Two-photon mapping of synaptic connectivity in the neocortex
Molecular Biology and Physiology of Neurons and Glial Cells
Final Report Abstract
In this project a method was established to map connectivity and weight of excitatory synaptic connections in brain slices of the mouse neocortex employing optogenetics. To test hundreds of potential connections, the red-shifted channelrhodopsin variant C1V1 was activated in neurons employing a custom-made two-photon microscope, while using patch clamp recordings to detect postsynaptic responses evoked by the activation of presynaptic neurons. Individual neurons were targeted using point stimulation-based patterns. Connectivity maps were obtained in brain slices of young adult mice, mapping connections both within and between layers of the neocortex. In addition, properties of responses obtained by C1V1 activation in single spines and dendrites as well as action potential generation by C1V1 activation were characterized. Rise times of responses to direct C1V1 activation were found to be drastically different from those of synaptic responses evoked by activation of presynaptic neurons, which is useful to distinguish the two from each other in mapping experiments. These results form a foundation for developing strategies to precisely influence activity patterns in in vivo preparations.
Publications
- (2012) Two-photon optogenetics of dendritic spines and neural circuits. Nature Methods 9: 1202-5
Packer AM, Peterka DS, Hirtz JJ, Prakash R, Deisseroth K, Yuste R
