Contact is repulsive, but please note the "enclosed"

Previous models of neuronal dendrite arborization suggested that contact-dependent self-avoidance between dendrite branches prevents self-crossings within the arbor. Two papers in Neuron show how integrin-mediated adhesion to the extracellular matrix restricts dendrites to a two-dimensional space to optimize this mechanism (Han et al., 2012; Kim et al., 2012).