Calcium imaging in the optic tectum of the adult zebrafish (Danio rerio)
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1
University of Bielefeld, Biology, Germany
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2
University of Bielefeld, Biology, Germany
During the last years the zebrafish (Danio rerio) became a popular model organism in neurophysiology and developmental neurobiology. Especially its amenability for genetic approaches led to its increasing usage in developmental and neurophysiological experiments. The optic tectum is the main center for processing visual information in fish and it is well known for its role in coordinating voluntary movements with multimodal sensory input. To achieve this, several sensory modalities are mapped within the tectum.
Our first aim is to establish the method of in-vivo calcium imaging of tectal neurons in adult zebrafish. This approach is extensively used in larval zebrafish but only up to the age of 9 days post-fertilization. Skin pigmentation and the development of a bony cranial roof after day 9 limited the technique to early larvae thus far. Moreover, we use conventional widefield fluorescence microscopy, in contrast to previous studies, in which two-photon imaging was necessary to resolve somatic signals from individual neurons. To this end, we use dextran-coupled dyes, which can be loaded into small groups of cells by a mechanical procedure or via local electroporation. Compared to the previously used procedure of pressure injection of a membrane-permeable dye, which stains numerous of neurons, our methods reduce crosstalk between individual neurons. First experiments show that our new approach for this technique leads to convincing results in the optic tectum of adult zebrafish. We were able to characterize direction and orientation selective cells with different stimuli, e.g. moving bars and dots, full field and counter phase flicker.
Currently we are using stimulus procedures to assess whether orientation and direction tuning of tectal cells are modified by neuronal adaptation. It is already known that sensory experience can lead to functional or even structural plasticity of tectal circuits in Xenopus larvae (Podgorski 2012) and that direction sensitivity can be modified rapidly by visual input during development (Engert 2002). Moreover, adaptation was shown to induce short-term plasticity of orientation preference in the visual cortex of cats (Dragoi 2001). Our experimental approach addresses short-term plasticity of visual computation in the adult zebrafish , and may in the future open the way to ask how maps of different modalities are integrated at the level of the optic tectum.
Figure: A: Mean response traces for different stimuli (flicker (black), moving dots (blue) and gratings (red)) in 8 different directions. B: A polar plot of the responses for the different types of stimuli illustrates the strong direction selectivity and the similarity of the preferred directions for the two types of motion responses (blue and red), as opposed to the non-selective character of the flicker responses (black). The strong somatic calcium signals during motion in a preferred direction, 0°-90°, were opposed to a very weak response to motion in the opposite direction (180°-270°) and intermediate responses in orthogonal directions (315° and 135°).
References
Dragoi V., Rivadulla C. and Sur M. Foci of orientation plasticity in visual cortex. Nature, VOL 411: 80-86 (2001)
Engert F., Tao H.W. , Zhang Li I. and Poo M. Moving visual stimuli rapidly induce direction sensitivity of developing tectal neurons. Nature, VOL 419: 470-475 (2002)
Podgorski K., Dunfield D., Haas K. Functional Clustering Drives Encoding Improvement in a Developing Brain Network during Awake Visual Learning. PLoS Biol 10(1): e1001236. doi:10.1371/journal.pbio.1001236 (2012)
Keywords:
calcium imaging,
optical imaging,
tectum opticum,
Zebrafish
Conference:
Tenth International Congress of Neuroethology, College Park. Maryland USA, United States, 5 Aug - 10 Aug, 2012.
Presentation Type:
Poster Presentation (see alternatives below as well)
Topic:
Sensory: Vision
Citation:
Kassing
V,
Engelmann
J and
Kurtz
R
(2012). Calcium imaging in the optic tectum of the adult zebrafish (Danio rerio).
Conference Abstract:
Tenth International Congress of Neuroethology.
doi: 10.3389/conf.fnbeh.2012.27.00155
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Received:
27 Apr 2012;
Published Online:
07 Jul 2012.
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Correspondence:
Miss. Vanessa Kassing, University of Bielefeld, Biology, Bielefeld, 33501, Germany, vanessa.kassing@uni-bielefeld.de