2. Action

Question 1

spinal contributions to action

Answer 1

corticospinal tract (M1 to LMN (alpha motor neurons) in ventral to muscle), contract/shorten muscles, in pairs
Other descending tracts as well (extrapyramidal tracts)

Question 2

Cerebellar path for action, general

Answer 2

quality control
M1 sends copy of motor command to contra cerebellum, receive ipsi proprioception, send to contra M1

Question 3

3 cerebellar lobes

Answer 3

Flocculonodular - vestibulocerebellum, balance, input vestibular nuclei, output fastigial and vestibular and to LMN to stabilize
Anterior - spinocerebellum, movement coord and execution for practiced, input proprioception and output interposed and descending tracts
Posterior - cerebrocerebellum, motor planning, input cortex, output dentate and thal/cortex,

Question 3

Prism adaptation and cerebellar damage

Answer 3

In healthy - if wear prisms, start out wonky but then correct, when take off prisms, overadjust so wonky, but correct soon
In damage - if wear prism, stay wonky, no correcting, BUT once take off prisms, immediately correct (never changed in 1st place)

Question 3

Basal ganglia parts

Answer 3

caudate nucleus
putamen
striatum = caudate + putamen
nucleus accumbens = junction of puta/caudate
globus pallidus (internal and external)
subthalamic nucleus
substantia nigra

Question 3

Motor loop basal ganglia

Answer 3

does practiced/fluid motion, outputs best response
M1 -> Putamen -> GO/STOP -> thalamus -> M1

Question 4

Go/stop circuitry

Answer 4

Cortex excites striatum (which gets +/- from substantia nigra)
striatum inhibits GP internal
GP inhibits thalamus
less inhibition on thal allows GO
for stop:
striatum sends inhibition to GP external
GP external inhibits GP internal
GP internal inhibits thalamus
inhibiting GP external means less inhibition on internal, meaning more inhibition on thalamus, STOPs thalamus

Question 5

Cortical areas

Answer 5

M1, premotor, frontal eye fields, broca’s area

Question 6

Population coding and BMI

Answer 6

each neuron has a tuning curve of firing for movement, for certain movements, groups of neurons do population coding to fire a direction
Brain Machine Interfaces can decode that population coding to decipher what movement was planned and do it for surgical patients

Question 7

Secondary motor areas

Answer 7

planning of actions
premotor cortex - connected to parietal lobe, externally-guided actions
supplemental motor area - connected to medial frontal, internally-guided actions (default)

Question 8

Mirror neurons and evolution

Answer 8

fire when a goal-oriented actions is observed (in any sense)
modulated by expertise, more firing if know how to do action oneself
maybe important for culture and empathy (learn skills and understand each other)