@article {4225,
	title = {Channelrhodopsin-2-assisted circuit mapping of long-range callosal projections.},
	journal = {Nature Neuroscience},
	volume = {10},
	year = {2007},
	month = {2007 May},
	pages = {663-8},
	abstract = {<p>The functions of cortical areas depend on their inputs and outputs, but the detailed circuits made by long-range projections are unknown. We show that the light-gated channel channelrhodopsin-2 (ChR2) is delivered to axons in pyramidal neurons in vivo. In brain slices from ChR2-expressing mice, photostimulation of ChR2-positive axons can be transduced reliably into single action potentials. Combining photostimulation with whole-cell recordings of synaptic currents makes it possible to map circuits between presynaptic neurons, defined by ChR2 expression, and postsynaptic neurons, defined by targeted patching. We applied this technique, ChR2-assisted circuit mapping (CRACM), to map long-range callosal projections from layer (L) 2/3 of the somatosensory cortex. L2/3 axons connect with neurons in L5, L2/3 and L6, but not L4, in both ipsilateral and contralateral cortex. In both hemispheres the L2/3-to-L5 projection is stronger than the L2/3-to-L2/3 projection. Our results suggest that laminar specificity may be identical for local and long-range cortical projections.</p>
},
	keywords = {Animals, Axons, Brain Mapping, Corpus Callosum, Embryo, Female, Functional Laterality, Inbred C57BL, Mammalian, Membrane Potentials, Mice, Nerve Net, Neural Pathways, Newborn, Patch-Clamp Techniques, Photic Stimulation, Pregnancy, Retinaldehyde, Rhodopsin, Somatosensory Cortex, Transgenic},
	issn = {1097-6256},
	doi = {10.1038/nn1891},
	author = {Petreanu, Leopoldo and Huber, Daniel and Sobczyk, Aleksander and Svoboda, Karel}
}
