%0 Generic
%A Fucke, Thomas
%D 2007
%F heidok:8349
%K Synaptische Integration , Anomale Rektifizierungneuron , computer simulation , postnatal development , voltage sensitive ion channels , synaptic integration
%R 10.11588/heidok.00008349
%T Biophysical Characterization and Simulation of Neocortical Layer 2/3 Pyramidal Neurons during Postnatal Development
%U https://archiv.ub.uni-heidelberg.de/volltextserver/8349/
%X Pyramidal neurons in layer 2/3 of the mammalian neocortex constitute the most abundant neocortical cell type, yet their biophysical properties are still poorly understood. In this thesis, fundamental properties of layer 2/3 pyramidal neurons of 1-to-6-weeks old rats were investigated with an approach combining in vitro electrophysiological characterization, reconstruction of cell morphologies, and numerical computer simulations. A specific goal was to identify ion channel mechanisms underlying the sub-threshold integrative properties of these cells and to reveal the developmental profile of channel expression. A simulated annealing algorithm was employed to numerically simulate layer 2/3 neurons and to generate valid models of varying complexity and constrained by experimental data. At all ages, layer 2/3 pyramidal neurons showed prominent anomalous rectification which could be attributed to inward-rectifier potassium (KIR) channels based both on pharmacological experiments and modeling. In contrast to other types of pyramidal neurons little hyperpolarization-activated current (Ih) was found. While morphological development essentially was complete at postnatal week 2, biophysical properties continued to change until week 4-6. In particular, input resistance strongly decreased with age, rendering the cells less excitable as the cortical network matures. Computer simulations showed that these properties will have a large impact on the integration of synaptic inputs during ongoing spontaneous activity in vivo. It is concluded, that layer 2/3 pyramidal neurons possess biophysical properties distinct from other pyramidal cells and that the prolonged postnatal development is critical for shaping synaptic integration and neocortical circuit activity in vivo.