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ref: Wichmann-1994.08 tags: STN normal physiology delong wichmann date: 02-27-2012 22:05 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-7983514[0] The Primate Subthalamic Nucleus. 1. Functional Properties in Intact Animals.

  • Lots of cells -- 301 cells in the STN, 1589 microstimulation sites, 72 cross-correlation pairs.
  • 55% modulated to passive contralateral movement, 86% of these to muscle palpitation, 25% to light touch.
  • Caudalventral STN devoid of calls responding to touch or movement.
  • Somatotopic organization: lateral arm, medial leg.
    • Representation of proximal muscles / portions much larger than distal portions, consistent with Carpenter 1950.
  • Mostly rate increases in response to step tracking tasks, usually uniphasic.
  • 40ua, 200-500 ms train duration, 400 Hz did not produce movement. Stimulation of the lateral borders often led to eye movements.
  • 11% of pairs were seen to be synchronized, separated by 100-200um.
    • Much smaller than in the cortex.
    • This strongly supports the concept of functional segregation in the basal ganglia-thalamocortical pathways.
  • Mean firing rate 23 Hz old studies, 19 Hz present study.
  • "Most hypotheses concerning the role of the basal ganglia in movement were derived from experience with diseases originating in the basal ganglia or from experiments involving the activation or inactivation of large parts of BG nuclei. These results are notoriously hard to interpret, because gross changes in motor circuit activity likely results in rather nonspecific activity changes in multiple parts of the neuraxis, unlike minute alterations in the firing patterns of individual neurons in the basal ganglia may have under physiological conditions".
  • Basal ganglia may have a role in the late phases of movement, perhaps even their termination.
  • "More is known about the role of the indirect pathway in the pathophysiology of movement disorders such as Parkinson's disease and ballism than in the control of normal movement." word, yes.

____References____

[0] Wichmann T, Bergman H, DeLong MR, The primate subthalamic nucleus. I. Functional properties in intact animals.J Neurophysiol 72:2, 494-506 (1994 Aug)