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ref: Zacksenhouse-2007.07 tags: Zacksenhouse 2007 Odoherty Nicolelis cortical adaptation BMI date: 01-06-2012 03:10 gmt revision:3 [2] [1] [0] [head]

PMID-17637835[0] Cortical modulations increase in early sessions with brain-machine interface.

  • "we demonstrate that the modulations of the firing-rates of cortical neurons increased abruptly after the monkeys started operating the BMI"
    • My hypothesis: is this like LMAN? Injection of noise for the purpose of exploration?
    • Their hypothesis: we are listening to the noise or effect of increased processing / congnitive load.
    • Alternative: decreased feedback / scrabled feedback makes the individual control signals themselves less controlled.
  • Describes spikes as inhomogeneous poisson processes, and breaks things down thusly.
  • Also develop a parametric model of neuronal firing based on tuning to movement, including velocity and acceleration.
  • Fano factor of recorded neurons increased during BCWH & BCWOH.
  • Percent overall modulation (POM) higher in brain control. That is, the variance explained not by the inhomogeneous poisson process, but rather by firing rate variations.
    • "[T]he ensemble-POM increased mainly due to an increase in the variance of the spike-count, which was not matched by the change in the mean spike-count."
  • Figure 6 is pretty convincing, actually.
  • PVM (percent velocity modulation) correlates strongly with POM, but with a fractional slope, indicating that veolocity tuning accounts for only a fraction of the variance.
    • "Since the increase in POM was not matched by increasing PVM or PKM, the higher neuronal rate modulations observed during brain control cannot be explained only by increased modulations due to the kinematics of the movement."

____References____

[0] Zacksenhouse M, Lebedev MA, Carmena JM, O'Doherty JE, Henriquez C, Nicolelis MA, Cortical modulations increase in early sessions with brain-machine interface.PLoS One 2:7, e619 (2007 Jul 18)