Article Figures & Data
Figures
- Figure 1.
Hebbian LTP induction in two different age groups of mice using perforated patch recordings. Ai, Aii, Current response during voltage clamp to negative 10 mV voltage step during development of perforated patch. For this sample cell, access resistance changed from ∼400 MΩ after 5 min to ∼80 MΩ after 20 min (Ai) and remained stable thereafter for the duration of the experiment (Aii). Bi, Bii, LTP induction protocol for both juvenile (P9-P14) (Bi) and young adult (P22-P28) (Bii) mice. A single EPSP was paired with a single postsynaptic action potential elicited by current injection (5 msec, 0.1-0.85 nA) repeated 30 times. After 20 min, a single EPSP was paired with a postsynaptic burst (20 msec, 0.1-0.85 nA). Stimulation artifacts and capacitance transients have been truncated for clarity. Ci, Cii, Normalized EPSP amplitude monitored over time for both juvenile (Ci) and young adult (Cii) mice. EPSP amplitudes were measured and expressed as a percentage of the mean of the amplitude measured during the last 3 min before single-spike pairing. Test inputs are shown with filled diamonds, and control input is shown with open circles. Error bars indicate SEM. Single arrowheads indicate an episode of single-spike pairing; double arrowheads indicate an episode of burst pairing. Inset, Averaged EPSP waveforms over 3 min periods from baseline period, 20 min after a single-spike pairing episode and 20 min after a burst-pairing episode from a typical cell, are plotted for both age groups of mice. Dotted traces of baseline waveforms are overlaid for direct comparison when potentiation has occurred. Stimulation artifacts have been truncated.
- Figure 2.
Developmental change in LTP induction in juvenile and young adult rats. A, B, Effectiveness of single-spike and burst pairing on EPSP potentiation in P12-P15 and P25-P29 rats. The plot shows the EPSP amplitude monitored over time (6 responses averaged per minute) expressed as a percentage of the mean amplitude before single-spike pairing, using whole-cell patch-clamp recordings. Single arrow heads indicate an episode of single-spike pairing; double arrow heads indicate an episode of burst pairing. Error bars indicate SEM. C, D, Normalized peak EPSP amplitude after pairing episode plotted against the developmental age of the rat (P12-P43). Data points are taken from P12-P15 and P25-P43 experimental groups (A, B) in addition to intermediate-aged rats from similar litters (P18-P23). Peak EPSP amplitude was expressed as a percentage of a 3 min baseline period immediately before each pairing episode. Double exponential functions were fitted to the data (robust fitting minimizing absolute deviations) and are shown as dotted lines in the graphs. E, Effectiveness of single-spike and burst-pairing episodes on EPSP potentiation in P30-P45 rats in the presence of 5 μm bicuculline methiodide. EPSP amplitudes (6 responses averaged per minute) expressed as a percentage of prepairing baseline period were monitored over time using whole-cell patch-clamp recordings. Single arrowheads indicate an episode of single-spike pairing; double arrowheads indicate an episode of burst pairing. Error bars indicate SEM. F, Measure of the changes in synaptic efficacy after both single-spike pairing and subsequent burst-pairing episodes relative to initial baseline responses for hippocampal rat slices taken from groups of younger rats (P12-P15), older rats (P25-P43), and older rats (P30-P45) in the presence of 5 μm bicuculline methiodide (bic). ss, Change in efficacy after single-spike pairing; bs, change in efficacy after burst-pairing episode. Error bars indicate SEM.
