Spike timing dependent plasticity in the intact brain: counteracting spurious spike coincidences.

Abstract

A computationally rich algorithm of synaptic plasticity has been proposed based on the experimental observation that the sign and amplitude of the change in synaptic weight is dictated by the temporal order and temporal contiguity between pre- and postsynaptic activities. For more than a decade, this spike-timing-dependent plasticity (STDP) has been studied mainly in brain slices of different brain structures and cultured neurons. Although not yet compelling, evidences for the STDP rule in the intact brain, including primary sensory cortices, have been provided lastly. From insects to mammals, the presentation of precisely timed sensory inputs drives synaptic and functional plasticity in the intact central nervous system, with similar timing requirements than the in vitro defined STDP rule. The convergent evolution of this plasticity rule in species belonging to so distant phylogenic groups points to the efficiency of STDP, as a mechanism for modifying synaptic weights, as the basis of activity-dependent development, learning and memory. In spite of the ubiquity of STDP phenomena, a number of significant variations of the rule are observed in different structures, neuronal types and even synapses on the same neuron, as well as between in vitro and in vivo conditions. In addition, the state of the neuronal network, its ongoing activity and the activation of ascending neuromodulatory systems in different behavioral conditions have dramatic consequences on the expression of spike-timing-dependent synaptic plasticity, and should be further explored.

Dendritic NMDA spikes are necessary for timing-dependent associative LTP in CA3 pyramidal cells

“…It should be noted that in our preparation a single bAP almost never triggered an NMDA spike and did not induce LTP. However, it is possible that single spikes may be able to more powerfully affect NMDA spikes or other dendritic processes in vivo 42, where background neuronal activity and neuromodulatory conditions are different43.…”

Tonic GABAAconductance favors temporal over rate coding in the rat hippocampus

“…stLTP can occur when the neuron receives synaptic input from many presynaptic cells and need to choose which input is more relevant (57). Although a relevance of stLTP as a general model for synaptic plasticity is sometimes put into question (58,59), this phenomenon has been demonstrated in different species and brain regions in vitro and in vivo (60)(61)(62)(63)(64). stLTP also has a broad appeal in computational neuroscience (65)(66)(67)(68)(69).…”

Spike Timing-Dependent Plasticity

“…While all STDP depends on precise timing and order of pre-and postsynaptic spikes, the precise temporal windows, magnitude, and sign of plasticity are remarkably diverse across synapses (Figure 9.2) (reviewed in Caporale and Dan, 2008;Shulz and Jacob, 2010). It has been observed at a wide variety of excitatory and inhibitory synapses in many brain areas and in multiple cell types and preparations, including neuronal cell cultures, in vitro brain slices, and in vivo.…”

“…Importantly, evidence for spike timing-dependent potentiation in mammalian cortex is weaker than for depression. One difficulty in comparing STDP between in vivo and in vitro models is the heterogeneity in experimental protocols applied to induce STDP (Shulz, 2010;Shulz and Jacob, 2010). In contrast, spike timing-dependent potentiation does clearly occur at developing retinotectal synapses (Engert et al, 2002).…”

“…While these studies suggest that STDP or STDP-like plasticity can occur in vivo, the functional importance of STDP relative to other synaptic learning rules during natural sensory input is unclear (reviewed in Caporale and Dan, 2008;Dan and Poo, 2006;Shulz and Jacob, 2010). That is, is STDP a major learning rule under natural conditions in vivo?…”