The influence of stimulation timing on late-associativity.

<p>The schematic diagram of our simulation experiment II. The horizontal axis denotes time (min). The black arrow at 0 min denotes the start of the l-LTP–inducing stimulation protocol at synapse L1. Other arrows indicate the stimuli in the e-LTP–inducing stimulation protocol at synapses E1–E15. Stimulus patterns are characterized by <i>s</i>_<i>E1</i> and <i>ds</i>_<i>E</i>. <i>s</i>_<i>E1</i> denotes the stimulation timing at synapse E1. We defined stimulus patterns in which all e-LTP–inducing stimulation protocols were conducted before the l-LTP–inducing stimulation protocol as the left window (<i>s</i>_<i>E1</i> < 0) and the patterns in which the e-LTP–inducing stimulation protocols were conducted after the l-LTP–inducing stimulation protocol as the right window (<i>s</i>_<i>E1</i> > 0). <i>ds</i>_<i>E</i> is the stimulus interval. (B) Spine head volumes of synapses E1–E15 180 min after stimulation with different stimulus patterns. Marker denotes the log-scale basal PRP level in the simulation. (C) Four types of enhancement tendencies. Types I–IV alternatively appear depending on the basal PRP level in a specific order (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0275059#pone.0275059.s001" target="_blank">S1</a>–<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0275059#pone.0275059.s006" target="_blank">S6</a> Figs for the enhancement tendencies under all stimulus patterns). (D) Basal PRP level dependency of the intragroup mean and standard deviation. Each marker line denotes a different stimulation interval. Background color denotes the range of basal PRP levels in which each type dominantly appears. Type I is red, Type II is blue, Type III is green, and Type IV is yellow.</p>