Dendritic organization of sensory input to cortical neurons in vivo.
In sensory cortex regions, neurons are tuned to specific stimulus features. For example, in the visual cortex, many neurons fire predominantly in response to moving objects of a preferred orientation. However, the characteristics of the synaptic input that cortical neurons receive to generate their output firing pattern remain unclear. Here we report a novel approach for the visualization and functional mapping of sensory inputs to the dendrites of cortical neurons in vivo. By combining high-speed two-photon imaging with electrophysiological recordings, we identify local subthreshold calcium signals that correspond to orientation-specific synaptic inputs. We find that even inputs that share the same orientation preference are widely distributed throughout the dendritic tree. At the same time, inputs of different orientation preference are interspersed, so that adjacent dendritic segments are tuned to distinct orientations. Thus, orientation-tuned neurons can compute their characteristic firing pattern by integrating spatially distributed synaptic inputs coding for multiple stimulus orientations.
Jia
Hongbo
H
Institute of Neuroscience and Center for Integrated Protein Science, Technical University Munich, Biedersteinerstrasse 29, 80802 Munich, Germany.
Rochefort
Nathalie L
NL
Chen
Xiaowei
X
Konnerth
Arthur
A
D000200:Action Potentials; D000818:Animals; D020013:Calcium Signaling; D003712:Dendrites / Q000502:physiology*; D051379:Mice; D008810:Mice, Inbred C57BL; D008959:Models, Neurological; D011984:Sensory Receptor Cells / Q000166:cytology / Q000502:physiology*; D013569:Synapses / Q000378:metabolism; D014793:Visual Cortex / Q000166:cytology*