Spike timing-dependent synaptic depression in the in vivo barrel cortex of the rat.
Spike timing-dependent plasticity (STDP) is a computationally powerful form of plasticity in which synapses are strengthened or weakened according to the temporal order and precise millisecond-scale delay between presynaptic and postsynaptic spiking activity. STDP is readily observed in vitro, but evidence for STDP in vivo is scarce. Here, we studied spike timing-dependent synaptic depression in single putative pyramidal neurons of the rat primary somatosensory cortex (S1) in vivo, using two techniques. First, we recorded extracellularly from layer 2/3 (L2/3) and L5 neurons, and paired spontaneous action potentials (postsynaptic spikes) with subsequent subthreshold deflection of one whisker (to drive presynaptic afferents to the recorded neuron) to produce "post-leading-pre" spike pairings at known delays. Short delay pairings (<17 ms) resulted in a significant decrease of the extracellular spiking response specific to the paired whisker, consistent with spike timing-dependent synaptic depression. Second, in whole-cell recordings from neurons in L2/3, we paired postsynaptic spikes elicited by direct-current injection with subthreshold whisker deflection to drive presynaptic afferents to the recorded neuron at precise temporal delays. Post-leading-pre pairing (<33 ms delay) decreased the slope and amplitude of the PSP evoked by the paired whisker, whereas "pre-leading-post" delays failed to produce depression, and sometimes produced potentiation of whisker-evoked PSPs. These results demonstrate that spike timing-dependent synaptic depression occurs in S1 in vivo, and is therefore a plausible plasticity mechanism in the sensory cortex.
Jacob
Vincent
V
Unité de Neurosciences Intégratives et Computationnelles, Centre National de la Recherche Scientifique, 91198 Gif sur Yvette, France.
Brasier
Daniel J
DJ
Erchova
Irina
I
Feldman
Dan
D
Shulz
Daniel E
DE
D000200:Action Potentials; D000818:Animals; D004569:Electroencephalography; D036881:Long-Term Synaptic Depression / Q000502:physiology*; D008297:Male; D008839:Microelectrodes; D008959:Models, Neurological; D009474:Neurons / Q000502:physiology; D018408:Patch-Clamp Techniques; D017729:Presynaptic Terminals / Q000502:physiology; D017966:Pyramidal Cells / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D011930:Reaction Time; D013003:Somatosensory Cortex / Q000502:physiology*; D013269:Stochastic Processes; D013997:Time Factors; D014110:Touch; D014738:Vibrissae / Q000294:innervation*