Article Figures & Data
Figures
- Figure 1.
Electrical stimulation in horizontal midbrain slices. A, Recording setup illustrating caudal or rostral placements of the bipolar stimulating electrodes. Analysis of caudal versus rostral IPSC: onset delay (B), rise slope (C), and time to peak amplitude (D). E, Example IPSCs illustrating control IPSCs (black) and in the μ-opioid receptor agonist, DAMGO (1 μM; green), for caudal or rostral inputs. F, Mean IPSC amplitude depression after DAMGO (1 µM), for each input. Error bars represent SEM.
- Figure 2.
Location of electrical stimulation determines expression of synaptic plasticity. A, Representative experiment showing LTP induction by HFS with a caudal electrode placement. Inset, Baseline (black traces) and 10–20 min after HFS (red traces). B, Mean IPSC amplitudes from a 10-min baseline and 10–20 min after caudal HFS (n = 16 cells). In this and subsequent figures, thicker black symbols/lines represent the mean response across all cells. C, Representative experiment with HFS of a rostral electrode. Inset, Baseline (black traces) and 10–20 min after HFS (red traces). D, Mean IPSC amplitudes from a 10-min baseline to 10–20 min after rostral HFS (n = 6 cells). E, Time course of averaged IPSC amplitudes before and after HFS (closed symbols = caudal, n = 16; open symbols = rostral, n = 6). F, Paired pulse ratios before and after caudal HFS from each cell that potentiated >10% of basal values (n = 12 cells). G, 1/CV2 values before and after caudal HFS from each cell that potentiated >10% of basal values (n = 12 cells); *p < 0.05, paired t test of amplitude of 10-min baseline versus 10–20 min after HFS, ns, not significant. Error bars represent SEM.
- Figure 3.
LFS of caudal electrode induces LTP. Representative experiment with LFS with a caudal electrode placement without APV (A) or with APV (B). Insets, Baseline (black traces) and 10–20 min after LFS (red traces). C, Time course of averaged IPSC amplitudes before and after LFS. D, Mean IPSC amplitudes from a 10-min baseline to 10–20 min after caudal LFS (n = 38 cells; without APV, n = 25, with APV, n = 13). E, Paired pulse ratios before and after caudal LFS from each cell that potentiated >10% of basal values (n = 22 cells). F, 1/CV2 values before and after caudal LFS from each cell that potentiated >10% of basal values (n = 19 cells). D–F, Gray symbols/lines, no APV, black symbols/lines, with APV present; *p < 0.05, paired t test of amplitude of 10-min baseline versus 10–20 min after LFS, ns, non significant. Error bars represent SEM.
- Figure 4.
No effect with low-frequency optical stimulation of VGAT+ synapses. A, Representative experiment with optical LFS. Inset, Baseline (black traces) and 10–20 min after LFS (red traces). B, Time course of averaged IPSC amplitudes before and after LFS (n = 7). C, Mean IPSC amplitudes from a 10-min baseline to 10–20 min after optical LFS (n = 7 cells). Error bars represent SEM, ns, not significant.
- Figure 5.
Forskolin potentiates GABAergic synapses evoked with caudal stimulation but does not prevent subsequent potentiation by caudal LFS. A, Representative experiment with 10 µM forskolin. Inset, Baseline (black traces) and in forskolin (gray traces). B, Time course of averaged IPSC amplitudes before and during forskolin. C, Mean IPSC amplitudes from a 10-min baseline to 10–20 min after forskolin addition (n = 14 cells). D, Representative experiment with caudal LFS after potentiation by 10 µM forskolin. Inset: baseline in forskolin (gray traces) and 10–20 min after LFS (red traces). E, Time course of averaged IPSC amplitudes before and after caudal LFS after forskolin-induced potentiation was established. F, Mean IPSC amplitudes from a 10-min baseline to 10–20 min after forskolin (n = 10 cells); *p < 0.05, paired t test of amplitude of 10-min baseline versus 10–20 min after forskolin or LFS. Error bars represent SEM.
- Figure 6.
LFS-induced LTP does not require postsynaptic calcium elevation or GPCR activation. A, Representative experiment with caudal LFS when 15 mM EGTA was included in the patch pipette. Inset, Baseline (black traces) and 10–20 min after LFS (red traces). B, Representative experiment with caudal LFS when 1 mM GDP-β-S was included in the patch pipette intracellular solution. Inset, Baseline (black traces) and 10–20 min after LFS (red traces). C, Time course of averaged IPSC amplitudes before and after caudal LFS with: normal KCl internal solution (black symbols, n = 14), or with 15 mM EGTA (orange symbols, n = 8) or 1 mM GDP-b-S (purple symbols, n = 8) in the pipette solution. D, Mean IPSC amplitudes normalized to a 10 minute baseline period at 10–20 min after LFS with the different internal solutions listed in C. Error bars represent SEM, ns, not significant.
Tables
Data structure Type of test 95% confidence interval aNormal distribution Two-tailed unpaired t test –0.79 to 0.98 bNormal distribution Two-tailed unpaired t test –85.83 to 119.6 cNormal distribution Two-tailed unpaired t test –0.99 to 1.01 dNormal distribution Two-tailed unpaired t test –27.21 to 32.06 eNormal distribution Two-tailed paired t test 18.20 to 162.8 fNormal distribution Two-tailed paired t test –78.82 to 59.01 gNormal distribution Two-tailed paired t test –0.43 to –0.002 hNormal distribution Two-tailed paired t test –2.47 to 3.56 iNormal distribution Two-tailed paired t test 5.89 to 85.91 jNormal distribution Two-tailed paired t test –0.17 to 0.0029 kNormal distribution Two-tailed paired t test –0.38 to 4.43 lNormal distribution Two-tailed paired t test –87.36 to 104.7 mNormal distribution Two-tailed paired t test –0.15 to 0.15 nNormal distribution Two-tailed paired t test –9.54 to 10.06 oNormal distribution Two-tailed paired t test 37.01 to 147.8 pNormal distribution Two-tailed paired t test –0.21 to 0.13 qNormal distribution Two-tailed paired t test 1.22 to 110.4 rNormal distribution One-way ANOVA High EGTA 99.09–210.7; GDP-β-S 115.9–153.4
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