Modulation of pyramidal neuron synaptic integration by LTPi.

<p>(A, Top) Representative overlapped traces of evoked EPSP/IPSP sequences (ePSP) in the absence of glutamatergic and GABAergic antagonists, before (black) and 15 min after induction of LTPi (red). LTPi was induced by postsynaptic AP bursts (5 APs at 100 Hz). (A, Bottom) Population E/I ratio analysis before and 15 min after AP burst firing. Data are represented as mean ± SEM. **<i>p</i><0.01. (B) Representative superimposed traces of aEPSPs summating to proximally evoked PSP at different time intervals before (black traces, Left) and 15 min after LTPi induction (red traces, Right). Arrowheads point to time intervals where the narrowing of the integration window is more evident. The inset illustrates a representative trace (blue) of recorded aEPSP elicited by somatic injection of an aEPSC. (C) Graph illustrating averaged aEPSP-ePSP summation before (black) and 15 min after LTPi induction (red). (D, Left) Schematic of the recording and stimulation configuration. Blue and red lines refer to inhibitory and excitatory afferents, respectively. (D, Right) Composite PSPs before (black traces, Left) and after (red traces, Right) induction of LTPi by AP bursts. Note change of waveform of proximal composite PSP (arrowhead). (E) Graphs showing average depolarizing peaks, areas, and EPSC/IPSC ratio of proximal and distal composite PSPs. No changes were observed in excitatory peak amplitude before and after LTPi. However, a significant reduction of PSP area and EPSC/IPSC ratio was present at proximal PSP selectively. (F) Examples of distal to proximal PSP summation at different time intervals before (Left, black traces) and 15 min after (Right, red traces) induction of LTPi. Arrowhead points to LTPi-dependent change of PSP waveform. (G) Graph illustrating averaged distal to proximal PSP summation before (black) and 15 min after LTPi induction (red). Data are single values mean ± SEM. *<i>p</i><0.05; **<i>p</i><0.001. Additional data and analyses are present in <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001903#pbio.1001903.s004" target="_blank">Figures S4</a> and <a href="http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.1001903#pbio.1001903.s005" target="_blank">S5</a>.