Although the basic anatomy and cellular components of the brain have been known for more than a century, we still do not understand how the brain works. This is in large part due to technical limitations in our ability to identify the function of brain circuits. New optogenetic technologies promise to greatly increase our understanding of brain circuit function. By scanning small spots of laser light, synaptic circuits can be mapped in brain slices from transgenic mice expressing channelrhodopsin-2 (ChR2). These light spots photostimulate presynaptic neurons expressing ChR2, while postsynaptic responses can be monitored in neurons that do not express ChR2. Correlating the location of the light spot with the amplitude of the postsynaptic response elicited at that location yields maps of the spatial organization of the synaptic circuits. This approach yields maps within minutes, which is 10,000 times faster than can be achieved with conventional paired electrophysiological methods. We have applied this high-speed technique to map local circuits in many brain regions. By measuring limb movement, this approach also can be used in vivo to define motor maps non-invasively. In summary, ChR2-mediated high-speed mapping promises to revolutionize our understanding of brain circuitry.
- Optogenetic mapping of brain circuitry
Awards and Honors:
- Max Planck Research Prize
- Alexander von Humboldt Fellow
- Stephen Kuffler Fellow, MBL, Woods Hole
- George Barth Geller Professor of Neurobiology, Duke Medical Center