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ref: Goldberg-2002.06 tags: DBS PD MPTP synchrony date: 02-22-2012 18:25 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-12040070[0] Enhanced synchrony among primary motor cortex neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine primate model of Parkinson's disease.

  • In the (MPTP) parkinsonian state, MI neurons discharged in long bursts (sometimes >2 sec long). These bursts were synchronized across many cells but failed to elicit detectable movement, indicating that even robust synchronous MI discharge need not result in movement.
    • These synchronized population bursts were absent from the GP and were on a larger timescale than oscillatory synchrony found in the GP of tremulous MPTP primates, suggesting that MI parkinsonian synchrony arises independently of basal ganglia dynamics.
  • Specificity of M1 neurons decreased to passive movement; GP showed no decrease in specificity.
    • Might be because of decreased specificity in the first place.
  • Again suggests that it's not rates but dynamics that underly pathophysiology.
  • Evarts 1965, Porter and Lemon 1993: the normal execution of voluntary movement is correlated with an increase in the synchronous discharge of primary motor cortex neurons.
  • No decrease in M1 activity w/ single unit discharge in M1 in MPTP monkeys & metabolic studies.
  • PD corresponds to a loss in specificity in the globus pallidus in response to passive joint manipulation (Filion et all 1988; Boraud et al 2000).
  • Nissl stain stains both neurons and glia (figure 2)
  • ISI plots (here called auto-associative index) markedly different before / after MPTP.
  • M1 can commonly be micro-excited with as little as 5ua (Murthy and Fetz, 1996; Tokuno and Nambu 2000).
  • Temporal width of pathological synchornization on the order of tens to hundreds of milliseconds.
  • Hypothesize loss of functional segregation along parallel corticobasal ganglia circuits (Alexander et al 1986, DeLong 1990)

____References____

[0] Goldberg JA, Boraud T, Maraton S, Haber SN, Vaadia E, Bergman H, Enhanced synchrony among primary motor cortex neurons in the 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine primate model of Parkinson's disease.J Neurosci 22:11, 4639-53 (2002 Jun 1)