2009
All events, 2009
“Tomorrow is another day": A 24 h persistent synaptic plasticity in hippocampal interneuron circuits
Lecture
Tuesday, August 18, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
“Tomorrow is another day": A 24 h persistent synaptic plasticity in hippocampal interneuron circuits
Dr. Israeli Ran
Dept of Physiology
University of Montreal, Canada
Hippocampal interneurons synchronize the activity of large neuronal ensembles during memory consolidation. Although the latter process is manifested as increases in synaptic efficacy which require new protein synthesis in pyramidal neurons, it is unknown whether such enduring plasticity occurs in interneurons. In the present talk, I will discuss a long-term potentiation (LTP) of transmission at individual interneuron excitatory synapses which persists for at least 24 h, after repetitive activation of type-1 metabotropic glutamate receptors [mGluR1-mediated chemical late LTP (cL-LTPmGluR1 )]. cL-LTPmGluR1 involves pre- and postsynaptic expression mechanisms and requires both transcription and translation via phosphoinositide 3-kinase/mammalian target of rapamycin and MAPkinase kinase extracellular signal-regulated protein kinase signaling pathways. Moreover, cL-LTPmGluR1 involves translational control at the level of initiation as it is prevented by hippuristanol, an inhibitor of eIF4A, and facilitated in mice lacking the cap-dependent translational repressor, 4E-BP. These results reveal novel mechanisms of long-term synaptic plasticity that are transcription and translation-dependent in inhibitory interneurons, indicating that persistent synaptic modifications in interneuron circuits may contribute to hippocampal-dependent cognitive processes.
Active Sensing by Bat Biosonar: Strategies of Information Flow Control
Lecture
Monday, August 17, 2009
Hour: 12:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Active Sensing by Bat Biosonar: Strategies of Information Flow Control
Dr. Marc Holderied
University of Bristol, UK
Abstract: Echolocation or biosonar is an alien sense to humans. For us as visually guided mammals it is hard to imagine what an echolocator's acoustic perception of its surroundings 'looks' like. Part of this difficulty arises because vision and biosonar differ fundamentally in a number of ways: a) Vision is based on two dimensional data, i.e. images focused on the retina in the eye, while bats evaluate a linear stream of echoes and have to reconstruct all directional/spatial information from the temporal and spectral properties of the echo stream; b) the number of sensory cells in hearing is much lower than in vision and c) biosonar is a case of active sensing, i.e. bats actively produce the signals with which they probe the environment, while vision (in the vast majority of cases) relies on external light sources. This combination of traits, i.e. limited bandwidth and active sensing has led to a number of behavioural adaptive strategies by which bats control what information about the environment becomes available to them. In a sense, external mechanisms to extract the relevant information from the plethora of available data are far more important in biosonar than in vision.
Hence, biosonar offers unique opportunities to study behavioural strategies of information flow control by active sensing. We employed high resolution acoustic tracking techniques and 3D laser scanning of natural habitats to study free flying bats in forests. We investigated how they adapt flight patterns, calling behaviour and sonar signal design to optimize information flow.
Movement selectivity in the human mirror system
Lecture
Tuesday, July 28, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Movement selectivity in the human mirror system
Ilan Dinstein New York University Visiting PhD Student – Malach Lab
Abstract: “Monkey mirror neurons are unique visuomotor neurons that respond when executing a particular movement (e.g. grasping, placing, or manipulating) and also when passively observing someone else performing that same movement. Importantly, subpopulations of mirror neurons respond in a selective manner to one preferred movement whether executed or observed. It has been proposed that the activity of mirror neurons underlies the monkey’s ability to perceive the goals and intentions of others. Human mirror neurons are thought to exist in two cortical areas, the anterior intraparietal sulcus (aIPS) and the ventral premotor (vPM), which have been called the human mirror system. A dysfunction in the responses of this system has been hypothesized to cause impairment in the ability to understand one another resulting in Autism. I will talk about three studies where we characterized the responses of the human mirror system using fMRI adaptation and classification techniques to assess their response selectivity for observed and executed hand movements. Two studies were performed with neurotypical individuals and the third with Autistic individuals.”
Role of Dopamine in Reward: Anatomical and Conceptual Issues
Lecture
Tuesday, July 14, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Role of Dopamine in Reward: Anatomical and Conceptual Issues
Dr. Satoshi Ikemoto
NIDA (Nat. Inst. on Drug Abuse)
Behavioral Neuroscience Research Branch
NIH, USA
Abstract: The mesolimbic dopamine system from the ventral tegmental area (VTA) to the ventral striatum has been implicated in reward. Using intracranial self-administration procedures, we found that rats learn to self-administer cocaine or amphetamine into the medial portion of the ventral striatum more readily than the lateral ventral striatum. Rats learn to self-administer drugs such as opiates and cholinergic drugs into the posterior portion of the VTA more readily than the anterior VTA. Axonal tracer experiments revealed that the medial ventral striatum is preferentially innervated by dopamine neurons localized in the posterior VTA, while the lateral ventral striatum is preferentially innervated by dopamine neurons in the anterolateral VTA. Therefore, the mesolimbic dopamine system from the posterior VTA to the medial ventral striatum appears to be more responsive for rewarding effects of drugs. In addition, we have studied the nature of the rewarding effects of drugs. We found that noncontingent administration of cocaine or amphetamine into the medial ventral striatum increases leverpressing, when leverpressing contingently elicits visual signals. These results suggest that a function of dopamine in the ventral striatum is to facilitate actions in response to salient stimuli. Dopamine in the medial ventral striatum also appears to facilitate associative learning as shown by conditioned place preference of cocaine. We suggest that ventral striatal dopamine induces an arousing state that facilitates ongoing appetitive responding and reinforcement.
Collective Motion and Decision-Making in Animal Groups
Lecture
Thursday, July 9, 2009
Hour: 12:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Collective Motion and Decision-Making in Animal Groups
Prof. Iain Couzin
Dept of Ecology and Evolutionary Biology
and Program in Computational and Mathematical Biology
Princeton University USA
Grouping organisms, such as schooling fish, often have to make rapid decisions in uncertain and dangerous environments. Decision-making by individuals within such aggregates is so seamlessly integrated that it has been associated with the concept of a “collective mind”. As each organism has relatively local sensing ability, coordinated animal groups have evolved collective strategies that allow individuals to access higher-order computational abilities at the collective level. Using a combined theoretical and experimental approach involving insect and vertebrate groups, I will address how, and why, individuals move in unison and investigate the principles of information transfer in these groups, particularly focusing on leadership and collective consensus decision-making. An integrated "hybrid swarm" technology is introduced in which multiple robot-controlled replica individuals interact within real groups allowing us new insights into group coordination. These results will be discussed in the context of the evolution of collective biological systems.
Neuronal Avalanches in the Cortex:A Case for Criticality
Lecture
Tuesday, July 7, 2009
Hour: 15:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Neuronal Avalanches in the Cortex:A Case for Criticality
Prof. Dietmar Plenz
Laboratory of Systems Neuroscience
NIMH, USA
Complex systems, when poised near a critical point of a phase transition between order and disorder, exhibit scale-free, power law dynamics. Critical systems are highly adaptive and flexibly process and store information, which prompted the conjecture that the cortex might operate at criticality. This view is supported by the recent discovery of neuronal avalanches in superficial layers of cortex. The spatiotemporal, synchronized activity patterns of avalanches form a scale-free organization that spontaneously emerges in vitro as well as in vivo in the anesthetized rat and awake monkeys. Avalanches are established at the time of superficial layer differentiation, require balanced fast excitation and inhibition, and are regulated via an inverted-U profile of NMDA/dopamine-D1 interaction. Neuronal synchronization in the form of avalanches naturally incorporates nested theta/gamma-oscillations as well as sequential activations as proposed for synfire chains. Importantly, a singleavalanche is not an isolated
network event, but rather its specific occurrence in time, its spatial spread, and overall size is part of an elementary organization of the dynamics that is described by three fundamental power laws. Overall, these results suggest that neuronal avalanches indicate a critical network dynamics at which the cortex gains universal properties found at criticality. These properties constitute a novel framework that allow for a precise quantification of cortex function such as the absolute discrimination of pathological from non-pathological synchronization, and the identification of maximal dynamic range for input-output processing.
Critical thoughts on critical periods: Are children better than adults at acquiring skills?
Lecture
Tuesday, July 7, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Critical thoughts on critical periods: Are children better than adults at acquiring skills?
Prof. Avi Karni
Department of Human Biology
University of Haifa
Physiological studies of the functional architecture of the basal ganglia neural networks
Lecture
Tuesday, June 30, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Physiological studies of the functional architecture of the basal ganglia neural networks
Prof. Hagai Bergman
Dept of Physiology and
The Interdisciplinary Center for Neural Computation
Hebrew University, Jerusalem
The basal ganglia (BG) are commonly viewed as two functionally related subsystems. These are the neuromodulators subsystem and the main-axis subsystem, in analogy with the critic-actor division of reinforcement learning agent.
We propose that the BG main axis is performing dimensionality reduction of the cortical input leading to optimal trade-off between maximization of future cumulative reward and minimization of the cost (information bottleneck).
In line with the information bottleneck dimensionality reduction model, BG main axis neurons maintain flat spike crosscorrelation functions, diverse responses to behavioral events, and broadly distributed values of signal and response correlations with zero population mean. On the other hand, the spontaneous and the evoked activity of BG dopaminergic and cholinergic modulators (critics) are significantly correlated.
BG plasticity and learning are therefore controlled by homogenous modulators effects associated with local coincidences of cortico-striatal activity.
Brain and Reality: How Does the Brain Generate Perceptions and Actions
Lecture
Tuesday, June 23, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Brain and Reality: How Does the Brain Generate Perceptions and Actions
Prof. Eilon Vaadia
Dept of Medical Neurobiology
Hadassah Medical School
Hebrew University, Jerusalem
Evoked neural synchrony, visual attention and grouping
Lecture
Tuesday, June 16, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Evoked neural synchrony, visual attention and grouping
Prof. Marius Usher
Dept of Psychology,
Tel Aviv University
Neural synchrony was proposed as a mechanism for visual attention, and more controversially, for grouping and figure-ground processing. In this talk I will first present evidence showing that evoked Gamma synchrony, via 50Hz subliminal flicker produces attentional orientation in the absence of awareness. Second, I will present data on the effects of evoked synchrony on grouping and figure-ground processing. The results indicate a fast temporal resolution for these processes (<20ms), which is mediated by lateral connections and which is sensitive to synchrony, but not to sustained oscillations of a specific frequency.
Collaboration with: S Cheadle, F Bauer, H Mueller.
Pages
2009
All events, 2009
Active Sensing by Bat Biosonar: Strategies of Information Flow Control
Lecture
Monday, August 17, 2009
Hour: 12:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Active Sensing by Bat Biosonar: Strategies of Information Flow Control
Dr. Marc Holderied
University of Bristol, UK
Abstract: Echolocation or biosonar is an alien sense to humans. For us as visually guided mammals it is hard to imagine what an echolocator's acoustic perception of its surroundings 'looks' like. Part of this difficulty arises because vision and biosonar differ fundamentally in a number of ways: a) Vision is based on two dimensional data, i.e. images focused on the retina in the eye, while bats evaluate a linear stream of echoes and have to reconstruct all directional/spatial information from the temporal and spectral properties of the echo stream; b) the number of sensory cells in hearing is much lower than in vision and c) biosonar is a case of active sensing, i.e. bats actively produce the signals with which they probe the environment, while vision (in the vast majority of cases) relies on external light sources. This combination of traits, i.e. limited bandwidth and active sensing has led to a number of behavioural adaptive strategies by which bats control what information about the environment becomes available to them. In a sense, external mechanisms to extract the relevant information from the plethora of available data are far more important in biosonar than in vision.
Hence, biosonar offers unique opportunities to study behavioural strategies of information flow control by active sensing. We employed high resolution acoustic tracking techniques and 3D laser scanning of natural habitats to study free flying bats in forests. We investigated how they adapt flight patterns, calling behaviour and sonar signal design to optimize information flow.
Movement selectivity in the human mirror system
Lecture
Tuesday, July 28, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Movement selectivity in the human mirror system
Ilan Dinstein New York University Visiting PhD Student – Malach Lab
Abstract: “Monkey mirror neurons are unique visuomotor neurons that respond when executing a particular movement (e.g. grasping, placing, or manipulating) and also when passively observing someone else performing that same movement. Importantly, subpopulations of mirror neurons respond in a selective manner to one preferred movement whether executed or observed. It has been proposed that the activity of mirror neurons underlies the monkey’s ability to perceive the goals and intentions of others. Human mirror neurons are thought to exist in two cortical areas, the anterior intraparietal sulcus (aIPS) and the ventral premotor (vPM), which have been called the human mirror system. A dysfunction in the responses of this system has been hypothesized to cause impairment in the ability to understand one another resulting in Autism. I will talk about three studies where we characterized the responses of the human mirror system using fMRI adaptation and classification techniques to assess their response selectivity for observed and executed hand movements. Two studies were performed with neurotypical individuals and the third with Autistic individuals.”
Role of Dopamine in Reward: Anatomical and Conceptual Issues
Lecture
Tuesday, July 14, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Role of Dopamine in Reward: Anatomical and Conceptual Issues
Dr. Satoshi Ikemoto
NIDA (Nat. Inst. on Drug Abuse)
Behavioral Neuroscience Research Branch
NIH, USA
Abstract: The mesolimbic dopamine system from the ventral tegmental area (VTA) to the ventral striatum has been implicated in reward. Using intracranial self-administration procedures, we found that rats learn to self-administer cocaine or amphetamine into the medial portion of the ventral striatum more readily than the lateral ventral striatum. Rats learn to self-administer drugs such as opiates and cholinergic drugs into the posterior portion of the VTA more readily than the anterior VTA. Axonal tracer experiments revealed that the medial ventral striatum is preferentially innervated by dopamine neurons localized in the posterior VTA, while the lateral ventral striatum is preferentially innervated by dopamine neurons in the anterolateral VTA. Therefore, the mesolimbic dopamine system from the posterior VTA to the medial ventral striatum appears to be more responsive for rewarding effects of drugs. In addition, we have studied the nature of the rewarding effects of drugs. We found that noncontingent administration of cocaine or amphetamine into the medial ventral striatum increases leverpressing, when leverpressing contingently elicits visual signals. These results suggest that a function of dopamine in the ventral striatum is to facilitate actions in response to salient stimuli. Dopamine in the medial ventral striatum also appears to facilitate associative learning as shown by conditioned place preference of cocaine. We suggest that ventral striatal dopamine induces an arousing state that facilitates ongoing appetitive responding and reinforcement.
Collective Motion and Decision-Making in Animal Groups
Lecture
Thursday, July 9, 2009
Hour: 12:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Collective Motion and Decision-Making in Animal Groups
Prof. Iain Couzin
Dept of Ecology and Evolutionary Biology
and Program in Computational and Mathematical Biology
Princeton University USA
Grouping organisms, such as schooling fish, often have to make rapid decisions in uncertain and dangerous environments. Decision-making by individuals within such aggregates is so seamlessly integrated that it has been associated with the concept of a “collective mind”. As each organism has relatively local sensing ability, coordinated animal groups have evolved collective strategies that allow individuals to access higher-order computational abilities at the collective level. Using a combined theoretical and experimental approach involving insect and vertebrate groups, I will address how, and why, individuals move in unison and investigate the principles of information transfer in these groups, particularly focusing on leadership and collective consensus decision-making. An integrated "hybrid swarm" technology is introduced in which multiple robot-controlled replica individuals interact within real groups allowing us new insights into group coordination. These results will be discussed in the context of the evolution of collective biological systems.
Neuronal Avalanches in the Cortex:A Case for Criticality
Lecture
Tuesday, July 7, 2009
Hour: 15:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Neuronal Avalanches in the Cortex:A Case for Criticality
Prof. Dietmar Plenz
Laboratory of Systems Neuroscience
NIMH, USA
Complex systems, when poised near a critical point of a phase transition between order and disorder, exhibit scale-free, power law dynamics. Critical systems are highly adaptive and flexibly process and store information, which prompted the conjecture that the cortex might operate at criticality. This view is supported by the recent discovery of neuronal avalanches in superficial layers of cortex. The spatiotemporal, synchronized activity patterns of avalanches form a scale-free organization that spontaneously emerges in vitro as well as in vivo in the anesthetized rat and awake monkeys. Avalanches are established at the time of superficial layer differentiation, require balanced fast excitation and inhibition, and are regulated via an inverted-U profile of NMDA/dopamine-D1 interaction. Neuronal synchronization in the form of avalanches naturally incorporates nested theta/gamma-oscillations as well as sequential activations as proposed for synfire chains. Importantly, a singleavalanche is not an isolated
network event, but rather its specific occurrence in time, its spatial spread, and overall size is part of an elementary organization of the dynamics that is described by three fundamental power laws. Overall, these results suggest that neuronal avalanches indicate a critical network dynamics at which the cortex gains universal properties found at criticality. These properties constitute a novel framework that allow for a precise quantification of cortex function such as the absolute discrimination of pathological from non-pathological synchronization, and the identification of maximal dynamic range for input-output processing.
Critical thoughts on critical periods: Are children better than adults at acquiring skills?
Lecture
Tuesday, July 7, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Critical thoughts on critical periods: Are children better than adults at acquiring skills?
Prof. Avi Karni
Department of Human Biology
University of Haifa
Physiological studies of the functional architecture of the basal ganglia neural networks
Lecture
Tuesday, June 30, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Physiological studies of the functional architecture of the basal ganglia neural networks
Prof. Hagai Bergman
Dept of Physiology and
The Interdisciplinary Center for Neural Computation
Hebrew University, Jerusalem
The basal ganglia (BG) are commonly viewed as two functionally related subsystems. These are the neuromodulators subsystem and the main-axis subsystem, in analogy with the critic-actor division of reinforcement learning agent.
We propose that the BG main axis is performing dimensionality reduction of the cortical input leading to optimal trade-off between maximization of future cumulative reward and minimization of the cost (information bottleneck).
In line with the information bottleneck dimensionality reduction model, BG main axis neurons maintain flat spike crosscorrelation functions, diverse responses to behavioral events, and broadly distributed values of signal and response correlations with zero population mean. On the other hand, the spontaneous and the evoked activity of BG dopaminergic and cholinergic modulators (critics) are significantly correlated.
BG plasticity and learning are therefore controlled by homogenous modulators effects associated with local coincidences of cortico-striatal activity.
Brain and Reality: How Does the Brain Generate Perceptions and Actions
Lecture
Tuesday, June 23, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Brain and Reality: How Does the Brain Generate Perceptions and Actions
Prof. Eilon Vaadia
Dept of Medical Neurobiology
Hadassah Medical School
Hebrew University, Jerusalem
Evoked neural synchrony, visual attention and grouping
Lecture
Tuesday, June 16, 2009
Hour: 12:30
Location:
Jacob Ziskind Building
Evoked neural synchrony, visual attention and grouping
Prof. Marius Usher
Dept of Psychology,
Tel Aviv University
Neural synchrony was proposed as a mechanism for visual attention, and more controversially, for grouping and figure-ground processing. In this talk I will first present evidence showing that evoked Gamma synchrony, via 50Hz subliminal flicker produces attentional orientation in the absence of awareness. Second, I will present data on the effects of evoked synchrony on grouping and figure-ground processing. The results indicate a fast temporal resolution for these processes (<20ms), which is mediated by lateral connections and which is sensitive to synchrony, but not to sustained oscillations of a specific frequency.
Collaboration with: S Cheadle, F Bauer, H Mueller.
Large-scale brain dynamics: Functional MRI of spontaneous and optically-driven neural activity
Lecture
Monday, June 15, 2009
Hour: 12:45
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Large-scale brain dynamics: Functional MRI of spontaneous and optically-driven neural activity
Dr. Itamar Kahn
Howard Hughes Medical Institute
Harvard University
A fundamental problem in brain research is how distributed brain systems work together to give rise to behavior. I seek to advance our understanding of principles underlying the dynamic interaction between multiple neural systems, how the different systems co-operate and/or compete to give rise to goal-directed behavior, and the dynamics of the system when one or more of its components fail.
Magnetic resonance imaging (MRI) methods allow us to simultaneously measure the function of multiple brain systems. In humans we can characterize the functional organization and specialization, and compare the system between health and disease. In animal models we can further dissect the circuits underlying these dynamics. In my work I aim to identify functional networks that span multiple cortical and subcortical regions, characterize their responses in the presence and absence of overt behavior, and modulate the observed dynamics. To advance these goals, I am developing new tools that will allow us to study large-scale neural systems across species.
In this talk, I will review recent studies that use functional neuroimaging in humans and animal models. I will describe how spontaneous fluctuations of the blood oxygenation level-dependent (BOLD) signal measured with MRI in awake resting humans, reveal functional subdivisions in the medial temporal lobe memory system and parietal and prefrontal cortical components linked to it. I will describe results from non-human primates demonstrating that this functional organization persists across the species, highlighting cortical components that have undergone considerable areal expansion in humans relative to non-human primates, how this method can be used to identify homologue regions, and more generally, what can be learned from a comparative perspective.
In the second part of my talk I will describe recent efforts to selectively modulate system dynamics. A lentivirus was used to target excitatory neurons in the rat cortex with light-activated cation channel channelrhodopsin-2. Using photostimulation to activate these neurons we were able to drive the BOLD response locally and in regions anatomically connected to the infected site in a variety of stimulation paradigms. I will discuss implications for understanding the BOLD signal and prospects for this approach in studying the microcircuit as well as large-scale brain dynamics. Finally, I will discuss the challenges and promises of whole-brain imaging in small animals, and how this work can provide avenues to bridge between a basic understanding of human behavior, large-scale neural dynamics, and psychiatric disorders where such dynamics are disrupted.
Pages
2009
All events, 2009
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