5 - sensorimotor system

Question 1

reflex

Answer 1

automatic & subconscious response, stretch or withdrawal reflex

Question 2

stretch reflex

Answer 2

monosynaptic response, does not go via CNS
spinal cord gets sensory information from afferent neuron, linking it directly to the efferent alpha motor neuron.
EPSP to muscle that needs to contract; IPSP to muscle that needs to relax

Question 3

withdrawal reflex

Answer 3

polysynaptic reflex (interneuron involved)

Question 4

posterior parietal association cortex

Answer 4

• posterior to primary somatosensory cortex (=postcentral gyrus)
• sensory input –> motor output
  input from: visual, auditory, somatosensory systems
  output to: dorsolateral prefrontal association cortex, (areas of secondary motor cortex, frontal eye field)

Question 5

dorsolateral prefrontal association cortex

Answer 5

• interacts with posterior parietal to initiate voluntary movement
• input from posterior parietal
• output to secondary motor cortex, primary motor cortex and frontal eye field

Question 6

secondary motor cortex

Answer 6

input from association cortex’
output to: primary motor cortex

parts of secondary motor cortex are:
supplementary & premotor (also cingulate motor areas)

Question 7

supplementary motor area (SMA)

Answer 7

control of internally generated movement, programming specific sequences of movement –> patterns

Question 8

premotor cortex (PMA)

Answer 8

control of externally generated movement, learning and executing complex movement guided by sensory information

Question 9

mirror neurons

Answer 9

match observed behaviour with internal motor representation of that behaviour

Question 10

primary motor cortex

Answer 10

• located in precentral gyrus, also called M1 or area 4
• controls parts of body capable of intricate movement
• motor homunculus!

Question 11

cerebellum

Answer 11

• 10% of brain mass, 50% of brain neurons
• precise control over movements
• performance of everyday voluntary tasks (walking, writing, etc)
• major role in learning of sequences in which time is critical
• also ensures that when one set of muscles initiates movement, opposing set acts as brake
• input from: primary motor cortex, secondary motor cortex
• output to: compares sources and corrects ongoing movement that isn’t going the way it should

Question 12

basal ganglia

Answer 12

• filter => blocking plans of action that are inappropriate

- neural loop -> receive cortical input from various areas & transmit it back to cortex via thalamus

Question 13

4 motorpathways

Answer 13

• dorsolateral corticospinal = direct & distal, contralateral
• dorsolateral corticorubrospinal = indirect & distal, contralateral
• ventromedial corticospinal = direct & proximal, ipsilateral
• ventromedial portico-brainstem-spinal = indirect & proximal, ipsilateral -> via four brain stem structures:
• tectum (auditory and visual info)
• vestibular nucleus (balance)
• reticular formation (motor programs for complex movement)
• motor nuclei (muscles of the face)

Question 14

Golgi tendon organs

Answer 14

respond to increased tension

protective function; if tension to extreme the Golgi tendon organ excite inhibitory interneurons to relax muscle

Question 15

muscle spindles

Answer 15

respond to changes in length