{945} revision 1 modified: 12-20-2011 22:26 gmt

PMID-3139485 Neural integration of movement: role of motor cortex in reaching.

  • Reviews his 2D and 3D population vector / cosine tuning results.
  • Isometric task in [13] varied as a sinusoidal function of load.
    • [1]3 Kalaska 1985 Area 4 and area 5: differences between the load direction-dependent discharge variability of cells during active postural fixation.
  • [14] suggests that separate motor cortical populations are concerned with the control of joint stiffness.
    • [14] Humphrey 1983 Seperate cortical systems for control of joint movement and joint stiffness: reciprocal activation and coactivation of antagonist muscles.
  • proximal muscles are controlled through C3-C4 propriospinal neurons, which receive input from corticospinal, rubrospinal, reticulospinal, and tectospinal tracts, and distribute axons to proximal motorneuron pools [25]
    • The propriospinal system seems to be selectively engaged during reaching movements [28].
    • There is corticspinal input on key inhibitory interneuron that mediates inhibition from afferent fibers to propriospinal neurons [29].
    • References in this from the cat.
  • This is similar to 'the sophisticated integration seen in the locomotor system' locomotive system.
  • From this, Georgopoulos supposes that the motor cortex is concerned with the specification of the direction of reaching in space.
  • He further supposes that this is enacted by individual motor cortical cells influence motoneuronal pools in a weighted fashion.
  • Looking back, I'm surprised at how clean his PV tuning plots are -- the neurons stop fiting when the monkey moves his arm in certain directions.