2012
All events, 2012
From Sound to Meaning –Dynamic Transformations in Auditory Signal-Processing
Lecture
Tuesday, May 22, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
From Sound to Meaning –Dynamic Transformations in Auditory Signal-Processing
Dr. Jonathan Fritz
Center for Auditory and Acoustic Research
University of Maryland, College Park, Maryland
How do we make sense of sensory inputs? One important clue may be the central role of selective and predictive attention, by focusing limited resources on behaviorally relevant sensory channels and modulating information flow at multiple stages, to improve perception.Our approach is to study the effect of attention on information processing at the single neuron level in the primary auditory cortex (A1) of animals trained on multiple auditory tasks that require selective attention to task-specific salient spectral frequency or temporal cues. Our results demonstrate that when animals actively attend to a task, their auditory cortical neurons can rapidly change their spectrotemporal filter characteristics to improve the animal’s performance. Thus, cortical sensory filters are not fixed, but are highly adaptive, and show dynamic, task-specific transformations during auditory behavior. To study the broader neural circuits involved in attention, we have initiated research on several other components in the network, including secondary auditory cortical areas, nucleus basalis, and the prefrontal cortex (PFC), a brain area known to play a key role in attention and decision-making. In contrast to A1, PFC responses are largely independent of the acoustic properties of sound, and encode an abstract, categorical representation of sound meaning. Recent studies show that electrical stimulation of PFC can elicit receptive field transformations in A1 neurons very similar to the attentional effects observed during behavior. Our working model suggests a top-down instructive role for PFC, and emphasizes the importance of interactions between multiple brain areas during selective attention that lead to matched auditory cortical filters for attended acoustic stimuli, creating a dynamic, evolving neural representation of task-salient sounds and thus optimizing perception on a moment-to-moment basis.
Comparing Apples and Oranges: the search for a common subjective value representation in the brain
Lecture
Sunday, May 20, 2012
Hour: 14:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Comparing Apples and Oranges: the search for a common subjective value representation in the brain
Dr. Dino Levy
Center for Neural Science,
New York University, NY
The ability of human subjects to choose between disparate kinds of rewards suggests that the neural circuits for valuing different reward types must converge. Economic theory suggests that these convergence points represent the subjective values (SVs) of different reward types on a common scale for comparison. I will describe two studies related to this theory. First, to directly examine this theory and to map the neural circuits for reward valuation, we had food and water deprived subjects make risky choices for money, food and water both in and out of a brain scanner. In the second study we sought to determine whether the risk preferences of these same rewards change as a function of internal state.
We found that risk preferences across reward types were highly correlated. We also found that partially distinct neural networks represent the SV of monetary and food rewards and that these distinct networks showed specific convergence points. In addition, we show that subjects tend to converge to a similar, weakly risk-averse attitude when deprived.
These results may suggest that partially distinct valuation networks for different reward types converge on a unified valuation network, which enables a direct comparison between different reward types and hence guides valuation and choice. When healthy humans are sated they show heterogeneity of risk preferences, but when deprived a convergence point appears to emerge. It is as if evolution pressure, when resources are scarce, drives humans to a similar level of risk aversion but allows heterogeneity when resources are plentiful.
Neuronal Avalanches in the Resting MEG of the Human Brain
Lecture
Thursday, May 17, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Neuronal Avalanches in the Resting MEG of the Human Brain
Dr. Oren Shriki
National Institute of Mental Health, Bethesda, Maryland
A major goal in systems neuroscience is to characterize normal cortical dynamics. Numerous in vitro and in vivo studies demonstrated that ongoing cortical dynamics are characterized by cascades of activity across many spatial scales, termed neuronal avalanches. Avalanche dynamics are identified by¬ two measures (1) a power law in the size distribution of activity cascades, with an exponent of -3/2 and (2) a branching parameter of 1, which reflects a balance in the propagation of cortical activity at the border of premature termination and potential exponential blow up. Here we analyzed resting state brain activity recorded using MEG from more than 100 healthy human subjects. We identified discrete events in the MEG signal and segmented them into cascades, using multiple timescales. Cascade-size distributions were found to obey power laws. At the timescale where the branching parameter was close to the critical value of 1, the power law exponent was -3/2, in line with expectations for neuronal avalanches. This behavior was robust to scaling of the number of sensors and to coarse-graining the sensor resolution. As controls, phase-shuffled data with the same power spectrum or empty-scanner data did not exhibit neuronal avalanches. These results indicate that normal resting cortical dynamics are well described by a critical branching process. Both theory and experiments suggest that cortical networks with such critical, scale-free dynamics optimize various types of information processing. Neuronal avalanches could thus provide a biomarker for disorders in information processing, paving the way for novel quantification of normal and pathological cortical states.
Imaging voltage with microbial rhodopsins
Lecture
Wednesday, May 9, 2012
Hour: 13:00
Location:
The David Lopatie Conference Centre
Imaging voltage with microbial rhodopsins
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
Monday, May 7, 2012
Hour: 12:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
STDP learning rules and plasticity in a small olfactory system
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
Sunday, May 6, 2012
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Odor representation in a small olfactory system
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
Tuesday, April 24, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
The Itching Line. Selective Silencing of Primary Afferents Reveals Two Distinct Itch-Specific Sensory Lines
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
Tuesday, April 17, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
The hippocampal-prefrontal circuit in psychiatric disease models
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
Tuesday, April 3, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Consciousness: An Evolutionary Approach
Prenatal stress programming of stress dysregulation:epigenetic and placental contributions
Lecture
Thursday, March 29, 2012
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prenatal stress programming of stress dysregulation:epigenetic and placental contributions
Prof. Tracy Bale
Neuroscience Center University of Pennsylvania
School of Veterinary Medicine, Philadelphia
Pages
2012
All events, 2012
From Sound to Meaning –Dynamic Transformations in Auditory Signal-Processing
Lecture
Tuesday, May 22, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
From Sound to Meaning –Dynamic Transformations in Auditory Signal-Processing
Dr. Jonathan Fritz
Center for Auditory and Acoustic Research
University of Maryland, College Park, Maryland
How do we make sense of sensory inputs? One important clue may be the central role of selective and predictive attention, by focusing limited resources on behaviorally relevant sensory channels and modulating information flow at multiple stages, to improve perception.Our approach is to study the effect of attention on information processing at the single neuron level in the primary auditory cortex (A1) of animals trained on multiple auditory tasks that require selective attention to task-specific salient spectral frequency or temporal cues. Our results demonstrate that when animals actively attend to a task, their auditory cortical neurons can rapidly change their spectrotemporal filter characteristics to improve the animal’s performance. Thus, cortical sensory filters are not fixed, but are highly adaptive, and show dynamic, task-specific transformations during auditory behavior. To study the broader neural circuits involved in attention, we have initiated research on several other components in the network, including secondary auditory cortical areas, nucleus basalis, and the prefrontal cortex (PFC), a brain area known to play a key role in attention and decision-making. In contrast to A1, PFC responses are largely independent of the acoustic properties of sound, and encode an abstract, categorical representation of sound meaning. Recent studies show that electrical stimulation of PFC can elicit receptive field transformations in A1 neurons very similar to the attentional effects observed during behavior. Our working model suggests a top-down instructive role for PFC, and emphasizes the importance of interactions between multiple brain areas during selective attention that lead to matched auditory cortical filters for attended acoustic stimuli, creating a dynamic, evolving neural representation of task-salient sounds and thus optimizing perception on a moment-to-moment basis.
Comparing Apples and Oranges: the search for a common subjective value representation in the brain
Lecture
Sunday, May 20, 2012
Hour: 14:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Comparing Apples and Oranges: the search for a common subjective value representation in the brain
Dr. Dino Levy
Center for Neural Science,
New York University, NY
The ability of human subjects to choose between disparate kinds of rewards suggests that the neural circuits for valuing different reward types must converge. Economic theory suggests that these convergence points represent the subjective values (SVs) of different reward types on a common scale for comparison. I will describe two studies related to this theory. First, to directly examine this theory and to map the neural circuits for reward valuation, we had food and water deprived subjects make risky choices for money, food and water both in and out of a brain scanner. In the second study we sought to determine whether the risk preferences of these same rewards change as a function of internal state.
We found that risk preferences across reward types were highly correlated. We also found that partially distinct neural networks represent the SV of monetary and food rewards and that these distinct networks showed specific convergence points. In addition, we show that subjects tend to converge to a similar, weakly risk-averse attitude when deprived.
These results may suggest that partially distinct valuation networks for different reward types converge on a unified valuation network, which enables a direct comparison between different reward types and hence guides valuation and choice. When healthy humans are sated they show heterogeneity of risk preferences, but when deprived a convergence point appears to emerge. It is as if evolution pressure, when resources are scarce, drives humans to a similar level of risk aversion but allows heterogeneity when resources are plentiful.
Neuronal Avalanches in the Resting MEG of the Human Brain
Lecture
Thursday, May 17, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Neuronal Avalanches in the Resting MEG of the Human Brain
Dr. Oren Shriki
National Institute of Mental Health, Bethesda, Maryland
A major goal in systems neuroscience is to characterize normal cortical dynamics. Numerous in vitro and in vivo studies demonstrated that ongoing cortical dynamics are characterized by cascades of activity across many spatial scales, termed neuronal avalanches. Avalanche dynamics are identified by¬ two measures (1) a power law in the size distribution of activity cascades, with an exponent of -3/2 and (2) a branching parameter of 1, which reflects a balance in the propagation of cortical activity at the border of premature termination and potential exponential blow up. Here we analyzed resting state brain activity recorded using MEG from more than 100 healthy human subjects. We identified discrete events in the MEG signal and segmented them into cascades, using multiple timescales. Cascade-size distributions were found to obey power laws. At the timescale where the branching parameter was close to the critical value of 1, the power law exponent was -3/2, in line with expectations for neuronal avalanches. This behavior was robust to scaling of the number of sensors and to coarse-graining the sensor resolution. As controls, phase-shuffled data with the same power spectrum or empty-scanner data did not exhibit neuronal avalanches. These results indicate that normal resting cortical dynamics are well described by a critical branching process. Both theory and experiments suggest that cortical networks with such critical, scale-free dynamics optimize various types of information processing. Neuronal avalanches could thus provide a biomarker for disorders in information processing, paving the way for novel quantification of normal and pathological cortical states.
Imaging voltage with microbial rhodopsins
Lecture
Wednesday, May 9, 2012
Hour: 13:00
Location:
The David Lopatie Conference Centre
Imaging voltage with microbial rhodopsins
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
Monday, May 7, 2012
Hour: 12:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
STDP learning rules and plasticity in a small olfactory system
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
Sunday, May 6, 2012
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Odor representation in a small olfactory system
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
Tuesday, April 24, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
The Itching Line. Selective Silencing of Primary Afferents Reveals Two Distinct Itch-Specific Sensory Lines
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
Tuesday, April 17, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
The hippocampal-prefrontal circuit in psychiatric disease models
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
Tuesday, April 3, 2012
Hour: 12:30
Location:
Gerhard M.J. Schmidt Lecture Hall
Consciousness: An Evolutionary Approach
Prenatal stress programming of stress dysregulation:epigenetic and placental contributions
Lecture
Thursday, March 29, 2012
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prenatal stress programming of stress dysregulation:epigenetic and placental contributions
Prof. Tracy Bale
Neuroscience Center University of Pennsylvania
School of Veterinary Medicine, Philadelphia
Pages
2012
All events, 2012
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