All-fiber-transmission photometry for simultaneous optogenetic stimulation and multi-color neuronal activity recording

Manipulating and real-time monitoring of neuronal activities with cell-type specificity and precise spatiotemporal resolution during animal behavior are fundamental technologies for exploring the functional connectivity, information transmission, and physiological functions of neural circuits in vivo. However, current techniques for optogenetic stimulation and neuronal activity recording mostly operate independently. Here, we report an all-fiber-transmission photometry system for simultaneous optogenetic manipulation and multi-color recording of neuronal activities and the neurotransmitter release in a freely moving animal. We have designed and manufactured a wavelength-independent multi-branch fiber bundle to enable simultaneous optogenetic manipulation and multi-color recording at different wavelengths. Further, we combine a laser of narrow linewidth with the lock-in amplification method to suppress the optogenetic stimulation-induced artifacts and channel crosstalk. We show that the collection efficiency of our system outperforms a traditional epi-fluorescence system. Further, we demonstrate successful recording of dynamic dopamine(DA) responses to unexpected rewards in the nucleus accumbens(NAc) in a freely moving mouse. We also show simultaneous dual-color recording of neuronal Ca2+ signals and DA dynamics in the NAc upon delivering an unexpected reward and the simultaneous optogenetic activating at dopaminergic terminals in the same location. Thus, our multi-function fiber photometry system provides a compatible, efficient, and flexible solution for neuroscientists to study neural circuits and neurological diseases.

Nose micro-blowing for asymmetric vortices control on blunt-nose slender body at high angle of attack

The asymmetric vortices over blunt-nose slender body at high angles of attack result in random side force. In this paper, a nose micro-blowing technology is used to control the asymmetric flow. Pressure measurement and particle image velocimetry （PIV） experiments are conducted in a low-speed wind tunnel to research effects of jet flow rate on asymmetric vortices over blunt-nose slender body. The angle of attack of the model is fixed at 50° and the Reynolds number for the experiments is 1.6× 105 based on diameter of aftbody. A blow hole （5 mm in diameter） on the nose is processed at circumferential angle θb = 90° and meridian angleγb = 20° with jet momentum ratio Cμ ranging from 5.30× 10-7 to 1.19 × 10-4. Tests are made under two kinds of perturbations. One is called single perturbation with only blow hole and the other is called combined perturbation consists of blow hole and additional granules set on nose. The results show that whether the model has the single perturbation or the combined one, the sectional side force ofx/D = 3 varies in the same direction with the increasement of Cμ and remains stable when Cμ is greater than 3.29× 10- 6. But the stable force values are different according to various perturbations. The fact proves that the size and direction of the side force of blunt-nose slender body can be controlled by the nose micro-blowing.

A neuropsin-based optogenetic tool for precise control of Gq signaling

G_(q)-coupled receptors regulate numerous physiological processes by activating enzymes and inducing intracellular Ca^(2+)signals.There is a strong need for an optogenetic tool that enables powerful experimental control over G_(q) signaling.Here,we present chicken opsin 5(cOpn5)as the long sought-after,single-component optogenetic tool that mediates ultra-sensitive optical control of intracellular G_(q) signaling with high temporal and spatial resolution.Expressing cOpn5 in HEK 293T cells and primary mouse astrocytes enables blue light-triggered,G_(q)-dependent Ca^(2+) release from intracellular stores and protein kinase C activation.Strong Ca^(2+) transients were evoked by brief light pulses of merely 10 ms duration and at 3 orders lower light intensity of that for common optogenetic tools.Photostimulation of cOpn5-expressing cells at the subcellular and single-cell levels generated fast intracellular Ca^(2+)transition,thus demonstrating the high spatial precision of cOpn5 optogenetics.The cOpn5-mediated optogenetics could also be applied to activate neurons and control animal behavior in a circuit-dependent manner.cOpn5 optogenetics may find broad applications in studying the mechanisms and functional relevance of G_(q) signaling in both non-excitable cells and excitable cells in all major organ systems.