Two-Photon Imaging of Neuronal Network Dynamics in Neocortex

Optical investigation of fast neuronal network dynamics in the intact neocortex—using appropriate activity-dependent indicators—requires single-cell resolution at large imaging depths and sufficient acquisition speed. These requirements are met by two-photon laser scanning microscopy, which has become one of the key methods for functional measurements of neuronal population activity in vivo, primarily in combination with calcium indicators. In this chapter we focus on various advanced two-photon imaging techniques that were recently developed to improve scanning speed, to enable 3D sampling from large numbers of neurons, or to extend imaging towards measurements in freely behaving animals. In general, sampling speed and population size trade off against each other. Currently, about 1,000 neurons can be measured with good signal-to-noise ratio at 1–10 Hz or a few tens of neurons can be optically recorded at 1 kHz. Measurements of local network activity have been used to either characterize spatial distributions of functional properties, such as orientation tuning in visual cortex, or reveal neuronal activation patterns on a fast time scale. We illustrate these new opportunities with examples from in vivo two-photon calcium imaging in mouse visual cortex. The chapter concludes with a discussion of the advantages and limitations of the various techniques and of future perspectives. The direct observation of neuronal network dynamics in living animals no doubt w...
Source: Springer protocols feed by Neuroscience - Category: Neuroscience Source Type: news