2010
All events, 2010
Chemosensory dysfunction in humans
Lecture
Sunday, June 20, 2010
Hour: 10:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Chemosensory dysfunction in humans
Prof. Thomas Hummel
Smell and Taste Clinic, Dept of Otorhinolaryngology
University of Dresden Medical School, Dresden
Abstract: The intent of this presentation is to help bridge the gap between the clinical realm and the research laboratory. The clinical literature has a growing mass of evidence showing how disorders such as epilepsy, Alzheimer’s disease, stroke, or surgically-induced injury to peripheral nerve, can have devastating effects on olfactory and gustatory functions. A loss of function might be an early symptom with diagnostic value that helps the clinician identify the disease state. The presentation will introduce the non-clinician to common diagnostic and experimental tests of olfactory and taste functions. Various causes of olfactory loss will be discussed, plus their therapy
Optimal adaptation of retinal processing to color contrasts
Lecture
Tuesday, June 15, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Optimal adaptation of retinal processing to color contrasts
Dr. Ronen Segev
Life Sciences Dept
Ben Gurion University of the Negev
The visual system continually adjusts its sensitivity to properties of the environment. This adaptation process starts in the retina, which encodes over 8 orders of magnitude of light intensity using a limited range of spiking outputs of the ganglion cell, the only cells to project axons to the brain, extending between zero to several hundreds spikes per second. While the different spectral sensitivities of photoreceptors give the first separation of color channels in the visual system, chromatic adaptation observed in psychophysical experiments is commonly thought to originate from high visual areas. We show that color contrast adaptation actually starts in the retina by ganglion cells adjusting their responses to spectral properties of the environment. Specifically, we demonstrate that the ganglion cells match their response to red-blue stimulus combinations according to the relative contrast of each of the input channels. Using natural scene statistics analysis and theoretical consideration, we show that the retina balances inputs from the two color channels optimally given the strong correlation between the long and short wavelengths in the natural environment. These results indicate that some of the sophisticated processing of spectral visual information attributed to higher visual processing areas can be actually performed by the retina.
Contrast Tuning in Face Cells
Lecture
Sunday, June 13, 2010
Hour: 12:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Contrast Tuning in Face Cells
Shay Ohayon
Graduate Student, Computation and Neural Systems, CALTECH
Several state-of-the-art computer vision systems for face detection, e.g., Viola-Jones [1], rely on region-based features that compute contrast by adding and subtracting average image intensity within different regions of the face. This is a powerful strategy due to the invariance of these features across changes in illumination (as proposed by Sinha [2]). The computational mechanisms underlying face detection in biological systems, however, remain unclear. We set to investigate the role of region-based features in the macaque middle face patch, an area that consists of face-selective neurons. We found that individual neurons were tuned to subsets of contrast relationships between pairs of face regions. The sign of tuning for these relationships was strikingly consistent across the population (for example, almost all neurons preferred a lower average intensity in the eye region relative to the nose region). Furthermore, the pairs and polarity of tuning were fully consistent with Sinha’s proposed ratio-template model of face detection [2]. Non-face images from the CBCL dataset that contained correct contrast polarities in pre-defined regions (facial parts) did not elicit increased firing in face-selective neurons, suggesting that the neurons are not only computing averaged intensity according to a fixed template, but are also sensitive to the specific shape of features within a region.
[1] Robust Real-time Object Detection, Paul Viola and Michael Jones.
Second International Workshop on Statistical and Computational Theories of Vision – Modeling, Learning, Computing, and Sampling.
Vancouver, Canada, July, 2001.
[2] Qualitative Representations for Recognition, Pawan Sinha. Proceedings of the Second International Workshop on Biologically
Motivated Computer Vision, Tubingen, November, 2002.
Sensory Coding and Decoding for Smooth Pursuit Eye Movements
Lecture
Thursday, June 10, 2010
Hour: 18:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Sensory Coding and Decoding for Smooth Pursuit Eye Movements
Prof. Stephen Lisberger
Dept of Physiology
University of California San Francisco
Featured Review:
Visual Guidance of Smooth-Pursuit Eye Movements: Sensation, Action, and What Happens in Between
S.G. Lisberger
Smooth pursuit eye movements transform visual motion into a rapid initiation of eye movement and sustained accurate tracking. The pursuit response is encoded in distinct responses of neural circuits for visual motion in area MT, implemented in the cerebellum and the smooth eye movement region of the frontal eye fields and controlled by volition on a rapid time scale. Lisberger reviews the features that make pursuit a model system for studying the general principles of sensory-motor processing in brain.
http://www.cell.com/neuron/abstract/S0896-6273%2810%2900198-4
Generalizing Learned Movement Skills from Infancy to Maturity
Lecture
Tuesday, June 8, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Generalizing Learned Movement Skills from Infancy to Maturity
Dr. Eilat Almagor
A Feldenkrais Trainer
The Rubin Academy of Music and Dance, Jerusalem
During the first year of life, babies learn skills of movement which serve them not only for their present stage, but are building blocks for future stages. There are special qualities of the learning process in early development stages, which allow the learned experiences to be generalized in later stages.
For example the skills that are learned in horizontal locomotion (crawling) are also applied in walking. This learning process is playful and rich with mistakes It is complex in the sense that at each moment there is an overlap of a few functions. For example, keeping the balance while lifting a toy.By observing video clips of a few babies playing, we will see some of the necessary qualities of the learning process.
We will also see movement lessons given to disabled children, providing them with the normal ingredients of the learning process, in spite of their disabilities.
Neuronal deficits in mouse models of Alzheimer's disease: structure, function, and plasticity
Lecture
Tuesday, June 1, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Neuronal deficits in mouse models of Alzheimer's disease: structure, function, and plasticity
Dr. Edward Stern
Brain Research Center,
Bar-Ilan University,
Associate in Neurobiology, Massachusetts General Hospital,
Assistant Professor of Neurology, Harvard Medical School
In the 104 years since Alois Alzheimer first described the neuropathological features underlying dementia in the disease that now bears his name, the changes in neuronal activity underlying the symptoms of the disease are still not understood. Using transgenic mouse models, it is now possible to directly measure changes in neuronal structure and function resulting from the accumulation of AD neuropathology.
We measured the changes in evoked responses to electrical and sensory stimulation of neocortical neurons in mice transgenic for human APP, in which soluble amyloid-β accumulates and insoluble plaques aggregate in an age-dependent manner. Our results reveal a specific synaptic deficit present in neocortical neurons in brains with a significant amount of plaque aggregation. We show that this deficit is related to the distortion of neuronal process geometry by plaques, and the degree of response distortion is directly related to the amount of plaque-burdened tissue traversed by the afferent neuronal processes, indicating that the precise connectivity of the neocortex is essential for normal information processing. Furthermore, we show that the physical distortion of neuronal processes by plaques is reversible by immunotherapy, revealing a larger degree of structural plasticity in neocortical neurons of aged animals. Taken together, these results indicate that it may be possible to slow or reverse the symptoms of AD.
Neuronal Response Clamp
Lecture
Sunday, May 30, 2010
Hour: 14:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Neuronal Response Clamp
Avner Wallach
Network Biology Research Laboratories, Technion
Guest Student, Ahissar Group, Dept of Neurobiology, WIS
Since the first recordings made of evoked action potentials it has become apparent that the responses of individual neurons to ongoing physiologically relevant input, are highly variable. This variability is manifested in non-stationary behavior of practically every observable neuronal response feature. We introduce the Neuronal Response Clamp, a closed-loop technique enabling full control over two important single neuron activity variables: response probability and stimulus-spike latency. The technique is applicable over extended durations (up to several hours), and is effective even on the background of ongoing neuronal network activity. The Response Clamp technique is a powerful tool, extending the voltage-clamp and dynamic-clamp approaches to the neuron's functional level, namely-its spiking behavior.
The Hippocampus in Space and Time
Lecture
Thursday, May 27, 2010
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
The Hippocampus in Space and Time
Prof. Howard Eichenbaum
Center for Memory and Brain
Boston University
In humans, hippocampal function is generally recognized as supporting episodic memory, whereas in rats, many believe that the hippocampus creates maps of the environment and supports spatial navigation. Is this a species difference, or is there a fundamental function of the hippocampus that supports cognition across species? Here I will discuss evidence that hippocampal neuronal activity in spatial memory is more related to the representation of routes than the maps, suggesting a potential function of the hippocampus in memory for unique sequences of events. Further studies support this view by showing that the hippocampus is critical to memory for sequential events in non-spatial episodic memories. Correspondingly, neural ensemble activity in the hippocampus involves a gradually changing temporal context representation onto which specific events might be coded. Finally, at the level of single-neuron spiking patterns, hippocampal principal cells encode specific times within spatial and non-spatial sequences (“time cells”, as contrasted with “place cells”), and encode specific events within sequence memories onto the representation of time. These findings support an emerging view that the hippocampus creates “scaffolding” for memories, representing events in their spatial and temporal context.
Associative Cortex in the First Olfactory Brain Relay Station?
Lecture
Thursday, May 13, 2010
Hour: 13:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Associative Cortex in the First Olfactory Brain Relay Station?
Prof. Diego Restrepo
Director, Neuroscience Program
Department of Cell and Developmental Biology
University of Colorado, Denver, CO
Synchronized firing of mitral cells in the olfactory bulb, the first relay station of the olfactory system, has been hypothesized to convey information to olfactory cortex. In this first survey of synchronized firing by mitral cells in awake behaving vertebrates, we find sparse divergent odor responses. Surprisingly, synchronized firing conveys information on odor value (is it rewarded?) rather than odor quality. Further, adrenergic block decreases the magnitude of odor divergence of synchronous firing. These data raise questions whether mitral cells contribute to decision-making, or convey expected outcomes used in prediction error calculation.
Sculpting the hippocampal cognitive map: experimental control over the coded parameter space
Lecture
Tuesday, May 11, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Sculpting the hippocampal cognitive map: experimental control over the coded parameter space
Dr. Genela Morris
Dept of Neurobiology and Ethology
University of Haifa
Although much work in the field of reinforcement learning has been devoted to understanding how animals and humans learn to perform the best action in each state of affairs, strikingly scant work targets the question of what constitutes such a state. In initial phases of learning, an animal or a person cannot know which facets of its rich experience should be attended to in order to identify their ‘state’. In a number of projects, we use tasks in which several different attributes can potentially be important for procuring rewards (odors, spatial location, previous actions), and specifically investigate the behavioral and neural processes underlying learning of which is the relevant state. This talk will focus on parameter coding by hippocampal primary neurons.
The hippocampus serves an important role in learning and memory. In humans, it is associated with declarative episodic memory. Single unit recordings of hippocampal neurons in freely behaving rats have shown that many of them act as place-cells, confining their firing to well-defined locations in space. We recorded the activity of hippocampal primary neurons in a specially devised olfactory space, in which rats foraged for reward based solely on olfactory cues and studied the dependence of the activity of these neurons on their availability. We show that place cells shifted their firing fields from room coordinates to olfactory coordinates as animals learned to rely on them in order to obtain reward.
The use of olfactory cues provides the additional benefit of careful control over the sensory inputs provided to the animals. Classical studies on hippocampal place-cells show that when the environment is visually altered, these hippocampal neurons 'remap', in a seemingly random manner. Although studies have been conducted to investigate the contribution of various visual aspects to the activity of place cells, the exact correlation of hippocampal cell firing to the visual input to the rats cannot be studied in freely behaving rats, because their field of view is unknown. By repeating the sequence of olfactory stimuli provided in the maze in a new environment, we study the relation between the neuronal responses of single neurons to given sensory stimuli in distinct spatial contexts. Preliminary results suggesting that the mapping of hippocampal neurons is not random, but critically depends on the sequence in which the different items are encountered, in support of the relational representation theory of hippocampal function.
Pages
2010
All events, 2010
Chemosensory dysfunction in humans
Lecture
Sunday, June 20, 2010
Hour: 10:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Chemosensory dysfunction in humans
Prof. Thomas Hummel
Smell and Taste Clinic, Dept of Otorhinolaryngology
University of Dresden Medical School, Dresden
Abstract: The intent of this presentation is to help bridge the gap between the clinical realm and the research laboratory. The clinical literature has a growing mass of evidence showing how disorders such as epilepsy, Alzheimer’s disease, stroke, or surgically-induced injury to peripheral nerve, can have devastating effects on olfactory and gustatory functions. A loss of function might be an early symptom with diagnostic value that helps the clinician identify the disease state. The presentation will introduce the non-clinician to common diagnostic and experimental tests of olfactory and taste functions. Various causes of olfactory loss will be discussed, plus their therapy
Optimal adaptation of retinal processing to color contrasts
Lecture
Tuesday, June 15, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Optimal adaptation of retinal processing to color contrasts
Dr. Ronen Segev
Life Sciences Dept
Ben Gurion University of the Negev
The visual system continually adjusts its sensitivity to properties of the environment. This adaptation process starts in the retina, which encodes over 8 orders of magnitude of light intensity using a limited range of spiking outputs of the ganglion cell, the only cells to project axons to the brain, extending between zero to several hundreds spikes per second. While the different spectral sensitivities of photoreceptors give the first separation of color channels in the visual system, chromatic adaptation observed in psychophysical experiments is commonly thought to originate from high visual areas. We show that color contrast adaptation actually starts in the retina by ganglion cells adjusting their responses to spectral properties of the environment. Specifically, we demonstrate that the ganglion cells match their response to red-blue stimulus combinations according to the relative contrast of each of the input channels. Using natural scene statistics analysis and theoretical consideration, we show that the retina balances inputs from the two color channels optimally given the strong correlation between the long and short wavelengths in the natural environment. These results indicate that some of the sophisticated processing of spectral visual information attributed to higher visual processing areas can be actually performed by the retina.
Contrast Tuning in Face Cells
Lecture
Sunday, June 13, 2010
Hour: 12:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Contrast Tuning in Face Cells
Shay Ohayon
Graduate Student, Computation and Neural Systems, CALTECH
Several state-of-the-art computer vision systems for face detection, e.g., Viola-Jones [1], rely on region-based features that compute contrast by adding and subtracting average image intensity within different regions of the face. This is a powerful strategy due to the invariance of these features across changes in illumination (as proposed by Sinha [2]). The computational mechanisms underlying face detection in biological systems, however, remain unclear. We set to investigate the role of region-based features in the macaque middle face patch, an area that consists of face-selective neurons. We found that individual neurons were tuned to subsets of contrast relationships between pairs of face regions. The sign of tuning for these relationships was strikingly consistent across the population (for example, almost all neurons preferred a lower average intensity in the eye region relative to the nose region). Furthermore, the pairs and polarity of tuning were fully consistent with Sinha’s proposed ratio-template model of face detection [2]. Non-face images from the CBCL dataset that contained correct contrast polarities in pre-defined regions (facial parts) did not elicit increased firing in face-selective neurons, suggesting that the neurons are not only computing averaged intensity according to a fixed template, but are also sensitive to the specific shape of features within a region.
[1] Robust Real-time Object Detection, Paul Viola and Michael Jones.
Second International Workshop on Statistical and Computational Theories of Vision – Modeling, Learning, Computing, and Sampling.
Vancouver, Canada, July, 2001.
[2] Qualitative Representations for Recognition, Pawan Sinha. Proceedings of the Second International Workshop on Biologically
Motivated Computer Vision, Tubingen, November, 2002.
Sensory Coding and Decoding for Smooth Pursuit Eye Movements
Lecture
Thursday, June 10, 2010
Hour: 18:00
Location:
Nella and Leon Benoziyo Building for Brain Research
Sensory Coding and Decoding for Smooth Pursuit Eye Movements
Prof. Stephen Lisberger
Dept of Physiology
University of California San Francisco
Featured Review:
Visual Guidance of Smooth-Pursuit Eye Movements: Sensation, Action, and What Happens in Between
S.G. Lisberger
Smooth pursuit eye movements transform visual motion into a rapid initiation of eye movement and sustained accurate tracking. The pursuit response is encoded in distinct responses of neural circuits for visual motion in area MT, implemented in the cerebellum and the smooth eye movement region of the frontal eye fields and controlled by volition on a rapid time scale. Lisberger reviews the features that make pursuit a model system for studying the general principles of sensory-motor processing in brain.
http://www.cell.com/neuron/abstract/S0896-6273%2810%2900198-4
Generalizing Learned Movement Skills from Infancy to Maturity
Lecture
Tuesday, June 8, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Generalizing Learned Movement Skills from Infancy to Maturity
Dr. Eilat Almagor
A Feldenkrais Trainer
The Rubin Academy of Music and Dance, Jerusalem
During the first year of life, babies learn skills of movement which serve them not only for their present stage, but are building blocks for future stages. There are special qualities of the learning process in early development stages, which allow the learned experiences to be generalized in later stages.
For example the skills that are learned in horizontal locomotion (crawling) are also applied in walking. This learning process is playful and rich with mistakes It is complex in the sense that at each moment there is an overlap of a few functions. For example, keeping the balance while lifting a toy.By observing video clips of a few babies playing, we will see some of the necessary qualities of the learning process.
We will also see movement lessons given to disabled children, providing them with the normal ingredients of the learning process, in spite of their disabilities.
Neuronal deficits in mouse models of Alzheimer's disease: structure, function, and plasticity
Lecture
Tuesday, June 1, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Neuronal deficits in mouse models of Alzheimer's disease: structure, function, and plasticity
Dr. Edward Stern
Brain Research Center,
Bar-Ilan University,
Associate in Neurobiology, Massachusetts General Hospital,
Assistant Professor of Neurology, Harvard Medical School
In the 104 years since Alois Alzheimer first described the neuropathological features underlying dementia in the disease that now bears his name, the changes in neuronal activity underlying the symptoms of the disease are still not understood. Using transgenic mouse models, it is now possible to directly measure changes in neuronal structure and function resulting from the accumulation of AD neuropathology.
We measured the changes in evoked responses to electrical and sensory stimulation of neocortical neurons in mice transgenic for human APP, in which soluble amyloid-β accumulates and insoluble plaques aggregate in an age-dependent manner. Our results reveal a specific synaptic deficit present in neocortical neurons in brains with a significant amount of plaque aggregation. We show that this deficit is related to the distortion of neuronal process geometry by plaques, and the degree of response distortion is directly related to the amount of plaque-burdened tissue traversed by the afferent neuronal processes, indicating that the precise connectivity of the neocortex is essential for normal information processing. Furthermore, we show that the physical distortion of neuronal processes by plaques is reversible by immunotherapy, revealing a larger degree of structural plasticity in neocortical neurons of aged animals. Taken together, these results indicate that it may be possible to slow or reverse the symptoms of AD.
Neuronal Response Clamp
Lecture
Sunday, May 30, 2010
Hour: 14:30
Location:
Nella and Leon Benoziyo Building for Brain Research
Neuronal Response Clamp
Avner Wallach
Network Biology Research Laboratories, Technion
Guest Student, Ahissar Group, Dept of Neurobiology, WIS
Since the first recordings made of evoked action potentials it has become apparent that the responses of individual neurons to ongoing physiologically relevant input, are highly variable. This variability is manifested in non-stationary behavior of practically every observable neuronal response feature. We introduce the Neuronal Response Clamp, a closed-loop technique enabling full control over two important single neuron activity variables: response probability and stimulus-spike latency. The technique is applicable over extended durations (up to several hours), and is effective even on the background of ongoing neuronal network activity. The Response Clamp technique is a powerful tool, extending the voltage-clamp and dynamic-clamp approaches to the neuron's functional level, namely-its spiking behavior.
The Hippocampus in Space and Time
Lecture
Thursday, May 27, 2010
Hour: 14:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
The Hippocampus in Space and Time
Prof. Howard Eichenbaum
Center for Memory and Brain
Boston University
In humans, hippocampal function is generally recognized as supporting episodic memory, whereas in rats, many believe that the hippocampus creates maps of the environment and supports spatial navigation. Is this a species difference, or is there a fundamental function of the hippocampus that supports cognition across species? Here I will discuss evidence that hippocampal neuronal activity in spatial memory is more related to the representation of routes than the maps, suggesting a potential function of the hippocampus in memory for unique sequences of events. Further studies support this view by showing that the hippocampus is critical to memory for sequential events in non-spatial episodic memories. Correspondingly, neural ensemble activity in the hippocampus involves a gradually changing temporal context representation onto which specific events might be coded. Finally, at the level of single-neuron spiking patterns, hippocampal principal cells encode specific times within spatial and non-spatial sequences (“time cells”, as contrasted with “place cells”), and encode specific events within sequence memories onto the representation of time. These findings support an emerging view that the hippocampus creates “scaffolding” for memories, representing events in their spatial and temporal context.
Associative Cortex in the First Olfactory Brain Relay Station?
Lecture
Thursday, May 13, 2010
Hour: 13:30
Location:
Arthur and Rochelle Belfer Building for Biomedical Research
Associative Cortex in the First Olfactory Brain Relay Station?
Prof. Diego Restrepo
Director, Neuroscience Program
Department of Cell and Developmental Biology
University of Colorado, Denver, CO
Synchronized firing of mitral cells in the olfactory bulb, the first relay station of the olfactory system, has been hypothesized to convey information to olfactory cortex. In this first survey of synchronized firing by mitral cells in awake behaving vertebrates, we find sparse divergent odor responses. Surprisingly, synchronized firing conveys information on odor value (is it rewarded?) rather than odor quality. Further, adrenergic block decreases the magnitude of odor divergence of synchronous firing. These data raise questions whether mitral cells contribute to decision-making, or convey expected outcomes used in prediction error calculation.
Sculpting the hippocampal cognitive map: experimental control over the coded parameter space
Lecture
Tuesday, May 11, 2010
Hour: 12:30
Location:
Jacob Ziskind Building
Sculpting the hippocampal cognitive map: experimental control over the coded parameter space
Dr. Genela Morris
Dept of Neurobiology and Ethology
University of Haifa
Although much work in the field of reinforcement learning has been devoted to understanding how animals and humans learn to perform the best action in each state of affairs, strikingly scant work targets the question of what constitutes such a state. In initial phases of learning, an animal or a person cannot know which facets of its rich experience should be attended to in order to identify their ‘state’. In a number of projects, we use tasks in which several different attributes can potentially be important for procuring rewards (odors, spatial location, previous actions), and specifically investigate the behavioral and neural processes underlying learning of which is the relevant state. This talk will focus on parameter coding by hippocampal primary neurons.
The hippocampus serves an important role in learning and memory. In humans, it is associated with declarative episodic memory. Single unit recordings of hippocampal neurons in freely behaving rats have shown that many of them act as place-cells, confining their firing to well-defined locations in space. We recorded the activity of hippocampal primary neurons in a specially devised olfactory space, in which rats foraged for reward based solely on olfactory cues and studied the dependence of the activity of these neurons on their availability. We show that place cells shifted their firing fields from room coordinates to olfactory coordinates as animals learned to rely on them in order to obtain reward.
The use of olfactory cues provides the additional benefit of careful control over the sensory inputs provided to the animals. Classical studies on hippocampal place-cells show that when the environment is visually altered, these hippocampal neurons 'remap', in a seemingly random manner. Although studies have been conducted to investigate the contribution of various visual aspects to the activity of place cells, the exact correlation of hippocampal cell firing to the visual input to the rats cannot be studied in freely behaving rats, because their field of view is unknown. By repeating the sequence of olfactory stimuli provided in the maze in a new environment, we study the relation between the neuronal responses of single neurons to given sensory stimuli in distinct spatial contexts. Preliminary results suggesting that the mapping of hippocampal neurons is not random, but critically depends on the sequence in which the different items are encountered, in support of the relational representation theory of hippocampal function.
Pages
2010
All events, 2010
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