All events, All years

Imaging voltage with microbial rhodopsins

Lecture
Date:
Wednesday, May 9, 2012
Hour: 13:00
Location:
The David Lopatie Conference Centre
Prof. Adam Cohen
|
Department of Chemistry and Chemical Biology Harvard University

In the wild, microbial rhodopsin proteins convert solar energy into a transmembrane voltage, which provides energy for their host. We engineered microbial rhodopsins to run backward: to convert membrane potential into a readily detectable optical signal. When expressed in a neuron or a cardiac myocyte, these voltage-indicating proteins convert electrical action potentials into visible flashes of fluorescence, allowing us to make movies of electrical activity in cells. Upon expression of the voltage indicator in E. coli, we discovered that bacteria generate electrical spikes too. These voltage-indicating proteins are a new class of environmentally sensitive fluorescent proteins that emit in the near infrared, are highly photostable, and have no homology to GFP or to any other fluorescent indicator. J. Kralj, D. R. Hochbaum, A. D. Douglass, A. E. Cohen, “Electrical spiking in Escherichia coli probed with a fluorescent voltage-indicating protein,” Science, 333, 345-348 (2011) J. Kralj*, A. D. Douglass*, D. R. Hochbaum*, D. Maclaurin, A. E. Cohen, “Optical recording of action potentials in mammalian neurons using a microbial rhodopsin," Nature Methods, 9, 90-95 (2012)

STDP learning rules and plasticity in a small olfactory system

Lecture
Date:
Monday, May 7, 2012
Hour: 12:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prof. Gilles Laurent
|
Max Planck Institute for Brain Research, Frankfurt

This second talk will focus on olfactory circuits in the context of learning. I will present first a couple of non-associative phenomena, both linking plasticity and synchrony. I will then describe more recent work connecting STDP and reward signals, indicating that STDP rules are labile and influenced by the context in which they are being used. If time allows, I will present the outlines of the new work that we started at MPI Brain Research, on computation in an ancient cortex.

Odor representation in a small olfactory system

Lecture
Date:
Sunday, May 6, 2012
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prof. Gilles Laurent
|
Max Planck Institute for Brain Research, Frankfurt

Exploiting the relative simplicity of insect brains, we have tried to describe and understand some of the rules, formats, mechanisms and logic of olfactory coding. This talk will focus on the formats of those representations, on circuit dynamics, on sparseness, and on the relation between representations of simple odors and mixtures.

The Itching Line. Selective Silencing of Primary Afferents Reveals Two Distinct Itch-Specific Sensory Lines

Lecture
Date:
Tuesday, April 24, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dr. Alexander Binshtok
|
Dept. of Medical Neurobiology Institute for Medical Research Israel Canada and Center for Research on Pain, Hebrew University Medical School Jerusalem

Histamine-dependent and histamine-independent itch are detected and transduced in primary sensory neurons through distinct molecular signaling mechanisms. It remains unclear, however, whether pruritogens activate these mechanisms within the same or different afferents and if these afferents are dispensable for pain. To address this, we have selectively blocked histamine-dependent and -independent primary afferent fibers in vivo using targeted delivery of the membrane-impermeant sodium-channel blocker, QX-314. Silencing histamine-sensitive pruriceptors abolished subsequent histamine-evoked scratching but not that produced by the histamine-independent pruritogens chloroquine and SLIGRL-NH2, and vice versa. We conclude that distinct fibers mediate the two itches. Moreover, we also demonstrate that targeted blockade of itch does not reduce pain-associated behavior, implying that pruriceptors are a labeled line only for itch.

The hippocampal-prefrontal circuit in psychiatric disease models

Lecture
Date:
Tuesday, April 17, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Joshua Gordon
|
Dept of Psychiatry, Columbia University and The New York State Psychiatric Institute

The hippocampus and prefrontal cortex, two brain regions frequently implicated in psychiatric illness, must cooperate to regulate both cognitive and emotional behaviors. We and others have shown that these two brain regions synchronize their activity during behavior. I will discuss the dynamics of this synchrony during working memory and anxiety, how it shapes neuronal responses in the prefrontal cortex, and how it is altered by genetic manipulations of relevance to psychiatric disease.

Consciousness: An Evolutionary Approach

Lecture
Date:
Tuesday, April 3, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall

Prenatal stress programming of stress dysregulation:epigenetic and placental contributions

Lecture
Date:
Thursday, March 29, 2012
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prof. Tracy Bale
|
Neuroscience Center University of Pennsylvania School of Veterinary Medicine, Philadelphia

On the representation of space in auditory cortex

Lecture
Date:
Tuesday, March 27, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Leon Deouell
|
Department of Psychology The Hebrew University of Jerusalem

Orienting in space is a cardinal aspect of goal directed behavior. Unlike the limited "field of view" of the vision somatosensation, audition is optimally situated to provide information from 360 degrees around us, without the need to foveate or reach. However, very little is known about the representation of space in auditory cortex. I will discuss a series of studies using fMRI and EEG in human subjects, in which we investigated the cortical locus of auditory spatial information, the interaction of cortical spatial representation with tonotopic representation, and whether secondary coordinate frameworks, beyond head-related ones (e.g., body- or world-centered), are represented in auditory cortex.

The neurophysiological basis of motor function and learning and memory in the octopus, an animal with aunique embodiment

Lecture
Date:
Tuesday, March 20, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Benny Hochner
|
Dept of Neurobiology, Silberman Institute of Life Sciences and the Interdisciplinary Center for Neuronal Computation. The Hebrew University of Jerusalem

The neurobiology of the octopus cannot be analyzed without considering its special morphology. I will start my talk by describing octopus ‘embodiment’. The “… embodied view suggests that the actual behavior emerges from the interactions dynamics of agent and environment through a continuous and dynamic interplay of physical and information processes” (Pfeifer et al., 2007). The octopus with its soft, flexible body and its large variety of active behaviors driven by a huge amount of sensory information is a special test-case for assessing this view in a biological system. I will review the motor control strategies that have evolved in the octopus to cope with this special morphology, which we are studying together with Tamar Flash. These results include a unique distribution of control and computational labor between the central and an elaborated peripheral nervous system. Continuing with this idea, I will show how a comparative, physiological analysis of learning and memory mechanisms in the octopus and cuttlefish revealed dichotomous differences in the site of plasticity in a simple fan-out fan-in network. The differences suggest the importance ‘self-organizational’ mechanisms in establishing the properties of a neural network to fit a specific embodiment.

Neuropeptide Modulation of Glutamate Excitotoxicity in Experimental Traumatic Brain Injury

Lecture
Date:
Sunday, March 18, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Bruce Lyeth
|
Dept of Neurological Surgery University of California, Davis

Traumatic brain injury (TBI) remains one of the leading causes of death and disability globally. In the United States, an estimated 1.7 million persons sustain TBI resulting in 275,000 hospitalizations and 52,000 deaths each year. TBI produces a rapid and excessive increase of glutamate into the extracellular milieu, which promotes excitotoxicity and neuronal degeneration resulting in cognitive deficits. N-acetylaspartylglutamate (NAAG) is a prevalent peptide neurotransmitter in the vertebrate nervous system that is released along with glutamate. NAAG modulates (reduces) excessive glutamate release by inhibitory actions at pre-synaptic metabotropic autoreceptors. We are examining the therapeutic potential of selective NAAG peptidase inhibitors in a rat model of experimental TBI. Experimental evidence will be presented examining the mechanistic and functional effects of NAAG peptidase inhibition in the traumatically injured rodent brain, with discussion of the implications for the acute treatment of human TBI.

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On the representation of space in auditory cortex

Lecture
Date:
Tuesday, March 27, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Leon Deouell
|
Department of Psychology The Hebrew University of Jerusalem

Orienting in space is a cardinal aspect of goal directed behavior. Unlike the limited "field of view" of the vision somatosensation, audition is optimally situated to provide information from 360 degrees around us, without the need to foveate or reach. However, very little is known about the representation of space in auditory cortex. I will discuss a series of studies using fMRI and EEG in human subjects, in which we investigated the cortical locus of auditory spatial information, the interaction of cortical spatial representation with tonotopic representation, and whether secondary coordinate frameworks, beyond head-related ones (e.g., body- or world-centered), are represented in auditory cortex.

The neurophysiological basis of motor function and learning and memory in the octopus, an animal with aunique embodiment

Lecture
Date:
Tuesday, March 20, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Benny Hochner
|
Dept of Neurobiology, Silberman Institute of Life Sciences and the Interdisciplinary Center for Neuronal Computation. The Hebrew University of Jerusalem

The neurobiology of the octopus cannot be analyzed without considering its special morphology. I will start my talk by describing octopus ‘embodiment’. The “… embodied view suggests that the actual behavior emerges from the interactions dynamics of agent and environment through a continuous and dynamic interplay of physical and information processes” (Pfeifer et al., 2007). The octopus with its soft, flexible body and its large variety of active behaviors driven by a huge amount of sensory information is a special test-case for assessing this view in a biological system. I will review the motor control strategies that have evolved in the octopus to cope with this special morphology, which we are studying together with Tamar Flash. These results include a unique distribution of control and computational labor between the central and an elaborated peripheral nervous system. Continuing with this idea, I will show how a comparative, physiological analysis of learning and memory mechanisms in the octopus and cuttlefish revealed dichotomous differences in the site of plasticity in a simple fan-out fan-in network. The differences suggest the importance ‘self-organizational’ mechanisms in establishing the properties of a neural network to fit a specific embodiment.

Neuropeptide Modulation of Glutamate Excitotoxicity in Experimental Traumatic Brain Injury

Lecture
Date:
Sunday, March 18, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Bruce Lyeth
|
Dept of Neurological Surgery University of California, Davis

Traumatic brain injury (TBI) remains one of the leading causes of death and disability globally. In the United States, an estimated 1.7 million persons sustain TBI resulting in 275,000 hospitalizations and 52,000 deaths each year. TBI produces a rapid and excessive increase of glutamate into the extracellular milieu, which promotes excitotoxicity and neuronal degeneration resulting in cognitive deficits. N-acetylaspartylglutamate (NAAG) is a prevalent peptide neurotransmitter in the vertebrate nervous system that is released along with glutamate. NAAG modulates (reduces) excessive glutamate release by inhibitory actions at pre-synaptic metabotropic autoreceptors. We are examining the therapeutic potential of selective NAAG peptidase inhibitors in a rat model of experimental TBI. Experimental evidence will be presented examining the mechanistic and functional effects of NAAG peptidase inhibition in the traumatically injured rodent brain, with discussion of the implications for the acute treatment of human TBI.

Beyond the Connectome: Variability, Compensation and Modulation in Rhythmic Neuronal Networks

Lecture
Date:
Thursday, March 15, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Eve Marder
|
Dept of Biology, Brandeis University

I will summarize recent theoretical and experimental work that shows that similar circuit outputs can be produced with highly variable circuit parameters. This work argues that the nervous system of each healthy individual has found a set of different solutions that give “good enough” circuit performance. Studies using the rhythmic central pattern generating networks in the crustacean stomatogastric nervous system argue that synaptic and intrinsic currents can vary far more than the output of the circuit in which they are found. These data have significant implications for the mechanisms that maintain stable function over the animal’s lifetime, and for the kinds of changes that allow the nervous system to recover function after injury. In this kind of complex system, merely collecting mean data from many individuals can lead to significant errors, and it becomes important to measure as many individual network parameters in each individual as possible. Multiple solutions in the population provide a substrate for evolutionary change in response to environmental perturbations.

Cortical Dynamics: bottom-up and local effects

Lecture
Date:
Tuesday, March 6, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Ilan Lampl
|
Dept of Neurobiology, WIS

Abstract: Adapting coding is ambiguous - the same response may have a different meaning depending on the history and the context of the stimulus. Using intracellular recordings in the brainstem of rats we found that changing the intensity of tactile stimulation has an opposite effect on the degree of adaptation in two major brainstem somatosensory subnuclei. Interestingly, using single cell and LFP recordings we found strong ‘signatures’ for these adaptation patterns in different cortical layers in a manner that was exactly predicted from previous in-vitro studies. We suggest that converging inputs from these ascending pathways in the cortex may partially solve the ambiguity of adapting coding. In the second part I will describe how the balance between excitation and inhibition is affected by adapting stimulation and how it is modulated by different cortical states. In particular, I will show that adaptation skews the balance toward excitation and that unexpectedly this process can facilitate cortical response to subsequent stimulation. In addition, by manipulating the depth of anesthesia we found that slow brain activity is characterized by enhanced inhibitory inputs but surprisingly without a significant effect on the magnitude of excitation, which suggests that despite the recurrent connectivity in the cortex some level of decoupling exists between cortical excitation and inhibition.

From Neuron to Network: The Role of DOC2B in Synaptic Transmission and Neuronal Burst Activity

Lecture
Date:
Tuesday, February 28, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Uri Ashery
|
Dept of Neurobiology, Tel Aviv University

The plasticity of the brain plays a key role in shaping our behavior, learning and memory. It is well known that plasticity is associated with alteration in synaptic strength and efficacy. Some of these effects correlate with changes in the levels of synaptic proteins. However, the implications of genetic alteration in synaptic proteins on the network activity of neurons are not known. We examine the effect of DOC2B, a synaptic neuronal Ca2+ sensor that is known for its ability to enhance synaptic transmission, on neuronal network activity. For that purpose we use MicroElectrode Array (MEA) technology to simultaneously record action potentials from multiple neurons in ex vivo neuronal network. Networks grown on MEA plates exhibit a repeated pattern of synchronized network-wide spiking activity (network burst) separated by periods of reduced activity. At the single-neuron level, DOC2B increased the frequency of spontaneous neurotransmitter release. However, its effect at the network level was restricted to the network bursts and was reflected as an increase in the number of spikes and the number of active neurons throughout the network burst, while surprisingly there was no effect on inter-burst spiking activity. In addition, DOC2B enhanced the number of full-blown network bursts, suggesting an impact on the input/output ratio of synaptic transmission. Further analysis suggested DOC2B’s activity was augmented during neuronal bursts and enhanced spontaneous and asynchronous release. This can increase the neuron’s sensitivity to incoming EPSPs and the number of spikes in the network burst. Additionally, our experiments support the hypothesis that DOC2B efficiently enhances synaptic refilling. Hence, this work shows that the changes at the network level complemented our knowledge on the cellular activity of DOC2B and suggests a role for DOC2B in shaping the firing properties of highly active neuronal networks.

Body Representation and Self-Consciousness From Embodiment to Minimal Phenomenal Selfhood

Lecture
Date:
Tuesday, February 14, 2012
Hour: 14:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Thomas Metzinger
|
Department of Philosophy University of Mainz, Germany

As a philosopher, I am interested in the relationship between body representation and the deep structure of self-consciousness. My epistemic goal in this lecture will be the simplest form of phenomenal self-consciousness: What exactly are the essential non-conceptual, pre-reflexive layers in conscious self-representation? What constitutes a minimal phenomenal self? Conceptually, I will defend the claim that agency is not part of the metaphysically necessary supervenience-basis for bodily self-consciousness. Empirically, I will draw on recent research focusing on out-of-body experiences (OBEs) and full-body illusions (FBIs). I will then proceed to sketch a new research program and advertise a new research target: "Minimal Phenomenal Selfhood", ending with an informal argument for the thesis that agency or “global control”, phenomenologically as well as functionally, is not a necessary condition for self-consciousness.

The timing of stress: relevance for its effect on rodent and human brain

Lecture
Date:
Thursday, February 9, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Marian Joels
|
Dept of Neuroscience and Pharmacology University Medical Center Utrecht, The Netherlands

Exploration of anatomy and physiology of oxytocin and vasopressin brain systems by recombinant viruses

Lecture
Date:
Wednesday, February 8, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Dr. Valery Grinevich
|
Dept of Molecular Neurobiology Max-Planck-Institute for Medical Research, Heidelberg

How We Know That We Know:The Process Underlying Subjective Confidence

Lecture
Date:
Tuesday, January 31, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Asher Koriat
|
Institute of Information Processing and Decision Making University of Haifa

How do people monitor the correctness of their answers and judgments? A self-consistency model is proposed for the basis of confidence judgments and their accuracy. The model assumes that the process underlying subjective confidence in general-knowledge questions and perceptual judgments has much in common with that underlying statistical inference about the outside world. Participants behave like intuitive statisticians who attempt to reach a conclusion about a population on the basis of a small sample of observations. Subjective confidence is based on the sampling of clues from memory, and represent an assessment of the likelihood that a new sample will yield the same decision. Results consistent with the model were obtained across several two-alternative forced-choice tasks. The model explains some of the basic observations about subjective confidence and generates new predictions.

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