Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN Kolloquium

Wednesday, 30.11.2005 17 c.t.

Uni-dimensional neuronal cultures

by Ofer Feinerman
from Weizmann Institute, Rehovot, Israel

Contact person: Fred Wolf

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Abstract

Uni-dimensional neuronal cultures Dissociated hippocampal neurons were plated unto prepatterned coverslips to form uni-dimensional networks. The linear connectivity simplifies network activity and facilitates modeling. Furthermore, this culture may be regarded as an in-vitro model of a layered network. After specifying network properties, such as linear neuronal density and connectivity profiles, the following issues were addressed: 1. Spontaneous activity sources. It was shown that spontaneous activity emanates uniquely from local pacemakers, and the interaction between these pacemakers was studied. 2. Population burst propagation velocity. Locally initiated activity develops to induce large population bursts that excite the full length of the culture. Two velocities of the population burst front were measured; in proximity of the initiation site, activity propagates slowly but then gains both in amplitude and velocity as it spreads to affect larger populations. Velocity measurements under various conditions were successfully compared to an existing theoretical model incorporating 'integrate and fire' neurons. 3. Rate code efficiency. Average firing rates were estimated by amplitudes of population bursts as imaged using a calcium sensitive dye. The propagation of this rate coded information was directly measured. It was shown that propagation relies on an excitatory/inhibitory balance, in the presence of which information decays within an order of ten synaptic connections. This decay is quantitatively described by regarding the linear culture as an information line and applying the Gaussian chain model. 4. Finally, the new technology was employed to construct simple neuronal devices. It is demonstrated that dictating network structure allows insights into the relation between local properties and global activity in the network. Patterned cultures can serve as a bridge between theoretical models and the relevant in-vivo structures.

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