RodriguezSFN2001
RELIABILITY AND PRECISION OF CORTICAL SPIKE RESPONSES TO SYNCHRONOUS INPUT:
DEPENDENCE ON SHAPE AND TEMPORAL DISTRIBUTION OF EPSCS
V.M. Rodriguez; M. Diesmann (2); B. Kampa; C. Mehring; A. Aertsen; D. Heck
Neurobiology and Biophysics,Inst. Biology III, Albert-Ludwigs-University, Freiburg, Germany
(2) Dept. of Nonlinear Dynamics, MPI fuer Stroemungsforschung, Goettingen, Germany
In theoretical work we investigated the propagation of synchronous spike activity in cortical networks (Diesmann et al. (1999) Nature 402:529-533). Here, we tested experimentally how precision and reliability of spike generation depend on shape, synchronization and number of input EPSCs. Using somatic whole-cell recordings (35oC) from rat layer 5 pyramidal neurons in vitro, we simulated the arrival of groups of EPSCs of various shapes (beta-functions) by current injection. Temporal jitter was introduced by convolution of EPSCs with gaussians of different standard deviations (SD). Four different EPSC shapes - normalized to charge - were evaluated: A) time to peak and decay time of 0.1 and 1 ms, respectively, B) 0.2 and 2 ms, C) 0.3 and 3 ms, and D) 3 and 7.5 ms. For each EPSC shape, SD was systematically varied. Reliability and precision of spike generation strongly depended on EPSC shape. All shapes produced precise and reliable spike responses for highly synchronized inputs (SD=0.1-2 ms). For short EPSCs (A,B), reliability and precision of spike generation dropped quickly with increasing SD. No spike occurred for SD>7-9ms. For slightly longer EPSCs (C,D), precision also decreased with increasing SD, but spike generation failed only for SD>25-30ms. Our results indicate that both temporal distribution and shape of EPSCs chritically determine the response characteristics of pyramidal cells.
Supported by: DFG:SFB-505/C7 and DAAD (V.R.)