Temporal coding: Difference between revisions

Revision as of 18:40, 10 May 2012

Revision as of 21:31, 10 May 2012

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==Implications==

The specificity of temporal coding requires highly refined technology to create informative, reliable, experimental data. Advances made in [[optogenetics]] allow neurologists to control spikes in individual neurons, offering electrical and spatial single-cell resolution. For example, blue light causes the light-gated ion channel [[channelrhodopsin]] to open, depolarizing the cell and producing a spike. When blue light is not sensed by the cell, the channel closes, and the neuron ceases to spike. The pattern of the spikes matches the pattern of the blue light stimuli. By inserting channelrhodopsin gene sequences into mouse DNA, researchers can control spikes and therefore certain behaviors of the mouse (e.g., making the mouse turn left).<ref name="youtube.com">Karl Diesseroth, Lecture. “Personal Growth Series: Karl Diesseroth on Cracking the Neural Code.” Google Tech Talks. November 21, 2008. http://www.youtube.com/watch?v=5SLdSbp6VjM</ref> Researchers, through optogenetics, have the tools to effect different temporal codes in a neuron while maintaining the same mean firing rate, and thereby can test whether or not temporal coding occurs in specific neural circuits.<ref name="Han X 2009">Han X, Qian X, Stern P, Chuong AS, Boyden ES. “Informational lesions: optical perturbations of spike timing and neural synchrony via microbial opsin gene fusions.” Cambridge, MA: MIT Media Lad, 2009. PubMed.</ref>

Optogenetic technology also has the potential to enable the correction of spike abnormalities at the root of several neurological and psychological disorders.<ref> name="Han X, Qian X, Stern P, Chuong AS, Boyden ES. “Informational lesions: optical perturbations of spike timing and neural synchrony via microbial opsin gene fusions.” Cambridge, MA: MIT Media Lad, 2009. PubMed.<"/ref> If neurons do encode information in individual spike timing patterns, key signals could be missed by attempting to crack the code while looking only at mean firing rates. Understanding any temporally encoded aspects of the neural code and being able to replicate these sequences in neurons could allow for greater control and treatment of neurological disorders such as [[depression (mood)|depression]] and [[Parkinson’s Disease]].<ref name="youtube.com"/> Controlling the precise spike intervals in single cells is more effective in controlling brain activity than adding chemicals and neurotransmitters intravenously.<ref name="youtube.com"/>Karl Diesseroth,Medical Lecture.possibilities “Personallike Growth Series: Karl Diesseroth on Cracking the Neural Code.” Google Tech Talks. November 21, 2008. http://www.youtube.com/watch?v=5SLdSbp6VjM</ref> Such medical possibilitiesthese bring up ethical controversies about such explicit manipulation of the brain. However, understanding where the brain uses a temporal code is important and valuable for neuroscientists and patients alike.

==See also==