FIGURE 3.

Using paired recordings to study plasticity. (A) Quadruple whole-cell recording in which PC 4 was connected to PC 1 (scale bar: 50 μm). (B) During the 10-min baseline period, 30-Hz trains were repeated every 18 sec in the connected pair of neurons. These bursts were separated by long intervals to avoid induction of long-term plasticity (Sjöström et al. 2001). During the induction, 5 action potentials at 50 Hz were repeated 15 times every 15 sec. The timing difference was +10 msec. After the induction, the baseline pattern was resumed (scale bars: 500 msec [baseline]/20 msec [induction], 20 mV). Asterisk denotes a 250-ms test pulse of −50 pA, used to monitor input resistance. (C) Time course of the first EPSP in the 30-Hz train shows LTP. The induction is illustrated by the gray area. Horizontal blue lines (top) represent time periods over which averages (inset) were taken (scale bars: 10 msec, 0.1 mV). Using such averaged traces, measuring changes in short-term plasticity (Costa et al. 2013) can be used to assess the locus of plasticity expression (Sjöström et al. 2003). (D) As a measure of recording quality, resting membrane potential, input resistance, and bath temperature were monitored throughout experiment. Blue and red indicate cell 1 and cell 4, respectively.