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Flip sides of the same brain: Words and faces are both mediated by universal computational principles

Lecture

Date:

Wednesday, April 27, 2011

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Prof. Marlene Behrmann

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Carnegie Mellon University, Pittsburgh Psychology/Center for the Neural Basis of Cognition

A key issue that continues to generate controversy concerns the nature of the psychological, computational and neural mechanisms that support the visual recognition of objects such as faces and words. While some researchers claim that visual recognition is accomplished by category-specific modules dedicated to processing distinct object classes, other researchers have argued for a more distributed system with only partially specialized cortical regions. Considerable evidence from both functional neuroimaging and neuropsychology would seem to favor the modular view, and yet close examination of those data reveal rather graded patterns of specialization that support a more distributed account. This talk presents theoretical and empirical data that explore a theoretical middle ground in which the functional specialization of brain regions arises from general principles and constraints on neural representation and learning that operate throughout cortex but that nonetheless have distinct implications for different classes of stimuli such as faces and words.

Microcircuit Dynamics in the Striatum

Lecture

Date:

Thursday, April 14, 2011

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Gilad Silberberg

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Assistant Professor, Dept of Neuroscience Karolinska Institute, Stockholm

Motor behaviour requires the meaningful integration of a multitude of sensory information. The basal ganglia are essential for such sensory-motor processing and underlie motor planning, performance, and learning. The striatum is the input layer of the basal ganglia, acting as a “hub” that receives glutamatergic and dopaminergic inputs from different brain regions. The intrastriatal microcircuit is a predominantly inhibitory GABAergic network comprised of a majority of projection neurons (medium spiny neurons, MSNs) and a minority of interneurons. In order to understand the operation of striatum it is essential to have a good description of the dynamic properties of the striatal microcicuitry and how it affects the activity striatal projection neurons. We use patch-clamp recordings in slice and in vivo combined with fluorescent microscopy and optogenetics to reveal the striatal microcircuit properties underlying sensorimotor processing

Mechanisms of axonal degeneration in health and disease

Lecture

Date:

Tuesday, April 12, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Prof. Avraham Yaron

|

Dept of Biological Chemistry, WIS

In the developing peripheral nervous system, many neurons die shortly after their axons have reached their target fields. This neuronal elimination serves as a mean to achieve a precise match between the number of neurons and the target innervation requirements. In addition, this process ensures that misguided axons, which do not reach their appropriate targets, will be eliminated. The regulation of this process is based on the limited production of various neurotrophic factors, insufficient to sustain the entire neuronal population. Since this loss usually occurs after the axons have already fully extended, some kind of axonal disintegration must escort the death of the cell body. The talk will describe our efforts to uncover the mechanisms of axonal elimination during this process, and their relevance to axonal degeneration in pathological condition

Brain Sciences Open Day

Lecture

Date:

Monday, April 11, 2011

Hour: 09:30 - 14:00

Location:

Gerhard M.J. Schmidt Lecture Hall

Conscious Perception in USN

Lecture

Date:

Tuesday, April 5, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Nachum Soroker

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Dept of Neurological Rehabilitation, Loewenstein Hospital, Raanana, and Sackler Faculty of Medicine Tel Aviv University

Patients with right hemisphere damage often exhibit a symptom complex where contra-lesional objects and events fail to induce an appropriate behavioral reaction. The most puzzling aspect of this syndrome - termed unilateral spatial neglect (USN) - is the failure of salient left-sided stimuli to attract attention and generate conscious perception. This phenomenon, which is often multi-modal, may happen in cases where the sensory pathways and the primary cortical areas are completely intact. Following a short description of the clinical manifestations, underlying anatomy and recovery patterns of USN, I will present data gathered in a series of studies done in our hospital, which aimed to clarify the nature of processing received by stimuli on the neglected side, and the effect of some theory-motivated manipulations aimed to ameliorate the impaired processing.

Dynamics of cortical activity

Lecture

Date:

Wednesday, March 30, 2011

Hour: 14:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. David A. McCormick

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Yale University School of Medicine, New Haven, CT

Do all Japanese paintings look the same? Styles and Schools in Japanese Art

Lecture

Date:

Tuesday, March 29, 2011

Hour: 14:00 - 18:00

Location:

Dolfi and Lola Ebner Auditorium

Prof. Itamar Procaccia

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Department of Chemical Physics, WIS

Engineered neuronal networks

Lecture

Date:

Tuesday, March 29, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Prof. Elisha Moses

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Department of Physics of Complex Systems, WIS

Neuronal cultures grown from hippocampal neurons exhibit a distinct all-or-none burst firing pattern. We introduce quantitative tools to investigate the properties of the network which lead to this kind of behavior, and identify the distribution of input connections as the dominant factor governing the behavior of the network. We show that one-dimensional networks display a significantly simpler behavior, and use this observation to design some computational neuronal circuits.

Mechanisms of Associative Learning in Young and Aging Brain

Lecture

Date:

Tuesday, March 22, 2011

Hour: 15:00

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. John Disterhoft

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Dept of Physiology Northwestern University Chicago, IL

The neuronal alterations which occur in important neuron populations in young adult animals and changes in those processes which occur during aging and cause age-related learning deficits are beginning to be understood with cellular to systems level analyses. We have studied these processes with hippocampus-dependent trace eyeblink conditioning tasks. Calcium and calcium-activated potassium currents, that help control intrinsic neuronal excitability and are altered during learning and in aging, have been extensively studied. In vivo recording studies of CA1 hippocampal pyramidal neurons during and after associative eyeblink conditioning demonstrate functional alterations during learning and aging. We have examined mechanisms underlying these alterations in firing rate by examining CA1 neurons in brain slices. These current and voltage clamp studies of alterations in the calcium-activated potassium currents that increase neuronal excitability during associative learning in young animals and age-associated changes in these currents that occur in learning-impaired aging animals will be described. Behavioral pharmacological studies have demonstrated that age-associated behavioral changes can be reversed by compounds targeting neuronal excitability. Intracellular signaling pathways and alterations in calcium currents that may lead to these changes in intrinsic excitability during learning are being explored.

Lazy Neurons for Good Shape or Filling in the Gaps...The Mind's Way

Lecture

Date:

Tuesday, March 15, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Ohad Ben-Shahar

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Dept of Computer Science Ben Gurion University

The phenomenon of visual curve completion, where the visual system completes the missing part (e.g., due to occlusion) between two contour fragments, is a major problem in perceptual organization research, both behaviorally and computationally. Previous computational approaches for the shape of percetually completed curves typically follow an axiomatic approach via formal descriptions of desired, image-based perceptual properties (e.g, minimum total curvature, roundedness, etc...). Unfortunately, however, it is difficult to determine such desired properties psychophysically and indeed there is no consensus in the literature for what they should be. Instead, in this paper we suggest to exploit the fact that curve completion occurs in early vision in order to formalize the problem in a space that abstracts the primary visual cortex (For the technically inclined, this space is called the unit tangent bundle associated with R2). We show that a single basic principle of “minimum energy consumption” in this space not only results in a rigorous, non axiomatic, computational theory, but also makes excellent predictions and explanations for recent perceptual findings in the literature

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All events, All years

Lazy Neurons for Good Shape or Filling in the Gaps...The Mind's Way

Lecture

Date:

Tuesday, March 15, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Ohad Ben-Shahar

|

Dept of Computer Science Ben Gurion University

The phenomenon of visual curve completion, where the visual system completes the missing part (e.g., due to occlusion) between two contour fragments, is a major problem in perceptual organization research, both behaviorally and computationally. Previous computational approaches for the shape of percetually completed curves typically follow an axiomatic approach via formal descriptions of desired, image-based perceptual properties (e.g, minimum total curvature, roundedness, etc...). Unfortunately, however, it is difficult to determine such desired properties psychophysically and indeed there is no consensus in the literature for what they should be. Instead, in this paper we suggest to exploit the fact that curve completion occurs in early vision in order to formalize the problem in a space that abstracts the primary visual cortex (For the technically inclined, this space is called the unit tangent bundle associated with R2). We show that a single basic principle of “minimum energy consumption” in this space not only results in a rigorous, non axiomatic, computational theory, but also makes excellent predictions and explanations for recent perceptual findings in the literature

Distinct layers or a continuum? A morphological and functional analysis of pyramidal cells in the supragranular layers of rat barrel cortex

Lecture

Date:

Thursday, March 10, 2011

Hour: 14:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Jochen Staiger

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Dept of Neuroanatomy University of Göttingen

Pyramidal neurons in supragranular layers II and III of rodent sensory cortices are a main target of ascending sensory information conveyed by columnar projections of layer IV as well as contextual information from neighboring columns or higher cortical areas. However, layer II is not separable from layer III on cytoarchitectonic grounds. We therefore investigated to which extent pyramidal neurons in the supragranular layers differ in their input-output connectivity. We obtained detailed spatial maps of layer-specific intracortical functional input connectivity for electrophysiologically and morphologically identified supragranular pyramidal neurons by combining local photolysis of caged glutamate with whole-cell patch-clamp recordings using biocytin-containing pipettes in rat barrel cortex in vitro. The main source of excitatory inputs onto all supragranular pyramidal cells was layer IV of the same column. This translaminar excitatory source was even more prominent than local and transcolumnar excitatory inputs from within the supragranular layers, both in density and strength. Additionally, many pyramidal neurons received a prominent excitatory layer Va input, often originating from beyond the “home” column. Among those pyramidal neurons we detected a significantly higher fraction of cells located in a putative layer II than in TZ or putative layer III. Our results indicate a strong but differential information transmission from layer IV as well as layer Va, both important cortical entry points for parallel streams of sensory information, toward the supragranular layers. Within supragranular layers, information processing in pyramidal neurons can be "fine tuned" through local and transcolumnar excitatory networks. Finally this integrated information is forwarded with a prominent transcolumnar component by putative layer II pyramidal cells but with an intracolumnar preponderance, including significant layer IV-backprojections, by putative layer III pyramidal neurons

Neural correlates of behavior in the rodent striatum

Lecture

Date:

Tuesday, March 8, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Dr. Dana Cohen

|

Gonda Brain Research Center Bar-Ilan University

The striatum consists of GABAergic projection neurons and various types of interneurons. Despite their relative scarcity, these interneurons play a key role in information processing in the striatum. We use multielectrode arrays to record the activity of striatal projection neurons and interneurons in behaving rodents. By comparing their responses we test the ability of the striatum to encode behaviorally relevant information such as movement and context.

Stimulus-specific adaptation – beyond the oddball paradigm

Lecture

Date:

Tuesday, March 1, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Prof. Israel Nelken

|

Dept of Neurobiology Hebrew University of Jerusalem

Stimulus-specific adaptation is the decrease in the responses to a common stimulus that does not generalize, or generalize only partially, to other stimuli. Stimulus-specific adaptation in the auditory modality has been studied mostly with oddball sequences, which consist of a common and a rare stimuli. Recently, we started to use a number of other sound sequences in order to study the properties of adaptation in auditory cortex. I will show that (1) SSA is not only the result of the adaptation of the response to the common stimulus - in addition, the responses to the rare tones have a component due to the deviance of the rare tone relative to the regularity set by the common tone; (2) neuronal responses in auditory cortex of rats show sensitivity to finer types of statistical regularities; and (3) SSA can be evoked by other sounds as well, including sounds as similar to each other as two tokens of white noise. These results suggest the existence of a highly sensitive 'statistical machine' that analyzes and interprets the auditory scene.

Deletion of the mouse genomic interval corresponding to human 16p11.2 causes autism-like phenotypes

Lecture

Date:

Wednesday, February 23, 2011

Hour: 15:00

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Guy Horev

|

Postdoctoral Fellow Cold Spring Harbor Laboratory

Autism is a neuro-cognitive disorder characterized by a broad spectrum of clinical features including repetitive behaviors, restricted interests, language impairment, and altered social interactions. Although chromosome rearrangements affecting specific genomic intervals have been found in patients with autism, the basis for this syndrome is unknown. Deletion of 16p11.2 has been associated with autism, and patients with this deletion have a wide range of clinical symptoms. Here we used chromosome engineering to generate mice with deletion of the 27 genes corresponding to those affected in autism patients with 16p11.2 deletion, as well as mice harboring duplication of the same region. Mice with decreased dosage of this region have unique phenotypes including neonatal lethality, alterations in the volumes of specific brain regions, as well as behaviors reminiscent of clinical features of autism. In particular, mice with 16p11.2 deletion showed behaviors that were repetitive and restricted to specific locations, in contrast to diploid controls that showed a gradual increase in freedom of movement under similar conditions. These findings provide the first functional evidence that compromised dosage of 16p11.2 is causal in autism.

Pavlovian-like behavior in microbes

Lecture

Date:

Tuesday, February 22, 2011

Hour: 12:30

Location:

Jacob Ziskind Building

Prof. Yitzhak (Tzachi) Pilpel

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Department of Molecular Genetics, WIS

The ability to anticipate and prepare in advance to changes in the environment is ascribed to neuronal systems in multi-cellular organisms. Yet by means of gene expression regulatory connectivity microbes too may have evolved to "anticipate" and prepare in advance. I will present evidence for microbial Pavlovian-like conditioning and discuss the similarities and differences to conditioning in the neuronal-cognitive context.

Mechanisms of vocal learning in the songbird: A hypothesis for the role of cortical-basal ganglia circuits

Lecture

Date:

Monday, February 21, 2011

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Michale Fee

|

Dept of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA

Young songbirds, like humans, learn their vocalizations by imitating their parents. This process happens in a series of stages. After memorizing the song of an adult tutor, young birds begin to babble, singing highly random variable sounds. By listening to their own sounds and comparing them with the memory of the tutor song, they gradually refine their song until it can be a nearly exact copy of the tutor. How all this happens at the level of neural circuitry is not yet clear, but recent experiments have begun to shed light on the brain regions and mechanisms involved in the generation of babbling and exploratory variability, in the evaluation of the song, and in the implementation of corrective plastic changes in the motor circuitry. I will describe our current hypothesis for how interacting cortical-basal ganglia circuits implement these various processes underlying vocal learning.

Unraveling the structure of time in the brain

Lecture

Date:

Sunday, February 20, 2011

Hour: 11:00

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Michale Fee

|

Dept of Brain and Cognitive Sciences, Massachusetts Institute of Technology, Cambridge, MA

Whether we are speaking, swimming, or playing the piano, we are crucially dependent on our brain?s capacity to step through sequences of neural states. Songbirds provide a marvelous animal model in which to study this phenomenon. Their stereotyped vocalizations have hierarchical temporal structure spanning two orders or magnitude in timescale ? from individual vocal gestures lasting ten milliseconds, to song syllables (~100 msec), to song motifs (~1 sec). Several brain areas have been proposed to control timing at these different timescales. By manipulating these circuits with temperature change and observing the effect on song structure, we have been able to localize a single ?clock? circuit in the premotor vocal pathway. Intracellular neuronal recordings during singing elucidate the mechanism by which this clock circuit operates. Our findings are consistent with the predictions of a synfire-chain model? a synaptically connected chain of neurons in HVC. Our findings are inconsistent with models in which subthreshold dynamics, such as ramps or oscillations, play a role in the control of timing.

A sensorimotor account of phenomenal consciousness

Lecture

Date:

Wednesday, February 16, 2011

Hour: 11:00

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. J Kevin O'Regan

|

Laboratoire Psychologie de la Perception CNRS - Université Paris Descartes

The problem of consciousness is sometimes divided into two parts: An "easy" part, which involves explaining how one can become aware of of something in the sense of being able to make use of it in one's rational behavior. This is called access consciousness. And a "hard" part, which involves explaining why sensations feel like something, or have a kind of sensory presence, rather than having no feel at all. This is called phenomenal consciousness. Phenomenal consciousness is considered hard because there seems logically no way physical mechanisms in the brain could explain such facts. For example why does red look red, rather than looking green, or rather than sounding like a bell. Indeed why does red have a feel at all? Why do pains hurt instead of just provoking avoidance reactions? The sensorimotor approach provides a way of answering these questions by appealing to the idea that feels like red and pain should not be considered as things that happen to us, but rather as modes of ineraction with the environment. I shall show how the idea can be applied to color, touch, pain, and sensory substitution. In addition to helping understand human consciousness, the approach has applications in virtual reality and in robotics.

New Insights on Structural Neuroplasticity from MRI

Lecture

Date:

Tuesday, February 15, 2011

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Yaniv Assaf

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Dept. of Neurobiology Tel Aviv University

Neuro-plasticity is one of the key processes in our brain's physiology. This process allows our brain to change itself, functionally and structurally, following the acquisition of a new skill or experience. While functional aspects of neuro-plasticity can be studied using non-invasive techniques such as fMRI, EEF and MEG, investigation of the structural tissue characteristics of neuro-plasticity requires invasive histological approaches. Long-term experience necessitates structural plasticity which, in the adult brain, is characterized by changes in the shape and number of the synapses (synaptogenesis) as well as other process (neurogenesis, gliogenesis and white matter plasticity). Structural MRI studies of brain plasticity reveal significant volumetric changes via voxel-based morphometry of T1 weighted scans. Yet, the micro-structure correlates of these changes are not well understood. Diffusion tensor imaging (DTI) became one of the most popular imaging techniques in neuroimaging and is regarded as a micro-structural probe. Recently, tract-based spatial statistics (TBSS) analysis of DTI scans before and after long-term motor coordination training (juggling) revealed regional fractional anisotropy (FA) increase in parietal pathways. In that study, FA changes were reported following few weeks of training. An open question is what happens at shorter term learning and memory processes? In a short term spatial navigation study performed both in humans and rodents, we found that diffusion MRI can detect structural changes in cell morphology induced by plasticity within mere hours. Both in humans and rodents, the micro-structural changes, as observed by MRI, were localized to the anticipated brain regions: hippocampus, para-hippocampus, visual cortex, cingulate cortex and insular cortex. Our results indicate that significant structural occur in the tissue within mere hours - an interesting result by itself from the neurophysiological point of view. However, by investigating the induced structural changes both by histology and MRI it is possible to elucidate the relations between tissue micro-structure and the diffusion MRI signal. Preliminary results of such comparison indicate that in gray matter tissue one of cellular correlates of diffusion MRI indices is the density and shape of astrocyte. Indeed more studies should be directed