Panel A shows line graphs of EMG responses. The x-axis represents time in milliseconds, and the y-axis represents the EMG amplitude in microvolts. Panel B contains bar graphs. The x-axis lists the mouse types, and the y-axis shows the H-response amplitude in millivolts. Panel C is a scatter plot showing the latency of responses following CP nerve stimulation for M-response, H-reflex in the TA muscle, and H-response in the Gs muscle. The x-axis lists individual mice, and the y-axis shows the latency in milliseconds. Panel D displays a line graph of superimposed antidromic action potentials in TA motor neurons following stimulation of the L4 ventral root. The x-axis represents time in milliseconds, and the y-axis shows the membrane potential in millivolts. Panel E contains confocal images of Neurobiotin-filled motor neurons, confirming their identity as those innervating the TA muscle. Panel F shows line graphs of EPSCs evoked at different frequencies for homonymous and antagonistic nerve stimulation. The x-axis represents time in milliseconds, and the y-axis shows the EPSC amplitude in picoamperes. Panel G and H are bar graphs showing the coefficient of variation for the latency of the EPSC onset following CP nerve and Tibial nerve stimulation, respectively. The x-axis lists the stimulation frequencies, and the y-axis shows the coefficient of variation. Panel I is a bar graph comparing CMAP latency in WT, C3 minus slash minus and CD47 minus slash minus mice following stimulation of CP nerve or Tb nerve. The x-axis lists the mouse types and stimulation conditions, and the y-axis shows the CMAP latency in milliseconds. Panel J is a scatter plot showing the resting membrane potential of recorded TA motor neurons in WT, C3 minus slash minus and CD47 minus slash minus mice. The x-axis lists the mouse types, and the y-axis shows the resting membrane potential in millivolts. Panel K displays a line graph of the firing frequency-to-current relationship in TA motor neurons from WT, C3 minus slash minus and CD47 minus slash minus mice. The x-axis represents the steps of current above the rheobase, and the y-axis shows the firing frequency in hertz.
H-responses evoked by antagonistic nerve stimulation in C1q −/− mice and intrinsic properties and morphological identification of TA motor neurons in WT, C3 −/− and CD47 −/− mice. (A) EMG responses from the TA and Gs muscles in response to CP nerve stimulation in a C1q−/− mouse. Red traces depict the average of five responses (shown in grey) acquired at 0.1 Hz. Black arrowheads indicate stimulation artifact. Green arrow indicates the H-reflex. Blue arrow indicates the inappropriate H-response in the antagonistic muscle (magnified in the inset). (B) Amplitude measurements of H-response following CP nerve stimulation in the TA muscle (CP nerve → TA EMG) and in the antagonistic Gs muscle (CP nerve → Gs muscle) in WT and C1q−/− mice. WT: N = 6 mice, C1q−/−: N = 6. Significance: *P < 0.05; unpaired t test; ns: no significance. (C) Latency of responses following CP nerve stimulation for M-response (empty circles), for H-reflex in the TA muscle (red squares), and for H-response in the antagonistic Gs muscle (red circles). In one mouse, no response was evident in the Gs muscle. ns: no significance, unpaired t test. (D) Superimposed antidromic action potentials in TA motor neuron following stimulation of the L4 ventral root. Red arrowhead indicates stimulation artifact. (E) Single optical plane confocal images of visualized Neurobiotin-filled motor neurons confirming their identity as of those innervating the TA muscle. Arrows show colocalization between Neurobiotin (blue) and CTb488 (green) (scale bar: 20 μm). (F) Jitter test of latency confirms monosynapticity of EPSCs. Example of superimposed EPSCs evoked at 0.1 Hz, 0.2 Hz, and 1 Hz. Vertical dotted line with arrows indicates time-locked onset of EPSC at different frequencies for either homonymous (CP nerve) or antagonistic (Tb nerve) stimulation. Recordings from a TA motor neuron in a CD47−/− mouse at P5. Black arrowheads indicate stimulus artifact. (G and H) Coefficient of variation for the latency of the EPSC onset in TA motor neurons following: (G) CP (homonymous) nerve stimulation and (H) Tb (antagonistic) nerve stimulation. ns: no significance, One-way ANOVA, Tukey’s post hoc test. (I) CMAP latency in WT, C3−/− and CD47−/− mice, following stimulation of CP nerve while recording in the TA muscle, or stimulation of the Tb nerve while recording from the Gs muscle. (J) Resting membrane potential of recorded TA motor neurons in WT, C3−/− and CD47−/− mice. Only one motor neuron was recorded per mouse. WT: N = 7 mice; C3−/−: N = 5; CD47−/−: N = 7. (K) Firing frequency-to-current relationship in TA motor neurons from WT, C3−/− and CD47−/− mice. ns: no significance. One-way ANOVA, post hoc Bonferroni’s test. CAMP, compound muscle action potential.