a. Why is the zebrafish model useful to address questions of neural circuit development and function?
b. What are the advantages, what are its limitations?
transparent —> neuronal development/ circuit development can be traced in vivo (Ca2+ imaging, electrophysiology, reporter lines)
embryos easily accesible
small, easy to handle, easy manipulation
genetic tractability
limitations: not that closely related to humans idk
2. Name and describe key neuroanatomical structures in the larval zebrafish brain that enable the larva to perform visually guided behaviors.
stimulus
retina
optic tectum
rectinospinal system
motoneurons in spinal cord segments
tail musculature —> locomotion
3. What types of behaviors can be studied in the larval zebrafish model? What is a goal-directed behavior? How does it differ from non-goal directed behaviors?
looming escape
prey
non-goal directed swimming (?)
goal-directed behaviour: e.g. prey and looming escape, induced by stimulus
non-goal directed behaviour: not caused by specific stimulus
4. Name different features, or dimensions, of a visual stimulus, and consider their impact on visually driven behaviors.
duration
space, shape
frequency
5. Describe various technical approaches to analyze visually-driven behaviors.
a. Consider the strengths and the limitations of different approaches.
b. How do the different approaches influence the behavior; what impact could they have on the results?
visual observation
a. + b. least impact on actual behaviour, least disturbance
hard to normalize, high bias, subjective (results dependt on observer), no to only very little parametrization
high-speed videography
a. + b. fish need to be moved to area where they can be observed by camera, camera might be visual stimulus, enables observeration of non-goal directed behaviuor, parametrization possible
controlled visual stimulation in a closed loop system dings
a.+b. complete control over visual stimulization , no non-directed behaviour, no “natural behavior”
6. Name and describe current methods to analyze larval zebrafish brain structure.
fluorescence microscopy
—> antibody staining, reporter system
electron microscopy
Ca2+ imaging
7. What can be done in zebrafish that cannot be done in other model systems? What are species-specific differences that affect the analysis of neural circuit analysis?
transparent?
8. Describe the concept of connectomes and projectomes of the brain or a given subregion of the central nervous system (e.g. the spinal cord, retina)? What is a wiring diagram? How can it be determined?
alles nur geraten
projectomes:
directed inforamtion flow? projectory axons, connect different brain areas e.g. projections from cerebellum to some other area
connectomes:
undirected
wiring diagram: maybe shows all connections in a neuronal circuit? can be determined using electrophysical experiments (e.g. patch clamp) and structural analysis such as fluorescence microscopy and reporters
9. What are the strengths and the limitations of ultrastructural analysis (based on electron microscopical imaging) of mapping the connectivity of a brain region?
limitation:
does only allow structural analysis and not functional analysis, no analysis of living animals possible, extensive sample preparation necessary, really expensive
strength:
allows identification and tracking of singular cells, cells do not need to be marked by antibody or reporter
10. What are the strengths and limitations of light microscopical approaches to investigate the structure and connectivity of the nervous system?
a. What types of light microscopy are particularly useful?
b. What are important considerations for fluorescence based light microscopical approaches?
limitations: hard to identify individual cells, resolution not as high, overlapping fluorescent signals, cells need to be actively visualized using fluorescent antibodies or reporters
a. two photon and widefield
b. photobleaching, cells have to be actively visualized
11. Name and describe techniques for measuring neural activity in the larval zebrafish brain
a. What techniques are applicable to measure population and network activity?
b. What techniques can be used to measure single cell activity?
c. What are important differences between the various approaches? What are the respective advantages and limitations? How can the various techniques be combined?
a.
patch clamp ( i think one can connect the glass thing to the whole animal and measure electrical currents or something, maybe measuring of motoneurons in spinal chord idk)
b.
patch clamp in whole cell and cell-attached mode of individual cells
c.
12. What type of information can be obtained from electrophysiological measurements at the single cell level? What types of signals can one measure using single cell patch-clamp recordings?
excitability of neurons
strength of excitation
13. Devise an experimental strategy to determine the neural circuits that underlie a given visually driven behavior.
a. How can you determine a causal role of a given brain region, cell type or circuit motif?
b. What steps would you take, which approaches would you use (if you had unlimited resources)?
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