Optical Imaging of Neuronal Activity in the Cerebellar Cortex Using Neutral Red

Excerpt

Over the last decade our laboratory has developed and used optical imaging techniques to monitor neuronal activity in the cerebellar cortex in vivo. These techniques include the use of voltage sensitive dyes [1–3], neutral red [4,5], flavoprotein autofluorescence [6,7], and Ca⁺⁺ imaging [7]. Optical imaging has allowed us to address a spectrum of questions about both normal and abnormal cerebellar cortical physiology.

This chapter focuses on the use of pH imaging, specifically neutral red, as a measure of neuronal activation in the cerebellar cortex. Our earliest attempts to use voltage sensitive dyes in the cerebellar cortex in vivo were disappointing due to the small size of the signal [3]. Therefore, we turned to other approaches to optically map neuronal activity in the cerebellum. The first of these approaches was neutral red imaging [4]. Neutral red imaging exploits the known close coupling between pH changes and neuronal activation [8,9]. In this chapter we discuss the theory underlying pH imaging with neutral red, describe the techniques used to image the cerebellar cortex in vivo, and provide examples of how neutral red imaging has generated insights into the functioning of cerebellar cortical circuits.