Neuroscience 2005 Abstract
| Presentation Number: | 728.12 |
|---|---|
| Abstract Title: | Functional implications of spatial distribution and linearity of Ih in dendrites. |
| Authors: |
London, M.*1
; Angelo, K.1
; Hausser, M.1
1Wolfson Inst. For Biomedical Res. and Department of Physiology, University Col. of London, London, United Kingdom |
| Primary Theme and Topics |
Neural Excitability, Synapses, and Glia: Cellular Mechanisms - Synaptic Transmission -- Synaptic integration |
| Secondary Theme and Topics | Neural Excitability, Synapses, and Glia: Cellular Mechanisms<br />- Ion Channels<br />-- HCN and non-selective cation channels |
| Session: |
728. Synaptic Integration: Cellular Determinants Poster |
| Presentation Time: | Tuesday, November 15, 2005 4:00 PM-5:00 PM |
| Location: | Washington Convention Center - Hall A-C, Board # H7 |
| Keywords: | Ih, Purkinje cell , Model, dendrites |
Previous studies have shown that in pyramidal neurons the density of the hyperpolarization-activated current Ih increases with distance from the soma and that the presence of Ih results in normalization of the temporal summation of EPSPs, such that the degree of summation is independent of the dendritic location of the inputs. We have recently shown that, in contrast, cerebellar Purkinje neurons exhibit a spatially uniform distribution of Ih (Angelo et al. SFN 2004). The temporal summation as a function of the dendritic location of the input is similar when Ih is present or blocked. Moreover, temporal summation of a train of PSPs in the presence of Ih is linear. This result is remarkable as Ih is a highly non-linear current which clearly participates in shaping of the voltage response. In order to quantitatively understand these results we constructed two models of Ih. The first model is a Hodgkin-Huxley-type model of a non-linear current based on data from dendritic cell-attached recordings from Purkinje neurons. The second model is a linear adaptation of the first model, which has the advantage of being voltage-dependent while still linear. The two models both provided a very good fit of the data on EPSP and IPSP summation in Purkinje neurons and have very similar predictions of the response within wide range of voltage deflections (less than 10% difference for EPSPs smaller than 6 mV). The conditions where the prediction error of the linear model becomes significant for the summation of EPSPs can be explained by the steady-state properties of Ih. We have also used this linear model to dissect the contribution of the two components of the Ih conductance (namely the baseline conductance and the voltage-dependent linear component) to the shaping of dendritic signals under different spatial distributions. We find that the spatial distribution of Ih over the dendrites does not have a significant effect on the temporal integration of EPSP and IPSPs in Purkinje cells.
Supported by HFSP,Lundbeck Foundet, Wellcome Trust
Sample Citation:
[Authors]. [Abstract Title]. Program No. XXX.XX. 2005 Neuroscience Meeting Planner. Washington, DC: Society for Neuroscience, 2005. Online.
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