Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Although the threshold for action potential initiation is lowest in the axon, the precise site of initiation is unknown. With multiple, simultaneous cell-attached recordings and immunofluorescent labeling, Häusser and colleagues find that action potentials initiate at the first node of Ranvier in cerebellar Purkinje neurons. This image shows the first node of Ranvier at the first axonal branchpoint of a Purkinje cell axon ensheathed in myelin. The axon is stained for calbindin (purple) and the myelin sheath for myelin basic protein (blue). (p 137)
Comm downregulates the Slit receptor Robo on commissural axons, thereby enabling midline crossing. Elegant new experiments show that Comm functions by diverting Robo to the endosomal pathway, preventing its delivery to the growth cone.
Despite 20 years of study, the mechanism underlying the cochlear amplifier remains contentious. In this issue, a novel in vitro cochlear preparation implicates calcium current–driven active stereocilia motion in generating amplification.
Voltage-gated ion channels shape the integration of synaptic input in dendrites. Forebrain-restricted deletion of the hyperpolarization-activated channel HCN1 enhances spatial learning, demonstrating a behavioral role for an active dendritic conductance.