title: Functional mapping of single spines in cortical neurons in vivo.
abstract: The individual functional properties and spatial arrangement of afferent synaptic inputs on dendrites have a critical role in the processing of information by neurons in the mammalian brain. Although recent work has identified visually-evoked local dendritic calcium signals in the rodent visual cortex, sensory-evoked signalling on the level of dendritic spines, corresponding to individual afferent excitatory synapses, remains unexplored. Here we used a new variant of high-resolution two-photon imaging to detect sensory-evoked calcium transients in single dendritic spines of mouse cortical neurons in vivo. Calcium signals evoked by sound stimulation required the activation of NMDA (N-methyl-D-aspartate) receptors. Active spines are widely distributed on basal and apical dendrites and pure-tone stimulation at different frequencies revealed both narrowly and widely tuned spines. Notably, spines tuned for different frequencies were highly interspersed on the same dendrites: even neighbouring spines were mostly tuned to different frequencies. Thus, our results demonstrate that NMDA-receptor-dependent single-spine synaptic inputs to the same dendrite are highly heterogeneous. Furthermore, our study opens the way for in vivo mapping of functionally defined afferent sensory inputs with single-synapse resolution.
authors.affiliation: Institute of Neuroscience and Center for Integrated Protein Science, Technical University Munich, Biedersteinerstrasse 29, 80802 Munich, Germany.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Chen
authors.forename: Ulrich
authors.initials: U
authors.lastname: Leischner
authors.forename: Nathalie L
authors.initials: NL
authors.lastname: Rochefort
authors.forename: Israel
authors.initials: I
authors.lastname: Nelken
authors.forename: Arthur
authors.initials: A
authors.lastname: Konnerth
mesh_terms: D000161:Acoustic Stimulation; D000818:Animals; D001931:Brain Mapping; D020013:Calcium Signaling; D049229:Dendritic Spines / Q000502:physiology*; D007091:Image Processing, Computer-Assisted; D051379:Mice; D008810:Mice, Inbred C57BL; D036641:Microscopy, Fluorescence, Multiphoton; D014793:Visual Cortex / Q000166:cytology / Q000502:physiology*