BIOPHYSICAL THEORY AND MODELING |
Amplitude variability and extracellular low-pass filtering of neuronal spikes
Klas H Pettersen 1 and Gaute T Einevoll 1*
1 Norwegian University of Life Sciences
* To whom correspondence should be addressed. E-mail: gaute.einevoll{at}umb.no.
Submitted on May 24, 2007
Revised on August 21, 2007
Accepted on 24 September 2007
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Abstract |
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The influence of neural morphology and passive electrical parameters on the width and amplitude of extracellular spikes is investigated by combined analytical and numerical investigations of idealized and anatomically reconstructed pyramidal and stellate neuron models. The main results are: (i) All models yield a low-pass filtering effect, that is, a spike-width increase with increasing distance from soma. (ii) A neuron's extracellular spike amplitude is seen to be approximately proportional to the sum of the dendritic cross-sectional areas of all dendritic branches connected to the soma. Thus, neurons with many, thick dendrites connected to soma will produce large amplitude spikes, and therefore have the largest radius of visibility. (iii) The spike shape and amplitude are found to be dependent on the
membrane capacitance and axial resistivity, but not on the membrane resistivity. (iv) The spike-amplitude decay with distance r is found to depend on dendritic morphology, and is decaying as 1/r n
with 1 
n 2 close to soma and n 
2 far away.
Key Words:
MUA, action potential, dendrites, extracellular spike, model, neuron
