Dark Exposure Extends the Integration Window for Spike-Timing-Dependent Plasticity

The Mind/Brain Institute, Johns Hopkins University, Baltimore, Maryland 21218, Tianjin Medical University, Tianjin Eye Hospital, Tianjin Key Laboratory of Ophthalmology and Visual Science, Tianjin 300070, China, Department of Neuroscience, Johns Hopkins University, Baltimore, Maryland 21205, and Department of Biology, University of Maryland, College Park, Maryland 20742.
The Journal of Neuroscience : The Official Journal of the Society for Neuroscience (Impact Factor: 6.34). 10/2012; 32(43):15027-35. DOI: 10.1523/JNEUROSCI.2545-12.2012
Source: PubMed


Metaplasticity, the adaptive changes of long-term potentiation (LTP) and long-term depression (LTD) in response to fluctuations in neural activity is well documented in visual cortex, where dark rearing shifts the frequency threshold for the induction of LTP and LTD. Here we studied metaplasticity affecting spike-timing-dependent plasticity, in which the polarity of plasticity is determined not by the stimulation frequency, but by the temporal relationship between near-coincidental presynaptic and postsynaptic firing. We found that in mouse visual cortex the same regime of deprivation that restricts the frequency range for inducing rate-dependent LTD extends the integration window for inducing timing-dependent LTD, enabling LTD induction with random presynaptic and postsynaptic firing. Notably, the underlying mechanism for the changes in both rate-dependent and time-dependent LTD appears to be an increase of NR2b-containing NMDAR at the synapse. Thus, the rules of metaplasticity might manifest in opposite directions, depending on the plasticity-induction paradigms.

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    • "In developing sensory cortices (<P20), this protocol results in timing-dependent potentiation (tLTP) when the EPSP precedes the AP and tLTD when the EPSP follows it (Markram et al., 1997; Sjö strö m et al., 2001). In agreement with previous studies performed in the absence of neuromodulators or GABA(A) receptor antagonists (Corlew et al., 2007; Guo et al., 2012; Seol et al., 2007), we failed to induce either tLTP or tLTD in P26–P30 normally reared (NR) mice (Figures 1A–1E). This suggests that developmental mechanisms tightly regulate STDP in the visual cortex. "

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