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ref: Brown-2003.04 tags: PD oscillations DBS date: 02-22-2012 16:06 gmt revision:4 [3] [2] [1] [0] [head]

PMID-12671940[0] Oscillatory nature of human basal ganglia activity: relationship to the pathophysiology of Parkinson's disease.

  • Break oscillations into > 30 Hz and < 60 Hz bands.
    • these two are inversely affected by movement, and inversely affected by dopamine treatment.
    • This seems inconsistent with the other literature. (?)
  • Lesions of the GPi improve dyskinesias, without deleterout effects on motor function.
  • The tact assumption from the MPTP monkey research is that synchronization and bursting is an abnormal phenomena.
    • Also suggest that synchronization may be a means of 'binding' or increasing the salience of input.
  • The degree of synchronization increases during non-oscillating periods in PD patients treated with the dopamine agonist apomorphine.
  • [27] PMID-11431506 and there is one report of locking in patients without tremor.
    • In both nuclei, APO increased the overall proportion of spikes in burst discharges (as detected with Poisson "surprise" analysis), and a greater proportion of cells with an irregular discharge pattern was observed.
    • During the OFF state, more than 15% of neurons tested (STN = 93, GPi = 63) responded to passive movement of two or more joints. After APO, this proportion decreased significantly to 7% of STN cells and 4% of GPi cells (STN = 28, GPi = 26).
    • Concurrent with a reduction in limb tremor, the percentage of cells with tremor-related activity (TCs) was found to be significantly reduced from 19 to 6% in the STN and 14 to 0% in the GPi following APO administration.
  • [31] PMID-9990083 there is evidence that human STN and GPi units firing at tremor frequency show only transient periods of locking to peripheral tremor
    • We found that GPi tremor-related activity at a given site could fluctuate between states of synchronization and independence with respect to upper limb tremor. Consistent with this finding, some paired recording sites within GPi showed periods of transient synchronization. These observations support the hypothesis of independent tremor-generating circuits whose coupling can fluctuate over time.
  • Monkeys treated with MPTP show pronounced increases in synchrony at < 30 Hz.
  • Levodopa markedly increases > 60 Hz coherence between GP & midline EEG.
    • "The synchronization of single units in STN or GPi at high frequencies has not been demonstrated in microelectrode studies to date. (2002).
    • HF coherence is found between SNT and GPi, and these structures w SMA.
  • Stimulation of the pallidium and enteopeduncular nucleus in cats at 3-10Hz leds to synchronization of the EEG and gradual slowing and eventual cessation of spontaneous movements.
    • Could this abnormal, low-frequency, synchronous oscillatory activity in GPi and its input STN act, by means of the thalamus, to hold the motor cortex in a low-frequency antikinetic state in Parkinson’s disease? [7].
  • There is a disappearance of > 60 Hz oscillations in the STN with drowsiness [29].
  • Complex movements are particuarly difficult for PD patients.
  • Human GPi neurons normally fire at 85 to 140 Hz -- so 130 Hz stimulation may entrain them.

Conclusion: he really thinks that there is a strong dichotomy between HF, pro-kinetic, and MF, anti-kinetic oscillations.

____References____

[0] Brown P, Oscillatory nature of human basal ganglia activity: relationship to the pathophysiology of Parkinson's disease.Mov Disord 18:4, 357-63 (2003 Apr)