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Consequences of the uncertainty principle of measurement for perception and action
Lecture
Wednesday, January 30, 2008
Hour: 13:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Consequences of the uncertainty principle of measurement for perception and action
Dr. Sergei Gepshtein
Brain Science Institute, RIKEN, Japan
The Salk Institute for Biological Studies, USA
What can we learn from the octopus about the evolution of neural system for learning and memory?
Lecture
Tuesday, January 29, 2008
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
What can we learn from the octopus about the evolution of neural system for learning and memory?
Dr. Binyamin Hochner
Hebrew University, Jerusalem
The octopus is an active hunter, a remarkable invertebrate whose complex behaviors rely on exceptionally good visual and tactile senses coupled with highly advanced learning and memory (LM) abilities. Studying the octopus LM system may therefore reveal characteristics universally important for mediation of complex behaviors. We developed slice and isolated brain preparations of the LM area in the octopus brain to characterize the short- and long-term neural plasticity. The importance of these processes for LM are been tested in behavioral experiments. The results support the importance of LTP in behavioral LM and suggest new ideas regarding the organization of short- and long-term memory systems.
Decoding neural signals for the control of movement
Lecture
Tuesday, January 22, 2008
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Decoding neural signals for the control of movement
Prof. Sara Solla
Northwestern University
The activity of neurons in primary motor cortex provides the signals that control our ability to execute movements. One of the crucial questions, still unresolved, is that of identifying the coordinate system used in the execution of movements: is it an Euclidean representation of the external space, or an actuator representation of the state of the muscles? We address this question through the analysis of data obtained for an awake behaving monkey. The data includes simultaneous recording of the activity of about one hundred neurons in motor cortex and of the activity of about ten muscles in the relevant limb. The analysis of this data involves a variety of techniques, from linear regression models to nonlinear methods for dimensionality reduction. I will review the current level of achievement in this active area of research and discuss its implications, both for understanding aspects of neural information processing that relate to natural behaviors and for extracting from these neural signals the information needed to guide prosthetic limbs and other types of external devices.
Cortical Maps, Dyanamic Innformation Processing and Perception
Lecture
Monday, January 21, 2008
Hour: 13:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Cortical Maps, Dyanamic Innformation Processing and Perception
Prof. Christopher Moore
McGovern Institute for Brain Research, MIT
I am interested in how neural dynamics, changes in neural sensitivity on the time scale of milliseconds to seconds, support rapid changes in perceptual capability. Our key focus is in testing the hypothesis that dynamics in early sensory cortices, such as the primary somatosensory cortex, play a key role in perception.
To examine these issues in a model where detailed invasive studies are possible, we study the vibrissa sensory system of rodents. To examine the broader relevance of these findings, we have a smaller parallel effort I human perception and imaging. A variety of our studies suggest that.
In this seminar, I will describe work we have done to understand the 'natural scene' of vibrissa perception, the signals that are generated during active surface contact. I will then describe how these signals are encoded in 2 recently discovered cortical maps, a frequency map, shaped by the resonance properties of the vibrissae, and a direction map, encoding the angle of vibrissa motion.
I will then discuss why having these cortical feature columns, with adjacent neurons sharing similar computational processing, may enhance information processing. Specifically, I will argue that this arrangement facilitates dynamic regulation of neural sensitivity by neuromodulators that have a more course spatial precision, on the order of 300-1000 microns. I will briefly mention the hemo-neural hypothesis, the proposal that changes in blood flow and volume may be one source of neural regulation on this spatial scale.
I will then describe an example of the dynamic regulation of spatial activation across a cortical map, resulting from adaptation during robust
thalamocortical input at 5-25 Hz. I will argue that this adaptation leads to a transition into a state that is enhanced for discrimination of alternative stimuli, but impoverished for detection of novel stimuli (decreased sensitivity).
To test the hypothesis that these kinds of cortical dynamics in the primary somatosensory cortex regulate perception, I will describe human MEG experiments showing that changes in the amplitude of SI activation regulate detection probability, and showing that these changes in perception and cortical amplitude are predicted by ongoing rhythmic activity in human SI at 5-25 Hz (the 'mu' rhythm).
Neural Circuits Underlying Sexually Dimorphic Social and Reproductive Behaviors
Lecture
Wednesday, January 16, 2008
Hour: 12:00
Location:
Dolfi and Lola Ebner Auditorium
Neural Circuits Underlying Sexually Dimorphic Social and Reproductive Behaviors
Dr. Tali Kimchi
Department of Molecular and Cellular Biology
Harvard University
My long term interest lies in the mechanistic understanding of sensory processes underlying behavioral responses in laboratory as well as natural wild environments. External sensory cues control complex behaviors such as mating, predator avoidance or orientation in space that are essential for the animal survival and the propagation of the species. In rodents, pheromones play a major role in controlling innate social and sexual responses including mating, nursing and aggression. However, although these behaviors display striking sexual dimorphisms, surprisingly few anatomical and molecular features have been identified that differentiate the male from the female brain.
Using genetic and behavioral tools, I have shown that the vomeronasal organ (VNO), an olfactory sensory organ in the nasal cavity of many mammals which detects pheromones, is responsible for the control of male- and female-specific social and sexual behaviors. Amazingly, female mice in which the VNO has been genetically or surgically inactivated engage in male-typical courtship and sexual behaviors including mounting, pelvic thrusting and courtship vocalization, that are indistinguishable from that of normal male mice. These findings suggest a model in which male and female circuits that regulate innate reproductive behaviors exist in the brain of both sexes, while a sex-specific chemosensory network enables pheromonal cues to control the sex-specificity of behavior.
To gain a deeper understanding of the molecular and neuronal processes underling sex-specific innate behaviors my lab will combine molecular and genetic tools, together with unique behavioral approaches, to study animal behavioral responses under natural ethologically relevant conditions. Furthermore, to uncover novel VNO-mediated pheromone responses that might have degenerated or been suppressed in inbred laboratory mouse lines, wild-caught mouse strains will be studied in wide range of behavioral, genetically and physiological assays.
Who's Afraid of Chaotic Networks? Model of Sensory and Motor Processing in the Face of Spontaneous Neuronal Activity
Lecture
Tuesday, January 15, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
Who's Afraid of Chaotic Networks? Model of Sensory and Motor Processing in the Face of Spontaneous Neuronal Activity
Prof. Larry Abbott
Columbia University
Large, strongly coupled neural networks tend to produce chaotic spontaneous activity. This might appear to make them unsuitable for generating reliable sensory responses or repeatable motor patterns. However, this is not the case. Inputs can induce a phase transition, leading to responses uncontaminated by chaotic "noise". Likewise, appropriately trained feedback units can control the chaos, resulting in a wide variety of repeatable output patterns. These issues will be discussed accompanied by examples and demonstrations.
Beyond Hebbian Plasticity – A Dynamic View of Memory Processing
Lecture
Monday, January 14, 2008
Hour: 13:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Beyond Hebbian Plasticity – A Dynamic View of Memory Processing
Prof. Karim Nader
Psychology Dept, McGill University, Montreal
Memory scientists have been inspired and directed for decades in their search for brain mechanisms mediating learning and memory by the postulates of D.O. Hebb. Two of Hebb's most influential postulates include that co-incident activation of pre-and post-synaptic cells could be a mechanism for learning (Hebbian/associative long term potentiation). In addition once a memory is aquired, it initially exists in a fragile, labile state, after which it becomes stabilized/consolidated in the brain. While these postulates have been incredibly influential and largely correct, the data suggests it is may be time to move beyond these postulates. Data will be presented to demonstrate that synapses may not be sensitive to co-incidence of pre- and post-synaptic activation, rather they may be sensitive to probability of their co-activation. Second, we demonstrate that even old consolidated memories return to a labile state when they are remember, and must be reconsolidated in order to persist. This suggests that the traditional Consolidation Hypotheses, including Hebb's postulates, are no longer sufficient to explain the data.
Motor learning with unstable neural representations
Lecture
Wednesday, January 9, 2008
Hour: 11:30
Location:
Wolfson Building for Biological Research
Motor learning with unstable neural representations
Dr. Uri Rokhni
MIT
It is usually assumed that the brain learns by changing neural circuits that are otherwise stable. However, recent experiments in monkeys show that the neural representation of movement in motor cortex is continually changing even without learning, when practicing a familiar task. We set to investigate the reason for these changes. We analyzed the empirical data and found that the changes are slow and random. We constructed a theoretical model of a cortical network that learns a motor skill by changing synaptic strengths. Our model explains how the network can change its synaptic strengths, and neural activity, without changing the motor behavior.
Additionally, our model replicates the observed changes when synaptic learning is assumed highly noisy. We speculate that this noise serves to explore different synaptic configurations during learning.
TRP channels, what are they and why are they important
Lecture
Tuesday, January 8, 2008
Hour: 12:15
Location:
Jacob Ziskind Building
TRP channels, what are they and why are they important
Prof. Baruch Minke
Hebrew University, Jeruslaem
TRP channels constitute a large and diverse family of proteins that are expressed in many tissues and cell types. The TRP superfamily is conserved throughout evolution from nematodes to humans. The name TRP is derived from a spontaneously occurring Drosophila mutant lacking TRP that responded to a continuous light with a Transient Receptor Potential (therefore, it was designated TRP by Minke). The Drosophila TRP and TRP-like (TRPL) channels, which are activated by the inositol lipid signaling cascade, were used later on to isolate the first mammalian TRP homologues. TRP channels mediate responses to light, nerve growth factors, pheromones, olfaction, taste, mechanical, temperature, pH, osmolarity, vasorelaxation of blood vessels, metabolic stress and pain. Furthermore, mutations in members of the TRP family are responsible for several diseases. Although a great deal is known today about members of the mammalian TRP channels, the exact physiological function and gating mechanisms of most channels are still elusive.
Removal of divalent open channel block by depolarization plays a critical role in learning and memory, which is mediated by the N-methyl-D-aspartate (NMDA) channel. TRP channels also exhibit open channel block, but the physiological mechanism of its removal is still unknown. We found that lipids produced by phospholipase C (PLC) and hypoosmotic solutions remove divalent open channel block from the Drosophila TRPL channels without depolarization. Application of lipids increased single channel current and caused impermeable cation influx. The tarantula peptide GsMTx-4 specifically blocks a range of stretch-activated channels, but not by specific interaction with the channel proteins themselves but rather by modification of the channel-lipid boundary. The GsMTx-4 toxin blocked the lipids effect on TRPL channels. We found remarkable commonality between the effects of lipids on the Drosophila TRPL and the mammalian NMDA channels. We suggest a new lipid-dependent mechanism to alleviate open channel block, which operates under physiological conditions, in synergism with depolarization. The profound effect of lipids modulation allows cross talk between channel activity and lipid-producing pathways.
Joint work with Moshe Parnas, Ben Katz & Shaya Lev
"A hierarchy of temporal receptive windows
Lecture
Tuesday, January 1, 2008
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
"A hierarchy of temporal receptive windows
Dr. Uri Hasson
New York University
Real-world events unfold at different time scales, and therefore cognitive and neuronal processes must likewise occur at different time scales. In the talk I will present a novel procedure that identifies brain regions responsive to the preceding sequence of events (past time) over different time scales. The fMRI activity was measured while observers viewed silent films presented forward, backward, or piecewise-scrambled in time. The results demonstrate that responses in different brain areas are affected by information that has been accumulated over different time scales, with a hierarchy of temporal receptive windows spanning from short (~4 s) to intermediate (~12 s) and long (~ 36 s). Thus, although we adopted an open-ended experimental protocol (free viewing of complex stimuli), we found that parametric manipulation of the temporal structure of a complex movie sequence produced lawful changes in cortical activity across different brain regions. In addition to the reliable cortical response patterns, I will also show that films exerted considerable control over the subjects' behavior (i.e., eye movements or galvanic skin responses). Finally, I will present few applications of this method for studying the neuronal correlates of complex human behaviors under more natural settings.
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:3.14" A Constant That is Fundamental to Visual Cortex Design"
Lecture
Wednesday, July 18, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
:3.14" A Constant That is Fundamental to Visual Cortex Design"
Prof. Fred Wolf
Research Group Theoretical Neurophysics
Max Planck Institute for Dynamics and Self-Organization
Gottingen, Germany
Circadian clocks in the limbic forebrain:
Lecture
Tuesday, July 10, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Circadian clocks in the limbic forebrain:
Prof. Shimon Amir
Concordia University Research Chair
Center for Studies in Behavioral Neurobiology
Department of Psychology
Concordia University, Montreal, Canada
"A Functional Circuit Underlying Male Sexual Behaviour Uncovered in
Lecture
Sunday, July 8, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
"A Functional Circuit Underlying Male Sexual Behaviour Uncovered in
Dr. Tali Kimchi
Dept of Molecular & Cellular Biology, Howard Hughes Medical Institute, Cambridge, MA
Integrate & Play Theory of Hippocampal Function:
Lecture
Monday, July 2, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Integrate & Play Theory of Hippocampal Function:
Dr. Dori Derdikman
Centre for the Biology of Memory
Norwegian University of Science & Technology (NTNU)
Trondheim, Norway
An alternative model to the Declarative-Memory & Cognitive Map theories of the function of the hippocampus is suggested. the new model may explain the deficits described in the famous case of H.M., who displayed total anterograde amnesia following a surgery in which a bilateral dissection of the whole medial-temporal lobe (MTL) was perfromed (Scoville and Milner, 1957) . According to the model, the main functions of the MTL are: (1) to act as an integrator (2) to detect novelty. The integrator function is used, for example, for generation of the place-cell and grid-cell system. Normally, the MTL is integrating an episode until it detects a novel situation. Once the MTL detects such a novel situation, it sends the executive brain (perhaps the basal ganglia and/or prefrontal cortex) a message that it is time to play a novel behavioral game. In the case of H.M., where the MTL is missing, the executive brain never gets the message that an episode is novel, and thus continues to play "old games". In principle, at least, if this model is correct, H.M. could be cured from his memory problem, if the executive brain would have received the missing novelty signals artificially.
Itch more than scratching the surface
Lecture
Monday, June 25, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Itch more than scratching the surface
Prof. Gil Yosipovitch
Dept of Dermatology, Neurobiology & Anatomy, & Regenerative Medicine, Wake Forest University Health Sciences Winston-Salem, NC
Predicting odor pleasantness from odor structure:Pleasantness as a reflection of the physical world
Lecture
Monday, June 18, 2007
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Predicting odor pleasantness from odor structure:Pleasantness as a reflection of the physical world
Prof. Noam Sobel
Dept of Neurobiology, WIS
The cell biology of Alzheimer's disease: Intracellular pathways to pathogenesis
Lecture
Monday, June 11, 2007
Hour: 12:00 - 13:00
Location:
Nella and Leon Benoziyo Building for Brain Research
The cell biology of Alzheimer's disease: Intracellular pathways to pathogenesis
Prof. Scott A. Small
Columbia University, School of Physicians and Surgeons, New York, NY
The Hippocampus and Memory: Consolidation or Transformation?
Lecture
Tuesday, May 29, 2007
Hour: 12:00 - 13:00
Location:
Nella and Leon Benoziyo Building for Brain Research
The Hippocampus and Memory: Consolidation or Transformation?
Dr. Gordon Winocur
Rotman Research Institute, Toronto, Ontario, Canada
Adaptation and integration in the multimodal space map of the barn owl
Lecture
Monday, May 21, 2007
Hour: 12:00 - 13:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Adaptation and integration in the multimodal space map of the barn owl
Dr. Yoram Gutfreund
Dept of Physiology & Biophysics, Faculty of Medicine, Technion, Haifa
Linking Network Archtecture to Neural Coding in the Olfactory System
Lecture
Monday, May 7, 2007
Hour: 12:00 - 13:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Linking Network Archtecture to Neural Coding in the Olfactory System
Dr. Roni Jortner
Interdisciplinary Center for Neural Computation Hebrew University of Jerusalem and Computation and Neural Systems, California Institute of Technology
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