Physiologically based calculation of steady-state evoked potentials and cortical wave velocities |
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Authors: | P A Robinson Po-chia Chen Lei Yang |
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Institution: | (1) School of Physics, The University of Sydney, Sydney, NSW, 2006, Australia;(2) Brain Dynamics Center, Westmead Millennium Institute, Westmead Hospital and Western Clinical School of The University of Sydney, Westmead, NSW, 2145, Australia |
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Abstract: | Steady-state evoked potentials (SSEPs) elicited by sinusoidal stimuli are predicted from a physiologically-based model, including
bielectrode and volume conduction effects. Comparison with visual SSEPs yields constraints on phase and latency of the retinothalamic
transfer function that are consistent with experiment. Predictions of phase velocities measured as SSEPs cross the cortex
are consistent with low values measured for slow waves in sleep, while resonant behavior induced by corticothalamic loops,
especially near the alpha peak, contributes to wide scatter in waking-state phase velocity measurements comparable to effects
from volume conduction. The common use of bielectrode derivations to compensate for volume conduction effects is examined
and shown to be incomplete, tending to lead to underestimates of phase velocity, especially at low frequencies and near the
alpha peak, due to incorrect elimination of true long-wavelength contributions to the SSEP. |
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Keywords: | |
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