simple and complex cells, gamma rhythms etc. Specific aims of this project were (1) to reconcile the picture of Hubel & Wiesel with the sparseness of LGN, (2) to address the extent to which cortex is driven by feedforward vs recurrent inputs, (3) to replicate and explain the diversity of neuronal responses seen in real cortex, and (4) to connect all of the above to dynamical interactions in local neuronal populations.

Excitation-inhibition interplay in the thalamocortical pathway controls timing of motor actions

Lecture

Date:

Tuesday, March 29, 2016

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Yifat Prut

|

Dept of Medical Neurobiology, IMRIC and ELSC,The Hebrew University, Hadassah Medical School, Jerusalem

Proper performance of voluntary movements requires the integration of both spatial and temporal information about the ensuing movements. The timing of actions is often considered to be dictated by cerebellar output that is relayed to the motor cortex via the motor thalamus. We investigated the mechanisms by which the cerebellar-thalamo-cortical (CTC) system controls temporal properties of motor cortical activity. We found that in primates the CTC pathway efficiently recruits motor cortical neurons in primary motor and premotor areas. Cortical responses to CTC activation were dominated by prolonged inhibition mediated by a feedforward mechanism. We further found that cortical cells that integrated CTC input fired transiently and synchronously at movement onset, when the timing of action is dictated. Moreover, when preventing the flow of information in the pathway the phasic firing at movement onset was reduced, but the preferred direction of the cells remained unchanged. These changes in neural firing were correlated with altered motor behavior: the monkeys were able to perform the task but with increased reaction and movement times. These results suggest that the CTC system affects cortical firing by changing the excitation-inhibition balance at movement onset in an extensive network of TC-activated motor cortical neurons. In this manner, the temporal pattern of neural firing is shaped, and firing across groups of neurons is synchronized to generate transiently enhanced firing.

Colouring Labelled Lines: Multispectral Mapping and Activity-Dependent Silencing of Primary Afferents as Tools to follow up their Reorganization in Chronic Pain

Lecture

Date:

Tuesday, March 22, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Alexander Binshtok

|

Dept of Medical Neurobiology, Institute for Medical Research Israel Canada Faculty of Medicine, Safra Center for Brain Sciences, The Hebrew University, Jerusalem

Dissecting the role of horizontal cells for retinal processing

Lecture

Date:

Tuesday, March 15, 2016

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Dr. Karin Dedek

|

Neurosensorics University of Oldenburg, Germany

In the mammalian retina, visual information is transduced into electrical signals by photoreceptors. These signals are transmitted from photoreceptors to bipolar cells and on to ganglion cells, which inform the brain about contrast, form, color, object motion and other features of the visual world. On its route through the retina, visual information is modulated by inhibitory networks formed by horizontal and amacrine cells. Here, I focus on horizontal cells. At so-called triad synapses, these interneurons receive glutamatergic input from photoreceptors and provide feedback and feedforward signals to photoreceptors and bipolar cells, respectively. In recent years, we used different techniques to analyze the role of horizontal cells: we 1) deleted electrical synapses between horizontal cells, 2) ablated the entire horizontal cell population, and 3) selectively silenced horizontal cells by input deprivation. From these studies we gathered that horizontal cells are important for the spatial and temporal tuning of ganglion cells and are necessary to maintain the integrity of the first synapse in the visual system.

How Biology Perceives Chemistry: The Mammalian Olfactory System

Lecture

Date:

Monday, March 14, 2016

Hour: 12:45

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Stuart Firestein

|

Dept of Biological Sciences Columbia University

The vertebrate nose is arguably the best chemical detector on the planet. It is estimated to be able to detect between 1 million and 1 trillion small molecules, known as odors. More importantly it can discriminate between hundred of thousands of these molecules, some differing by only a carbon atom. It performs this task using a large family of G-protein coupled receptors (GPCRs) in the periphery and a surprisingly shallow circuit of only two synapses to olfactory cortex. A considerable challenge, and interesting puzzle, in olfaction is how the brain uses neural space to encode a distinctly non-spatial stimulus. Unlike the other senses olfactory stimuli vary along multiple dimensions and do not lend themselves to a spatial representation. New approaches to odor classification in the periphery, along with recent data on pyriform (olfactory) cortex developed in numerous laboratories regarding suggest novel solutions to this problem. These “olfactory solutions” may be seen operating in other brain systems as well.

From Vision to Decisions and Navigation in Mouse Cortex

Lecture

Date:

Wednesday, March 9, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Matteo Carandini

|

University College London

As signals progress along the early visual system, they undergo a remarkable transformation. One synapse away from the eye, in Lateral Geniculate Nucleus, responses are still highly repeatable, and they can be predicted fairly well by simple model of image processing. One further synapse away, in Primary Visual Cortex (V1), responses become hugely affected by activity that originates within the brain, which varies from trial to trial, and can be closely related to behavior. For instance, a major factor that controls responses of neurons in the mouse visual cortex is locomotion. In mouse V1, locomotion changes the nature of spatial integration, reducing the strength of lateral interactions. Moreover, locomotion interacts with vision to affect responses during navigation, perhaps to help the animal estimate is own movement. In the parietal visual areas that follow V1 a further factor affecting responses is decision. The activity of neurons in those areas thus reflects the interactions of vision, decision, and navigation. Current efforts in our laboratory are aimed at studying these interactions.

How to scientifically study the functions of consciousness: in search of the right paradigm

Lecture

Date:

Monday, March 7, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Liad Mudrik

|

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

Abstract: Generations of scholars of different disciplines have struggled with the mystery of conscious awareness. How does it come about? And, no less importantly, what does it do? To meet the challenge of scientifically operationalizing this question, different experimental manipulations have been developed. With these methods researchers managed to demonstrate surprisingly high-level forms of unconscious processing, like semantic integration, executive control, emotional judgments, reading and arithmetic operations. Consequently, some have suggested that consciousness may not hold any unique functional role. In this talk, I will present experiments which employ such methods, and point out their implications and limitations. I will then introduce our search for new means to probe unconscious processes and examine consciousness' role in thought and behavior.

Sex differences in neuropsychological disorders: Why should we care?

Lecture

Date:

Tuesday, March 1, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Anat Biegon

|

Director, Center on Gender, Hormones and Health Stony Brook University School of Medicine, NY

Gender differences affect the prevalence, presentation, treatment response and outcome of many neuropsychiatric disorders; including Alzheimer's disease, multiple sclerosis, depression and anxiety. However, despite a female majority among sufferers of these disorders, women were historically excluded from clinical trials; and the overwhelming majority preclinical studies on disease mechanisms and new drug development are conducted exclusively on males. Consequently, women are 50% more likely than men to experience adverse drug reactions, and between 1997 and 2001, 80% of the drugs removed from the market were specifically implicated in adverse side effects or deaths of female patients. Drawing on examples from diverse neuropathologies, the talk will describe the current status and the future potential of research and education on gender based medicine; aiming to level the field and gain insight into the influence of sex an gonadal hormones on CNS physiology and pathology.

The interplay between social arousal and social memory: lessons from the social brain

Lecture

Date:

Tuesday, February 23, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Shlomo Wagner

|

Sagol Dept of Neurobiology University of Haifa

The ability to distinguish between individuals of the same species is the basis for all mammalian social relationships. This ability, termed social recognition memory (SRM), is mediated by a specific network of limbic areas in the brain, and is modulated by several neuromodulators, such as oxytocin and the CRH-related peptide urocortin-3. I will discuss behavioral and electrophysiological data suggesting a role for arousal-driven theta rhythmicity in this neural network during acquisition of social memory. I will also discuss the contributions of oxytocin and urocortin-3 to the social memory and the relationship between them. Finally, I will discuss a possible role for emotional states in cognitive processes such as learning and memory.

On the dual role of IGF-1 receptor in information processing at hippocampal synapses

Lecture

Date:

Tuesday, February 16, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Inna Slutsky

|

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

The insulin-like growth factor-1 receptor (IGF-1R) signaling is a key regulator of lifespan, growth, and development. While reduced IGF-1R signaling delays aging and Alzheimer’s disease progression, whether and how it regulates information processing at central synapses remains elusive. Here, we show that presynaptic IGF-1Rs are basally active, regulating synaptic vesicle release and short-term plasticity in excitatory hippocampal neurons. Acute IGF-1R blockade or transient knockdown suppresses spike-evoked synaptic transmission and presynaptic cytosolic Ca2+ transients, while promoting spontaneous transmission and resting Ca2+ level. This dual effect on transmitter release is mediated by mitochondria that attenuate Ca2+ buffering in the absence of spikes and decrease ATP production during spiking activity. We conclude that the mitochondria, activated by IGF-1R signaling, constitute a critical regulator of information processing in hippocampal neurons by maintaining evoked-to-spontaneous transmission ratio, while constraining synaptic facilitation at high frequencies. Excessive IGF-1R tone may contribute to hippocampal hyperactivity associated with Alzheimer’s disease.

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All events, All years

From Vision to Decisions and Navigation in Mouse Cortex

Lecture

Date:

Wednesday, March 9, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Matteo Carandini

|

University College London

As signals progress along the early visual system, they undergo a remarkable transformation. One synapse away from the eye, in Lateral Geniculate Nucleus, responses are still highly repeatable, and they can be predicted fairly well by simple model of image processing. One further synapse away, in Primary Visual Cortex (V1), responses become hugely affected by activity that originates within the brain, which varies from trial to trial, and can be closely related to behavior. For instance, a major factor that controls responses of neurons in the mouse visual cortex is locomotion. In mouse V1, locomotion changes the nature of spatial integration, reducing the strength of lateral interactions. Moreover, locomotion interacts with vision to affect responses during navigation, perhaps to help the animal estimate is own movement. In the parietal visual areas that follow V1 a further factor affecting responses is decision. The activity of neurons in those areas thus reflects the interactions of vision, decision, and navigation. Current efforts in our laboratory are aimed at studying these interactions.

How to scientifically study the functions of consciousness: in search of the right paradigm

Lecture

Date:

Monday, March 7, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Liad Mudrik

|

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

Abstract: Generations of scholars of different disciplines have struggled with the mystery of conscious awareness. How does it come about? And, no less importantly, what does it do? To meet the challenge of scientifically operationalizing this question, different experimental manipulations have been developed. With these methods researchers managed to demonstrate surprisingly high-level forms of unconscious processing, like semantic integration, executive control, emotional judgments, reading and arithmetic operations. Consequently, some have suggested that consciousness may not hold any unique functional role. In this talk, I will present experiments which employ such methods, and point out their implications and limitations. I will then introduce our search for new means to probe unconscious processes and examine consciousness' role in thought and behavior.

Sex differences in neuropsychological disorders: Why should we care?

Lecture

Date:

Tuesday, March 1, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Anat Biegon

|

Director, Center on Gender, Hormones and Health Stony Brook University School of Medicine, NY

Gender differences affect the prevalence, presentation, treatment response and outcome of many neuropsychiatric disorders; including Alzheimer's disease, multiple sclerosis, depression and anxiety. However, despite a female majority among sufferers of these disorders, women were historically excluded from clinical trials; and the overwhelming majority preclinical studies on disease mechanisms and new drug development are conducted exclusively on males. Consequently, women are 50% more likely than men to experience adverse drug reactions, and between 1997 and 2001, 80% of the drugs removed from the market were specifically implicated in adverse side effects or deaths of female patients. Drawing on examples from diverse neuropathologies, the talk will describe the current status and the future potential of research and education on gender based medicine; aiming to level the field and gain insight into the influence of sex an gonadal hormones on CNS physiology and pathology.

The interplay between social arousal and social memory: lessons from the social brain

Lecture

Date:

Tuesday, February 23, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Shlomo Wagner

|

Sagol Dept of Neurobiology University of Haifa

The ability to distinguish between individuals of the same species is the basis for all mammalian social relationships. This ability, termed social recognition memory (SRM), is mediated by a specific network of limbic areas in the brain, and is modulated by several neuromodulators, such as oxytocin and the CRH-related peptide urocortin-3. I will discuss behavioral and electrophysiological data suggesting a role for arousal-driven theta rhythmicity in this neural network during acquisition of social memory. I will also discuss the contributions of oxytocin and urocortin-3 to the social memory and the relationship between them. Finally, I will discuss a possible role for emotional states in cognitive processes such as learning and memory.

On the dual role of IGF-1 receptor in information processing at hippocampal synapses

Lecture

Date:

Tuesday, February 16, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Inna Slutsky

|

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

The insulin-like growth factor-1 receptor (IGF-1R) signaling is a key regulator of lifespan, growth, and development. While reduced IGF-1R signaling delays aging and Alzheimer’s disease progression, whether and how it regulates information processing at central synapses remains elusive. Here, we show that presynaptic IGF-1Rs are basally active, regulating synaptic vesicle release and short-term plasticity in excitatory hippocampal neurons. Acute IGF-1R blockade or transient knockdown suppresses spike-evoked synaptic transmission and presynaptic cytosolic Ca2+ transients, while promoting spontaneous transmission and resting Ca2+ level. This dual effect on transmitter release is mediated by mitochondria that attenuate Ca2+ buffering in the absence of spikes and decrease ATP production during spiking activity. We conclude that the mitochondria, activated by IGF-1R signaling, constitute a critical regulator of information processing in hippocampal neurons by maintaining evoked-to-spontaneous transmission ratio, while constraining synaptic facilitation at high frequencies. Excessive IGF-1R tone may contribute to hippocampal hyperactivity associated with Alzheimer’s disease.

The neurobiology of visual search in barn owls

Lecture

Date:

Tuesday, February 9, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Yoram Gutfreund

|

Rappaport Faculty of Medicine, Technion, Haifa

Nature has created mechanisms to detect salient objects like food, prey or mates. Visual search is the process of shifting gaze from one salient object to another. It has both a stimulus driven bottom-up component as well as a task-driven top-down component. This is well studied in human and primates but not so much in other animals. It is, therefore, a challenge to increase our understanding of visual search in non-primate animals. The barn owl is a predator having frontally oriented eyes, but lacking eye movements. Because of such specializations, this bird offers itself for the study of visual search. We study mechanisms of visual search in this animal on both the behavioural and neurophysiological levels. In this talk I will present our main findings on these matters.

Dissecting striatal circuits in learning and decision making

Lecture

Date:

Thursday, January 28, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Ilana Witten

|

Princeton Neuroscience Institute, NJ

I will describe two lines of work in mice aimed at dissecting the role of neuromodulation in the striatum in regulating reward-related learning and decision making. The first story addresses the question of how dopaminergic neurons that innervate the striatum support both learning and action generation, with results suggesting that distinct subpopulations of dopamine neurons support each function. The second story identifies a role for cholinergic interneurons in the ventral striatum in the formation of reward-context associations, with results pointing to a potent ability of the cholinergic neurons in regulating behaviorally-relevant plasticity.

Sensory mechanisms of long-distance navigation in birds

Lecture

Date:

Sunday, January 17, 2016

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Dmitry Kishkinev

|

Research Fellow, School of Biological Sciences, Queen's University Belfast, Northern Ireland, UK

Displacement studies have clearly showed that birds are able to perform true navigation, i.e. they can find direction leading to destination from unfamiliar territory. Yet, the sensory mechanisms of navigation remain poorly understood. There are two primary hypotheses explaining the sensory nature of navigation: (1) a magnetic map hypothesis proposes that birds use parameters of the geomagnetic field which predictably distributed on the globe. This hypothesis claims that the magnetic receptor cells used for navigation reside in the upper beak (the so-called ‘beak organ’), and transmit information via the trigeminal nerve to the brain; (2) an olfactory map hypothesis assumes that birds can use olfaction and smell their position by taking advantage of odours predictably distributed in the atmosphere. In the last decade, I together with my co-workers have experimentally tested both hypotheses in migratory songbird species by combining sensory manipulations with displacements both in Europe and North America. Specifically, in our main model species, Eurasian reed warblers (Acrocephalus scirpaceus), a long-distance nocturnal migrant, we have found that this species (and maybe other songbird migrants) use geomagnetic cues and the magnetoreceptors embedded in the trigeminal system for geographical positioning. In parallel with our studies, there is a growing support for olfactory long-distance navigation in sea birds and homing pigeons. In my talk, I will overview the challenges of understanding true navigation in birds and present the most important advances in the context of other relevant studies.

Reprogramming in vivo neural circuits by engineering new synaptic connections

Lecture

Date:

Wednesday, January 13, 2016

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Ithai Rabinowitch

|

Fred Hutchinson Cancer Research Center, Seattle USA

Synaptic connections between neurons are a fundamental building block of neural circuits. They determine circuit function, and shape whole animal behavior. In order to understand the causal role of synapses in regulating circuit function I have developed a novel synaptic engineering approach that consists of genetically inserting new electrical synapses between specified neurons in vivo. I have successfully implemented this technique in C. elegans circuits and have used it in a variety of applications. For example, for revealing a coincidence detecting mechanism in a nose-touch circuit, for switching olfactory preferences from attraction to a favorable odor into aversion, and for investigating a cross-modal mechanism that compensates for the loss of one sense by sharpening another. Synaptic engineering is thus a powerful new approach that should be widely applicable to a range of animals, enabling to probe, modify and potentially also repair neural circuits. In the long run interventional techniques such as synaptic engineering could make it possible to “upgrade” the nervous system.

PKA signaling network: Visualizing through Macromolecular Assembly and High Resolution Imaging of the Brain

Lecture

Date:

Tuesday, January 12, 2016

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Dr. Ronit Ilouz

|

Dept of Pharmacology, University of California San Diego

cAMP dependent Protein kinase (PKA) plays a critical role in numerous neuronal functions including neuronal excitability, synaptic plasticity, learning and memory. Specificity in PKA signaling is achieved in part by the four functionally non-redundant regulatory (R) subunits. The inactive holoenzyme has a dimeric R subunit bound to two Catalytic (C) subunits. The full-length holoenzyme crystal structures allow me to understand how isoform-specific assembly can create distinct holoenzyme structures that each defines its allosteric regulation. High-resolution large-scale mosaic images provide global views of brain sections and allow identification of subcellular features. Analysis of multiple regions demonstrates that the R isoforms are concentrated within discrete regions and express unique and consistent patterns of subcellular localization. Using the miniSOG technique for correlating fluorescent microscopy with electron microscopy I find RIβ in the mitochondria within the cristae and the inner membrane, and in the nucleus, modifying the existing dogma of cAMP-PKA in the nucleus. Down-regulation of the nuclear RIβ, but not RIIβ, decreased L-LTP related signaling as reported by CREB phosphorylation in primary neuronal cultures, consistent with deficits observed in RIβ knockout mice. Furthermore, we show that a point mutation in the RIβ gene, that is associated with a neurodegenerative disease, abolishes dimerization while retaining robust interaction with the catalytic subunit. As a consequence, the interaction with an A-Kinase Anchoring Protein (AKAP) was also diminished. This mutation abolishes the AKAP-mediated targeting of RIβ holoenzymes to specific cellular compartments, which is consistent with an accumulation of RIβ in neuronal inclusions in patients carrying this mutation. These diverse interdisciplinary tools are defining PKA signaling as highly localized complexes that are targeted to specific sites in the cell in close to proximity to substrates and other signaling molecules where activity is then regulated by local levels of cAMP and calcium as well as kinases and phosphatases.