ニューロエンジニアリング Neuroengineering
P1-2-220 刺激波形制御による大脳皮質下領域の選択的神経刺激法の計算機シミュレーション Computer simulation of selective stimulation of subcortical nerve fibers by stimulus waveform control ○上野彩子1, 片山統裕1, 辛島彰洋1, 中尾光之1 ○Ayako Ueno1, Norihiro Katayama1, Akihiro Karashima1, Mitsuyuki Nakao1 東北大院・情報科学・応用情報科学・バイオモデリング論1 Biomodeling Lab, Dept Applied Information Sciences, GSIS, Tohoku univ, Sendai, JAPAN1 During brain surgery, it is important to determine functional brain and cortico-cortical pathways to keep them intact to preserve patients' quality of life (QOL). Cortical and subcortical brain mappings are the techniques that deliver direct current stimulation to brain surface and beneath gray matter to identify the brain area and nerve fibers related to higher-order functions. However, due to non-selectivity of the effect of conventional electrical stimulation methods, it has been hard to obtain precise spatial distribution of nerve fibers in the subcortical region. If it is possible to recruit distant axons without recruiting close axons to the electrode or change the targeted axons by manipulating the stimulus parameters, it would be useful to estimate the spatial distribution of subcortical fibers. In this study, we investigated the electrical stimulation of subcortical mapping to evaluate axon-to-electrode distance-selectivity. We constructed an anisotropic multi-layer volume conductor of human brain of which white matter layer is partly exposed. A mathematical model of human myelinated nerve was embedded in the volume conductor. The axonal response to an extracellular columned electrode on the white matter surface was numerically calculated. It is clarified that a conventional rectangular biphasic pulse activates axons non-selectively. To improve the distance-selectivity, a novel waveform which is composed of double exponential curves and a pulse is proposed. It is found that the stimulus with the proposed waveform can recruit fibers at a restricted distance from the electrode (target region). In addition, the target region can be shifted by changing stimulus intensity. These results suggest the usefulness of the proposed stimulus waveform for distance-selective recruitment for subcortical brain mapping.	P1-2-221 刺激タイミングに依存した、神経回路網の時空間活動パターン Stimulus timing dependent spike pattern characteristic of a neuronal network ○伊東嗣功1, 工藤卓1 ○Hidekatsu Ito1, Suguru N Kudoh1 関西学院大学大学院　理工学研究科　情報科学1 Dept informatics, Kwasnei Gakuin Univ , Japan1 Brain neuronal network structure is modified by input from outer world in activity dependent manner. To analyze electrical activity evoked by inputs from external world or mutual electrical interaction between neuronal networks, we prepared a dissociated culture of rat hippocampal neurons on a multi-electrodes array (MEA) dish. MEA dish are suitable for analyzing such complex neuronal network dynamics and developmental processes of network formation. Dissociated neurons reorganized a complex networks autonomously on a MEA dish and frequent spontaneous electrical activity was observed. To elucidate reproducibility of response against an electrical input, we applied single and paired electrical stimuli to the neuronal network. We found that temporal pattern of spikes evoked by a single current stimulation changed after paired stimuli with 1s ISI. Initially, an averaged spike number within 500 ms time window immediately and 1 s after a single electrical stimulation were 1873±226 and 1904±414, respectively. These spike numbers were changed to 1452±219 and 2508±354 after 1 s interval paired stimulations. Second time window 1 s after a single stimulation corresponds to the timing immediately after a second stimulation of paired stimuli. It suggested that the response evoked by a single stimulation changed to include response evoked by a second stimulation, even though, actually, there is no second response. The phenomenon was confirmed in both mature and immature culture. These results suggest that temporal pattern of inputs is preserved even in semi-artificial condition of a cultured neuronal network.
P1-2-222 Dynamics of Multiple, Interconnected Neuronal Populations Cultured on a High-Density Microelectrode Array System ○Kosmas Deligkaris1,2, Sungho Kim1, Douglas J. Bakkum3, Andreas Hierlemann3, Urs Frey1,2 Frey Initiative Research Unit, RIKEN Quantitative Biology Center, Kobe, Japan1, Osaka University, Graduate School of Frontier Biosciences, Osaka, Japan2 Microelectrode arrays (MEA) allow for extracellular recording and stimulation of in-vitro developing neuronal networks and acute slices. They have been used for studies on development [1], plasticity [2] and pharmacology [3]. Activity patterns of in-vitro growing cultures include network-wide firing events (bursts) and pair-wise correlated firing [4]. Learning-induced short and long-term plasticity can alter the number and strength of synaptic connections as well as burst profiles [5]. To reveal the dynamics of activity-dependent mechanisms and their relation to single-cell and neural circuit information processing we are employing a high-density MEA (HDMEA) [6] based system. The HDMEA contains 11,011 electrodes at a density of 3,150 electrodes/mm2. This allows for i) plating of low-density cultures and ii) growing of multiple small networks on a single chip. In this work, we present our results from multiple, interconnected neuronal populations cultured on a single HDMEA chip. We investigate burst profiles, burst propagation and correlated firing events of the confined populations. As a further improvement, we propose a 96-well plate with integrated HDMEAs in each well. This device will help address two commonly observed problems: i) variation in environmental conditions for each sample and ii) the large amount of data required for statistical analysis. 1: Biophysics, Quarterly Reviews of, 35, 63-87, 2002 2: Bio Systems, 88(1-2), 1-15, 2006 3: Biosensors Bioelectronics, 18, 627-634, 2003 4: Brain Research, 1093(1), 41-53, 2006 5: Biomedical Engineering, IEEE Transactions on, 56(4), 1220-1227, 2009 6: Solid-State Circuits, IEEE Journal of, 45, 467-482, 2010

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