Table 3.

Predictors	Estimates	std. Error	CI	Statistic	p	Chi-square (df)	p
Purdue Pegboard test
(Intercept)	11.97	0.73	10.53 – 13.41	16.34	< 0.001
Age Group						141.91 (1)	< 0.001
YA	Reference
OA	− 2.49	0.92	− 4.30 – − 0.69	− 2.72	0.007
GABA	− 0.19	0.43	− 1.05 – 0.66	− 0.44	0.66	4.65 (1)	0.03
Age Group x GABA						6.52 (1)	0.01
Age Group OA:GABA	0.54	0.58	− 0.61 – 1.69	0.92	0.36
Brain Region						3.23 (6)	0.78
SMA	Reference
L DLPFC	− 0.01	0.57	− 1.12 – 1.11	− 0.01	0.99
L SM1	0.21	0.65	− 1.07 – 1.49	0.32	0.75
L PMd	0.17	0.67	− 1.15 – 1.49	0.25	0.80
R DLPFC	0.42	0.58	− 0.72 – 1.56	0.73	0.47
R SM1	0.63	0.72	− 0.78 – 2.03	0.88	0.38
R PMd	− 0.26	0.68	− 1.59 – 1.07	− 0.39	0.70
Age Group x Brain Region						4.08 (6)	0.67
Age Group OA: Brain Region L DLPFC	0.73	0.81	− 0.87 – 2.32	0.90	0.37
Age Group OA: Brain Region L SM1	0.28	0.87	− 1.43 – 1.98	0.32	0.75
Age Group OA: Brain Region L PMd	0.25	0.88	− 1.47 – 1.98	0.29	0.77
Age Group OA: Brain Region R DLPFC	− 0.30	0.85	− 1.97 – 1.36	− 0.36	0.72
Age Group OA: Brain Region R SM1	− 1.24	1.07	− 3.33 – 0.86	− 1.16	0.25
Age Group OA: Brain Region R PMd	0.04	0.87	− 1.66 – 1.75	0.05	0.96
Observations	399
R2 Nagelkerke	0.65
AIC	1482.11
Finger tapping (averaged across simultaneous and alternated finger tapping)
(Intercept)	70.27	5.51	59.43 – 81.10	12.75	< 0.001
Age Group						287.12 (1)	< 0.001
YA	Reference
OA	− 20.69	6.90	− 34.26 – − 7.11	− 3.00	0.003
GABA	− 1.06	3.27	− 7.48 – 5.37	− 0.32	0.75	0.76 (1)	0.39
Age Group x GABA						0.78 (1)	0.38
Age Group OA: GABA	1.02	4.40	− 7.63 – 9.66	0.23	0.82
Brain Region						8.97 (6)	0.18
SMA	Reference
L DLPFC	0.88	4.25	− 7.47 – 9.23	0.21	0.84
L SM1	− 4.41	4.89	− 14.02 – 5.20	− 0.90	0.37
L PMd	5.71	5.04	− 4.21 – 15.63	1.13	0.26
R DLPFC	6.12	4.36	− 2.45 – 14.68	1.40	0.16
R SM1	− 7.93	5.38	− 18.51 – 2.65	− 1.48	0.14
R PMd	2.94	5.09	− 7.07 – 12.94	0.58	0.56
Age x Brain Region						5.47 (6)	0.49
Age Group OA: Brain Region L DLPFC	− 0.75	6.11	− 12.76 – 11.26	− 0.12	0.90
Age Group OA: Brain Region L SM1	3.99	6.53	− 8.86 – 16.83	0.61	0.54
Age Group OA: Brain Region L PMd	− 2.99	6.60	− 15.96 – 9.98	− 0.45	0.65
Age Group OA: Brain Region R DLPFC	− 0.85	6.37	− 13.37 – 11.67	− 0.13	0.89
Age Group OA: Brain Region R SM1	13.83	8.02	− 1.94 – 29.60	1.72	0.09
Age Group OA: Brain Region R PMd	− 2.17	6.51	− 14.97 – 10.64	− 0.33	0.74
Observations	399
R2 Nagelkerke	1.00
AIC	3092.44
Bimanual Tracking Task
(Intercept)	− 0.48	0.11	− 0.69 – − 0.26	− 4.43	< 0.001
Age						280.6 (1)	< 0.001
YA	Reference
OA	− 0.54	0.13	− 0.81 – − 0.28	− 4.03	< 0.001
GABA	− 0.02	0.06	− 0.14 – 0.11	− 0.3.	0.77	2.09 (1)	0.15
Age x GABA						9.03 (1)	0.003
Age OA:GABA	0.13	0.09	− 0.04 – 0.29	1.48	0.14
Brain Region						6.40 (6)	0.38
SMA	Reference
L DLPFC	− 0.04	0.08	− 0.21 – 0.12	− 0.52	0.60
L SM1	− 0.05	0.10	− 0.24 – 0.14	− 0.54	0.59
L PMd	− 0.16	0.10	− 0.35 – 0.03	− 1.63	0.10
R DLPFC	− 0.10	0.09	− 0.26 – 0.07	− 1.12	0.26
R SM1	0.03	0.11	− 0.18 – 0.23	0.26	0.79
R PMd	− 0.10	0.10	− 0.29 – 0.10	− 0.98	0.33
Age x Brain Region						1.80 (6)	0.94
Age Group OA: Brain Region L DLPFC	− 0.05	0.12	− 0.28 – 0.19	− 0.38	0.71
Age Group OA: Brain Region L SM1	− 0.04	0.13	− 0.29 – 0.21	− 0.30	0.76
Age Group OA: Brain Region L PMd	0.08	0.13	− 0.17 – 0.33	0.63	0.53
Age Group OA: Brain Region R DLPFC	− 0.07	0.12	− 0.31 – 0.18	− 0.54	0.59
Age Group OA: Brain Region R SM1	− 0.08	0.16	− 0.39 – 0.22	− 0.53	0.60
Age Group OA: Brain Region R PMd	− 0.01	0.13	− 0.26 – 0.24	− 0.08	0.94
Observations	399
R2 Nagelkerke	0.47
AIC	− 51.81