PMID-4966614[] Relation of pyramidal tract activity to force exerted during voluntary movement
- PTNs with high conduction velocity tend to be silent during motor quiescence and show phasic activity with movement.
- PTNs with lower axonal conduction velocities are active in the absence of movement; with movement they show both upward and downward modulations of the resting discharge.
- many PTNs responded to a conditional stimulus before the movement.
- in this study, they wanted to determine if phasic response was more correlated with displacement or with force.
- did this with two different motions (flexion and extension) in two different force loads (opposing flexion and opposing extransion)
- movements were slow (or at least nonballistic) and somewhat controlled - they had to last between 400 and 700ms.
- monkeys usually carried out 3,000 cycles of the movement daily !!
- "prior to the experiment, hte authour was biased to think that the displacement model (where the cortex commands a location/movement of the arm, which is then accomplished through feedback & feedforward mechanisms e.g. in the spinal cord) was correct; experimental results seem to indicate that force is very strongly represented in PTN population.
- many PTN firing rates reflected dF/dt very strongly.
- old, good paper. made with 'primitive' technology - but why do we need to redo this?
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