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[0] Pastalkova E, Itskov V, Amarasingham A, Buzsáki G, Internally generated cell assembly sequences in the rat hippocampus.Science 321:5894, 1322-7 (2008 Sep 5)

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ref: -0 tags: implicit motor sequence learning basal ganglia parkinson's disease date: 03-06-2012 22:47 gmt revision:2 [1] [0] [head]

PMID-19744484 What can man do without basal ganglia motor output? The effect of combined unilateral subthalamotomy and pallidotomy in a patient with Parkinson's disease.

  • Unilateral lesion of both STN and GPi in one patient. Hence, the patient was his own control.
    • DRastically reduced the need for medication, indicating that it had a profound effect on BG output.
  • Arm contralateral lesion showed faster reaction times and normal movement speeds; ipsilateral arm parkinsonian.
  • Implicit sequence learning in a task was absent.
  • In a go / no-go task when the percent of no-go trials increased, the RT speriority of contralateral hand was lost.
  • " THe risk of persistent dyskinesias need not be viewed as a contraindication to subthalamotomy in PD patients since they can be eliminated if necessary by a subsequent pallidotomy without producting deficits that impair daily life.
  • Subthalamotomy incurs persistent hemiballismus / chorea in 8% of patients; in many others chorea spontaneously disappears.
    • This can be treated by a subsequent pallidotomy.
  • Patient had Parkinsonian symptoms largely restricted to right side.
  • Measured TMS ability to stimulate motor cortex -- which appears to be a common treatment. STN / GPi lesion appears to have limited effect on motor cortex exitability 9other things redulate it?).
  • conclusion: interrupting BG output removes such abnormal signaling and allows the motor system to operate more normally.
    • Bath DA presumably calms hyperactive SNr neurons.
    • Yuo cannot distrupt output of the BG with compete imuntiy; the associated abnormalities may be too subtle to be detected in normal behaviors, explaniing the overall clinical improbement seen in PD patients after surgery and the scarcity fo clinical manifestations in people with focal BG lesions (Bhatia and Marsden, 1994; Marsden and Obeso 1994).
      • Our results support the prediction that surgical lesions of the BG in PD would be associated with inflexibility or reduced capability for motor learning. (Marsden and Obeso, 1994).
  • It is better to dispense with faulty BG output than to have a faulty one.

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ref: Pastalkova-2008.09 tags: hippocampus Buzsaki sequences date: 09-22-2008 21:25 gmt revision:1 [0] [head]

PMID-18772431[0] Internally generated cell assembly sequences in the rat hippocampus.

  • The task was unique: the rats had to run in a wheel for 10-20 seconds before choosing the left or right arms of a figure-8 maze. The rats were rewarded with water if they alternated arm choice.
  • Looked at the activity of pyramical cells - many of them place cells as well as episode-cells - in the hippocampus, and found that the pattern of firing per neuron was predictable and predictive or which choice the rat would take after running in the wheel.
  • The same pattern of hippocampal firing was not found in a control running task (one that did not require a choice).
  • The pattern of firing was phase locked to the theta oscillations in the hippocampus; this phase relationship gradually advanced during the course of trials.
  • During the wheel running, there seemed to be a series of delayed firing bursts by the hippocampal neurons.

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