Topic 5 - Cortical and Subcortical Structures of the Brain Involved in Sensation and Movement

Question 1

Frontal Lobe

Answer 1

1. Higher order cognition

2. Motor function

Question 2

Occipital Lobe

Answer 2

Processes visual info

Passes info to parietal ans temporal lobes

Question 3

Temporal Lobe

Answer 3

Receives info from occipital lobe and then identifies objects

Question 4

Parietal Lobe

Answer 4

Contains primary somatosensory lobe

3D representation of space and our body in 3D space

Question 5

Overview of Brodman’s areas and order

Answer 5

1. From eye to primary and secondary visual cortices
2. Somatosensory info to primary and secondsry somatosensory cortices
3. Both those ^ to posterior parietal cortex
4. Premotor area
5. Primary motor cortex
6. Pyrammidal tracts

Question 6

Primary Somatosensory Cortex

Answer 6

Received somatosensory movement related info from dorsal column pathway snd spinocervico tract

Also projects info to other cortical areas as well as SC

Has 4 functional structures

Question 7

4 Functionsl Structures of the Primary Somatosensory Cortex (S1)

Answer 7

3a - muscle stretch
3b - cutaneous receptors -> touch
1 - rapidly adapting cutaneous receptors (respond when stimulus turns on an off, but not when tbere is sustained stimulus)
2 - deep pressue -> from skin and muscles

Question 8

Posterior Parietal Cortex (PPC)

Answer 8

Receives somatosensory, visual, and vestibular info

Outputs to other sensory cortices and the premotor correx and cerebellum

Question 9

3 specific roles of PPC

Answer 9

1. Spatial coordinations for action ans attention
   - understanding of body in space
   - attending to relevant spatial locations and info
2. Response selection & programming
   - helps produce skilled ations with PrM -> ideomotor & ideationsl apraxia
3. Integration of hand and eye position
   - being able to perform efficient correction
   - > optic ataxia no longer able to effectively modify movements

Question 10

Premotor Cortex and 4 functions (PrM)

Answer 10

Inputs/outputs to S1, PPC, SMA, M1 prefrontal association areas and subcortical structures

1. Regulates prox and dist mysculature
   (Prox-> ventral corticospinal tract, dist-> lateral corticospinal tract)
2. Response selection and programming via connections with PPC
   - setting parameters (force, speed, etc)
   - from PPC, what action is most appropriate based on spatial info of objects and limbs
   - multiJOINT coordination
3. Storage of motor plan
4. Motor learning (consolidation if motor program)

Question 11

Supplementary Motor Area (SMA)

Ext of PrM

Answer 11

Inputs / outputs -> S1, PPC, PrM, M1 other subcortical areas and alpha MNs

1. Regulates prox and dist musculature
2. Response programming
   - coordination of multiLIMB movements
3. Mental practice

Question 12

Primary Motor Cortex (M1)

Answer 12

Inputs - S1, PPC, SMA, PrM and subcortical sites (cerebellum and basal ganglia)

Outputs

• reciprocal connection w/ inout structures
• pyrammidal neurons of lat and vent corticospinak tracts (alpha and gamma MNs, afferents, efferents)

Fxn
- responsibke for translating movement info to behaviour

Question 13

Where are directionally tuned cells most often found?

Answer 13

M1 and PrM

Question 14

3 rules of directionally tuned cells

How they work

Answer 14

1. Fire the most for movement in a specific direction
2. Fire less for movements deviating from the specific direction
3. Are inhibited if movement is in complete opposite direction (ex 90-> 270 or 180->360)

Question 15

What 3 things do directionslly tuned cells tells us about movement?

Answer 15

1. Direction of movement
2. Force of movement (⬆️ in firing rate results in increase in force)
3. Demonstrate a role in movement planning (bc they begin to ⬆️ rate if firing prior to movement onset -> look a population vector graph)

Question 16

What do mirror neurons do? (Parietal and PrM areas)

Answer 16

Fire both during the execution and observation of action

• so possibke role in action, learning, and anticipating someone else’s action

Question 17

3 functions of brain stem centres

Answer 17

Postural responses

Startile elicited and triggered responses (pre programmes responses)

Locomotion -> decerebrate cat

Complex, adaptable, goal direction responses that aren’t entirely voluntary in nature

Question 18

Sup peduncle

Answer 18

Midbrain - cerebellem

Output from cerebellum

(Ex. Output from cerebellum goes through sup peduncle to get to thalamus)

Question 19

Mid peduncle

Answer 19

Pons - cerebellum

Input from cortex

Question 20

Inf peduncle

Answer 20

Medulla - cerebellum

Input from and Output to SC

Question 21

List 3 functional divisions of cerebellum

Answer 21

1. Vestibulocerebellum
2. Cerebrocerebellum
3. Spinocerebellum

Question 22

Vestibulocerebellum function

Answer 22

(Vestibular sys cerebellum)

Governs posture and eye movements

The three vestibulo descendinf tracts:

1. Vestibulotecto tract
   - vestibulooccular reflex, vestibular control of eye movements
2. Lateral vestibulospinal tract
   - postural responses of limbs to vestibulo info
3. Medial vestibulospinal tract
   - reflexive hesd movements to vestibular perturbations

Question 23

Cerebrocerebellum function

Answer 23

Planning and initiation of movements (can ⬆️ RT if area is damaged)

• coordinating movements with external timing
• timing antagonist (2nd) burst of triphasic EMG

Question 24

Spinocerebellum function

Answer 24

Planning and execution of movements

• feedback based movements corrections
• timing of antagonist (2nd) burst of triphasic EMG

Question 25

Cerebellum input & output

Answer 25

Input

• afferent connections from SC via brain stem
• efferent commands from PrM and M1 via brain stem (pons)

Output

• indirect connections to SC via brain stem
• indirect connections to PrM and M1 via thalamus

Question 26

Basal Ganglia input

Answer 26

Comes in via striatum

Comes in from many cerbreal structures either direct from cortex or indirect from thalamus

Question 27

Basal Ganglia Output

Answer 27

Back to cortex via the thalamus

-many projections from GPi (internal globus pallidus).

• small pathway from substantia nigra to superior colliculus
  
  • eye movements

Question 28

Direct vs indirect pathways of BG

Answer 28

Direct - facilitation of goal response

Indirect - inhibition of non-goal response