MNS activation and waking

Ok - back to what I was INITIALLY thinking about this morning : neuroendocrinology of transitions between sleep and waking.

PRE-READING

Observed :

• 1. at initial waking, low conscious data rate, low motor reaction times
• 2. hypoxia ( O2 constrained by beddings etc. ) associated increased wakefulness and stress
• 3. excessive heat ( due to insulation ) associated increased wakefulness and stress
• 4. intentional activation of motor units ( any muscle activity, but commonly seen as clenching, curling, or stretching in the morning ) associated with increased wakefulness but not necessarily stress

Inferred :

• 5. seems that (2,3) are via cortisol, so that makes sense
• 6. seems that (4) is doing something complicated, and I am now reading about neural signal voltages and frequencies

READING yields ...

• 7. "Recruitment" refers to the number of motor units activated. This increases from zero load, and "rate coding" only kicks in more after 80% of recruitment.
• 8. Recruitment of fibres by twitch-type* (Henneman Size Principle) :
• - slow, 1* : lowest activation threshold, "playful"
• - fast, 2a : mid-stage
• - fast, 2b : last-stage, largest motor units, "powerful" 
• 9. Motor neural "rate coding" frequencies :
• - 150 to 200 Hz in elite, trained athletes
• - 60 to 120 Hz in normal, initiation of heavily loaded movement
• - 30 to 60 Hz for sustained, heavy loads
• - 15 to 20 Hz under conditions of fatigue, to protect muscles
• 10a. The system adjacent to, but underlying the triple-network, is ARAS / the Ascending reticular activating system ( add pointer to RAS <- a candidate for consciousness functionality). Conscious MNS activity may originate here.
• 10b. Nerves in muscle spindles and Golgi tendon organs : send proprioceptive feedback back to the CNS, causing stimulation. 
• 10c. High-frequency rate-coding utilises monoaminergic (neurotransmitter) pathways : effects spill over into the cerebral cortex.