Wednesday, March 25, 2015

Crayfish (invertebrates) suffer from anxiety as well..

A work, published in Science by French researchers from Université de Bordeaux (France), shows the presence of a neural mechanism of an anxiety-like behavior in animal, specifically crayfish, throughout evolution. It is claimed that anxiety has only been found in human and a few other vertebrates. This is the first case discovered in the history that anxiety-like behavior also exists in invertebrates. Additionally, they have also found that this emotion weakens and disappears as anxiolytic is injected (suggesting a similar mechanism as in human).

 Figure 1: Photo of a crayfish used in the experiment (in the cross-shaped mazed)

First of  all, anxiety is a form of behavioral response to stress, including lasting fear and nervousness. This involuntary response raises awareness and the ability of detecting threats in individuals, consequently, increasing their life expectancy.

During experiment, researchers repeatedly exposed crayfish to an electric field (stress environment) for thirty minutes before placing them in an aquatic cross-shaped maze. The maze was set up in a way that two of its arms were lit up and the other two were kept dark. Dark area was found to be reassuring for crayfish. Results of the experiments illustrate a tendency that those that are anxious stay in the dark arms of the maze and those who are not anxious (in the control group) remain throughout the whole maze.

From a neuro-biological standpoint, this anxiety response is related to an increase in serotonin level in brain. This neurotransmitter, is responsible for the feelings of well-being and happiness is released when body experiences stress, suppressing anxious feelings. Researchers have also injected a dose of anxiolytic, commonly used in human (benzodiazepine), to crayfish and found similar effects as if in human: weakening the symptoms of anxiety.

Researchers believe that this analysis of this ancestral behavior will essential for studying the neuronal bases of this emotion. This is also a behavioral study on a unique model, which is invertebrates. Further studies can be done based upon the finding from this experiment. 

Posted by Phi Duong (Group A)

12 comments:

  1. Wow, very strange how crayfish, of all things, experience anxiety. I often find myself wondering if wild animals have the ability to experience emotions the way we do, and it is very fascinating to see that these invertebrates are complex enough to do so because it could help to prolong their life. Poor little guys! Nice job.

    Erika Nevins

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    1. Hi Erika,
      I have read an article while researching about this experiment that most mammals and vertebrates have found to experience emotions. However, their emotional experiences tend to be simpler and less vivid than humans' emotions. Thank you for your comment.
      Phi Duong

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  2. Another aspect to use in studying anxiety can be great for the medical field, especially since many of us have our fair share of anxiety we deal with.

    The article was also a tad humorous. The image of a crayfish stressing out like most of us do before a big test put a smile on my face.

    -Dan Staiculescu

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    1. Dan,
      Thank you for your comment! I agree with you that studies on anxiety or even any other behavioral or emotional responses in animal are beneficial for medical field. Since we all share a common ancestor.
      Phi Duong

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  3. I bet there are a lot of animals that have a reaction to stress that resembles anxiety. It makes you consider what the evolutionary advantages are of having anxiety. It seems simple enough that the feeling of discomfort is enough to motivate animals to escape the feeling, much like pain. Even still, the concept of anxiety is a much more cognitive in comparison to pain, so it's surprising nonetheless to see it in something like crayfish.
    -Patrick O'Loughlin

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    1. Patrick,
      I totally agree with your opinion. Your point actually is a further explanation for my statement above that anxiety raises awareness in animals. Thank you for your comment.
      Phi Duong

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  4. I think we often overlook the possibility that many lab subjects could have anxiety. I recall doing a class experiment in which we assessed aggressive behavior; the crayfish had to be handled extensively and your article points out that that may have induced a lot of anxiety in them, as they are capable of such an emotion. Good information!
    -Meghan Harrington

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    1. Meghan,
      I am not sure if touching crayfish would induce a lot of anxiety in them because I don't know how much sensation there is on their shells. However, it is very possible that they might get anxious from being touched or handled. By the way, your class experiment sounds very interesting to me. I'm wondering what class did you take because I think I would like to be involved in that type of experiments.
      Phi Duong

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  5. Great post Phi , I always find it interesting to read about emotion in animals. You find that there is a lot more going on inside the mind's of some creatures than you would expect.

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    1. John,
      I agree with your point. I would expect animals with more developed nervous system have more complex emotional and behavioral responses. But there's always something unexpected in nature. Thanks for your comment.
      Phi Duong

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  6. This is interesting that in humans as in crayfish having anxiety must of been beneficial for their survival. Also how anxiolytic that is used for humans also has an effect on the crayfish, I wonder what kind of connection they share.

    - Jazmin Granadeno

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    1. Jazmin,
      To answer your question, I would recall a little of my knowledge from my anthropology course that we are all traced back to one common ancestor. The reason for crayfish or other invertebrates to have similar emotion like us would very likely that humans (primates) and invertebrates are more closely related than to other simpler animals
      Phi Duong

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