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Epigenetic mechanisms in memory formation
Lecture
Sunday, April 15, 2007
Hour: 12:00 - 13:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Epigenetic mechanisms in memory formation
Prof. David Sweatt
Head, Neurobiology Dept and Mcknight Brain Institute, University of Alabama, Birmingham AL
Dr. Sweatt's seminar will focus on molecular mechanisms underlying learning and memory. Dr. Sweatt uses knockout and transgenic mice to investigate signal transduction mechanisms in the hippocampus, a brain region known to be critical for higher-order memory formation in animals and humans. His talk will describe transcriptional regulation in memory formation, focusing on studies of transcription factors, regulators of chromatin structure, and other epigenetic mechanisms, in order to understand the role of regulation of gene expression in synaptic plasticity and memory.
Optimal decoding of neural population responses in the primate visual cortex
Lecture
Monday, March 26, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Optimal decoding of neural population responses in the primate visual cortex
Dr. Eyal Seidemann
Center for Perceptual Systems
and Depts. of Psychology and Neurobiology
The University of Texas at Austin
How are simple perceptual decisions formed based on noisy neural signals that are distributed over large populations of neurons in early sensory cortical areas? To begin to address this fundamental question, we used a combination of real-time imaging andvelectrophysiological techniques to measure directly population responses in the primary visual cortex (V1) of monkeys while they performed a reaction-time visual detection task. We then evaluated different candidate models for detecting the target from the measured neural responses. Our analysis reveals that previously proposed methods for pooling neural responses over space and time are highly inefficient given the statistics of V1 population responses. We derived the optimal decoder of V1 responses and show that it can be approximated by simple neural circuits. Finally, we show that an optimal decoder that uses the signals from the monkey's cortex can outperform the monkey, indicating that inefficiencies at, or downstream to, V1 limit performance in simple detection tasks. The list of people I would like to meet with that I've sent to Alon is only partial. I'll be happy to meet with anyone in the Dept. that is available and is interested in meeting with me.
Medial frontal cortex involvement in error processing and delay discounting
Lecture
Monday, March 19, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Medial frontal cortex involvement in error processing and delay discounting
Prof. Steven D. Forman
University of Pittsburgh, School of Medicine, Pittsburgh, PA
Background: Opiate addicts entering methadone maintenance treatment exhibit decreased medial frontal cortex activation with occurrence of error (negative) events. The strength of this error-related cortical signal correlated with discrimination performance and moment-to-moment cognitive control. In the clinical setting the strength of this signal predicted individual treatment adherence (e.g., time maintained in treatment before drop-out). While the latter finding suggests a connection between error processing and complex decisions involving choices between immediate and delayed goals, we did not have direct evidence supporting this connection. Methods: Subjects performed both the Go/NoGo task and a delay-discounting task while brain activity was monitored using event-related fMRI. Results: The medial frontal cortex region previously associated with error processing also displayed significant activation during delay discounting. Moreover, the individual strength of brain activation while processing errors correlated with that exhibited during processing decisions between immediate and delayed hypothetical rewards. Supported by NIH grant DA11721 and VA CPPF and MERIT awards.
Novel mechanisms for stress-induced hippocampal dysfunction: dendritic spines and CRH
Lecture
Monday, March 12, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Novel mechanisms for stress-induced hippocampal dysfunction: dendritic spines and CRH
Prof. Tallie Z. Baram
Prof. Pediatrics, Anatomy & Neurobiology and Neurology Danette Shepard Professor of Neurological Sciences, University of California at Irvine, Irvine CA
Whereas brain development is governed primarily by genetic factors, early-life experience, including stress, exerts long-lasting influence on neuronal structure and function. Baram's talk focuses on the hippocampus as the target of early-life stress because of its crucial role in learning and memory. The consequences of early-life stress on hippocampus-dependent cognitive tasks and synaptic plasticity will be described, as well as the the structural changes in dendrites and dendritic spines. New data will discuss the potential role of altered spine dynamics in the cellular mechanisms by which stress impacts the structure and function of hippocampal neurons.
Brain functions: from basic research to clinical applications
Conference
Monday, March 12, 2007
Hour:
Location:
Brain functions: from basic research to clinical applications
The perception of curvature and its neural substrate
Lecture
Monday, March 5, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
The perception of curvature and its neural substrate
Dr. Ohad Ben-Shahar
Department of Computer Science,
Ben Gurion University of the Negev
The analysis of texture patterns, and texture segregation in particular, are at the heart of visual processing. In this work we question the accepted view that the (perceptual and computational) detection of salient perceptual singularities (i.e., borders) between perceptually coherent texture regions is tightly dependent upon feature *gradients*. Specifically, we study smooth orientation-defined textures (ODTs) and show psychophysically that they exhibit striking perceptual singularities even without any outstanding gradients in their defining feature (i.e., orientation). By studying oriented patterns from a (differential) geometric point of view we then develop a theory that accurately predicts their perceptual singularities from two ODT *curvatures*. Finally, in searching for the cortical substrate of curvature computation, we show how its critical role at the perceptual level could be reflected physiologically in the functional organization of the primary visual cortex via the connectivity patterns of long range horizontal connections.
Entorhinal grid cells and hippocampal memory
Lecture
Tuesday, February 27, 2007
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Entorhinal grid cells and hippocampal memory
Prof. Edvard I. Moser
Director, Centre for the Biology of Memory, Norwegian University of Science and
Technology, Trondheim, Norway
Representation in entorhinal grid cells
Lecture
Monday, February 26, 2007
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Representation in entorhinal grid cells
Prof. May-Britt Moser
Co-director, Centre for the Biology of Memory, Norwegian University of Science and
Technology, Trondheim, Norway
Structural and functional changes induced by prenatal stress
Lecture
Monday, February 19, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Structural and functional changes induced by prenatal stress
Prof. Marta Weinstock-Rosin
Department of Pharmacology, The Hebrew University of Jerusalem
Adaptive mechanisms in the auditory system
Lecture
Monday, February 12, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Adaptive mechanisms in the auditory system
Prof. Merav Ahissar
Department of Psychology, Faculty of Social Sciences, The Hebrew University of Jerusalem
The mechanisms underlying our remarkable ability to form coherent and
meaningful percepts in our complex environment are still an unresolved
mystery. I propose that fast adaptive processes occurring at all levels of
the processing hierarchy play a major role in this ability. I will give
examples from speech perception and from tone comparison. A unique
population in this respect are individuals with reading and learning
disabilities. Their adaptive stimulus-specific mechanisms are impaired,
with broad perceptual and cognitive consequences.
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When is it worth working: Behavioral, physiological, genetic, and modeling experiments investigating motivation and reward expectancy
Lecture
Sunday, January 7, 2007
Hour: 10:00 - 11:00
Location:
Nella and Leon Benoziyo Building for Brain Research
When is it worth working: Behavioral, physiological, genetic, and modeling experiments investigating motivation and reward expectancy
Dr. Barry J. Richmond
Chief, Section on Neural Coding and Computation Laboratory of Neuropsychology, National Institute of Mental Health,
NIH, DHHS, USA
The intensity or vigor of goal-directed behavior is a correlate of the motivation underlying it. Motivation is related to the subjective value of rewards and is moderated, or even completely dissipated, if the perceived effort or discomfort seems too great. Under what circumstances do we seek a goal or a reward? To study motivated behavior in monkeys, we use several variants of a task in which monkeys must perform some work, in this case detecting when a target spot turns from red-to-green, to obtain a drop of juice. We use another visual stimulus, a cue, to indicate how much discomfort must be endured, e.g., the number of trials to be worked, to obtain the reward. The monkeys learn about the cues quickly, often after just a few trials. The number of errors becomes proportional to amount of work remaining before reward, achieving our goal of manipulating motivation. This is a behavior in which the monkeys decrease their performance in response to an increased predicted workload. Temporal difference models have provided an important framework for interpreting goal directed-behavior, and in economics, game theory has been used to model choice behavior. A key concept in these models is to determine how the value of the reward is modulated by some parameter of the experiment, such as changing the reward size, or the amount of time needed to obtain the reward. In learning or adaptation the TD algorithm predicts that behavior should be (and in artificial systems is) adapted to maximize long-term reward. By examining the influence of reward size, waiting time, and amount of work, we can examine in what ways different model succeed and fail. Our data show that performances depend on work completed since preceding reward (sunk cost effect), and accumulated reward (over whole sessions) and work. In addition this behavior can be used to learn about categorization and rule learning. Using single neuronal recording, regional ablation, and molecular ablation of the D2 receptor we show that dopamine-rich brain regions have signals related to the balance between reward and work.
Stress and the Brain – a Molecular View
Lecture
Tuesday, January 2, 2007
Hour: 12:00 - 13:15
Location:
Nella and Leon Benoziyo Building for Brain Research
Stress and the Brain – a Molecular View
Dr. Daniela Kaufer
Department of Integrative Biology
Helen Wills Neuroscience Institute, University of California
Berkeley, CA
My lab studies the molecular basis of neural and hormonal mechanisms of stress responses. Using interdisciplinary multilevel approach we look at the plasticity of the brain in dealing with physiological and pathological events. In this talk I will describe three current projects: Hormonal Regulation of Neural Stem Cells. Determining the environmental and internal cues that control the proliferation and fate choices of stem cells in the adult hippocampus, and their role in functional plasticity. RNA Regulatory Mechanisms in Neural Stress Responses. RNA regulation, specifically, alternative splicing and microRNA expression as a fine tuning neural stress mechanism. The Molecular Mechanisms of post-trauma Epileptogenesis. Determine the mechanism underlying epileptogenesis following blood brain barrier damage.
Synaptic maintenance - Insights from live imaging experiments
Lecture
Monday, January 1, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Synaptic maintenance - Insights from live imaging experiments
Dr. Noam Ziv
Dept of Physiology, Faculty of Medicine, Technion
Recent studies suggest that central nervous system (CNS) synapses persist
for many weeks, months and even lifetimes, yet little is
known on the mechanisms that allow these structures to persist for so
long despite the many deconstructive processes acting at biological
systems and neurons in particular. As a step toward a better
understanding of synaptic maintenance we set out to examine some of the
deconstructive and reconstructive forces acting at individual CNS
synapses. To that end we studied the molecular dynamics of several
presynaptic and postsynaptic cytomatrix molecules. Fluorescence
recovery after photobleaching (FRAP) and photoactivation experiments
revealed that these molecules are continuously incorporated into and lost
from individual synaptic structures within tens of minutes.
Moreover, these dynamics can be accelerated by synaptic activity.
Finally, we find that synaptic molecules are continuously exchanged
between nearby synaptic structures at similar rates and that these rates
greatly exceed the rates at which synapses are replenished with molecules
arriving from somatic sources. Our findings indicate that the dynamics of
key synaptic matrix molecules may be dominated by local protein exchange
and redistribution, whereas protein synthesis and degradation serve to
maintain and regulate the sizes of local, shared pools of these proteins.
The nature of these dynamics raises intriguing questions as to how
synapses manage to maintain their
individual, use-dependent structural and functional characteristics over
long durations.
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