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Neuronal Activity Regulates Diffusion Across the Neck of Dendritic Spines
Brenda L. Bloodgood and
Bernardo L. Sabatini*
In mammalian excitatory neurons, dendritic spines are separatedfrom dendrites by thin necks. Diffusion across the neck limitsthe chemical and electrical isolation of each spine. We foundthat spine/dendrite diffusional coupling is heterogeneous anduncovered a class of diffusionally isolated spines. The barrierto diffusion posed by the neck and the number of diffusionallyisolated spines is bidirectionally regulated by neuronal activity.Furthermore, coincident synaptic activation and postsynapticaction potentials rapidly restrict diffusion across the neck.The regulation of diffusional coupling provides a possible mechanismfor determining the amplitude of postsynaptic potentials andthe accumulation of plasticity-inducing molecules within thespine head.
Department of Neurobiology, Harvard Medical School, 220 Longwood Avenue, Boston, MA 02115, USA.
* To whom correspondence should be addressed. E-mail: bsabatini{at}hms.harvard.edu
