Spike timing dependent plasticity


Spike timing dependent plasticity

Spike timing dependent plasticity (STDP) is a general term for functional changes in neurons and at synapses that are sensitive to the timing of action potentials in connected neurons. The phrase 'STDP' typically refers to increases or decreases in the efficacy of synaptic transmission (known as synaptic plasticity), though it can also refer to other functional changes, such as altered dendritic integration. STDP can result from presynaptic spikes preceding postsynaptic spikes (known as pre-post spiking) and postsynaptic spikes preceding presynaptic spikes (known as post-pre spiking). The timing sensitivities are on the order of milliseconds. Usually, pre-post spiking causes long-term potentiation (LTP) of the synapse, and post-pre spiking causes long-term depression (LTD, although pre-spiking by >40 ms may lead to LTD. [ [http://www.cs.stir.ac.uk/~vcu/STDP.htm STDP Models ] ] .

History

The first experiments that specifically examined the effect of millisecond relative timing of pre and postsynaptic action potentials was carried out by W. B. Levy and O. Steward in 1983. However, STDP was not established at the cellular level until Henry Markram, in Bert Sakmann's laboratory, used dual patch clamping techniques to repetitively activate pre-synaptic neurons 10 milliseconds before post-synaptic target neurons, and found the strength of the synapse increased. When the activation order was reversed so that the pre-synaptic neuron was activated 10 milliseconds after its post-synaptic target neuron, the strength of the pre-to-post synaptic connection decreased. Further work, first by Li Zhang and Mu Ming Poo in 1998, mapped the entire time course relating pre- and post-synaptic activity and synaptic change, to show that in their preparation synapses that are activated within 5-40 ms before a postsynaptic spike are strengthened, and those that are activated within a similar time window after the spike are weakened. This phenomenon has been observed in various other preparations, with some variation in the time-window relevant for plasticity. Several reasons for timing-dependent plasticity have been suggested. For example, STDP might operate as a learning rule that maximizes the mutual information between inputs and outputs of simple networks, and provide a function for Hebbian learning and development [cite journal | doi = 10.1038/78829 | year = 2000 | month = Sep | author = Song, S; Miller, Kd; Abbott, Lf | title = Competitive Hebbian learning through spike-timing-dependent synaptic plasticity | volume = 3 | issue = 9 | pages = 919–26 | pmid = 10966623 | journal = Nature neuroscience] .

From Hebbian Rule to STDP

According to the Hebbian Rule synapses increase their efficacy if the synapse persistently causes the postsynaptic target neuron to generate action potentials. An often used but not entirely accurate simplification is "those who fire together, wire together". With recent advancements in technology we can more precisely measure the spike timing of neurons. As it turns out, the synaptic connection between two neurons is more likely to strengthen if the presynaptic neuron fires off shortly before the postsynaptic neuron. Revisiting, the Hebbian rule, we can tweak it to accommodate the new model. Synapses increase their efficacy if the presynaptic neuron is activated momentarily before the postsynaptic neuron is activated. OR Synapses in which the pre-synaptic input fired before the postsynaptic cell get stronger; in the inverse situation, the synapse gets weaker.

ee also

* Synaptic plasticity
* Didactic organisation

References

*Rumsey C.C., Abbott L.F. Equalization of Synaptic Efficacy by Activity- and Time- Dependent Synaptic Plasticity. J Neurophysiol 91: 2273-2280, 2004.

* Debanne D, Gahwiler BH, Thompson SM. Asynchronous pre- and postsynaptic activity induces associative long-term depression in area CA1 of the rat hippocampus in vitro. Proc Natl Acad Sci U S A. 1994 Feb 1;91(3):1148-52. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=7905631&query_hl=2&itool=pubmed_DocSum]

* Levy WB, Steward O. Temporal contiguity requirements for long-term associative potentiation/depression in the hippocampus. Neuroscience. 1983 Apr;8(4):791-7. [http://faculty.virginia.edu/levylab/Publications/]

* Markram H., Lubke J., Frotscher M., Sakmann B. [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?holding=npg&cmd=Retrieve&db=PubMed&list_uids=8985014&dopt=Abstract Regulation of synaptic efficacy by coincidence of postsynaptic APs and EPSPs] . "Science" 275, 213-5 (1997)

* Bi G.Q., Poo M.M. [http://www.jneurosci.org/cgi/content/abstract/18/24/10464 Synaptic modifications in cultured hippocampal neurons: dependence on spike timing, synaptic strength, and postsynaptic cell type] . "Journal of Neuroscience" 18, 10464-72 (1998)

* Sjostrom PJ, Turrigiano GG, Nelson SB [http://www.neuron.org/content/article/abstract?uid=PIIS0896627301005426 Rate, timing, and cooperativity jointly determine cortical synaptic plasticity] Neuron 2001 Dec 20;32(6):1149-64

* Senn W., Markram H., Tsodyks M.; [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?holding=npg&cmd=Retrieve&db=PubMed&list_uids=11177427&dopt=Abstract An algorithm for Modifying Neurotransmitter Release Probability Based on Pre- and Postsynaptic Spike Timing] . "Neural Computation" 13, 35-67 (2000)

* Roberts P.D., Bell C.C. ; Spike-timing dependent synaptic plasticity in biological systems. "Biological Cybernetics", 87, 392-403 (2002)

* Chechik G.; [http://ai.stanford.edu/~gal/ps_files/chechik_stdp.pdf Spike Time dependent plasticity and relevant information maximization] . "Neural Computation" 15(7) p.1481-1510, (2003)

* Lisman J., Spruston N.; [http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?holding=npg&cmd=Retrieve&db=PubMed&list_uids=16136666&dopt=Abstract Postsynaptic depolarization requirements for LTP and LTD: a critique of spike timing-dependent plasticity] . "Nature Neuroscience' 8, 839-41 (2005)

External links


Wikimedia Foundation. 2010.

Look at other dictionaries:

  • Dendritic spike — Figure A. shows the idealized phases of an action potential. Figure B. is a recording of an actual action potential N.B. Actual recordings of action potentials are often distorted compared to the schematic view because of variations in… …   Wikipedia

  • Synaptic plasticity — In neuroscience, synaptic plasticity is the ability of the connection, or synapse, between two neurons to change in strength. There are several underlying mechanisms that cooperate to achieve synaptic plasticity, including changes in the quantity …   Wikipedia

  • Nonsynaptic plasticity — Brain connectivity network Nonsynaptic plasticity is a form of neuroplasticity that involves modification of ion channel function in the axon, dendrites, and cell body that results in specific changes in the integration of EPSPs and IPSPs, thus… …   Wikipedia

  • Didactic organisation — is the ability of neurons within a network to impart their pattern of synaptic connectivity and/or response properties to other neurons. The term didactic is used because this kind of influence is unidirectional; each individual instance of… …   Wikipedia

  • Dendritic spine — Spiny dendrite of a striatal medium spiny neuron. Common types of dendri …   Wikipedia

  • Models of neural computation — are attempts to elucidate, in an abstract and mathematical fashion, the core principles that underlie information processing in biological nervous systems, or functional components thereof. This article aims to provide an overview of the most… …   Wikipedia

  • Action potential — In physiology, an action potential is a short lasting event in which the electrical membrane potential of a cell rapidly rises and falls, following a consistent trajectory. Action potentials occur in several types of animal cells, called… …   Wikipedia

  • Long-term depression — (LTD), in neurophysiology, is the weakening of a neuronal synapse that lasts from hours to days. It results from either strong synaptic stimulation (as occurs in the cerebellar Purkinje cells) or persistent weak synaptic stimulation (as in the… …   Wikipedia

  • Temporal coding — The temporal coding is a type of neural coding which relies on precise timing of action potentials or inter spike intervals.Combined with traditional rate coding models, temporal coding can provide additional information with the same rate.There… …   Wikipedia

  • NeuroElectroDynamics — or NED is the study of the dynamics and interaction of electrical charges in the brain [1]. The word neuroelectrodynamics is derived from neuro meaning neurons, electro electric field and dynamics meaning movement. The main idea of NED is that… …   Wikipedia