Jacobson, Gilad A. and Diba, Kamran and Yaron-Jakoubovitch, Anat and Oz, Yasmin and Koch, Christof and Segev, Idan and Yarom, Yosef (2005) Subthreshold voltage noise of rat neocortical pyramidal neurones. Journal of Physiology, 564 (1). pp. 145-160. ISSN 0022-3751. http://resolver.caltech.edu/CaltechAUTHORS:20130816-103154296
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Neurones are noisy elements. Noise arises from both intrinsic and extrinsic sources, and manifests itself as fluctuations in the membrane potential. These fluctuations limit the accuracy of a neurone's output but have also been suggested to play a computational role. We present a detailed study of the amplitude and spectrum of voltage noise recorded at the soma of layer IV–V pyramidal neurones in slices taken from rat neocortex. The dependence of the noise on holding potential, synaptic activity and Na+ conductance is systematically analysed. We demonstrate that voltage noise increases non-linearly as the cell depolarizes (from a standard deviation (s.d.) of 0.19 mV at −75 mV to an s.d. of 0.54 mV at −55 mV). The increase in voltage noise is accompanied by an increase in the cell impedance, due to voltage dependence of Na+ conductance. The impedance increase accounts for the majority (70%) of the voltage noise increase. The increase in voltage noise and impedance is restricted to the low-frequency range (0.2–2 Hz). At the high frequency range (5–100 Hz) the voltage noise is dominated by synaptic activity. In our slice preparation, synaptic noise has little effect on the cell impedance. A minimal model reproduces qualitatively these data. Our results imply that ion channel noise contributes significantly to membrane voltage fluctuations at the subthreshold voltage range, and that Na+ conductance plays a key role in determining the amplitude of this noise by acting as a voltage-dependent amplifier of low-frequency transients.
|Additional Information:||Issue published online: 22 MAR 2005; Article first published online: 22 MAR 2005; (Resubmitted 14 December 2004; accepted after revision 27 January 2005; first published online 3 February 2005). c2005 The Physiological Society. This work was supported by the National Institute of Mental Health, by the National Science Foundation, and by the Human Frontier Science Program. G.A.J. was funded by a fellowship from the Israeli Ministry of Science. K.D. was supported by a postdoctoral fellowship from the Sloan-Swartz Center for Theoretical Neuroscience at Caltech. We thank Hanoch Meiri for valuable technical assistance.|
|Group:||Koch Laboratory, KLAB|
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|Deposited By:||KLAB Import|
|Deposited On:||12 Jan 2008 00:51|
|Last Modified:||18 Sep 2013 20:03|
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