The Bernstein Center for Computational Neuroscience Freiburg


Announcement for the next
Informal Seminar
Michele Giugliano
University of Bern

IN VITRO MEAS AND NOISY CURRENT INJECTION : TOWARDS NETWORK-CLAMP?

Wednesday, October 6th, 2004
11:15h
Center court (Rm. 551)
Neurobiology & Biophysics
Schaenzlestr. 1
79104 Freiburg

Abstract:
Estimates of the number of synaptic contacts of a neocortical cell range between 5000 and 60000, 70% of them originating from intracortical areas. Furthermore, neocortical neurons fire spontaneously at a frequency of 5-20Hz in awake animals. These considerations define a scenario in which neurons experience large synaptic currents (i.e. hundreds of postsynaptic potentials over a ms-time scale). Such an intense background activity induces random-walk fluctuations in the postsynaptic membrane potentials and it is thought to have a profound impact on the neuronal integrative properties, on the response dynamics to external stimuli, as well as on the activity-dependent plasticities. These implications have been never systematically studied in vivo, because of the technical difficulties related to intracellular and patch-clamp recordings in behaving animals. On the other hand, in vitro preparations are widely employed as reduced models, but in spite of the many advantages they do not accurately represent the realistic cortical networks physiology. Similarly, conventional electrophysiological protocols are used to investigate single-neuron and network properties, under unaccurate and artificial conditions. In this talk, I will present the results from two different research projects. These projects are linked as they have been inspired by a common theoretical framework, related to the Extended Mean Field Theory of synaptic interactions in network models. They both deal with an attempt at recreating more realistic conditions for the investigation of the electrophysiological properties of individual neocortical neurons as well as the collective activity, emerging at the network level. The first part of the talk will summarize the contributions at restoring a realistic network input drive in acute cortical slices, by a novel application of substrate arrays of three-dimensional microelectrodes (MEAs), employed for distributed noisy electrical stimulation. The second part will focus on the stationary as well as dynamical discharge properties of neurons from acute neocortical slices, as well as mature cultures of neurons dissociated from rat neocortex, upon noisy current-clamp stimulation.
The talk is open to the public. Guests are cordially invited!
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