One of the central goals of neuroscience is to decipher the specific contributions of neural mechanisms to different aspects of sensory perception. Since achieving this goal requires tools capable of precisely perturbing and monitoring neural activity across a multitude of spatiotemporal scales, this aim has inspired the innovation of many optical technologies capable of manipulating and recording neural activity in a minimally invasive manner. The interdisciplinary nature of neurophotonics requires a broad knowledge base in order to successfully develop and apply these technologies, and one of the principal aims of this chapter is to provide some basic but fundamental background information in terms of both physiology and optics in the context of all-optical two-photon neurophysiology experiments. Most of this information is expected to be familiar to readers experienced in either domain, but is presented here with the aim of bridging the divide between disciplines in order to enable physicists and engineers to develop useful optical technologies or for neuroscientists to select appropriate tools and apply them to their maximum potential.
The first section of this chapter is dedicated to a brief overview of some basic principles of neural physiology relevant for controlling and recording neuronal activity using light. Then, the selection of appropriate actuators and sensors for manipulating and monitoring particular neural signals is discussed, with particular attention paid to kinetics and sensitivity. Some considerations for minimizing crosstalk in optical neurophysiology experiments are also introduced. Next, an overview of the state-of-the-art optical technologies is provided, including a description of suitable laser sources for two-photon excitation according to particular experimental requirements. Finally, some detailed, technical, information regarding the specific wavefront engineering approaches known as Generalized Phase Contrast (GPC) and temporal focusing is provided.
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