Test-Retest Reliability of Homeostatic Plasticity in the Human Primary Motor Cortex
Table 1
Test-retest reliability (intraclass correlation coefficient [ICC]) estimates for cortical measures recorded across days 0, 2, 7, and 14.
Cortical measures
Cortical measures across days
ICC (95% CI)
Day 0 ()
Day 2 ()
Day 7 ()
Day 14 ()
rMT (% maximum stimulator output)
44 ± 7
45 ± 6
45 ± 7
44 ± 6
0.92 (0.76–0.98)
S1mV (% maximum stimulator output)
54 ± 9
55 ± 11
56 ± 12
55 ± 12
0.95 (0.87–0.99)
Corticomotor excitability (mV)
1.0 ± 0.5
1.2 ± 0.9
1.0 ± 0.8
1.1 ± 0.9
0.80 (0.47–0.94)
Corticomotor responsebaseline (mV)
1.4 ± 0.3
1.3 ± 0.3
1.2 ± 0.3
1.4 ± 0.5
0.41 (−0.72–0.84)
Homeostatic responsebaseline 0 min (mV)
0.8 ± 0.2
0.8 ± 0.2
0.8 ± 0.4
0.8 ± 0.3
0.58 (−0.01–0.88)
Homeostatic responsebaseline 10 min (mV)
0.7 ± 0.2
0.8 ± 0.2
0.7 ± 0.2
0.6 ± 0.1
0.61 (−0.03–0.89)
Homeostatic responsebaseline 20 min (mV)
0.8 ± 0.4
0.7 ± 0.2
0.8 ± 0.2
0.7 ± 0.2
0.43 (−0.67–0.85)
Homeostatic responsebetween 0 min (mV)
0.6 ± 0.1
0.6 ± 0.2
0.8 ± 0.4
0.7 ± 0.4
0.61 (−0.03–0.89)
Homeostatic responsebetween 10 min (mV)
0.5 ± 0.2
0.6 ± 0.2
0.6 ± 0.3
0.5 ± 0.2
0.67 (0.12–0.91)
Homeostatic responsebetween 20 min (mV)
0.6 ± 0.3
0.5 ± 0.2
0.7 ± 0.3
0.6 ± 0.2
0.60 (−0.06–0.89)
Cortical measures: (i) resting motor threshold (rMT), (ii) transcranial magnetic stimulator (TMS) intensity needed to elicit an average peak-to-peak MEP amplitude of 1 mV(S1mV), (iii) corticomotor excitability (motor-evoked potential (MEP) amplitude recorded at 120% of rMT), (iv) the corticomotor response to the first block of anodal tDCS normalised to baseline (corticomotor responsebaseline), and (v) the corticomotor (homeostatic) response to the second block of anodal tDCS normalised to “baseline” (homeostatic responsebaseline) and “between” (homeostatic responsebetween) at 0 min, 10 min, and 20 min follow-ups.
