ScienceDaily (Aug. 13, 2010) — Single neurons in the brain are surprisingly
good at distinguishing different sequences of incoming information according
to new research by UCL neuroscientists.
The study, published August 12 in Science and carried out by researchers
based at the Wolfson Institute for Biomedical Research at UCL, shows that
single neurons, and indeed even single dendrites, the tiny receiving elements
of neurons, can very effectively distinguish between different temporal
sequences of incoming information.
This challenges the widely held view that this kind of processing in the
brain requires large numbers of neurons working together, as well as
demonstrating how the basic components of the brain are exceptionally
powerful computing devices in their own right.
First author Tiago Branco said: "In everyday life, we constantly need to use
information about sequences of events in order to understand the world around
us. For example, language, a collection of different sequences of similar
letters or sounds assembled into sentences, is only given meaning by the
order in which these sounds or letters are assembled.
"The brain is remarkably good at processing sequences of information from the
outside world. For example, modern computers will still struggle to decode a
rapidly spoken sequence of words that a 5 year-old child will have no trouble
understanding. How the brain does so well at distinguishing one sequence of
events from another is not well understood but, until now, the general belief
has been that this job is done by large numbers of neurons working in concert
with each other."
Using a mouse model, the researchers studied neurons in areas of the brain
which are responsible for processing sensory input from the eyes and the
face. To probe how these neurons respond to variation in the order of a
number of inputs, they used a laser to activate inputs on the dendrites in
precisely defined patterns and recorded the resulting electrical responses of
the neurons.
Surprisingly, they found that each sequence produced a different response,
even when it was delivered to a single dendrite. Furthermore, using
theoretical modelling, they were able to show that the likelihood that two
sequences can be distinguished from each other is remarkably high.
Senior author Professor Michael Hausser commented: "This research indicates
that single neurons are reliable decoders of temporal sequences of inputs,
and that they can play a significant role in sorting and interpreting the
enormous barrage of inputs received by the brain.
"This new property of neurons and dendrites adds an important new element to
the "toolkit" for computation in the brain. This feature is likely to be
widespread across many brain areas and indeed many different animal species,
including humans."
Funding for this study was provided by the Gatsby Charitable Foundation and
the Wellcome Trust.
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網址：
http://www.sciencedaily.com/releases/2010/08/100812151632.htm
論文(Science Express)：
http://www.sciencemag.org/cgi/content/abstract/science.1189664
蠻有趣的文章，
主要是說，一個神經元可以分辨不同序列的電刺激。
就算是在一個樹突上刺激也有這個效果，
這個說明，除了刺激的空間分佈(刺激在神經細胞的不同位子)，
刺激的時間分佈也會影響輸出的結果。
如此一來，assembly model, grandmother cell之戰，
又準備開戰了 XD
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