FIG 3.

The reduction of CLN‐evoked responses on dSPN was attributable to postsynaptic mechanisms. (A) Input–output curves of CLN‐evoked EPSCs in dSPNs from control (black) and parkinsonian (red) mice. Left: Representative traces of CLN‐evoked EPSCs. Right: CLN‐EPSC areas (pC) are plotted against laser intensity. Control vs. parkinsonian (laser power [mW]): P < 0.001 (8.35), P < 0.001 (6.25), P = 0.006 (4.41), P = 0.293 (2.04), P = 0.438 (0.98), rank‐sum test. Control: n = 30, N = 14. Parkinsonian: n = 25, N = 9. (B) AMPA/NMDA ratios of CLN synapses on dSPNs from control and parkinsonian mice. Left: representative traces showing CLN‐EPSCs evoked by whole field stimulation. AMPA EPSCs were measured by peak amplitude at −70 mV. NMDA EPSCs were measured at +40 mV. Downward arrowheads indicate the time point (200 ms from stimulation) when NMDA EPSCs were measured. Right: box plots of AMPA/NMDA ratios of CL synapses on dSPN from control and parkinsonian mice. Control vs. parkinsonian; P = 0.0275, rank‐sum test. Control: n = 11, N = 8. Parkinsonian: n = 5, N = 5. (C and D) Paired‐pulse ratios of CLN‐evoked EPSCs in dSPNs. (C) Representative traces of CLN‐dSPN EPSC when CL axons are optically stimulated with 50 ms interval. (D) Box plots of paired‐pulse ratios at 20 Hz stimulation. P = 0.633, rank‐sum test. Control: n = 18, N = 11, parkinsonian: n = 11, N = 8. (E and F) Examples of CLN input mappings from dSPNs of control (E) and parkinsonian (F). Projection image superimposed by mapping grid. Gray dots indicate responsive sites with <50% failure rates. Blue dots indicate responsive sites with 51% < failure rate < 90%. Scale bar; 20 μm. Middle: example traces with failure rate (FR). Gray thin lines are evoked responses at a typical stimulation spot. Thick black lines are averages of the individual traces. Scale bar: 10 pA and 20 ms. (G) Box plots of the number of responsive sites in dSPN from control and parkinsonian mice. Control median value; 22, parkinsonian median value; 17. Control vs. parkinsonian; P = 0.2162, rank‐sum test. Control: n = 12, N = 7, parkinsonian: n = 8, N = 6. (H) Cumulative probability of CLN‐dSPN EPSC peak amplitudes obtained from input mapping experiments. Control vs. parkinsonian; P < 0.001, KS test. Control: event number: n = 192, parkinsonian: event number: n = 144. (I) Cumulative probability of failure rates of CLN‐dSPN EPSC. P = 0.066, KS test. Control: event number: n = 286, parkinsonian: event number: n = 154. (J) Variance plots of CLN‐dSPN EPSC. The events with over 50% failure rates were analyzed. Control: event number: n = 193, parkinsonian: event number: n = 89. (K) Summary diagram of the change of synaptic strength after 6‐OHDA lesion. [Color figure can be viewed at wileyonlinelibrary.com]