Volume 9 Issue 6, June 2006

Macrophages near neuronal cell bodies can promote regeneration in an otherwise inhibitory environment. Now Yin et al. identify oncomodulin as a factor secreted from macrophages that promotes extensive regeneration of lesioned optic nerve axons when applied together with elevated cyclic AMP (cAMP) and mannose.

During development, neurons destined for different neocortical layers are sequentially generated. Shen et al. report that this timing is programmed within individual progenitor cells and depends mainly on cell-intrinsic mechanisms.

Dendritic spines confine activity-dependent changes to the affected synapses. A paper in this issue reports that retarded diffusion in dendrites of aspiny interneurons may create dendritic biochemical compartments without spines.

Exactly how animals switch between different sleep states remains unknown. A new study in Nature provides a glimpse into the mechanisms and anatomy of the brain regions that trigger rapid eye movement sleep.