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Informationsverarbeitung in Neuronen und Netzwerken in kortikalen Hirnschnitten unter in vivo - ähnlichen Bedingungen
Information processing in cortical neurons and networks - recreation of in vivo - like conditions in brain slice preparations
Project funding (Div. I-III)
Institut für Physiologie Medizinische Fakultät Universität Bern
Institution of higher education
University of Berne - BE
Neurophysiology and Brain Research
01.04.2005 - 30.06.2008
neuronal integration; somatosensory cortex; in vivo - like activity; somatodendritic interaction
Lay Summary (English)
In recent years, basic mechanisms have been identified for information processing in the somatosensory cortex - on the level of single neurons as well as on the level of the neuronal network. On the cellular level, information processing requires dynamic mechanisms, which allow the detection of simultaneously active inputs. The pyramidal cells in layer V of the somatosensory cortex are able to detect coincident synaptic activity from different afferents along their somatodendritic axis.
Therefore, inputs to the somatic and the distal apical regions are computed locally and separately and the output of the cell can change qualitatively upon the interaction of these compartments. On the network level, the flow of the information within the sensory barrel cortex is based on the independence of the barrel columns coding for the respective whiskers.The investigation of cellular and network properties was done nearly exclusively in acute brain slice preparations, which are characterized by non-physiological low levels of synaptic activity compared to the in vivo situation. The concomitantly altered passive cell parameters like membrane potential, input resistance, and membrane time constant make it difficult to predict the integrative behavior of neurons in vivo. If one has in mind the marked effect of GABAergic shunting in the barrel cortex, also the network response under the in vivo conditions with a decreased input resistance may differ from that seen in the slice preparation. On the other hand, it is technically nearly impossible to study the integrative properties of neurons and networks in vivo in a way which is that controlled like in vitro.
The dilemma can be overcome by an acute slice with a recreated in vivo - like activity. It combines the advantages of an easily accessible in vitro preparation and the situation within the acting brain. In order to achieve this, we will activate the synaptic release probability in the slices and thereby bring the passive membrane properties into a physiological range.We are on the way to establish such an advantageous preparation to better define the active processes on the cellular and network level during integration. Then, we will study electrophysiological phenomena which have been proven to be critically dependent on the passive properties.
In vitro studies have provided us with a good idea of the abilities neurons and networks may have. If successful, the proposed experiments will bring us one step ahead and we can estimate the actual cellular electrophysiological properties and patterns of information flow in the integrating brain.
Direct link to Lay Summary
Last update: 21.02.2013
Responsible applicant and co-applicants
Institut für Physiologie & Pathophysiologie Universität Mainz
Department of Neurobiology University of Chicago
Associative processes and dendritic conductances in neocortical layer V pyramidal cells.
Project funding (Div. I-III)