Team:SUSTech Shenzhen/Description
Description
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Why Caenorhabditis elegans?
Caenorhabditis elegans, a widely used model organism, is the objective in our project, because its whole genome has been sequenced, and it is also the only organism to have its connectome(neuronal ‘wiring diagram’) completed by 2012 [1][2]. Adault C.elegans is about 1mm in length, 45μm in wideth and it is easily observed and manipulated under stereomicroscope[3][4].What more, C.elegans has a phenomenon known as eutely, which means it has fixed ‘genetically determined number of cells’[5].These all are of great help when we doing neural operation.
Compared with other model organism like Mus musculus, which needs approximately two to three months to get matured, C.elegans possesses shorter lifespan. It is a self-fertilizing hermaphrodite lives for two to three weeks[6]. Lifespan-regulating genes in c. elegans. , 2, 16010.Whithin this cycle the genetics is immutable. At the same time, it can also propagate sexually, which means that the genetic phenotype of it is easy to control.
How does our system look like?
Normally, the formation of a new ability is corresponding with the specific environment signal induc-ing, so in our project we need the specific stimulation to train worms and let them obtain new abilities. In C.elegans, we hope that the stimulation can be localized to the target neurons for the accuracy and efficiency. Different behaviors of the worms are controlled by different neurons, and due to their sen-sitivity to odors, many behaviors, such as attraction, avoidance, feeding, or mating, can be induced by different chemicals. In our project, we choose the olfactory neurons ( AWA &AWB) to accomplish our design. The attrac-tive odorant diacetyl is detected by the receptor protein ODR- 10, which is normally expressed in the AWA olfactory neurons. The repulsive odorant 2-nonanone is detected by the AWB olfactory neu-rons. With the expression of CoChR and Chrimson in these neurons, worms can get attractive and repulsive response to blue light and red light, so we can use lights to induce them to learn new behav-iors.
Skinner Box
Skinner Box is a laboratory apparatus used to study animal behavior invented by Burrhus Frederic Skinner(1904—1990), and it uncloses the secret of the operant behavior. Skinner’s study deeply influenced American education at that time. He divided the behaviors into two types: respondent behavior which induced by some known stimulus like Pavlov's dog, and another is operant behavior caused by a subject itself like Skinner's pigeon. In our life, most behaviors or reflects are operant behaviors and operant reflects, so it’s very important to study the mechanism of Skinner box. The structure forming the shell of it is a chamber large enough to easily accommodate the animal being used as a subject. (Commonly used model animals include rodents—usually lab rats—pigeons, and primates). An operant conditioning chamber permits experimenters to study behavior conditioning (training) by teaching a subject animal to perform certain actions (like pressing a lever) in response to specific stimuli, such as a light or sound signal.[7][8] There are several manipulandums in the box, which can automatically detect the occurrence of a behavioral response or action. Typical operands for primates and rats are response levers; if the subject presses the lever, the opposite end moves and closes a switch that is monitored by a computer or other programmed device. When the lever is pressed, food, water, or some other type of reinforcement (a consequence that will strengthen an organism's future behavior whenever that behavior is preceded by a specific antecedent stimulus.) might be dispensed. In some instances, the floor of the chamber may be electrified. The rats learn to press the lever through several training periods because of the awards or the punishments. [9] The researchers can also control the probability between the lever and the switch, for example, the food will not be given to the rats until the rats press the lever for about 30-40 times. In this experiment, scientists find that although the food will be given after the rats press the lever so many times, the rats will still press the lever ceaselessly. It is just like the gambles among the people. In our project, we train the transgenic C. elegans and control the behavior of them by lights. Expression of two channelrhodopsins in the olfactory receptor neuron pair provides worms with the preference and aversion to specific wavelengths, and the corresponding lights are employed to reinforce their addictive or abstemious attitude to alcohol. Those reflects or behaviors are all operant behaviors and operant reflects which can be helpful for people’s more deep studies about the nerve and behaviors.
References
- ↑ [1]Caenorhabditis elegans(WIKIPEDIA). Retrieved September 25, 2017 https://en.wikipedia.org/wiki/Caenorhabditis_elegans
- ↑ [2]Brenner, S., Draft, A. N. C., Chklovskii, D., System, F. F. N., Brain, T. M., & Seung, S., et al. . The connectome debate: is mapping the mind of a worm worth it?. Scientific American
- ↑ [1]Caenorhabditis elegans(WIKIPEDIA). Retrieved September 25, 2017 https://en.wikipedia.org/wiki/Caenorhabditis_elegans
- ↑ [3]Chen, Y., Scarcelli, V., & Legouis, R. (2017). Approaches for studying autophagy in caenorhabditis elegans. Cells 6(3)
- ↑ [1]Caenorhabditis elegans(WIKIPEDIA). Retrieved September 25, 2017 https://en.wikipedia.org/wiki/Caenorhabditis_elegans
- ↑ [4]Uno, M., & Nishida, E. (2016)
- ↑ [1]R.Carlson, Neil (2009). Psychology-the science of behavior. U.S: Pearson Education Canada; 4th edition. p. 207. ISBN 978-0-205-64524-4.
- ↑ [2]Krebs, John R.(1983). "Animal behaviour: From Skinner box to the field". Nature. 304 (5922): 117. Bibcode:1983Natur.304..117K. PMID 6866102. doi:10.1038/304117a0
- ↑ Brembs, Björn. "Operant conditioning in invertebrates". Current Opinion in Neurobiology. 13 (6): 710–717. doi:10.1016/j.conb.2003.10.002
