Inter‐ and intralimb oscillator coupling in Parkinsonian tremor

Hurtado, J. M.; Lachaux, Jean-Philippe; Beckley, Dennis J.; Gray, Charles M.; Sigvardt, Karen A.

doi:10.1002/1531-8257(200007)15:4<683::aid-mds1013>3.0.co;2-#

Cited by 64 publications

(32 citation statements)

References 33 publications

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“…Note, however, that the amount of common bilateral input remained fairly small throughout the experiment in agreement with previous Wndings of bilateral independent tremor activity (Marsden et al 1969;Lauk et al 1999;Marsden et al 1999;Hurtado et al 2000). There, MU synchronization was examined primarily between bilateral hand muscles, whereas in the present experiment the increase in 8-12 Hz bilateral synchronization was found between upper-arm muscles.…”

Section: Discussionsupporting

confidence: 91%

Bilateral motor unit synchronization is functionally organized

Boonstra

Daffertshofer

et al. 2006

Exp Brain Res

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To elucidate the neural interactions underlying bimanual coordination, we investigated in 11 participants the bilateral coupling of homologous muscles in an isometric force production task involving fatiguing elbow Xexion and extension. We focused on changes in motor unit (MU) synchronization as evident in EMG recordings of relevant muscles. In contrast to a related study on leg muscles, the arm muscles did not exhibit MU synchronization around 16 Hz, consistent with our hypothesis that 16 Hz MU synchronization is linked to balance maintenance. As expected, bilateral MU synchronization was apparent between 8 and 12 Hz and increased with fatigue and more strongly so for extensor than for Xexor muscles. MU synchronization in that frequency band is interpreted in terms of common bilateral input and substantiates the idea that common input is functionally organized. Since these Wndings are consistent with the literature on mirror movements, they suggest that both phenomena may be related.

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Section: Discussionsupporting

confidence: 91%

Bilateral motor unit synchronization is functionally organized

Boonstra

Daffertshofer

et al. 2006

Exp Brain Res

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“…This phenomenon is occasionally observed in human patients (Vidailhet et al, 1999) and may be attributed to tremor masking by severe akinesia and rigidity. As in human studies (Hurtado et al, 2000;Raethjen et al, 2000;Ben-Pazi et al, 2001), the DRT states were characterized by a low coherence level between the tremor of the limbs even in Off states; however, in the levodopa-naive state, limb tremor was highly coherent. These results indicate (in line with the electrophysiological studies discussed below) that DRT causes major changes in the functional organization of the basal ganglia.…”

Section: Tremor Analysismentioning

confidence: 58%

Dopamine Replacement Therapy Does Not Restore the Full Spectrum of Normal Pallidal Activity in the 1-Methyl-4-Phenyl-1,2,3,6-Tetra-Hydropyridine Primate Model of Parkinsonism

et al. 2006

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Current physiological studies emphasize the role of neuronal oscillations and synchronization in the pathophysiology of Parkinson's disease; however, little is known about their specific roles in the neuronal substrate of dopamine replacement therapy (DRT). We investigated oscillatory activity and correlations throughout the different states of levodopa-naive parkinsonism as well as "Off-On" and dyskinetic states of DRT in the external globus pallidum (GPe) of tremulous (vervet) and rigid-akinetic (macaque) monkeys and in the internal globus pallidum (GPi) of the vervet monkey. We found that, although oscillatory activity of cells and interneuronal correlation in both pallidal segments increases after induction of parkinsonism with 1-methyl-4-phenyl-1,2,3,6-tetra-hydropyridine (MPTP) and decreases in response to DRT, important differences exist between the two pallidal segments. In the GPi, the fraction of oscillatory cells and relative power of oscillations were significantly higher than in the GPe, and the dominant frequency was within the range of 7.5-13.5 Hz compared with a range of 4.5-7.5 Hz within the GPe. The interneuronal correlations were mostly oscillatory in the GPi, whereas at least half are non-oscillatory in the GPe. We demonstrate that the tremor characteristics after exposure to DRT do not resemble those of the normal or the levodopa-naive state. Moreover, although DRT reverses the MPTP-induced neuronal changes (rate, pattern, and pairwise correlations), the balance between GPe and GPi fails to restore. We therefore suggest that this imbalance reflects additional abnormal organization of the basal ganglia networks in response to dopamine replacement and may constitute the physiological substrate of the limitations and side effects of chronic DRT.

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“…It was originally suggested by Alberts et al (1969) that PD tremor is generated by segregated parallel networks, each involving a different limb. This idea was supported by studies showing that different limbs oscillate independently of each other (Ben-Pazi et al 2001;Hurtado et al 2000;Raethjen et al 2000). A recent study has further confirmed this hypothesis by showing that tremor-related activity in the globus pallidus can be coherent with one tremulous limb but not with the other (Hurtado et al 2005).…”

Section: Introductionmentioning

confidence: 77%

Increased Gamma Oscillatory Activity in the Subthalamic Nucleus During Tremor in Parkinson's Disease Patients

Weinberger¹,

Hutchison²,

Lozano³

et al. 2009

Journal of Neurophysiology

127

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. Rest tremor is one of the main symptoms in Parkinson's disease (PD), although in contrast to rigidity and akinesia, the severity of the tremor does not correlate well with the degree of dopamine deficiency or the progression of the disease. Studies suggest that akinesia in PD patients is related to abnormal increased beta (15-30 Hz) and decreased gamma (35-80 Hz) synchronous oscillatory activity in the basal ganglia. Here we investigated the dynamics of oscillatory activity in the subthalamic nucleus (STN) during tremor. We used two adjacent microelectrodes to simultaneously record neuronal firing and local field potential (LFP) activity in nine PD patients who exhibited resting tremor during functional neurosurgery. We found that neurons exhibiting oscillatory activity at tremor frequency are located in the dorsal region of STN, where neurons with beta oscillatory activity are observed, and that their activity is coherent with LFP oscillations in the beta frequency range. Interestingly, in 85% of the 58 sites examined, the LFP exhibited increased oscillatory activity in the low gamma frequency range (35-55 Hz) during periods with stronger tremor. Furthermore, in 17 of 26 cases where two LFPs were recorded simultaneously, their coherence in the gamma range increased with increased tremor. When averaged across subjects, the ratio of the beta to gamma coherence was significantly lower in periods with stronger tremor compared with periods of no or weak tremor. These results suggest that resting tremor in PD is associated with an altered balance between beta and gamma oscillations in the motor circuits of STN.

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Inter‐ and intralimb oscillator coupling in Parkinsonian tremor

Cited by 64 publications

References 33 publications

Bilateral motor unit synchronization is functionally organized

Bilateral motor unit synchronization is functionally organized

Dopamine Replacement Therapy Does Not Restore the Full Spectrum of Normal Pallidal Activity in the 1-Methyl-4-Phenyl-1,2,3,6-Tetra-Hydropyridine Primate Model of Parkinsonism

Increased Gamma Oscillatory Activity in the Subthalamic Nucleus During Tremor in Parkinson's Disease Patients

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