  Colloidal gels are a prototypical example of a heterogeneous network solid
whose complex properties are governed by thermally-activated dynamics. In this
Letter we experimentally establish the connection between the intermittent
dynamics of individual particles and their local connectivity. We interpret our
experiments with a model that describes single-particle dynamics based on
highly cooperative thermal debonding. The model, in quantitative agreement with
experiments, provides a microscopic picture for the structural origin of
dynamical heterogeneity in colloidal gels and sheds new light on the link
between structure and the complex mechanics of these heterogeneous solids.
