Past events | The department of Brain Sciences

All events, 2014

Spiking patterns and cortical neuron detectability

Lecture

Date:

Wednesday, August 13, 2014

Hour: 11:00

Location:

Nella and Leon Benoziyo Building for Brain Research

Guy Doron, PhD

|

Postdoc Prof. Matthew Larkum Lab Humboldt University of Berlin

In recent years, substantial advances have been made towards directly linking single-cell activity and sensation. While it was shown that the activity of single cortical neurons can evoke measurable sensory effects, the relation between the regularity, frequency and number of action potentials (APs) to the evoked sensations is unknown and it is still unclear, how these effects depend on cell type and the precise discharge pattern. In a previous study we used nanostimulation, a technique that allows in vivo manipulation of spike activity and identification of individual neurons (Houweling et al., 2010), to provide evidence that individual neurons in the rat barrel cortex can have an impact on behavioral responses in a detection task. In this talk I will discuss the effects of spike train irregularity, frequency and number on the detectability of single-neuron stimulation in rat somatosensory cortex. Our data imply that the behaving animal is sensitive to single neurons' spikes and even to their temporal patterning.

Linking dynamics of neural activity to movement and decisions

Lecture

Date:

Wednesday, August 6, 2014

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Dr. Mati Joshua

|

Dept of Neurobiology Duke University, Durham, NC, USA

Neurons continuously modulate their activity in time and magnitude; it is unclear how the dynamics of activity is related to brain computations and to behavior. In the first part of my talk I will show how we link between the dynamics of activity and the computation in the cerebellum-brainstem circuitry that generates eye movement. We found that dynamics of responses of neurons support a hierarchical organization of a neural integrator. In the second part of my talk I will show how we use the smooth pursuit eye movement to continuously readout the decision process. I will present a new framework for studying the neural mechanisms for decisions.

The functional architecture of the ventral stream and its role in visual categorization

Lecture

Date:

Tuesday, July 8, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Kalanit Grill-Spector

|

Dept of Psychology and Neurosciences Institute Stanford University, CA

Visual categorization is thought to occur in the human ventral temporal cortex (VTC), but how this categorization is achieved is still largely unknown. I will consider the computations and representations that are necessary for categorization, and examine how the microanatomical and macroanatomical layout of the VTC might optimize them to achieve rapid and flexible visual categorization. I will propose that efficient categorization is achieved by organizing representations in a nested spatial hierarchy in the VTC. This spatial hierarchy serves as a neural infrastructure for the representational hierarchy of visual information in the VTC and thereby enables flexible access to category information at several levels of abstraction.

How much information can a population of neurons transmit to its target?

Lecture

Date:

Tuesday, June 24, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Ehud Kaplan

|

Dept of Neuroscience, Icahn School of Medicine at Mount Sinai, New York

The technology of recording the discharge of a large number of neurons has advanced greatly in the past few years. However, the analytical approaches that can extract new insights from such recordings have lagged behind. In particular, until recently there was no way to calculate the amount of (Shannon) information that a population of spiking neurons transmits to its target. In this talk I shall describe a new method that we have developed for this purpose, and discuss briefly ts potential use and limitations.

Synaptic mechanisms of sensory perception

Lecture

Date:

Wednesday, June 18, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Carl Petersen

|

Brain Mind Institute, Ecole Polytechnique Federale de Lausanne (EPFL),Lausanne, Switzerland

A key goal of modern neuroscience is to understand the neural circuits and synaptic mechanisms underlying sensory perception. Here, I will discuss our efforts to characterise sensory processing in the mouse barrel cortex, a brain region known to process tactile information relating to the whiskers on the snout. Each whisker is individually represented in the primary somatosensory neocortex by an anatomical unit termed a ‘barrel’. The barrels are arranged in a stereotypical map, which allows recordings and manipulations to be targeted with remarkable precision. In this cortical region it may therefore be feasible to gain a quantitative understanding of neocortical function. We have begun experiments towards this goal using whole-cell recordings, voltage-sensitive dye imaging, viral manipulations, optogenetics and two-photon microscopy. Through combining these techniques with behavioral training, our experiments provide new insight into sensory perception at the level of individual neurons and their synaptic connections.

How do rewards affect visual cortex?

Lecture

Date:

Tuesday, June 17, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Wim Vanduffel

|

Dept of Neurosciences, KU Leuven, Belgium Harvard Medical School, MA

I will discuss data from a series of monkey fMRI experiments showing evidence for a reward induced spatially-selective modulation of visual cortical activity. These effects reflect a dopamine-dependent reward-prediction error signal that may be caused by ventral mid-brain nuclei. I will also discuss data from our first microstimulation experiments in the monkey targeting the ventral midbrain which revealed profound functional network changes in the reward circuitry and changes in behavior during a free choice task in monkeys.

Magnetic Resonance Spectroscopy (MRS) as a Tool for Probing Brain Metabolism in Vivo

Lecture

Date:

Tuesday, June 10, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Assaf Tal

|

Department of Chemical Physics, WIS

Magnetic resonance is used mostly to image the intense signal arising from the water molecules in vivo, yielding high resolution anatomical maps. However, by suppressing the water signal, it is possible to detect the much weaker signals of less abundant metabolites, including creatine, choline, GABA, glutamine/glutamate and several others: this is termed Magnetic Resonance Spectroscopy (MRS). I will attempt to provide a broad overview of how this metabolic information can be leveraged to study the human brain by presenting in-vivo data from our multiple sclerosis cohort, as well as discuss the main difficulties associated with MRS and how the research we conduct aims to rectify them.

High spatial and temporal dynamics of sequential binding amongst cortical areas:an MEG study

Lecture

Date:

Tuesday, May 20, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Moshe Abeles

|

Bar-Ilan University The Hebrew University of Jerusalem

We assume that while preforming any higher brain function, multiple cortical regions interact with some fairly fixed temporal order. This type of process needs to be studied with a resolution of a few ms. Such sequences of coordinated activities amongst multiple cortical locations was revealed in ongoing activity with milliseconds accuracy. That was achieved without the need for averaging over time or frequencies. The analysis was based on recording MEG and reconstructing the cortical current-dipole-amplitudes at multiple points. In these current-dipole traces instances of brief activity undulations were automatically detected and used to reveal where and when cortical points interact.

Homeostatic regulation of intrinsic excitability and circuit function

Lecture

Date:

Wednesday, May 14, 2014

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Eve Marder

|

Faculty of Biology and Volen National Center for Complex Systems, Brandeis University

Neurons and networks must constantly rebuild themselves in response to the continual and ongoing turnover of all of the ion channels and receptors that are necessary for neuronal signaling. A good deal of work argues that stable neuronal and network function arises from homeostatic negative feedback mechanisms. Nonetheless, while these mechanisms can produce a target activity or performance, they are also consistent with a good deal of recent theoretical and experimental work that shows that similar circuit outputs can be produced with highly variable circuit parameters. This work argues that the nervous system of each healthy individual has found a set of different solutions that give “good enough circuit performance. I will describe new computational models (O’Leary et al., PNAS 2013; Neuron in press, 2014) for cellular homeostasis that give insight into a variety of experimental observations, including correlations in the expression of ion channel genes. In response to perturbation these homeostatic models usually compensate for perturbations, but some perturbations elude compensation. Moreover, situations can arise in which the homeostatic mechanisms result in aberrant behavior, such as may occur in disease.

Janus-faced gating-modifiers targeting the voltage sensor of voltage-gated cation channels:A new approach to cure hyperexcitability disorders

Lecture

Date:

Tuesday, May 13, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Bernard Attali

|

Sagol School of Neuroscience and Dept of Physiology and Pharmacology Sackler Medical School, Tel Aviv University

Some of the fascinating features of voltage-sensing domains (VSD) in voltage-gated cation channels (VGCC) are their modular nature and adaptability. Here we examined the VSD promiscuity of VGCC, using non-toxin gating-modifiers, NH17 and NH29, which share closely related structures and stabilize Kv7.2 potassium channels, in the closed and open state, respectively. NH17 and NH29 exert opposite gating-modifier effects on TRPV1 channels, operating respectively, as an activator and a blocker of TRPV1 currents. Combined mutagenesis and electrophysiology, structural homology modeling, molecular docking and molecular dynamics simulation indicate that both compounds target the VSD of TRPV1 channels, which like vanilloids are involved in π-π stacking, H-bonding and hydrophobic interactions. Reflecting the VSD promiscuity, they also affect the lone VSD proton channel mVSOP. Remarkably, NH29 alleviates neuropathic pain in rats, suggesting that sometimes, promiscuous VSD ligands may be therapeutically beneficial. Thus, structurally related, yet different molecules can interact with the VSD of the same VGCC, while the same gating-modifier can promiscuously interact with different VGCC. Subtle differences at the VSD-ligand interface will dictate whether the gating-modifier stabilizes channels in either the closed or the open state.

Pages

All events, 2014

Spiking patterns and cortical neuron detectability

Lecture

Date:

Wednesday, August 13, 2014

Hour: 11:00

Location:

Nella and Leon Benoziyo Building for Brain Research

Guy Doron, PhD

|

Postdoc Prof. Matthew Larkum Lab Humboldt University of Berlin

In recent years, substantial advances have been made towards directly linking single-cell activity and sensation. While it was shown that the activity of single cortical neurons can evoke measurable sensory effects, the relation between the regularity, frequency and number of action potentials (APs) to the evoked sensations is unknown and it is still unclear, how these effects depend on cell type and the precise discharge pattern. In a previous study we used nanostimulation, a technique that allows in vivo manipulation of spike activity and identification of individual neurons (Houweling et al., 2010), to provide evidence that individual neurons in the rat barrel cortex can have an impact on behavioral responses in a detection task. In this talk I will discuss the effects of spike train irregularity, frequency and number on the detectability of single-neuron stimulation in rat somatosensory cortex. Our data imply that the behaving animal is sensitive to single neurons' spikes and even to their temporal patterning.

Linking dynamics of neural activity to movement and decisions

Lecture

Date:

Wednesday, August 6, 2014

Hour: 12:30

Location:

Nella and Leon Benoziyo Building for Brain Research

Dr. Mati Joshua

|

Dept of Neurobiology Duke University, Durham, NC, USA

Neurons continuously modulate their activity in time and magnitude; it is unclear how the dynamics of activity is related to brain computations and to behavior. In the first part of my talk I will show how we link between the dynamics of activity and the computation in the cerebellum-brainstem circuitry that generates eye movement. We found that dynamics of responses of neurons support a hierarchical organization of a neural integrator. In the second part of my talk I will show how we use the smooth pursuit eye movement to continuously readout the decision process. I will present a new framework for studying the neural mechanisms for decisions.

The functional architecture of the ventral stream and its role in visual categorization

Lecture

Date:

Tuesday, July 8, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Kalanit Grill-Spector

|

Dept of Psychology and Neurosciences Institute Stanford University, CA

Visual categorization is thought to occur in the human ventral temporal cortex (VTC), but how this categorization is achieved is still largely unknown. I will consider the computations and representations that are necessary for categorization, and examine how the microanatomical and macroanatomical layout of the VTC might optimize them to achieve rapid and flexible visual categorization. I will propose that efficient categorization is achieved by organizing representations in a nested spatial hierarchy in the VTC. This spatial hierarchy serves as a neural infrastructure for the representational hierarchy of visual information in the VTC and thereby enables flexible access to category information at several levels of abstraction.

How much information can a population of neurons transmit to its target?

Lecture

Date:

Tuesday, June 24, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Ehud Kaplan

|

Dept of Neuroscience, Icahn School of Medicine at Mount Sinai, New York

The technology of recording the discharge of a large number of neurons has advanced greatly in the past few years. However, the analytical approaches that can extract new insights from such recordings have lagged behind. In particular, until recently there was no way to calculate the amount of (Shannon) information that a population of spiking neurons transmits to its target. In this talk I shall describe a new method that we have developed for this purpose, and discuss briefly ts potential use and limitations.

Synaptic mechanisms of sensory perception

Lecture

Date:

Wednesday, June 18, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Carl Petersen

|

Brain Mind Institute, Ecole Polytechnique Federale de Lausanne (EPFL),Lausanne, Switzerland

A key goal of modern neuroscience is to understand the neural circuits and synaptic mechanisms underlying sensory perception. Here, I will discuss our efforts to characterise sensory processing in the mouse barrel cortex, a brain region known to process tactile information relating to the whiskers on the snout. Each whisker is individually represented in the primary somatosensory neocortex by an anatomical unit termed a ‘barrel’. The barrels are arranged in a stereotypical map, which allows recordings and manipulations to be targeted with remarkable precision. In this cortical region it may therefore be feasible to gain a quantitative understanding of neocortical function. We have begun experiments towards this goal using whole-cell recordings, voltage-sensitive dye imaging, viral manipulations, optogenetics and two-photon microscopy. Through combining these techniques with behavioral training, our experiments provide new insight into sensory perception at the level of individual neurons and their synaptic connections.

How do rewards affect visual cortex?

Lecture

Date:

Tuesday, June 17, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Wim Vanduffel

|

Dept of Neurosciences, KU Leuven, Belgium Harvard Medical School, MA

I will discuss data from a series of monkey fMRI experiments showing evidence for a reward induced spatially-selective modulation of visual cortical activity. These effects reflect a dopamine-dependent reward-prediction error signal that may be caused by ventral mid-brain nuclei. I will also discuss data from our first microstimulation experiments in the monkey targeting the ventral midbrain which revealed profound functional network changes in the reward circuitry and changes in behavior during a free choice task in monkeys.

Magnetic Resonance Spectroscopy (MRS) as a Tool for Probing Brain Metabolism in Vivo

Lecture

Date:

Tuesday, June 10, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Dr. Assaf Tal

|

Department of Chemical Physics, WIS

Magnetic resonance is used mostly to image the intense signal arising from the water molecules in vivo, yielding high resolution anatomical maps. However, by suppressing the water signal, it is possible to detect the much weaker signals of less abundant metabolites, including creatine, choline, GABA, glutamine/glutamate and several others: this is termed Magnetic Resonance Spectroscopy (MRS). I will attempt to provide a broad overview of how this metabolic information can be leveraged to study the human brain by presenting in-vivo data from our multiple sclerosis cohort, as well as discuss the main difficulties associated with MRS and how the research we conduct aims to rectify them.

High spatial and temporal dynamics of sequential binding amongst cortical areas:an MEG study

Lecture

Date:

Tuesday, May 20, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Moshe Abeles

|

Bar-Ilan University The Hebrew University of Jerusalem

We assume that while preforming any higher brain function, multiple cortical regions interact with some fairly fixed temporal order. This type of process needs to be studied with a resolution of a few ms. Such sequences of coordinated activities amongst multiple cortical locations was revealed in ongoing activity with milliseconds accuracy. That was achieved without the need for averaging over time or frequencies. The analysis was based on recording MEG and reconstructing the cortical current-dipole-amplitudes at multiple points. In these current-dipole traces instances of brief activity undulations were automatically detected and used to reveal where and when cortical points interact.

Homeostatic regulation of intrinsic excitability and circuit function

Lecture

Date:

Wednesday, May 14, 2014

Hour: 12:30

Location:

Arthur and Rochelle Belfer Building for Biomedical Research

Prof. Eve Marder

|

Faculty of Biology and Volen National Center for Complex Systems, Brandeis University

Neurons and networks must constantly rebuild themselves in response to the continual and ongoing turnover of all of the ion channels and receptors that are necessary for neuronal signaling. A good deal of work argues that stable neuronal and network function arises from homeostatic negative feedback mechanisms. Nonetheless, while these mechanisms can produce a target activity or performance, they are also consistent with a good deal of recent theoretical and experimental work that shows that similar circuit outputs can be produced with highly variable circuit parameters. This work argues that the nervous system of each healthy individual has found a set of different solutions that give “good enough circuit performance. I will describe new computational models (O’Leary et al., PNAS 2013; Neuron in press, 2014) for cellular homeostasis that give insight into a variety of experimental observations, including correlations in the expression of ion channel genes. In response to perturbation these homeostatic models usually compensate for perturbations, but some perturbations elude compensation. Moreover, situations can arise in which the homeostatic mechanisms result in aberrant behavior, such as may occur in disease.

Janus-faced gating-modifiers targeting the voltage sensor of voltage-gated cation channels:A new approach to cure hyperexcitability disorders

Lecture

Date:

Tuesday, May 13, 2014

Hour: 12:30

Location:

Gerhard M.J. Schmidt Lecture Hall

Prof. Bernard Attali

|

Sagol School of Neuroscience and Dept of Physiology and Pharmacology Sackler Medical School, Tel Aviv University

Some of the fascinating features of voltage-sensing domains (VSD) in voltage-gated cation channels (VGCC) are their modular nature and adaptability. Here we examined the VSD promiscuity of VGCC, using non-toxin gating-modifiers, NH17 and NH29, which share closely related structures and stabilize Kv7.2 potassium channels, in the closed and open state, respectively. NH17 and NH29 exert opposite gating-modifier effects on TRPV1 channels, operating respectively, as an activator and a blocker of TRPV1 currents. Combined mutagenesis and electrophysiology, structural homology modeling, molecular docking and molecular dynamics simulation indicate that both compounds target the VSD of TRPV1 channels, which like vanilloids are involved in π-π stacking, H-bonding and hydrophobic interactions. Reflecting the VSD promiscuity, they also affect the lone VSD proton channel mVSOP. Remarkably, NH29 alleviates neuropathic pain in rats, suggesting that sometimes, promiscuous VSD ligands may be therapeutically beneficial. Thus, structurally related, yet different molecules can interact with the VSD of the same VGCC, while the same gating-modifier can promiscuously interact with different VGCC. Subtle differences at the VSD-ligand interface will dictate whether the gating-modifier stabilizes channels in either the closed or the open state.