Levodopa-sensitive, dynamic changes in effective connectivity during simultaneous movements in Parkinson's disease

Palmer, Samantha; Eigenraam, Lisette; Hoque, Tasnuva; McCaig, R.G.; Troiano, André R.; McKeown, Martin J.

doi:10.1016/j.neuroscience.2008.06.053

Cited by 64 publications

(54 citation statements)

References 50 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…However, our patients could execute the task at the same level as the healthy participants. Therefore, we speculate that the connectivity of cortico-cerebellar motor connections is increased to compensate for the defective function of the basal ganglia in order to perform self-initiated movements correctly in PD patients (Catalan et al, 1999;Helmich et al, 2009;Palmer et al, 2009;Wu et al, 2010c). In addition, many of the observed increased connections are positively correlated with the UPDRS motor score ( Table 2).…”

Section: Discussionmentioning

confidence: 93%

“…Functional connectivity is defined as the temporal correlations between spatially remote neurophysiological events, whereas effective connectivity is defined as the influence one neuronal system exerts over another (Friston 1994). These methods are increasingly being used to investigate PD-induced modifications of brain networks (Rowe et al, 2002;Ma and Wang, 2008;Helmich et al, 2009;Palmer et al, 2009;van Eimeren et al, 2009;Jahanshahi et al, 2010;Wu et al, 2010a, c). The common finding of these studies is that in addition to the regional activation changes, the connectivity of brain networks also has PD-related modifications during performing various motor tasks.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Effective connectivity of brain networks during self-initiated movement in Parkinson's disease

et al. 2011

View full text Add to dashboard Cite

Section: Discussionmentioning

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Effective connectivity of brain networks during self-initiated movement in Parkinson's disease

et al. 2011

View full text Add to dashboard Cite

“…Such task-related FC is not as commonly studied as resting-state FC, though several groups have published measures of effective connectivity (EC) during a task (Helmich et al, 2009;Palmer et al, 2009Palmer et al, , 2010Wu et al, 2010Wu et al, , 2011b. EC differs from FC in that it is measured during a traditional fMRI scan (i.e., with alternating task blocks), rather than in what we refer to as an fcMRI scan, in which the subject is in a constant state throughout the entire scan.…”

Section: Discussionmentioning

confidence: 99%

Exercise Therapy for Parkinson's Disease: Pedaling Rate Is Related to Changes in Motor Connectivity

et al. 2016

View full text Add to dashboard Cite

Forced-rate lower-extremity exercise has recently emerged as a potential safe and low-cost therapy for Parkinson's disease (PD). The efficacy is believed to be dependent on pedaling rate, with rates above the subjects' voluntary exercise rates being most beneficial. In this study, we use functional connectivity magnetic resonance imaging (MRI) to further elucidate the mechanism underlying this effect. Twenty-seven PD patients were randomized to complete 8 weeks of forced-rate exercise (FE) or voluntary-rate exercise (VE). Exercise was delivered using a specialized stationary bicycle, which can augment patients' voluntary exercise rates. The FE group received assistance from the cycle. Imaging was conducted at baseline, end of therapy, and after 4 weeks of follow-up. Functional connectivity (FC) was determined via seed-based correlation analysis, using activationbased seeds in the primary motor cortex (M1). The change in FC after exercise was compared using linear correlation with pedaling rate. Results of the correlation analysis showed a strong positive correlation between pedaling rate and change in FC from the most affected M1 to the ipsilateral thalamus. This effect persisted after 4 weeks of follow-up. These results indicate that a plausible mechanism for the therapeutic efficacy of high-rate exercise in PD is that it improves thalamo-cortical connectivity.

show abstract

“…18 The cerebellum, a structure in the hindbrain, traditionally associated with pure motor control, is now considered to be essential for the development of forward models, such as predicting the sensory consequences of motor actions. 26 However, a number of studies have suggested that increased cerebellar activity may partially compensate for deficient basal ganglia circuits (e.g., [29][30][31], resulting in alterations in a broad repertoire of movement in PD.…”

Section: Introductionmentioning

confidence: 99%

Assessing Manual Pursuit Tracking in Parkinson’s Disease Via Linear Dynamical Systems

2011

View full text Add to dashboard Cite

Quantitative assessment of motor performance is important for diseases of motor control, such as Parkinson's disease (PD). Manual tracking tasks are well suited for motor assessment, as they can be performed concomitantly with brain mapping techniques. Here we propose utilizing second-order linear dynamical systems to assess manual pursuit tracking performance. With the desired trajectory as the input, and the subject's actual motor response as the output, a linear model characterized by natural frequency and damping ratio is identified for each subject. We applied this method to 10 PD subjects (on and off L: -dopa medication) and 10 normal subjects performing a multi-frequency sinusoidal tracking task. Model parameters were more sensitive than overall tracking errors in determining significant differences between groups. The effect of L: -dopa medication was to reduce the damping ratio and make the range in natural frequency across individuals approach that of normal subjects. We interpret the changes in damping ratio and natural frequency as possibly related to suppression of compensatory cerebellar activity and/or improvement of motor program selection, and the changes in natural frequency as an implicit strategy to maintain settling time in the face of reduce damping ratio. Our results suggest that simple linear dynamical system models can be a powerful method to assess tracking performance in Parkinson's disease because of the additional insight they can provide into neurological processes.

show abstract

Levodopa-sensitive, dynamic changes in effective connectivity during simultaneous movements in Parkinson's disease

Cited by 64 publications

References 50 publications

Effective connectivity of brain networks during self-initiated movement in Parkinson's disease

Effective connectivity of brain networks during self-initiated movement in Parkinson's disease

Exercise Therapy for Parkinson's Disease: Pedaling Rate Is Related to Changes in Motor Connectivity

Assessing Manual Pursuit Tracking in Parkinson’s Disease Via Linear Dynamical Systems

Contact Info

Product

Resources

About