Theoretical and Experimental Neurobiology Unit at OIST

Theoretical and Experimental Neurobiology Unit at the Okinawa Institute of Science and Technology Principal Investigator Dr. Klaus M. Stiefel `stiefel@oist.jp` +81-98-921-3927 The goal of this research unit is to shed more light on the function of individual brain cells. For that purpose, we are using a combination of experimental and theoretical approaches. The experimental approaches are whole-cell patch clamp recordings in slices of the mouse frontal cortex. Data acquisition is done with LabView. The basic question we want to answer is “what type of computer is a neuron”? We are studying several aspects of the signal processing of neurons, such as their precision, phase-reset curves as well as their behavior under intrinsic and forced oscillations. As neurons in the cortex are subject to a variety of neuromodulatory (dopaminergic, cholinergic) influences, we are also studying all the afromentioned phenomena in cells subjected to these modulators. The theoretical approaches are biophysical simulations of neurons and the use of genetic algorithms. We are following a number of avenues here. One are biophysical simulations of single- and multicompartmental neuron models in NEURON. With this we aim to reproduce the experimental results and thus confirm that we understand the components giving rise to the electrophysiological dynamics we observed. Once this is achieved, we use the simulations to predict neuronal behavior under in-vivo conditions. We also use these simulations to investigate fundamental features of the excitability of the type of neuron in question. Examples of such features are the bifurcation leading to spiking and the ability of neurons to act as integrators or coincidence detectors. Another direction we are taking is the construction of multi-scale models of the brain. Neural information processing happens at a number of scales: Synaptic plasticity depends on the interplay of signaling molecules in the subcellular pre- and postsynaptic structures of many neurons. Single neurons can compute stimulus features, such as the direction of visual motion (optic lobe neurons in the fly) or the location of a sound (avian brainstem neurons). Brain areas, like the visual cortex in mammals, compute statistical features of visual scenes. For some functions of the nervous system, such as reinforcement learning, the tight cooperation between different brain areas is necessary. Thus, the brain operates at a number of interacting spatial and temporal scales. Constructing models which incorporate more than one of these scales will be a major challenge for theoretical neurobiology in the coming years and we hope to contribute to this endeavor. We are also very interested in the correlation between dendritic shape and function. To investigate this relationship, we have developed a method of finding models of neurons with denritic trees optimized for a given type of computation. This method utilizes genetic algorithms as a search method and L-systems as a method for generating dendritic trees. Terry Sejnowski, together with whom this idea started, gave an excellent talk (video available online) on the subject at the Redwood Center for Theoretical Neuroscience. Current lab members:
Dr. Klaus M. Stiefel	Principal investigator
Dr. Ben Torben-Nielsen	Post-doc, Dendritic morphology.
Maxence LeVasseur	Researcher, In vitro recordings of the frontal cortex.
Ryoko Uchida	Administrative assistant
Former lab members, we still like them:
Yunike Shimizu	Administrative assistant until January 2007
Dr. Arthur Flexer	Visitor, February 2007
Prof. Peter J. Thomas	Visitor, November 2007
Scientific Meetings: We are involved in the organization of some exciting workshops, courses and conferences:
Upcoming Meetings:
Okinawa Computational Neuroscience Course 2008		OIST Seaside House, Okinawa	June 16^th - July 4^th 2008
Multi-Scale Phenomena in Biology		OIST Seaside House, Okinawa	November 4^th - 6^th 2008

Previous Meetings:
Inverse Problems in Biology		OIST Seaside House, Okinawa	April 20^th -22^nd 2007
Okinawa Computational Neuroscience Course 2007		OIST Seaside House, Okinawa	June 25^th– July 13^th 2007
OIST – Salk Joint Neuroscience Meeting		Salk Institute, La Jolla, CA, USA	November 8^th - 10^th 2007
Hardware and software for large-scale biological computing in the next decade		OIST Seaside House, Okinawa	December 11^th - 14^th 2007
Interesting Marine Biology Fact of the Month Contact Information: Dr. Klaus M. Stiefel Theoretical and Experimental Neurobiology Unit Okinawa Institute of Science and Technology 12-22, Suzaki, Uruma, Okinawa 904-2234 Japan Tel. +81-98-921-3927 stiefel@oist.jp

Theoretical and Experimental Neurobiology Unit

at the Okinawa Institute of Science and Technology

Principal Investigator Dr. Klaus M. Stiefel

Hardware and software for large-scale biological computing in the next decade