Past events | The department of Brain Sciences

All events, 2009

Large-scale brain dynamics: Functional MRI of spontaneous and optically-driven neural activity

Lecture

Date:

Monday, June 15, 2009

Hour: 12:45

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

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.

Optical control of neural population activity and growth

Lecture

Date:

Tuesday, June 9, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Shy Shoham

|

Faculty of Biomedical Engineering Technion – I.I.T. Haifa

Retinal neuroprosthetics can potentially be used to address some of the major degenerative disorders that cause blindness, including Retinitis Pigmentosa and Macular Degeneration, by bypassing the degenerated photoreceptor layer, and interfacing directly the more viable Retinal Ganglion Cells (RGCs). I will describe the development of new optical and computational tools aimed at allowing controlled experimental emulation of activity patterns in a large population of retinal ganglion cells and their correlation structure. First, we introduce new optical systems allowing control of increasingly complex spatiotemporal activity patterns in neural populations, focusing on holographic photo-stimulation which has several fundamental advantages in this application. Next, we introduce a general new computational strategy based on correlation distortions, for controlling and analyzing the pair-wise correlation structure (defined in terms of auto- and cross-correlation functions) in multiple synthetic spike trains. This approach can be used to generate stationary or non-stationary network activity patterns with predictable spatio-temporal correlations. In a final part of the talk I will describe a new approach for exact, flexible control of neurite outgrowth in three-dimensional neural structures, and its possible applications.

Omega-3 fatty acids are essential for neuronal migration and dopaminergic wiring in the developing brain

Lecture

Date:

Wednesday, June 3, 2009

Hour: 12:00

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Ephraim Yavin

|

Dept of Neurobiology, WIS

Diminished levels of docosahexaenoic acid (DHA, 22:6n-3), the major polyunsaturated fatty acid (FA) synthesized from alpha linolenic acid (ALA, 18:3n-3), have been implicated in changes in neurotransmitter production, ion channels disruption and impairments of a variety of cognitive, behavioural and motor functions in the developing and the adult mammal. We studied neuronal migration in the cortex and hippocampus of newborn and postnatal rats after ALA-deficiency, beginning on the 2nd day after conception and continuing for three weeks after birth. A marked decrease in the migration of bromodeoxyuridine(+)/NeuN(+)/Neurofilament(+) and glia fibrilary acidic protein(-) neuronal cells to the dense cortical plate was accompanied by a corresponding abundance of non-migrating cells in several regions such as cortical layers IV-VI, corpus callosum and the sub-ventricular zone of ALA-deficient newborn. Similarly, a delayed migration of cells to CA1 and dentate gyrus areas was noticed while most cells were retained in the subicular area adjacent to the hippocampus. The delay in migration was transient most likely due to a temporary reelin disorganization. In addition to these changes a drastic reduction in tyrosine hydroxylase (TH) and vesicular monoamine transporter-2 (VMAT-2) levels, both of which are prerequisites for appropriate synthesis and transport of DA were noticed by RNA subtractive hybridization and proteomic techniques. Concomitantly, a large increase in DA receptors DAR1 and DAR2 were noticed. The transient impairment induced by ALA deprivation may compromise the organization of neuronal assemblies and result in aberrant neuronal connectivity (lateral connections) to enhance the risk of neurodevelopmental disorders including cerebral palsy.

The Neural Dynamics of Perception

Lecture

Date:

Tuesday, June 2, 2009

Hour: 15:00

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Donald Katz

|

Dept of Psychology and Neuroscience Brandeis University

Much of the research done in sensory neuroscience is founded on the assumption that "sensory" function can be adequately characterized without knowledge of response dynamics, trial-to-trial variability, between-neuron interactions, or stimulus-response relationships. My lab's research demonstrates that single-neuron taste responses in gustatory cortex (GC) in fact contain dynamics that reflect tight perception-action coupling: across 1.5 sec, these responses progress from first "coding" the presence of taste on the tongue, then the identity of that taste, and finally the taste's palatability. In this talk, I will describe the tests that we have done to relate these response dynamics to changes (attentional, motivational, and learning-related) at longer time-scales, and our evidence that they reflect coherent, attractor-like processes emerging from interactions among local and distributed networks of neurons.

Perception and Brain Plasticity in Humans: New Insights from Phase-locking Fourier Approaches to fMRI

Lecture

Date:

Tuesday, May 26, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Amir Amedi

|

Hadassah Medical School Hebrew University Jerusalem

An integrative approach towards understanding the neural basis of congenital prosopagnosia

Lecture

Date:

Tuesday, May 19, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Galia Avidan

|

Dept of Psychology and Zlotowski Center for Neuroscience Ben Gurion University of the Negev

Congenital prosopagnosia (CP) refers to the deficit in face processing that is apparently life-long in duration, arises in the absence of brain damage of any form and occurs in individuals with intact sensory and intellectual function. As such, CP provides a unique model in which to explore the psychological and neural bases of normal face processing. Despite the growing interest in CP, the neural mechanism giving rise to this disorder is still unclear. We addressed this issue by adopting an integrative approach in which both functional and structural imaging techniques were combined. Specifically, using fMRI, we have documented normal face selective activation in face -related regions in occipito-temporal cortex but in contrast, revealed abnormal activation in these individuals in frontal regions, suggesting that information propagation between frontal and occipito-temporal regions is disrupted in this disorder. Consistently with this account, diffusion tensor imaging (DTI) measures revealed that the two major posterior-anterior tracts (inferior longitudinal fasciculus, inferior fronto-occipital fasciculus) through the fusiform face area (FFA) had significantly fewer fibers and lower fractional anisotropy (FA) values in CP. Finally, along the same line, structural imaging data revealed a significant reduction in volume of the anterior fusiform gyrus in the CP group, but normal volume at the location of the functionally defined FFA. Thus, taken together, these findings provide, for the first time, a comprehensive account for the neural deficits underlying congenital prosopagnosia and shed light on the underlying distributed circuit mediating normal face processing.

Behavioral and neurophysiological correlates of GABA modulation in the basal ganglia

Lecture

Date:

Tuesday, May 5, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Izhar Bar-Gad

|

Gonda Brain Research Center Bar Ilan University

The cortico-basal ganglia pathway is involved in normal motor control and implicated in multiple movement disorders. We used focal microinjections of the GABA-A antagonist bicuculline to the sensorimotor putamen of behaving primates to induce stereotyped tics similar to those observed in human Tourette syndrome. The tics were accompanied by synchronized phasic changes in the local field potential and single cell activity of neurons throughout the cortico-basal ganglia loop. We also used focal injection of bicuculline to different functional domains of the globus pallidus external segment (GPe) to induce a variety of hyper-behavioral symptoms. These, symptoms varied between dyskinesia, stereotypy and attention deficit depending on injection site within the motor, limbic and associative domains respectively. The injections led to distributed uncorrelated changes in firing pattern throughout the cortico-basal ganglia loop. The neurophysiological findings and their implication on models of information processing in the basal ganglia will be discussed in the lecture.

Odotopic maps, odor coding, rats, mice, and behavior

Lecture

Date:

Monday, May 4, 2009

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Burton Slotnick

|

Dept of Psychology American University

What is the neural code for odor quality perception? Perhaps the most widely accepted view is spatial: that different odors are represented at the level of the olfactory bulb by bulbar patterns of activation, a so-called odotopic combinatorial coding for the receptive fields of olfactory sensory neurons. The primary evidence for this view comes from variety of imaging studies demonstrating orderly relationships between chemical structure of odorants and sites of activation across the olfactory bulb. However, behavioral studies with rodents fail to support predictions based on anatomy but open new avenues for research on this still elusive sensory modality.

Interactions between environmental changes and brain plasticity in birds

Lecture

Date:

Monday, April 27, 2009

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Anat Barnea

|

Dept of Natural and Life Sciences The Open University of Israel

Neurogenesis (birth of new neurons) occurs in many vertebrates, including humans. Most of the new neurons die before reaching destination. Those which survive migrate to various brain regions, replace older ones and connect to existing circuits. Evidence suggests that this replacement is related to acquisition of new information. Therefore, neuronal replacement is seen as a form of brain plasticity that enables organisms to adjust to environmental changes. However, direct evidence of a causal link between replacement and learning remains elusive. I will review a few of our studies which tried to uncover conditions that influence new neuronal recruitment and survival, and how these phenomena relate to the life of birds. We hypothesize that an increase in new neuron recruitment is associated with expected or actual increase in memory load, particularly in brain regions that process and perhaps store this new information. Moreover, since new neuronal recruitment is part of a turnover process, we assume that the same conditions that favor the survival of some neurons induce the death of others. I will offer a frame and rational for comparing neuronal replacement in the adult avian brain, and try to uncover the pressures, rules, and mechanisms that govern its constant rejuvenation. I will discuss a variety of behaviors and environmental conditions (food-hoarding, social change, parent-offspring recognition, migration) and their effect on new neuronal recruitment in relevant brain regions. I will describe various approaches and techniques which we used in those studies (behavioral, anatomical, cellular and hormonal), and will emphasize the significance of studying behavior and brain function under natural or naturalistic conditions.

Neural decoding and optimal filtering: on a reverse engineering view of neural information processing

Lecture

Date:

Monday, April 20, 2009

Hour: 12:00

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Ron Meir

|

Faculty of Electrical Engineering Technion, Haifa

Pages

All events, 2009

Optical control of neural population activity and growth

Lecture

Date:

Tuesday, June 9, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Shy Shoham

|

Faculty of Biomedical Engineering Technion – I.I.T. Haifa

Retinal neuroprosthetics can potentially be used to address some of the major degenerative disorders that cause blindness, including Retinitis Pigmentosa and Macular Degeneration, by bypassing the degenerated photoreceptor layer, and interfacing directly the more viable Retinal Ganglion Cells (RGCs). I will describe the development of new optical and computational tools aimed at allowing controlled experimental emulation of activity patterns in a large population of retinal ganglion cells and their correlation structure. First, we introduce new optical systems allowing control of increasingly complex spatiotemporal activity patterns in neural populations, focusing on holographic photo-stimulation which has several fundamental advantages in this application. Next, we introduce a general new computational strategy based on correlation distortions, for controlling and analyzing the pair-wise correlation structure (defined in terms of auto- and cross-correlation functions) in multiple synthetic spike trains. This approach can be used to generate stationary or non-stationary network activity patterns with predictable spatio-temporal correlations. In a final part of the talk I will describe a new approach for exact, flexible control of neurite outgrowth in three-dimensional neural structures, and its possible applications.

Omega-3 fatty acids are essential for neuronal migration and dopaminergic wiring in the developing brain

Lecture

Date:

Wednesday, June 3, 2009

Hour: 12:00

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Ephraim Yavin

|

Dept of Neurobiology, WIS

Diminished levels of docosahexaenoic acid (DHA, 22:6n-3), the major polyunsaturated fatty acid (FA) synthesized from alpha linolenic acid (ALA, 18:3n-3), have been implicated in changes in neurotransmitter production, ion channels disruption and impairments of a variety of cognitive, behavioural and motor functions in the developing and the adult mammal. We studied neuronal migration in the cortex and hippocampus of newborn and postnatal rats after ALA-deficiency, beginning on the 2nd day after conception and continuing for three weeks after birth. A marked decrease in the migration of bromodeoxyuridine(+)/NeuN(+)/Neurofilament(+) and glia fibrilary acidic protein(-) neuronal cells to the dense cortical plate was accompanied by a corresponding abundance of non-migrating cells in several regions such as cortical layers IV-VI, corpus callosum and the sub-ventricular zone of ALA-deficient newborn. Similarly, a delayed migration of cells to CA1 and dentate gyrus areas was noticed while most cells were retained in the subicular area adjacent to the hippocampus. The delay in migration was transient most likely due to a temporary reelin disorganization. In addition to these changes a drastic reduction in tyrosine hydroxylase (TH) and vesicular monoamine transporter-2 (VMAT-2) levels, both of which are prerequisites for appropriate synthesis and transport of DA were noticed by RNA subtractive hybridization and proteomic techniques. Concomitantly, a large increase in DA receptors DAR1 and DAR2 were noticed. The transient impairment induced by ALA deprivation may compromise the organization of neuronal assemblies and result in aberrant neuronal connectivity (lateral connections) to enhance the risk of neurodevelopmental disorders including cerebral palsy.

The Neural Dynamics of Perception

Lecture

Date:

Tuesday, June 2, 2009

Hour: 15:00

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Donald Katz

|

Dept of Psychology and Neuroscience Brandeis University

Much of the research done in sensory neuroscience is founded on the assumption that "sensory" function can be adequately characterized without knowledge of response dynamics, trial-to-trial variability, between-neuron interactions, or stimulus-response relationships. My lab's research demonstrates that single-neuron taste responses in gustatory cortex (GC) in fact contain dynamics that reflect tight perception-action coupling: across 1.5 sec, these responses progress from first "coding" the presence of taste on the tongue, then the identity of that taste, and finally the taste's palatability. In this talk, I will describe the tests that we have done to relate these response dynamics to changes (attentional, motivational, and learning-related) at longer time-scales, and our evidence that they reflect coherent, attractor-like processes emerging from interactions among local and distributed networks of neurons.

Perception and Brain Plasticity in Humans: New Insights from Phase-locking Fourier Approaches to fMRI

Lecture

Date:

Tuesday, May 26, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Amir Amedi

|

Hadassah Medical School Hebrew University Jerusalem

An integrative approach towards understanding the neural basis of congenital prosopagnosia

Lecture

Date:

Tuesday, May 19, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Galia Avidan

|

Dept of Psychology and Zlotowski Center for Neuroscience Ben Gurion University of the Negev

Congenital prosopagnosia (CP) refers to the deficit in face processing that is apparently life-long in duration, arises in the absence of brain damage of any form and occurs in individuals with intact sensory and intellectual function. As such, CP provides a unique model in which to explore the psychological and neural bases of normal face processing. Despite the growing interest in CP, the neural mechanism giving rise to this disorder is still unclear. We addressed this issue by adopting an integrative approach in which both functional and structural imaging techniques were combined. Specifically, using fMRI, we have documented normal face selective activation in face -related regions in occipito-temporal cortex but in contrast, revealed abnormal activation in these individuals in frontal regions, suggesting that information propagation between frontal and occipito-temporal regions is disrupted in this disorder. Consistently with this account, diffusion tensor imaging (DTI) measures revealed that the two major posterior-anterior tracts (inferior longitudinal fasciculus, inferior fronto-occipital fasciculus) through the fusiform face area (FFA) had significantly fewer fibers and lower fractional anisotropy (FA) values in CP. Finally, along the same line, structural imaging data revealed a significant reduction in volume of the anterior fusiform gyrus in the CP group, but normal volume at the location of the functionally defined FFA. Thus, taken together, these findings provide, for the first time, a comprehensive account for the neural deficits underlying congenital prosopagnosia and shed light on the underlying distributed circuit mediating normal face processing.

Behavioral and neurophysiological correlates of GABA modulation in the basal ganglia

Lecture

Date:

Tuesday, May 5, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Izhar Bar-Gad

|

Gonda Brain Research Center Bar Ilan University

The cortico-basal ganglia pathway is involved in normal motor control and implicated in multiple movement disorders. We used focal microinjections of the GABA-A antagonist bicuculline to the sensorimotor putamen of behaving primates to induce stereotyped tics similar to those observed in human Tourette syndrome. The tics were accompanied by synchronized phasic changes in the local field potential and single cell activity of neurons throughout the cortico-basal ganglia loop. We also used focal injection of bicuculline to different functional domains of the globus pallidus external segment (GPe) to induce a variety of hyper-behavioral symptoms. These, symptoms varied between dyskinesia, stereotypy and attention deficit depending on injection site within the motor, limbic and associative domains respectively. The injections led to distributed uncorrelated changes in firing pattern throughout the cortico-basal ganglia loop. The neurophysiological findings and their implication on models of information processing in the basal ganglia will be discussed in the lecture.

Odotopic maps, odor coding, rats, mice, and behavior

Lecture

Date:

Monday, May 4, 2009

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Burton Slotnick

|

Dept of Psychology American University

What is the neural code for odor quality perception? Perhaps the most widely accepted view is spatial: that different odors are represented at the level of the olfactory bulb by bulbar patterns of activation, a so-called odotopic combinatorial coding for the receptive fields of olfactory sensory neurons. The primary evidence for this view comes from variety of imaging studies demonstrating orderly relationships between chemical structure of odorants and sites of activation across the olfactory bulb. However, behavioral studies with rodents fail to support predictions based on anatomy but open new avenues for research on this still elusive sensory modality.

Interactions between environmental changes and brain plasticity in birds

Lecture

Date:

Monday, April 27, 2009

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Anat Barnea

|

Dept of Natural and Life Sciences The Open University of Israel

Neurogenesis (birth of new neurons) occurs in many vertebrates, including humans. Most of the new neurons die before reaching destination. Those which survive migrate to various brain regions, replace older ones and connect to existing circuits. Evidence suggests that this replacement is related to acquisition of new information. Therefore, neuronal replacement is seen as a form of brain plasticity that enables organisms to adjust to environmental changes. However, direct evidence of a causal link between replacement and learning remains elusive. I will review a few of our studies which tried to uncover conditions that influence new neuronal recruitment and survival, and how these phenomena relate to the life of birds. We hypothesize that an increase in new neuron recruitment is associated with expected or actual increase in memory load, particularly in brain regions that process and perhaps store this new information. Moreover, since new neuronal recruitment is part of a turnover process, we assume that the same conditions that favor the survival of some neurons induce the death of others. I will offer a frame and rational for comparing neuronal replacement in the adult avian brain, and try to uncover the pressures, rules, and mechanisms that govern its constant rejuvenation. I will discuss a variety of behaviors and environmental conditions (food-hoarding, social change, parent-offspring recognition, migration) and their effect on new neuronal recruitment in relevant brain regions. I will describe various approaches and techniques which we used in those studies (behavioral, anatomical, cellular and hormonal), and will emphasize the significance of studying behavior and brain function under natural or naturalistic conditions.

Neural decoding and optimal filtering: on a reverse engineering view of neural information processing

Lecture

Date:

Monday, April 20, 2009

Hour: 12:00

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Ron Meir

|

Faculty of Electrical Engineering Technion, Haifa

The representation of value in the human brain

Lecture

Date:

Tuesday, April 7, 2009

Hour: 12:30

Location:

Jacob Ziskind Building

Prof. Ifat Levy

|

Yale University

The neural representation of value is a matter of great debate. In particular, it is not clear whether multiple valuation systems exist, each representing value under different conditions, or whether a single system that uses a “common currency” for the representation of value under many different conditions can be identified. I will present two studies in which we combined experimental methods from behavioral economics with functional MRI to study the representation of value in the human brain. The first study compared choices under two terms of uncertainty: risk, when probabilities of different outcomes are known, and ambiguity, when such probabilities are not known. Our results show that although subjects exhibit markedly different choice behaviors under these two conditions, a single system, consisting of the striatum and the medial prefrontal cortex (MPFC) encodes choice values in both cases. In the second study we used MPFC activation elicited by passive viewing of goods in the scanner to predict subsequent choices between these goods made outside of the scanner. Our predictions were significantly above chance, suggesting that the same valuation system is engaged whether or not choice is required. Based on these results together with previous studies we suggest that the striatum and the MPFC are the final common pathway for valuation – other areas may be differentially involved in encoding value under different conditions, but all of these areas should transfer their output to the final system to guide choice behavior.