The objective of this study is to test the hypothesis that bradykinesia in PD can be characterized a disorder of scaling, where the term scaling is taken to apply to movement velocity, movement amplitude and movement force. This hypothesis is made anatomically specific, as follows. It is argued that: 1) in normal subjects movement scalings chiefly controlled by the basal ganglia; 2) in pre-pallidotomy patients scaling control will be cortical; and 3) in post-pallidotomy PD patients, the cerebellum and thalamus will assume dominance. As these hypotheses are anatomically well specified and involve structures at a large remove from one another, it is proposed that PET functional brain imaging be used to test them. This is done by means of a battery of 18 limb-movement conditions in which the demands for velocity, amplitude and force are systematically varied. The same battery of movement tasks (simplified to ten conditions in PD patients, to accommodate physical fatigue) is applied to normal volunteers, pre-pallidotomy PD patients on and off medications, and post-pallidotomy PD patients on and off medications.
| Grafton, S T; Turner, R S; Desmurget, M et al. (2006) Normalizing motor-related brain activity: subthalamic nucleus stimulation in Parkinson disease. Neurology 66:1192-9 |
| Desmurget, Michel; Turner, Robert S; Prablanc, Claude et al. (2005) Updating target location at the end of an orienting saccade affects the characteristics of simple point-to-point movements. J Exp Psychol Hum Percept Perform 31:1510-36 |
| Sathian, K (2005) Visual cortical activity during tactile perception in the sighted and the visually deprived. Dev Psychobiol 46:279-86 |
| Desmurget, M; Grafton, S T; Vindras, P et al. (2004) The basal ganglia network mediates the planning of movement amplitude. Eur J Neurosci 19:2871-80 |
| Desmurget, M; Grafton, S T; Vindras, P et al. (2003) Basal ganglia network mediates the control of movement amplitude. Exp Brain Res 153:197-209 |
| Turner, Robert S; Grafton, Scott T; McIntosh, Anthony R et al. (2003) The functional anatomy of parkinsonian bradykinesia. Neuroimage 19:163-79 |
| Vanlancker-Sidtis, Diana; McIntosh, Anthony Randal; Grafton, Scott (2003) PET activation studies comparing two speech tasks widely used in surgical mapping. Brain Lang 85:245-61 |
| Turner, Robert S; Desmurget, Michel; Grethe, Jeff et al. (2003) Motor subcircuits mediating the control of movement extent and speed. J Neurophysiol 90:3958-66 |
| Grea, Helene; Pisella, Laure; Rossetti, Yves et al. (2002) A lesion of the posterior parietal cortex disrupts on-line adjustments during aiming movements. Neuropsychologia 40:2471-80 |
