All events, 2011

Synaptic mechanisms of sensory perception

Lecture
Date:
Wednesday, January 19, 2011
Hour: 10:00
Location:
Gerhard M.J. Schmidt Lecture Hall
Prof. Carl Petersen
|
Brain Mind Institute, EPFL Lausanne, Switzerland

Ode To Memory A mini-series devoted to memory in cinema

Lecture
Date:
Tuesday, January 18, 2011
Hour: 14:00
Location:
Dolfi and Lola Ebner Auditorium
Prof. Yadin Dudai
|
Dept of Neurobiology, WIS

A cellular mechanism for general enhancement of learning capability

Lecture
Date:
Tuesday, January 18, 2011
Hour: 12:30
Location:
Jacob Ziskind Building
Dr. Edi Barkai
|
University of Haifa

Learning-related cellular modifications occur not only at synapses but also in the intrinsic properties of the neurons. Learning-induced enhancement in neuronal excitability is evident in hippocampal and piriform cortex pyramidal neurons following a complex olfactory-discrimination operant conditioning task. Such enhanced excitability is manifested in reduced spike frequency adaptation that results from reduction in the slow afterhyperpolarization (AHP), which develops after a burst of action potentials. AHP reduction is apparent throughout the pyramidal cells neuronal population. The AHP amplitude tends to return back to its initial value within days when training is suspended. This recovery is accompanied by reduced learning capability, but not by loss of memories for learned odors. The post-burst AHP reduction is mediated by decreased conductance for a specific calcium-dependent potassium current, the slow IAHP. This long-lasting reduction is dependent on persistent activation of the PKC and ERK second messenger systems. Similar long-lasting AHP reduction can be induced in-vitro by repetitive synaptic stimulation or by kainate application. Such activity-dependent AHP reduction is occluded by prior learning. Olfactory-learning induced enhanced neuronal excitability in CA1 pyramidal neurons is also accompanied by enhanced learning capability in a novel hippocampus-dependent task, the Morris water maze. We suggested that AHP reduction is the cellular mechanism that enables neuronal ensembles to enter into a state which may be best termed "learning mode". This state lasts for up to several days and its behavioral manifestation is enhanced learning capability in tasks that depend on these particular neuronal ensembles. Specifically, enhanced neuronal excitability sets a time window in which most neurons in the relevant neuronal network are more excitable, and thus activity-dependent synaptic modifications are more likely to occur.

What the brain knows about what’s in the nose: Neural processing of pheromone signals

Lecture
Date:
Monday, January 17, 2011
Hour: 12:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Dr. Yoram Ben-Shaul
|
Harvard University

Understanding the neuronal events linking sensory inputs with behavioral outputs in complex organisms is a central goal of neuroscience. First steps in this enormous endeavor can be made by focusing on the relatively simple and stereotyped class of chemosensory triggered innately encoded physiological processes. Until recently, analysis of the circuits that underlie these processes was hampered by the lack of a reliable method for stimulus delivery to the vomeronasal system, which in mice, like many other mammals, plays a key role in processing pheromonal information. To address this issue, I developed an experimental preparation that allows in-vivo stimulus delivery to the mouse vomeronasal system and combined it with multisite neuronal recordings to measure stimulus evoked neuronal activity. Recordings from the early processing stage of the accessory olfactory bulb reveal the broad range and high acuity of ethologically relevant sensory representations, and furthermore suggest that these involve integrative processing. Recording from subsequent processing relays in the vomeronasal amygdala reveal several similarities to the olfactory bulb representations but also some intriguing differences raising new hypotheses about the role of the amygdala in these processes. Finally, I will describe how I am extending this approach by employing optogenetic techniques to record neuronal activity from scarce and genetically defined neurons in subsequent processing regions. Taken together, these experiments are beginning to illuminate the function of entire neuronal circuits involved in mediating ethologically and clinically relevant endocrine processes.

Topographic mapping of a hierarchy of temporal receptive windows using natural stimuli

Lecture
Date:
Thursday, January 13, 2011
Hour: 12:00
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prof. Uri Hasson
|
Dept of Psychology, Princeton University

Space and time are two fundamental properties of our physical and psychological realms. While much is known about the integration of information across space within the visual system, little is known about the integration of information over time. Using two complementary methods of functional magnetic resonance imaging (fMRI) and intracranial electroencephalography (iEEG), I will present evidences that the brain uses similar strategies for integrating information over space and over time. It is well established that neurons along visual cortical pathways have increasingly large spatial receptive fields. This is a basic organizing principle of the visual system: neurons in higher-level visual areas receive input from low level neurons with smaller receptive fields and thereby accumulate information over space. Drawing an analogy with the spatial receptive field (SRF), we defined the temporal receptive window (TRW) of a neuron as the length of time prior to a response during which sensory information may affect that response. As with SRFs, the topographical organization of the TRWs is distributed and hierarchical. The accumulation of information over time is distributed in the sense that each brain area has the capacity to accumulate information over time. The processing is hierarchical because the capacity of each TRW increases from early sensory areas to higher order perceptual and cognitive areas. Early sensory cortices such as the primary auditory or visual cortex have relatively short TRWs (up to hundreds of milliseconds), while the TRWs in higher order areas can accumulate information over many minutes.

Multimodal interactions in primary auditory cortex: Laminar dependence & modulation by general anesthetics

Lecture
Date:
Tuesday, January 11, 2011
Hour: 12:30
Location:
Jacob Ziskind Building
Prof. Matthew I. Banks
|
University of Wisconsin, USA

Current theories of the neural basis of sensory awareness suggest that neocortex is constantly comparing expected with observed sensory information. This comparison arises through the integration of ascending inputs from the sensory periphery and descending cortical inputs from the same or other sensory modalities. The importance of this integrative process for awareness is suggested by its selective loss upon anesthetic-induced hypnosis and during slow-wave sleep, but how this integration and its disruption by anesthetics occur within a cortical column is unclear. Using electrophysiological and imaging techniques in rodents in vivo and in brain slices, we show that extrastriate visual cortex provides descending input to primary auditory cortex that modulates responses to auditory stimuli, and that the integration of these information streams is disrupted by general anesthetics.

A Neural Mechanism for Reasoning and Believing

Lecture
Date:
Wednesday, January 5, 2011
Hour: 15:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prof. Michael Shadlen
|
Physiology and Biophysics Dept University of Washington

Spatial Memory, Healthy Cognition and Successful Aging

Lecture
Date:
Wednesday, January 5, 2011
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Prof. Veronique Bohbot
|
Faculty of Medicine McGill University, Quebec, Canada

Young healthy participants spontaneously use different strategies in a virtual radial maze, an adaptation of a task typically used with rodents. We have previously shown using fMRI that people who use spatial memory strategies have increased activity in the hippocampus whereas response strategies are associated with activity in the caudate nucleus. In addition, we used Voxel Based Morphometry (VBM) to identify brain regions co-varying with the navigational strategies individuals used. Results showed that spatial learners have significantly more grey matter in the hippocampus and less grey matter in the caudate nucleus than response learners. The relationship between spatial memory strategies and grey matter of the hippocampus was replicated with healthy older adults. Furthermore, we found a positive correlation between spatial memory strategies and the MoCA, which is a test sensitive to mild cognitive impairment. Since low grey matter in the hippocampus is a risk factor for cognitive deficits in normal aging and for Alzheimer’s disease, our results suggest that using spatial memory in our everyday lives may protect against degeneration of the hippocampus and associated cognitive deficits These results have important implications for intervention programs aimed at healthy and successful aging.

Visual Inference by Composition

Lecture
Date:
Tuesday, January 4, 2011
Hour: 12:30
Location:
Jacob Ziskind Building
Prof. Michal Irani
|
Dept of Computer Science and Applied Mathematics, WIS

In this talk I will show how complex visual tasks can be performed by exploiting redundancy in visual data. Comparing and integrating data recurrences allows to make inferences about complex scenes, without any prior examples or prior training. I will demonstrate the power of this approach to several visual inference problems (as time permits). These include: 1. Detecting complex objects and actions (often based only on a rough hand-sketch of what we are looking for). 2. Summarizing visual data (images and video). 3. Super-resolution (from a single image). 4. Prediction of missing visual information. 5. Detecting the "irregular" and "unexpected". 6. "Segmentation by Composition".

Pages

All events, 2011

Multimodal interactions in primary auditory cortex: Laminar dependence & modulation by general anesthetics

Lecture
Date:
Tuesday, January 11, 2011
Hour: 12:30
Location:
Jacob Ziskind Building
Prof. Matthew I. Banks
|
University of Wisconsin, USA

Current theories of the neural basis of sensory awareness suggest that neocortex is constantly comparing expected with observed sensory information. This comparison arises through the integration of ascending inputs from the sensory periphery and descending cortical inputs from the same or other sensory modalities. The importance of this integrative process for awareness is suggested by its selective loss upon anesthetic-induced hypnosis and during slow-wave sleep, but how this integration and its disruption by anesthetics occur within a cortical column is unclear. Using electrophysiological and imaging techniques in rodents in vivo and in brain slices, we show that extrastriate visual cortex provides descending input to primary auditory cortex that modulates responses to auditory stimuli, and that the integration of these information streams is disrupted by general anesthetics.

A Neural Mechanism for Reasoning and Believing

Lecture
Date:
Wednesday, January 5, 2011
Hour: 15:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Prof. Michael Shadlen
|
Physiology and Biophysics Dept University of Washington

Spatial Memory, Healthy Cognition and Successful Aging

Lecture
Date:
Wednesday, January 5, 2011
Hour: 12:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Prof. Veronique Bohbot
|
Faculty of Medicine McGill University, Quebec, Canada

Young healthy participants spontaneously use different strategies in a virtual radial maze, an adaptation of a task typically used with rodents. We have previously shown using fMRI that people who use spatial memory strategies have increased activity in the hippocampus whereas response strategies are associated with activity in the caudate nucleus. In addition, we used Voxel Based Morphometry (VBM) to identify brain regions co-varying with the navigational strategies individuals used. Results showed that spatial learners have significantly more grey matter in the hippocampus and less grey matter in the caudate nucleus than response learners. The relationship between spatial memory strategies and grey matter of the hippocampus was replicated with healthy older adults. Furthermore, we found a positive correlation between spatial memory strategies and the MoCA, which is a test sensitive to mild cognitive impairment. Since low grey matter in the hippocampus is a risk factor for cognitive deficits in normal aging and for Alzheimer’s disease, our results suggest that using spatial memory in our everyday lives may protect against degeneration of the hippocampus and associated cognitive deficits These results have important implications for intervention programs aimed at healthy and successful aging.

Visual Inference by Composition

Lecture
Date:
Tuesday, January 4, 2011
Hour: 12:30
Location:
Jacob Ziskind Building
Prof. Michal Irani
|
Dept of Computer Science and Applied Mathematics, WIS

In this talk I will show how complex visual tasks can be performed by exploiting redundancy in visual data. Comparing and integrating data recurrences allows to make inferences about complex scenes, without any prior examples or prior training. I will demonstrate the power of this approach to several visual inference problems (as time permits). These include: 1. Detecting complex objects and actions (often based only on a rough hand-sketch of what we are looking for). 2. Summarizing visual data (images and video). 3. Super-resolution (from a single image). 4. Prediction of missing visual information. 5. Detecting the "irregular" and "unexpected". 6. "Segmentation by Composition".

Pages

All events, 2011

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