→ shoxx:最後有寫說 是後續研究的要點吧XD 06/17 13:51
Crayfish Brain May Offer Rare Insight Into Human Decision Making
ScienceDaily (June 16, 2010) — Crayfish make surprisingly complex,
cost-benefit calculations, finds a University of Maryland study -- opening
the door to a new line of research that may help unravel the cellular brain
activity involved in human decisions.
The Maryland psychologists conclude that crayfish make an excellent,
practical model for identifying the specific neural circuitry and
neurochemistry of decision making. They believe their study is the first to
isolate individual crayfish neurons involved in value-based decisions.
Currently, there's no direct way to do this with a human brain.
The study is being published in the Proceedings of the Royal Society B.
"Matching individual neurons to the decision making processes in the human
brain is simply impractical for now," explains University of Maryland
psychologist Jens Herberholz, the study's senior author.
"History has shown that findings made in the invertebrate nervous systems
often translate to more complex organisms. It's unlikely to be exactly the
same, but it can inform our understanding of the human brain, nonetheless.
The basic organization of neurons and the underlying neurochemistry are
similar, involving serotonin and dopamine, for example."
Herberholz adds that his lab's work may inform ongoing studies in rodents and
primates. "Combining the findings from different animal models is the only
practical approach to work out the complexities of human decision making at
the cellular level."
The experiments offered the crayfish stark decisions -- a choice between
finding their next meal and becoming a meal for an apparent predator. In
deciding on a course of action, they carefully weighed the risk of attack
against the expected reward, Herberholz says.
Using a non-invasive method that allowed the crustaceans to freely move, the
researchers offered juvenile Louisiana Red Swamp crayfish a simultaneous
threat and reward: ahead lay the scent of food, but also the apparent
approach of a predator.
In some cases, the "predator" (actually a shadow) appeared to be moving
swiftly, in others slowly. To up the ante, the researchers also varied the
intensity of the odor of food.
How would the animals react? Did the risk of being eaten outweigh their
desire to feed? Should they "freeze" -- in effect, play dead, hoping the
predator would pass by, while the crayfish remained close to its meal -- or
move away from both the predator and food?
To make a quick escape, the crayfish flip their tails and swim backwards, an
action preceded by a strong, measurable electric neural impulse. The
specially designed tanks could non-invasively pick up and record these
electrical signals. This allowed the researchers to identify the activation
patterns of specific neurons during the decision-making process.
Although tail-flipping is a very effective escape strategy against natural
predators, it adds critical distance between a foraging animal and its next
meal.
The crayfish took decisive action in a matter of milliseconds. When faced
with very fast shadows, they were significantly more likely to freeze than
tail-flip away.
The researchers conclude that there is little incentive for retreat when the
predator appears to be moving too rapidly for escape, and the crayfish would
lose its own opportunity to eat. This was also true when the food odor was
the strongest, raising the benefit of staying close to the expected reward. A
strong predator stimulus, however, was able to override an attractive food
signal, and crayfish decided to flip away under these conditions.
"Our results indicate that when the respective values of tail-flipping and
freezing change, the crayfish adjust their choices accordingly, thus
preserving adaptive action selection," the researchers write. "We have now
shown that crayfish, similar to organisms of higher complexity, integrate
different sensory stimuli that are present in their environment, and they
select a behavioural output according to the current values for each choice."
The next step is to identify the specific cellular and neurochemical
mechanisms involved in crayfish decisions, which is more feasible in an
animal with fewer and accessible neurons, Herberholz says. That research is
now underway.
Herberholz's research is funded by grants from the National Science
Foundation and University of Maryland's Division of Research.
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原始網址：
http://www.sciencedaily.com/releases/2010/06/100615191751.htm
大意是說研究員利用龍蝦覓食與避敵的行為來研究決策。
食物是味道，而敵人是移動速度快或慢的影子，
研究顯示當龍蝦做出決策的時候，會有幾毫秒的電訊號被量測到，當他們遇到很快的影子
的時候，通常他們會定住不動，以裝死來取代逃跑 XD。
看內文的描述還蠻生動的XD。
但我很好奇的是他們量測的方法，根據內文是利用一個特製裝有sensor的水槽來測量。
那我很好奇這樣如何推測是哪個神經元傳遞出的訊號呢？
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※ 編輯: mulkcs 來自: 140.112.33.135 (06/17 10:53)