Biomedical Engineering Reference
In-Depth Information
Chapter 7
Monitoring Neural Activity with Genetically
Encoded Ca
2+
Indicators
Azusa Kamikouchi and André Fiala
Abstract
Visualizing the activity of nerve cells using genetically encoded indicator
proteins has emerged to a widely used technique in the fi eld of neuroscience. In
particular, intracellular Ca
2+
dynamics represents a parameter that is closely corre-
lated with neuronal excitation, and a variety of genetically encoded Ca
2+
sensors
have been developed. The fruit fl y
Drosophila melanogaster
is an extremely useful
model organism to use these indicators because of its sophisticated genetic tools to
express an artifi cial genetic construct in a spatially and temporally controlled pat-
tern within the nervous system. Binary expression systems, for which large amount
of different fl y strains exist, enable a targeted expression in selective neuronal popu-
lations. Advanced fl uorescence microscopical visualization techniques (see Part 3)
allow for real-time monitoring of neural activity patterns. In
Drosophila
, optical
Ca
2+
imaging has been used to analyze basic principles of neuronal coding and pro-
cessing, e.g., olfactory coding, visual stimulus processing, taste perception, mecha-
nosensation, or learning and memory. In this chapter, we will review how genetic
targeting methods can be used in
Drosophila
to monitor neural Ca
2+
activity in vivo
in order to study how individual neurons or neuronal ensembles encode stimulus
information.
