PMID-17021028[0] Correlations Between the Same Motor Cortex Cells and Arm Muscles During a Trained Task, Free Behavior, and Natural Sleep in the Macaque Monkey
- used their implanted "neurochip" recorder that recorded both EMG and neural activity. The neurochip buffers data and transmits via IR offline. It doesn't have all that much flash onboard - 16Mb.
- used teflon-insulated 50um tungsten wires.
- confirmed that there is a strong causal relationship, constant over the course of weeks, between motor cortex units and EMG activity.
- some causal relationships between neural firing and EMG varied dependent on the task. Additive / multiplicative encoding?
- this relationship was different at night, during REM sleep, though (?)
- point out, as Todorov did, that Stereotyped motion imposes correlation between movement parameters, which could lead to spurrious relationships being mistaken for neural coding.
- Experiments with naturalistic movement are essential for understanding innate, untrained neural control.
- references {597} Suner et al 2005 as a previous study of long term cortical recordings. (utah probe)
- during sleep, M1 cells exhibited a cyclical patter on quiescence followed by periods of elevated activity;
- the cycle lasted 40-60 minutes;
- EMG activity was seen at entrance and exit to the elevated activity period.
- during periods of highest cortical activity, muscle activity was completely suppressed.
- peak firing rates were above 100hz! (mean: 12-16hz).
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