title: Imaging membrane potential in dendritic spines.
abstract: Dendritic spines mediate most excitatory inputs in the brain. Although it is clear that spines compartmentalize calcium, it is still unknown what role, if any, they play in integrating synaptic inputs. To investigate the electrical function of spines directly, we used second harmonic generation (SHG) imaging of membrane potential in pyramidal neurons from hippocampal cultures and neocortical brain slices. With FM 4-64 as an intracellular SHG chromophore, we imaged membrane potential in the soma, dendritic branches, and spines. The SHG response to voltage was linear and seemed based on an electro-optic mechanism. The SHG sensitivity of the chromophore in spines was similar to that of the parent dendritic shaft and the soma. Backpropagation of somatic action potentials generated SHG signals at spines with similar amplitude and kinetics to somatic ones. Our optical measurements of membrane potential from spines demonstrate directly that backpropagating action potentials invade the spines.
authors.affiliation: Howard Hughes Medical Institute, Department of Biological Sciences, Columbia University, New York, NY 10027, USA.
authors.forename: Mutsuo
authors.initials: M
authors.lastname: Nuriya
authors.forename: Jiang
authors.initials: J
authors.lastname: Jiang
authors.forename: Boaz
authors.initials: B
authors.lastname: Nemet
authors.forename: Kenneth B
authors.initials: KB
authors.lastname: Eisenthal
authors.forename: Rafael
authors.initials: R
authors.lastname: Yuste
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D049229:Dendritic Spines / Q000737:chemistry / Q000502:physiology*; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D018613:Microscopy, Confocal; D018408:Patch-Clamp Techniques; D017966:Pyramidal Cells / Q000737:chemistry / Q000502:physiology; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds
chemical_list: C092350:FM 4-64; D011726:Pyridinium Compounds; D000644:Quaternary Ammonium Compounds