title: Modulation of synaptic plasticity by the coactivation of spatially distinct synaptic inputs in rat hippocampal CA1 apical dendrites.
abstract: The phenomenon whereby the relative timing between presynaptic and postsynaptic spiking determines the direction and extent of synaptic changes in a critical temporal window is known as spike timing-dependent synaptic plasticity (STDP). We have previously reported that STDP profiles can be classified into two types depending on their layer-specific location along CA1 pyramidal neuron dendrites in the rat hippocampus, suggesting that there are differences in information processing between the proximal dendrite (PD) and distal dendrite (DD). However, how the different types of information processing interact at different dendritic locations remains unclear. To investigate how the temporal information of inputs to PD influences information processing at DD, PD stimulation was applied while the STDP protocol was simultaneously applied at DDs of CA1 pyramidal neurons. Synaptic plasticity induced by the STDP protocol at DDs was enhanced or depressed depending on the timing of the back-propagating action potentials (bAPs) and the excitatory and inhibitory postsynaptic potentials elicited by PD stimulation. These results suggested that bAPs function as carriers of temporal information of PD inputs to DD. Next, the influence of DD on PD was investigated using the same protocol. Synaptic plasticity at PD was modulated only if the pairing stimuli were applied to elicit coincidental timing of bAP and the excitatory postsynaptic potential. Such coding modulations could provide the basis for a novel learning rule and may be important factors in the integration of spatiotemporal input information in neural networks in the brain.
authors.affiliation: Graduate School of Brain Sciences, Tamagawa University, 6-1-1 Tamagawa-gakuen, Machida, Tokyo, Japan.
authors.forename: Masashi
authors.initials: M
authors.lastname: Kondo
authors.forename: Tatsuo
authors.initials: T
authors.lastname: Kitajima
authors.forename: Satoshi
authors.initials: S
authors.lastname: Fujii
authors.forename: Minoru
authors.initials: M
authors.lastname: Tsukada
authors.forename: Takeshi
authors.initials: T
authors.lastname: Aihara
mesh_terms: D000200:Action Potentials / Q000502:physiology; D000818:Animals; D056547:CA1 Region, Hippocampal / Q000502:physiology*; D003712:Dendrites / Q000502:physiology*; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D018408:Patch-Clamp Techniques; D051381:Rats; D017208:Rats, Wistar; D013569:Synapses / Q000502:physiology
keywords: 6-cyano-7-nitroquinoxaline-2,3-dione; ACSF; AP5; Back-propagating action potential; CMOS; CNQX; D-2-amino-5-phosphonovaleric acid; DD; Dendritic integration; EPSP; IPSP; LTD; LTP; Optical imaging; PD; SEM; STDP; STDP-induction stimuli; STDPS; Synaptic plasticity; TS; TTX; VSD; Voltage-sensitive dye; artificial cerebrospinal fluid; bAP; back-propagating action potential; complementary metal oxide semiconductor; distal dendrite; excitatory postsynaptic potential; inhibitory postsynaptic potential; long-term depression; long-term potentiation; proximal dendrite; spike timing-dependent plasticity; standard error of the mean; test stimulus; tetrodotoxin; voltage-sensitive dye