High-speed mapping of synaptic connectivity using photostimulation in Channelrhodopsin-2 transgenic mice

doi:10.1073/pnas.0700384104

High-speed mapping of synaptic connectivity using photostimulation in Channelrhodopsin-2 transgenic mice

*Department of Neurobiology, Duke University, Durham, NC 27710;
^†Center for Neuroscience and Cell Biology, University of Coimbra, 3004-517 Coimbra; Portugal;
^‡Division of Biophysics, Center for Disease Biology and Integrative Medicine, Faculty of Medicine, University of Tokyo, Tokyo 113-0033, Japan;
^§Precursory Research for Embryonic Science and Technology, Japan Science and Technology Agency, Saitama 332-0012, Japan; and
^¶Department of Bioengineering, Stanford University, Palo Alto, CA 94305

Edited by Richard W. Tsien, Stanford University School of Medicine, Stanford, CA, and approved March 16, 2007 (received for review January 15, 2007)

Abstract

To permit rapid optical control of brain activity, we have engineered multiple lines of transgenic mice that express the light-activated cation channel Channelrhodopsin-2 (ChR2) in subsets of neurons. Illumination of ChR2-positive neurons in brain slices produced photocurrents that generated action potentials within milliseconds and with precisely timed latencies. The number of light-evoked action potentials could be controlled by varying either the amplitude or duration of illumination. Furthermore, the frequency of light-evoked action potentials could be precisely controlled up to 30 Hz. Photostimulation also could evoke synaptic transmission between neurons, and, by scanning with a small laser light spot, we were able to map the spatial distribution of synaptic circuits connecting neurons within living cerebral cortex. We conclude that ChR2 is a genetically based photostimulation technology that permits analysis of neural circuits with high spatial and temporal resolution in transgenic mammals.

Footnotes

^‖To whom correspondence may be addressed. E-mail: georgea{at}neuro.duke.edu or feng{at}neuro.duke.edu
Author contributions: H.W., J.P., and M.M. contributed equally to this work; H.K., W.C.H., G.F., and G.J.A. designed research; H.W., J.P., and M.M. performed research; K.M., J.N., L.Q., D.W., F.Z., E.B., K.D., and G.F. contributed new reagents/analytic tools; H.W., J.P., and M.M. analyzed data; and H.W., K.D., W.C.H., G.F., and G.J.A. wrote the paper.
The authors declare no conflict of interest.
This article is a PNAS Direct Submission.
This article contains supporting information online at www.pnas.org/cgi/content/full/0700384104/DC1.
Abbreviations:

ChR2,

Channelrhodopsin-2;

CNQX,

6-cyano-7-nitroquinoxaline-2,3-dione;

IPSC,

inhibitory postsynaptic current;

YFP,

yellow fluorescent protein.