Coherent control of an opsin in living brain tissue

Abstract

Retinal-based opsins are light-sensitive proteins. The photoisomerization reaction of these proteins has been studied outside cellular environments using ultrashort tailored light pulses1–5. However, how living cell functions can be modulated via opsins by modifying fundamental nonlinear optical properties of light interacting with the retinal chromophore has remained largely unexplored. We report the use of chirped ultrashort near-infrared pulses to modulate light-evoked ionic current from Channelrhodopsin-2 (ChR2) in brain tissue, and consequently the firing pattern of neurons, by manipulating the phase of the spectral components of the light. These results confirm that quantum coherence of the retinal-based protein system, even in a living neuron, can influence its current output, and open up the possibilities of using designer-tailored pulses for controlling molecular dynamics of opsins in living tissue to selectively enhance or suppress neuronal function for adaptive feedback-loop applications in the future.

Time-resolved serial femtosecond crystallography at the European XFEL

“…Close inspection and kinetic interpretation of the TR-SFX data allow an intimate view of mechanical aspects of signal transduction [41] and catalysis [42,43], with specific atomic displacements linked to specific protein function. The close relationship between structural dynamics and function established in this way provides new avenues for the control [26,44,45] and understanding of biological function, which then also paves the way to a deeper understanding of the mechanism of biomacromolecular reactions in biomedically and biologically significant macromolecules. A step-by-step protocol for a successful TR-SFX experiment with PYP at the EuXFEL is available on the Protocol Exchange [46].…”

Considerations regarding one-photon phase control

“…For systems with macroscopic relaxation times, repeated interaction with pulsed lasers can create non-trivial effects. 48 This assumption can be tested by varying the repetition rate: if it holds, changing the repetition rate will lead only to a change in the average power of the beam at the sample, resulting in a linear change of the signal.…”

An efficient spectral method for numerical time-dependent perturbation theory

“…We have recently applied the FLIPT algorithm to the simulation of quantum dynamics arising from two-photon absorption in retinal to understand the mechanism of a quantum control experiment on living brain cells. 12,53 Here, we focus on the performance properties of the FLIPT algorithm, and the application of the FLIPT method to spectroscopy.…”