PMID-21147836[0] Resting oscillatory cortico-subthalamic connectivity in patients with Parkinson’s disease
- Used MEG plus LFP recordings of the STN.
- Two spatially and spectrally separated networks were identified.
- A temporoparietal-brainstem network was coherent with the subthalamic nucleus in the alpha (7-13 Hz) band,
- whilst a predominantly frontal network was coherent in the beta (15-35 Hz) band.
- Dopaminergic medication modulated the resting beta network, by increasing beta coherence between the subthalamic region and prefrontal cortex.
- Idea of characterizing connectivity based on synchronization / comodulation: (Fries 2005).
- Synchronization is exaggerated in Parkinson's disease (Sharott et al 2005b, Mallet et al 2008).
- Some patients had dopamine dysregulation syndrome and medication-induced hypersexuality.
- None of the > 45 Hz STN LFP patterns had a scalp pattern consistent with a cortical source.
- Cortical source frequency not really that different between ON and OFF medication, except at maybe tremor frequencies.
- But cortex drives the subthalamic area robustly.
- That said, these patients were at rest.
- Small difference between ON and OFF states possibly because they were at rest.
- Both healthy subjects and those with parkinson's disease show resting connectivity between basal ganglia and the SMA, temporopareital area and parts of the prefrontal cortex. (Postuma and Dagher 2006); Helmich et al 2010).
- Beta band coupling between cerebral cortex and subthalamic nucleus drops before and during movement (Cassidy et al 2002 PMID-12023312; Lalo et al 2008)
- During imagination of movement (Kuhn et al 2008).
- During action observation (Alegre et al 2010).
- Is this consistent with the conflict / reinforcement learning hypothesis?
- A big problem is determining if the oscillations are pathological or non-pathological
- Impossible to control, since we cannot record from healthy humans.
____References____
[0] Litvak V, Jha A, Eusebio A, Oostenveld R, Foltynie T, Limousin P, Zrinzo L, Hariz MI, Friston K, Brown P, Resting oscillatory cortico-subthalamic connectivity in patients with Parkinson's disease.Brain 134:Pt 2, 359-74 (2011 Feb) |
|