Fig. 1

Mean arterial pressure, spinal cord blood flow and local field potentials. a Sciatic nerve stimulation produced intensity-dependent increases in MAP. Without anesthesia, MAP changes tended to be smaller but this effect did not reach significance (p = 0.064). An individual example of SCBF changes in both conditions for maximal (9.6 mA), intermediate (2.4 mA) and minimal (0.1 mA) stimulus intensity is shown in b. c Sciatic nerve stimulation also produced intensity-dependent increases in SCBF. However, these responses were not affected by anesthesia. An individual example of SCBF changes in both conditions for maximal (9.6 mA), intermediate (2.4 mA) and minimal (0.1 mA) stimulus intensity is shown in d. e LFP amplitude was larger at higher intensities compared with lower intensities but changes were not linear. Amplitude stopped increasing and even tended to decrease at the highest intensities. An individual example of SCBF changes in both conditions for maximal (9.6 mA), intermediate (2.4 mA) and minimal (0.1 mA) stimulus intensity is shown in f. Note the negative deflection (N1) and the positive wave (P). Also note the latency shift due to anesthesia (see Table 2 for details). Error bars = SEM, n = 6. *p < 0.05; **p < 0.01; ***p < 0.001 compared with the 0.1-mA intensity