Variability of quantal synaptic currents in thalamocortical
neurons
Mike Neubig, Alain Destexhe and Terrence J. Sejnowski
Thalamus and Related Systems 2: 153-168, 2003.
Abstract:
Broad amplitude variability and skewed distributions are
characteristic features of quantal synaptic currents (minis) at
central synapses. The relative contributions of the various
underlying sources are still debated. Through computational models of
thalamocortical neurons, we separated intra- from extra-synaptic
sources. Our simulations indicate that the external factors of local
input resistance and dendritic filtering generate equally small
amounts of negatively skewed synaptic variability. The ability of
these two factors to reduce positive skew increased as their
contribution to variability increased, which in control trials for
morphological, biophysical, and experimental parameters never
exceeded 10% of the range. With these dendritic factors ruled out, we
tested multiple release models, which led to distributions with
clearly non-physiological multiple peaks. We conclude that
intra-synaptic organization is the primary determinant of synaptic
variability in thalamocortical neurons and, due to extra-synaptic
mechanisms, is more potent than the data suggested. Thalamocortical
neurons, especially in rodents, constitute a remarkably favorable
system for molecular genetic studies of synaptic variability and its
functional consequence.
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