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===The visual system===
In the [[Visual cortex#Primary visual cortex (V1)|primary visual cortex]] of macaques, the timing of the first spike relative to the start of the stimulus was found to provide more information than the interval between spikes. However, the interspike interval could be used to encode additional information, which is especially important when the spike rate reaches its limit, as in high-contrast situations. For this reason, temporal coding may play a part in coding defined edges rather than gradual transitions.<ref>Victor, Johnathan D. (2005). [http://dx.doi.org/10.1016/j.conb.2005.08.002 "Spike train metrics"]. ''Current Opinion in Neurobiology'', 15(5):585–592.</ref>
The specificity of temporal coding requires highly refined technology to create informative, reliable, experimental data. Advances made in [[optogenetics]] allowed neurologists to control spikes in individual neurons, offering electrical and spatial single-cell resolution. For example, when blue light is perceived, a [[channelrhodopsin]] in pond scum opens, depolarizing the cell and producing a spike. When blue light is not sensed, 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>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>▼
===The olfactory system===
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==Implications==
Optogenetic technology has the potential to help researchers crack the neural code and enable the correction of spike abnormalities at the root of several neurological and psychological disorders.<ref>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> There is a possibility that the neuron encodes information in individual spike timing, and 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]] 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, 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> Such medical possibilities bring up ethical controversies about such explicit manipulation of the brain. While the benefits could be enormous, so could the abuses. However, understanding where the brain uses a temporal code is important and valuable for neuroscientists and patients alike.▼
▲The specificity of temporal coding requires highly refined technology to create informative, reliable, experimental data. Advances made in [[optogenetics]]
▲Optogenetic technology also has the potential to
==See also==
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