Visualization of functional neural circuits in zebrafish
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1
National Institute of Genetics, Molecular and Developmental Biology, Japan
To understand how neuronal activities lead to behavioral outputs, it is desirable to record the neuronal activity from a population of neurons in the brain during behavior. Generation of action potentials can be indirectly detected by measuring calcium influx via voltage-gated calcium ion channels in the neurons. Recent progress in the improvement of DNA-encoded calcium indicators (DECIs) enabled us to express the fluorescent calcium probe in a genetically specified population of neurons and image the neuronal activities at a single-cell spatial resolution. We have developed a genetic method to express one of the DECIs, GCaMP in specific cells using Gal4-UAS system in zebrafish. Gal4 is a yeast-derived transcription activator which binds to its target DNA sequence, UAS (Upstream Activator Sequence) and drives the downstream gene. We have conducted Gal4 gene/enhancer trap screenings to make a collection of Gal4 transgenic zebrafish with specific Gal4 expression that was driven by a transcriptional regulation of the nearby gene. To date, we have established about 1,000 Gal4 gene/enhancer trap lines with tissue specific expression pattern. We also generated UAS:GCaMP transgenenic fish. By mating UAS:GCaMP transgenic fish and a Gal4 fish, we can co-express Gal4 and UAS:GCaMP genes in specific neuronal cells, which can be used in calcium imaging study. In a proof-of-principle experiment, we introduced an improved GCaMP in the spinal motoneurons and successfully observed the network activity that was associated with a spontaneous muscle contraction at the early stage of development. Next, we applied our method to the study of visual perception in feeding behavior. Zebrafish larvae feed on paramecia. This behavior is highly dependent on vision. Optic tectum is a visual center for visual processing in teleost fish. We asked how a paramecium, a natural object for the zebrafish larvae, is represented in the brain during prey capture behavior. We could visualize real-time activation of the tectal neurons on the visuotopic map while a zebrafish larva perceives a swimming paramecium. Furthermore, we found that selective activation of the anterior tectum is associated with the prey capture behavior. We propose that specific activation of a set of neurons on the visuotopic map leads to prey capture behavior, which is hardwired in zebrafish.
References
Muto A, Ohkura M, Kotani T, Higashijima S, Nakai J, Kawakami K. Genetic visualization with an improved GCaMP calcium indicator reveals spatiotemporal activation of the spinal motor neurons in zebrafish. Proc Natl Acad Sci U S A. 2011 Mar 29;108(13):5425-30.
Keywords:
Behavior,
calcium imaging,
GCaMP,
Paramecium,
prey capture,
Vision,
Zebrafish
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Invited Symposium (only for people who have been invited to a particular symposium)
Topic:
Sensory: Vision
Citation:
Muto
A and
Kawakami
K
(2012). Visualization of functional neural circuits in zebrafish.
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00064
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Received:
04 Jul 2012;
Published Online:
07 Jul 2012.
*
Correspondence:
Dr. Akira Muto, National Institute of Genetics, Molecular and Developmental Biology, Mishima, Shizuoka, 411-8540, Japan, akira.muto@med.toho-u.ac.jp