Table 2.

Relationship of imaging and clinical measures to motor performance in PD (model type 3)

Motor variable:	RT (ms)		VMx93 (m/s)		MT9 (m/s)		Pin200 (g)		Pin200SD (g)		TongMx (kg)
Outcome:	D	ND	D	ND	D	ND	D	ND	D	ND
Caudate Kocc (min−1)
t	−1.27	−1.90	−3.27	−2.18	−2.04	−1.49	4.67	1.61	−0.89	−2.18	1.10
P	0.10	0.03*	0.001**	0.02*	0.03*	0.07	0.001**	0.06	0.18	0.01*	0.13
Putamen Kocc (min−1)
t	−0.45	−1.20	−3.10	−1.52	0.79	−1.47	3.8	1.05	−0.15	−1.90	0.90
P	0.32	0.11	0.001**	0.07	0.22	0.07	0.001**	0.15	0.43	0.02*	0.18
UPDRS Total
t	0.82	−0.67	0.14	−1.80	0.12	0.28	1.20	0.06	1.00	2.90	−2.05
P	0.20	0.25	0.44	0.04*	0.12	0.39	0.11	0.47	0.16	0.002**	0.02*

Model type 3: Outcome = 1 + Motor Variable + Age + Gender + random(Subject) + I; degrees of freedom = 67 (PD patients only). Dependent variables (left side of equation) are mean caudate FDOPA K_occ (averaged between brain hemispheres), mean putamen FDOPA K_occ, and total UPDRS scores. Motor variables (right side of the equation), modeled separately for the dominant (D) and non-dominant (ND) hand, were RT, VMx93, MT9, Pin200, and Pin200SD. The significance of contribution of each motor variable to the model is tested using a contrast that yields a t-statistic and P-value.

^*P = 0.01–0.05

^**P = 0.001–0.009

^***P < 0.001.

Abbreviations and variables: D, dominant hand; FDOPA, [¹⁸F]fluoro-L-dopa; K_occ, uptake of FDOPA; MT9, movement time to achieve peak velocity during the longest movement; ND, non-dominant hand; Pin200, mean force accuracy for 200 g target (Pin200); Pin200SD, standard deviation in force accuracy at 200 g; RT, simple reaction time; TongMx, maximum tongue protrusion strength; UPDRS, Unified Parkinson's Disease Rating Scale total score; VMx93, maximum instantaneous movement velocity scaling to reach distance (peak velocity for 9-inch reach [~22.9 cm] – peak velocity for 3-inch reach [~7.6 cm])