Past events | The department of Brain Sciences

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Novel homeostatic mechanisms in a neurodevelopmental mice model of Angelman syndrome

Lecture

Date:

Tuesday, April 8, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Hanoch Kaphzan

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Laboratory for Neurobiology of Psychiatric Disorders Dept of Neurobiology, University of Haifa

Angelman syndrome (AS) is a human neuropsychiatric disorder associated with autism, mental retardation, motor dysfunction, and epilepsy. In most cases, AS is caused by the deletion of small portions of chromosome 15, which includes the UBE3A gene. The UBE3A gene encodes an enzyme termed ubiquitin ligase E3A. A mouse model of AS has been generated and these mice exhibit abnormalities that correlate with neurological alterations observed in humans with AS. One of the prominent affected brain regions in AS is the hippocampus. We characterized the CA1 pyramidal neurons in the AS mice, and observed alterations in the intrinsic membrane properties of these cells between AS mice and their wild-type littermates. These alterations were correlated with increased expression of specific proteins, mainly related to the axon initial segment (AIS). Furthermore, the AIS morphology of these neurons in the AS mice was also found to be altered. By determining the temporal sequence for the increased expression of these proteins we have discovered the precipitating event for the observed AIS alterations which coincides with the homeostatic model of the neuron. Finally, we rescued the hippocampal pathology via a genetic manipulation based on this understanding. Taken together, our findings are the first to suggest that AIS plasticity alterations exist in mammalian brain in-vivo and could be involved in neuropsychiatric disorders such as AS. They also offer a novel conceptualization of neuropsychiatric disorders and propose the option for an innovative therapeutic strategy.

Decision confidence: from statistical principles to the neurobiological mechanisms behind

Lecture

Date:

Monday, April 7, 2014

Hour: 14:00

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Adam Kepecs

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Cold Spring Harbor Laboratory

: Decision confidence is a forecast about the correctness of one’s decision. It is often regarded as a higher-order function of the brain requiring a capacity for metacognition that may be unique to humans. If confidence manifests itself to us as a subjective feeling, how can then one identify it amongst the brain’s electrical signals in an animal in order to uncover its neural basis? We tackled this issue by using mathematical models to gain traction on the problem of confidence, allowing us to identify neural correlates and mechanisms. I will begin with a normative statistical theory that enables us to establish that human self-reports of confidence are based on a computation of statistical decision confidence. Next, I will present computational algorithms that can be used to estimate confidence and decision tasks that we developed to behaviorally read out this estimate in humans and rats. Finally, I will discuss the neural basis of decision confidence, focusing on the role of the orbitofrontal cortex.

Uncertainty in human brain and behavior

Lecture

Date:

Sunday, April 6, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Ifat Levy

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Decision Neuroscience Lab Yale School of Medicine

Uncertainty is inherent to any situation we encounter. Our individual attitudes towards uncertainty strongly affect our evaluation of different available options and our behavior based on these evaluations. In the talk I will describe a series of studies in which we combine experimental economics and other behavioral methods with functional MRI to study the behavioral and neural characteristics of attitudes towards uncertainty and learning under uncertainty.

The memory function of sleep

Lecture

Date:

Thursday, April 3, 2014

Hour: 11:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Dr. Jan Born

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The Institute for Medical Psychology and Behavioural Neurobiology University of Tübingen

Compensatory boosting of cortical inputs to striatal cholinergic interneurons in mouse models of Huntington's disease

Lecture

Date:

Tuesday, March 25, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Joshua A. Goldberg

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Dept of Medical Neurobiology, Institute of Medical Research Israel–Canada The Faculty of Medicine, The Hebrew University of Jerusalem

In Huntington’s disease (HD) – a devastating autosomal-dominant neurodegenerative disease – the striatum displays reduced cholinergic markers, despite the resiliency of cholinergic interneurons (ChIs) – the source of striatal acetylcholine – to the neurodegeneration that decimates striatal projection neurons. Autonomous spiking of ChIs is unchanged in transgenic HD mice, suggesting a functional deficit in extrinsically driven activity. Using two transgenic mouse models of HD, we show that ChI responses to cortical input are boosted by a post-synaptic up-regulation of the persistent sodium current. This boosting is replicated by in wild-type mice by diminished activation of group I metabotropic glutamate receptors (mGluRs). Activation of group I mGluRs in HD mice counters the boosting. We propose that the recently described loss of thalamic synapses in striatum, reduces group I mGluR activation in ChIs which promotes boosting of cortical inputs. The augmentation of cortical inputs may function to compensate for the lost thalamic glutamatergic drive.

Efficient Coding in Active Perception

Lecture

Date:

Tuesday, March 11, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Jochen Triesch

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FIAS-Frankfurt Institute of Advanced Studies

The goal of perceptual systems is to provide useful knowledge about the environment and to encode this information efficiently. As such, perception is an active process that often involves the movement of sense organs such as the eyes. This active nature of perception has typically been neglected in current theories describing how nervous systems learn sensory representations. Here we present an approach for intrinsically motivated learning during active perception that treats the learning of sensory representations and the learning of movements of the sense organs in an integrated manner. In this approach, a generative model learns to encode the sensory data while a reinforcement learner directs the sense organs so as to make the generative model work as efficiently as possible. To this end, the reinforcement learner receives an intrinsic reward signal that measures the encoding quality currently obtained by the generative model. In the context of binocular vision, the approach is shown to lead to a self-calibrating stereo vision system that learns a representation for binocular disparity while at the same time learning proper vergence eye movements to fixate objects. The approach is quite general and can be applied to other types of eye movements such as smooth pursuit movements during motion perception. It may also be extended to different sensory modalities. Somewhat surprisingly, the approach also offers a new perspective on the development of imitation abilities.

From Sensory Neural Codes to Behavior

Lecture

Date:

Wednesday, March 5, 2014

Hour: 14:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Moshe Parnas

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Centre for Neural Circuits and Behaviour University of Oxford

Most neurons involved in perceptual judgments are at least two synapses removed from sensory receptors. Psychophysical models that link perception to the physical qualities of external stimuli are thus black boxes. Opening these black boxes is challenging and requires comprehensive estimates of activity in many neurons carrying perceptually relevant signals. Because sensory representations are distributed over large numbers of neurons, such estimates have generally remained elusive. Here, we take advantage of the well-characterized olfactory system of fruit flies to relate knowledge of the neuronal population representations of odors to behavioral measures of odor discrimination. Flies detect odors using ~50 types of olfactory receptor neurons (ORNs). ORN axons segregate anatomically by receptor type and transmit signals via separate synaptic relays, to discrete classes of excitatory projection neurons (ePNs). Previously, ORN responses to odors and a transformation estimating PN spike rates from measured ORN spike rates were presented. ePNs project to the mushroom body, and the lateral horn (LH). The LH, thought to be responsible of naïve behavior, also receives input from a functionally uncharacterized group of GABAergic inhibitory PNs (iPNs). The fact that iPNs target exclusively the LH hints at a possible function of these inhibitory neurons in naïve behavior. We formulate and test a simple model of innate odor discrimination that takes as its input the estimated PN signals projected onto the LH and generates as its output a prediction of whether two odors can be distinguished. We show that the main determinant of discriminability is the distance between the PN activity patterns evoked by two odors. Experimental manipulations of this distance have graded predictable perceptual consequences. We further show that, inhibition by iPNs makes closely related odors easier to distinguish, in all likelihood by imposing a high-pass filter on ePN output that stretches the distances between partially overlapping odor representations.

Decoding Consciousness

Lecture

Date:

Tuesday, February 25, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Geraint Rees

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Institute of Cognitive Neuroscience, University College London (UCL)

Electrophysiological signatures of consciousness

Lecture

Date:

Tuesday, February 18, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Stanislas Dehaene

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College de France and INSERM-CEA Cognitive Neuroimaging Unit

Mapping Neuroplasticity Underlying Addictive Behavior

Lecture

Date:

Sunday, February 16, 2014

Hour: 10:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Dr. Yonatan (Yoni) Kupchik

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Dept of Neurosciences, Medical University of South Carolina,Charleston, South Carolina, USA.

Understanding the neural circuitry underlying addictive behavior is essential as a first step towards treating addiction. The nucleus accumbens and the ventral pallidum are two interconnected regions known to mediate reward-related behavior. Using a multidisciplinary approach I describe synaptic changes in both regions following exposure to cocaine. However, the connectivity patterns between these regions and how specific projections are affected by drugs of abuse remain elusive. In an attempt to elucidate the nature of these connections I will show preliminary results calling for a re-examination of the current thinking about accumbal inputs to the ventral pallidum. Future work will engage in describing how these pathways are differentially changed in drug addiction.

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All events, All years

Decoding Consciousness

Lecture

Date:

Tuesday, February 25, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Geraint Rees

|

Institute of Cognitive Neuroscience, University College London (UCL)

Electrophysiological signatures of consciousness

Lecture

Date:

Tuesday, February 18, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Stanislas Dehaene

|

College de France and INSERM-CEA Cognitive Neuroimaging Unit

Mapping Neuroplasticity Underlying Addictive Behavior

Lecture

Date:

Sunday, February 16, 2014

Hour: 10:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Dr. Yonatan (Yoni) Kupchik

|

Dept of Neurosciences, Medical University of South Carolina,Charleston, South Carolina, USA.

Understanding the neural circuitry underlying addictive behavior is essential as a first step towards treating addiction. The nucleus accumbens and the ventral pallidum are two interconnected regions known to mediate reward-related behavior. Using a multidisciplinary approach I describe synaptic changes in both regions following exposure to cocaine. However, the connectivity patterns between these regions and how specific projections are affected by drugs of abuse remain elusive. In an attempt to elucidate the nature of these connections I will show preliminary results calling for a re-examination of the current thinking about accumbal inputs to the ventral pallidum. Future work will engage in describing how these pathways are differentially changed in drug addiction.

Acute and chronic effects of oxytocin on emotinality and on the consequences of chronic psychosocial stress

Lecture

Date:

Thursday, February 13, 2014

Hour: 10:00

Location:

Camelia Botnar Building

Prof. Dr. Inga D. Neumann

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Dept of Behavioural and Molecular Neuroendocrinology Regensburg University

Brain oxytocin has been repeatedly shown to exert anxiolytic effects and to inhibit the activity of the HPA axis. These acute effects are mediated via activation of hypothalamic oxytocin receptors, which are GPCR, and subsequently of the MAPK pathway. In order to establish oxytocin as a potential psychotherapeutic option, effects of chronic neuropeptide treatment need to be studied. Chronic intracerebral infusion of oxytocin over 2 weeks dose-dependently increased anxiety-related behaviour and reduced oxytocin receptor binding within relevant brain regions. Thus, before oxytocin can be considered a therapeutic option to treat patients suffering from, for example, autism, schizophrenia, social phobia or drug addiction, thorough investigations are needed to reveal alterations of the endogenous oxytocin system. However, application of the low dose of oxytocin to male mice during 3-weeks exposure to an established chronic psychosocial stress paradigm - the chronic subordinate colony housing - attenuated the adverse chronic stress effects on immunological, physiological and emotional parameters further supporting ist stress-protective properties. http://www.uni-regensburg.de/biologie-vorklinische-medizin/neurobiologie-tierphysiologie/team-mitarbeiter/prof-dr-inga-d-neumann/index.html

The match/mismatch hypothesis: Are physiological alterations following stress exposure adaptive?

Lecture

Date:

Wednesday, February 12, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Mathias V. Schmidt

|

Max Planck Institute of Psychiatry, Munich, Germany

Chronic stress is widely regarded as key risk factor for a variety of diseases, including depression. Yet, while some individuals are vulnerable to stress, others are remarkably resilient. It seems clear that genetic predispositions interact with environmental demands such as chronic stress and modulate its long-term outcome. In addition, there is abundant evidence that environmental circumstances early in life are capable of shaping the adult phenotype. In the last years two seemingly opposing views on early life stress have emerged, the two-hit model and the mismatch model. While the first hypothesis states that aversive experiences early in life predispose individuals to be more vulnerable to aversive challenges later in life, the second hypothesis argues that aversive experiences early in life result in individuals that are better adapted to aversive challenges later in life. There are published data that support either hypotheses, but the interaction with genetic predispositions has rarely been addressed. In my presentation I will propose that both views may be accurate and that the outcome of an early-life stress exposure depend on the genetic background of the individual. In addition, even within the same individual certain phenotypes may be progressively affected by multiple stress exposures (two-hit model), while other phenotypes would be most affected under mismatched conditions. I will illustrate the potential of genetic variations to modulate the outcome of early life adversity and discuss research strategies necessary to address the issue of genetic*development*environment interaction.

Insect inspired robotics:from unmanned micro-aerial-vehicles to the Mars explorer

Lecture

Date:

Tuesday, February 11, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Amir Ayali

|

Dept of Zoology, Faculty of Life Sciences Tel Aviv University

Insects are an inexhaustible source for scientists who desire to inspire ideas, processes, structures and functions from biology and implement them into engineering, specifically those interested in locomotion and in the improvement of robot mobility. Novel insights are offered based on a collaborative and combined approach that includes high-speed video monitoring of behavior, electrophysiological recordings of nerves and muscles activity, mathematical modeling and computer simulations. An overview will be presented of several different research projects focusing on cockroach running, caterpillar crawling (soft robotics), locust jumping, flight (remote control), and swarming.

Resolution of Ambiguity:Clues to the Mechanisms of Reading

Lecture

Date:

Tuesday, February 4, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Zohar Eviatar

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Dept of Psychology and the Institute of Information Processing and Decision Making (IIPDM) University of Haifa

The human race has been reading and writing for only 5,000 years, suggesting that the mechanisms for these processes involve both cultural evolution and biological exaptation. Brain mechanisms of reading are hard to discern because skilled reading is so fast and efficient. Use of ambiguous words allows us to slow down some of these processes and explore the interactions of orthographic, phonological, and semantic processes. We took advantage of the characteristics of Hebrew to explore the relative effects of phonological and semantic ambiguity on access to meaning. Twenty-three participants performed a semantic decision talk on pairs of words. Half the pairs were constituted of two unambiguous words, and in half, the first word was either a homophonic homograph (like bank), or a heterophonic homograph (like tear). Our procedure allowed us to separately examine two stages of the access to meaning: the activation of multiple meanings, and then the selection of the appropriate meaning. Previous imaging studies of ambiguity resolution have not made this distinction. In the first stage, we show that different regions of the left hemisphere respond differentially to homophones and to heterophones in both whole brain analysis and in ROI comparisons of sub-regions of both anterior and posterior regions of the left hemisphere. In the second stage, in meaning selection, we again see different effects that are dependent of the phonological status of the ambiguous word, and also similar effects of the interaction between frequency effects and contextual effects in the two hemispheres. We interpret these findings in the context of a brain model of reading.

Mechanisms of local circuit dynamics in freely moving animals

Lecture

Date:

Monday, January 27, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Eran Stark

|

NYU Neuroscience Institute Langone Medical Center New York University

Much of what we know about how neurons interact and form ensemble activity patterns comes from recordings in cell cultures, brain slices, and anesthetized animals, yet dynamics in the intact brain of a behaving animal might differ. I will describe an approach to the study of local circuit dynamics in freely-moving animals, namely the combination of high-density extracellular recordings coupled with multi-site/multi-color optogenetic stimulation, combined with in-vivo pharmacology. This approach, applied to the rodent neocortex and hippocampus, yielded surprising insight into mechanisms of multiple phenomena, including spiking regime resonance, the generation of high-frequency oscillations, and spike phase precession.

Mechanisms of vocal learning in songbirds and humans

Lecture

Date:

Monday, January 20, 2014

Hour: 14:30

Location:

Wolfson Building for Biological Research

Dr. Dina Lipkind

|

Hunter College The City University of New York

Songbirds are a great model for studying how the brain solves the challenges of vocal imitation, since, like human infants, young songbirds learn to produce complex vocal sequences that are exact copies of those of adult conspecifics. This feat is thought to be accomplished by matching the bird's motor performance to a memorized sensory template. To study this process experimentally, we use a computer interface that presents birds with specific vocal imitation tasks and records their entire vocal output during the process. Applying this methodology to vocal combinatorial learning, we trained juvenile zebra finches to swap syllable order in their song, or insert a new syllable into a string. Surprisingly, solving these tasks required a prolonged stage of learning new transitions between syllables one by one, indicating that the ability to rearrange vocal sounds is not the starting point of vocal learning, but a laboriously achieved endpoint. Analysis of babbling development data of human infants revealed that infants face a similar challenge in acquiring new transitions between syllables, suggesting that birds and humans share a common developmental stage of gradually learning to combine sounds into sequences. In a current set of experiments, I am testing hypotheses about the computations involved in sensori-motor vocal learning. For example, is the motor output matched to the sensory template as a single unit, or is the match computed independently for different levels of the song hierarchy? Preliminary results suggest that matching vocal performance to the template occurs independently on at least two levels: the level of individual syllables, and the level of syllable sequences, suggesting that learning on these levels is carried out by distinct neural mechanisms.

Restoration of Sight with Photovoltaic Retinal Prosthesis

Lecture

Date:

Tuesday, January 14, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Yossi Mandel, MD, PhD, MHA

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Ophthalmic Sciences and Engineering Lab Faculty of Life Sciences Bar Ilan University

Retinal degenerative diseases, such as Retinitis Pigmentosa (RP) and Age related Macular Degeneration (AMD), lead to loss of sight due to degeneration of photoreceptors, yet the inner retinal neurons which process the visual signals and relay them to the brain are relatively well preserved. Patterned electrical stimulation of the inner retinal neurons can elicit patterned visual perception, thereby restoring sight to some degree, as was demonstrated in recent clinical trials. However, current RF-powered implants require bulky electronics and trans-scleral cables, making implantation very complex and prone to failures. Even more importantly, low visual acuity achieved with the current implants limits their applicability to very small fraction of patients. We have developed a wireless photovoltaic retinal prosthesis, in which camera-captured images are projected onto the retina using pulsed near-IR light. Each pixel in the subretinal implant directly converts pulsed light into local electric current to stimulate the nearby inner retinal neurons. Implants with pixel sizes of 280, 140 and 70µm were successfully implanted in the subretinal space of wild type and degenerate rats, and elicited robust cortical responses (eVEP) upon stimulation with NIR light. Amplitude of the eVEP increased with peak irradiance and pulse duration, and decreased with frequency in the range of 2-20Hz, similar to the visible light response. Modular design of the arrays allows scalability to a large number of pixels, and combined with the ease of implantation, offers a promising approach to restoration of sight in patients blinded by retinal degenerative diseases. Activation of the retinal bipolar cells by the implant makes our model a unique tool for studying retinal circuitry by comparing the response to stimuli elicited by the subretinal implant to those naturally elicited by visible light. I will discuss our novel approach to quantitative assessment of the visual acuity provided by the implant, as well as some unique aspects of prosthetic vision, such as stroboscopic stimulation. The theoretical and practical limits of visual acuity will be discussed along with future directions for restoration of sight to the blind.