Dr. Hegemann’s research focused almost entirely on the characterization of natural sensory photoreceptors, mainly from microalgae. Hegemann has characterized behavioral and photoelectric responses of the unicellular alga, Chlamydomonas, which cumulated in the claim that the photoreceptors for these responses was a rhodopsin that unified the sensor and ion channel in one protein. He finally proved this hypothesis by identifying the light-gated channel, channelrhodopsin and by demonstrating its functionality in animal cells.
Of equal importance, his group discovered the fundamental principles of the unique channelrhodopsin proteins in molecular detail by a wide range of genomic, biophysical, electrophysiological and structural techniques with many mutants in close collaboration with Karl Deisseroth. This led to their deciphering of the unprecedented light-gated ion channel mechanism, including its pore gating by photons and its ion selectivity. This basic work also fundamentally enabled optogenetics (the technology wherein light-activated proteins– first and foremost channelrhodopsin- allow control of selected cells within systems as complex as the mammalian brain, with unprecedented precision in space and time by delivery of light).
Optogenetics has been successfully employed to enhance our understanding of neural circuit function mediating normal behavior and dysfunction underlying neurological and psychiatric disorders. Optogenetics is a technology that has revolutionized the field of neuroscience and has enabled a new generation of experiments that probe the causal roles of specific neural circuit components.