SS 2006

Computational Neuroscience: Oberseminar (31196)

Dr. Laurenz Wiskott, Prof. Andreas V. M. Herz, and Dr. Richard Kempter

Oberseminar: Monday 14-15 Uhr in the ITB seminar room (Invalidenstraße 43)

In this seminar various topics of current research in computational neuroscience are presented. Attendees should have basic knowledge in neuroscience and computational neuroscience, e.g. from the courses "Computational Neuroscience I-IV".

Talks

03.04.2006 Jan Benda
"Tuning curves and neural coding"

Abstract: I review two papers on neural tuning curves. The first one investigates which part of the tuning curves carries most information about the stimulus (Daniel A. Butts and Mark S. Goldman (2006): Tuning Curves, Neuronal Variability, and Sensory Coding. PLoS Biol, 4, e92), the second discusses optimal tuning curves (M. Bethge and D. Rotermund and K. Pawelzik (2002): Optimal short-term population coding: when fisher information fails. Neural Comput, 14, 2317-2351).

10.04.2006 Aki Naito

08.05.2006 Laurenz wiskott
"A Tutorial on Inference in Graphical Models" (lecture notes)

15.05.2006 Andreas Lüschow (Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin)
"A combination of electrophysiological and behavioural data as objective measure of the impairment in congenital prosopagnosia."

22.05.2006 Susan Udin (Department Of Physiology And Biophysics, Buffalo, NY)
"Visual experience shapes the brain: Binocular maps in the developing Xenopus tectum"

29.05.2006 Uwe Roehner
"On Types of Neurons"

19.06.2006 Mathias Franzius

26.06.2006 Paula Kuokkanen
"Hearing Aids"

03.07.2006 Robert Schmidt

10.07.2006 Pablo E. Jercog (Physics Dept. 4 Washington Place, New York, NY, 10003.)
"Bilateral Asymmetry of Excitatory Synaptic Properties Shapes Interaural Time Delay Processing in Gerbil Medial Superior Olive"

Abstract: Interaural time difference (ITD) is thought to be the primary cue encoded by Medial Superior Olivary (MSO) neurons. MSO neurons receive synaptic inputs that are driven by the ipsi- and contralateral ear, and discharge rate depends on the arrival time differences of these two inputs. In vivo recordings from individual gerbil MSO neurons demonstrate that ITD tuning is asymmetric and peak discharge rate is produced just beyond the physiological range (approx.130 µs in gerbil), on the contralateral-leading side The observations support a slope code rather than a place code. Based on experimental data and simulations, we present a new model to explain the asymmetric location of the ITD range. We propose a mechanism that relies on bilateral differences in arrival-time statistics of the excitatory inputs, e.g., greater jitter on the contralateral side. A broader distribution of arrival times for synaptic inputs from the contralateral side creates summated EPSPs in the soma more spread in time from that side. This asymmetry in the arrival times leads to an asymmetry in the ITD function. Using a thick (approx. 450 µm) horizontal brain slice preparation, we activated the afferent bundles from either ipsi- or contralateral ventral cochlear nucleus (VCN) while recording intracellularly from MSO neurons. We found larger variability in EPSP amplitudes, halfwidths and rising times for contralateral, as compared to ipsilateral, stimulation in most neurons. Our experimental results combined with simulations suggest that bilateral differences in the arrival time statistics of the EPSPs contribute to shaping and positioning the ITD response function.

28.08.2006 Roland Schaette

04.09.2006 Martin Stemmler

11.09.2006 Henning Sprekeler

18.09.2006 Felix Creutzig
"Overcompleteness and efficient representations"

Abstract: There is wide agreement among neuroscientist that one can learn receptive fields of the visual system using machine learning techniques. The basis vectors of the auditory system are, however, less clear. I will shortly present one successful approach of learning auditory receptive fields based on overcomplete representations (Lewicki, 2002). I will try to give an elementary example to show that overcompleteness is a useful ingredient for efficient representations. What are problems related to overcompleteness and how can these be solved? I will give relations to information theoretic principles. The talk will have review style.

25.09.2006 Michael Bendels
"Development and Verification of a Laser Photostimulation System for Analyzing Brain Circuits."

Abstract: Laser photostimulation is a technique for understanding the functional organization of complex neuronal circuits in the brain. This approach is based on the locally-focused photolysis and short-time activation of a caged transmitter, e.g. glutamat. By measuring the postsynaptic potentials of a single target neuron in response to consecutive super-threshold stimulation of neurons in a brain slice, detailed maps of the location, strength, polarity, and number of inputs converging to the target cell can be constructed. This talk describes the technique of photostimulation, outlines the necessary intrumentation, and presents first steps of the development of a computer-controlled photostimulation system. Several examples of applications ranging from direct stimulation of single cells to the reconstruction of circuits in the hippocampal formation are presented.

Laurenz Wiskott, http://www.neuroinformatik.ruhr-uni-bochum.de/PEOPLE/wiskott/

03.04.2006		Jan Benda "Tuning curves and neural coding" Abstract: I review two papers on neural tuning curves. The first one investigates which part of the tuning curves carries most information about the stimulus (Daniel A. Butts and Mark S. Goldman (2006): Tuning Curves, Neuronal Variability, and Sensory Coding. PLoS Biol, 4, e92), the second discusses optimal tuning curves (M. Bethge and D. Rotermund and K. Pawelzik (2002): Optimal short-term population coding: when fisher information fails. Neural Comput, 14, 2317-2351).
10.04.2006		Aki Naito
08.05.2006		Laurenz wiskott "A Tutorial on Inference in Graphical Models" (lecture notes)
15.05.2006		Andreas Lüschow (Charité-Universitätsmedizin Berlin, Campus Benjamin Franklin) "A combination of electrophysiological and behavioural data as objective measure of the impairment in congenital prosopagnosia."
22.05.2006		Susan Udin (Department Of Physiology And Biophysics, Buffalo, NY) "Visual experience shapes the brain: Binocular maps in the developing Xenopus tectum"
29.05.2006		Uwe Roehner "On Types of Neurons"
19.06.2006		Mathias Franzius
26.06.2006		Paula Kuokkanen "Hearing Aids"
03.07.2006		Robert Schmidt
10.07.2006		Pablo E. Jercog (Physics Dept. 4 Washington Place, New York, NY, 10003.) "Bilateral Asymmetry of Excitatory Synaptic Properties Shapes Interaural Time Delay Processing in Gerbil Medial Superior Olive" Abstract: Interaural time difference (ITD) is thought to be the primary cue encoded by Medial Superior Olivary (MSO) neurons. MSO neurons receive synaptic inputs that are driven by the ipsi- and contralateral ear, and discharge rate depends on the arrival time differences of these two inputs. In vivo recordings from individual gerbil MSO neurons demonstrate that ITD tuning is asymmetric and peak discharge rate is produced just beyond the physiological range (approx.130 µs in gerbil), on the contralateral-leading side The observations support a slope code rather than a place code. Based on experimental data and simulations, we present a new model to explain the asymmetric location of the ITD range. We propose a mechanism that relies on bilateral differences in arrival-time statistics of the excitatory inputs, e.g., greater jitter on the contralateral side. A broader distribution of arrival times for synaptic inputs from the contralateral side creates summated EPSPs in the soma more spread in time from that side. This asymmetry in the arrival times leads to an asymmetry in the ITD function. Using a thick (approx. 450 µm) horizontal brain slice preparation, we activated the afferent bundles from either ipsi- or contralateral ventral cochlear nucleus (VCN) while recording intracellularly from MSO neurons. We found larger variability in EPSP amplitudes, halfwidths and rising times for contralateral, as compared to ipsilateral, stimulation in most neurons. Our experimental results combined with simulations suggest that bilateral differences in the arrival time statistics of the EPSPs contribute to shaping and positioning the ITD response function.
28.08.2006		Roland Schaette
04.09.2006		Martin Stemmler
11.09.2006		Henning Sprekeler
18.09.2006		Felix Creutzig "Overcompleteness and efficient representations" Abstract: There is wide agreement among neuroscientist that one can learn receptive fields of the visual system using machine learning techniques. The basis vectors of the auditory system are, however, less clear. I will shortly present one successful approach of learning auditory receptive fields based on overcomplete representations (Lewicki, 2002). I will try to give an elementary example to show that overcompleteness is a useful ingredient for efficient representations. What are problems related to overcompleteness and how can these be solved? I will give relations to information theoretic principles. The talk will have review style.
25.09.2006		Michael Bendels "Development and Verification of a Laser Photostimulation System for Analyzing Brain Circuits." Abstract: Laser photostimulation is a technique for understanding the functional organization of complex neuronal circuits in the brain. This approach is based on the locally-focused photolysis and short-time activation of a caged transmitter, e.g. glutamat. By measuring the postsynaptic potentials of a single target neuron in response to consecutive super-threshold stimulation of neurons in a brain slice, detailed maps of the location, strength, polarity, and number of inputs converging to the target cell can be constructed. This talk describes the technique of photostimulation, outlines the necessary intrumentation, and presents first steps of the development of a computer-controlled photostimulation system. Several examples of applications ranging from direct stimulation of single cells to the reconstruction of circuits in the hippocampal formation are presented.