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ref: -2013 tags: microscopy space bandwidth product imaging resolution UCSF date: 06-17-2019 14:45 gmt revision:0 [head]

How much information does your microscope transmit?

  • Typical objectives 1x - 5x, about 200 Mpix!

{1297}
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ref: -0 tags: RF microstimulation UCSF date: 09-04-2014 18:42 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-4550167[1] Sensory responses elicited by subcortical high frequency electrical stimulation in man. -- everything innovative has already been done in the 70s!

  • "A radiofrequency current of 100 kHz sine wave was applied to therapeutic targets in the human brain and produced unpleasant sensory responses. Increasing the applied frequency to 250 kHz eliminated these responses.
  • Targets:
    • Near the junctions between the ventral lateral and the posteroventral lateral thalamic nuclei in patients with dyskinesias
    • Medial lemniscus in patients with intractable pain.
  • Frequently the patients reported that hte 100kHz radiofrequency current produced a severe unpleasant tingling or burning sensation.
    • The sensation was similar in quality and site to that elicited by 60 pps fstimulation, but tended to be much more intense and could not be tolerated by the patients.
  • The current necessary to produce sensory responses could produce a temperature change of less than 0.5 deg C as measured by our thermistor monitor.
  • Brown and Brackett {1298} have shown that motor responses are obtained when stimulating subcortical structures in the cat with frequencies as high as 100 kHz.
    • From 50 Hz to 25 kHz, they found the response to be smooth and definite.
    • Above 25 kHz the responses from most areas consisted of quick transient jerks at the onset of stimulus.
  • Other workers dealing with a variety of structures have reported stimulus responses to quite high frequencies.
    • As the frequency is raised, the current required for excitation increases.
    • Ultimately I 2RI^2R heating and tissue destruction provide the upper frequency limit for excitation.

{1072}
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ref: Starr-2005.06 tags: STN DBS MPTP UCSF dystonia date: 02-28-2012 17:59 gmt revision:5 [4] [3] [2] [1] [0] [head]

PMID-15703229[0] Spontaneous pallidal neuronal activity in human dystonia: comparison with Parkinson's disease and normal macaque.

  • both dystonia and PD.
  • Several firing rate changes:
    • dystonic patients showed decreased GPI firing.
    • PD patients showed higher pallidial discharge
    • GPi discharge rate was inversely correlated with dystonia severity.
  • Control with recordings from normal monkeys.
  • GPi showed increased oscillatory activity in the 2- to 10-Hz range (theta) and increased bursting activity in both dystonia and PD as compared with the normal NHPs.

____References____

[0] Starr PA, Rau GM, Davis V, Marks WJ Jr, Ostrem JL, Simmons D, Lindsey N, Turner RS, Spontaneous pallidal neuronal activity in human dystonia: comparison with Parkinson's disease and normal macaque.J Neurophysiol 93:6, 3165-76 (2005 Jun)