Pre Cortical Areas

Question 1

What are the pre cortical areas

Answer 1

The supplemental motor area (more medial to brain)
The Premotor cortex (more lateral
Both are in the frontal lobe

Question 2

Inputs to the SMA?

Answer 2

posterior parietal cortex

Basal ganglia and dentate nucleus (via thalamus) (planning loop)

Question 3

Outputs of SMA

Answer 3

Striatum of the BG (planning loop)

M1/spinal cord/PMC

Question 4

On EEG what occurs on the SMA prior to activation of left and right M1 region?

Answer 4

Increase in activity
Since this increase in activity is observed for both left and right M1 the SMA on either hemisphere is linked via the corpus callosum

Question 5

What is the function of the SMA?

Answer 5

Selects movements based on remembered sequences
Programming distal complex sequences of movement via projections to m1
Coordinates axial muscle movements via direct input to descending tracts
coordination of bilateral movements

Question 6

On measuring blood flow in the brain what occurs in the SMA on simple, complex and imaginary complex movements?

Answer 6

Simple movement = M1+S1 increase blood flow
Complex = SMA and M1+S1 
Imaginary complex (mental rehearsal) = SMA

Question 7

In terms of movement planning what does the SMA do?

Answer 7

Plans movements based on remembered internal cues e.g. Playing a tune on the piano

Question 8

What does rTMS of the SMA do?

Answer 8

During a sequence of complex movements it will cause break down of movement pattern

Question 9

What occurs on lesions of the SMA?

Answer 9

Very rare to have isolated SMA lesions

• Effects bilateral coordination i.e. Will be pronounced when subject tries to two different things with each arm at the same time. Doing the same thing will appear more successful
• movement apraxia (inability to initiate specific and purposely movements despite an functions motor and sensory pathway

Question 10

What are the inputs to the PMC?

Answer 10

PPC

Dentate nucleus of cerebellum via thalamus (planning loop)

Question 11

Outputs of the PMC?

Answer 11

Cerebellum (mainly)
BG
M1
Medial brainstem tracts - allows adjustment of body to allow for coordinated movement to take place

Question 12

What occurs on electrical stimulation of the SMA?

Answer 12

Postural adjustments
Body orientation change
Could be bilateral or unilateral
Closing and opening oh hands

Question 13

The PMC has 3 main functions. What are they?

Answer 13

Signal preparation of movement to visual stimuli
Signal various sensory aspects associated with movement
Fire differently depending in inferred intention of movement non just movement itself

Question 14

To what are PMC neurons sensitive to?

Answer 14

The direction of movement I.e. On certain PMC neurons will fire when driven a particular vector target cue. Will not fire on go cue

Question 15

How has it been shown the PMC prepares for movement based on visual stimuli?

Answer 15

Animals given a visual instruction stimuli which will cause PMC to fire prior to execution. They will firing in interval between instruction and go cue

Question 16

How does the PMC fire in response to sensory aspects of motor acts?

Answer 16

They will fire observing someone else make a particular movement e.g. Opening a nut. The neurons which fire are called mirror neurons and fire on in response to visually observing an action
The PMC will also fire due to the sounds associated with a motor act e.g. The sound of opening a nut
/ way of understanding the action of others

Question 17

Give an example of how PMC neurons fire in responce to inferred intention of movement.

Answer 17

Will fire on preparation fo reaching a cup to drink rather than washing it up.