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[0] Schwartz AB, Cortical neural prosthetics.Annu Rev Neurosci 27no Issue 487-507 (2004)[1] Carmena JM, Lebedev MA, Henriquez CS, Nicolelis MA, Stable ensemble performance with single-neuron variability during reaching movements in primates.J Neurosci 25:46, 10712-6 (2005 Nov 16)

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ref: Schwartz-1994.07 tags: Schwartz drawing spiral monkeys population vector PV date: 01-16-2012 18:52 gmt revision:1 [0] [head]

PMID-8036499[0] Direct cortical representation of drawing


[0] Schwartz AB, Direct cortical representation of drawing.Science 265:5171, 540-2 (1994 Jul 22)

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ref: Schwartz-1988.08 tags: Georgopoulos 1988 motor coding cortex population vector date: 12-20-2011 00:49 gmt revision:3 [2] [1] [0] [head]

PMID-3411361[0] Primate motor cortex and free arm movements to visual targets in three-dimensional space. I. Relations between single cell discharge and direction of movement.

  • 475/568 (83%) of cells varied in an orderly fashion with movement -- tuned to a movement direction.
    • As before, binned the firing based on movement direction.
  • generalize 2-D results [1][2]
  • Totally awesome tracking system: a spark gap was attached to the monkey's wrist and was discharged every 20ms. The sonic signal was picked up by at least 3 of the 8 ultrasonic recievers placed at the corners of the workspace and the xyz coordinates were calculated from the sonic delays using a microprocessor-based system.
  • monkey(s) had to press lighted buttons (arcade buttons) within this workspace.
  • otherwise same materials / methods as before.
  • every effort was made to isolate initially negative-going action potentials, and indication that the neuron was less likely to be damaged.
    • fiber spikes are initially positive. Cite Mountcastle et al 1969.
  • EMG signals gained 3000 and bandpassed 100-500Hz. rather narrow, but normal I guess.
  • Neural data recorded as interspike intervals.
  • vectoral dot-product tuning of cells, with the coeficients set by multiple linear regression.
    • This is equivalent to cosine tuning.
  • rather complicated CUSUM for determining onset of activity - including inhibition.
  • as in the earlier study, 60% of cells were tuned in the reaction time, and 85% within the movement time.
  • EMG activity looks like it can be described with cosine tuning as well.
  • 3D tuning directed over the whole space.
  • Residuals of firing rates measured with respect to the tuning functions; residuals were mean zero and approximately the same spread, and were distributed equally over the 3D space.
  • movement latency about 300ms. pretty quick reaction time?
  • Got some pretty awesome graphics for 1986 :)
  • The discharge rate of motor cortical cells varies with the magnitude of force and that cells with higher thresholds are recruited at progressively higher forces (Hepp-Reymond et al 1978).
  • Murphy et al 1982 found that ICMS to M1 caused rotation about single joints, which is inconsistent with cosine tuning (would require complex tuning, or tuning to joints).
  • They argue that cosine tuning refects transformatino by the propriospinal system, which engages patterns of muscle activity.
    • Most PTNs can influence several motoneuron pools in the spinal cord. (Fetz and Finocchio 1975, Fetz and Cheney 1978, 1980 ... Lemon 1986, Cheney and Fetz 1985)
    • Suggest that PTNs related to the weighted combinations of muscles.


[0] Schwartz AB, Kettner RE, Georgopoulos AP, Primate motor cortex and free arm movements to visual targets in three-dimensional space. I. Relations between single cell discharge and direction of movement.J Neurosci 8:8, 2913-27 (1988 Aug)
[1] Georgopoulos AP, Kalaska JF, Caminiti R, Massey JT, On the relations between the direction of two-dimensional arm movements and cell discharge in primate motor cortex.J Neurosci 2:11, 1527-37 (1982 Nov)
[2] Thach WT, Correlation of neural discharge with pattern and force of muscular activity, joint position, and direction of intended next movement in motor cortex and cerebellum.J Neurophysiol 41:3, 654-76 (1978 May)

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ref: Schwartz-2004.01 tags: Schwartz BMI prosthetics M1 review 2004 date: 04-05-2007 16:12 gmt revision:1 [0] [head]

PMID-15217341[0] Cortical Neuro Prosthetics

  • closed-loop control improves performance. see [1]
    • adaptive learning tech, when coupled to the adaptability of the cortex, suggests that these devices can function as control signals for motor prostheses.