Week 7: Motor control

Question 1

The central motor system is arranged as a hierarchy of control levels, which three?

Answer 1

1. Highest level
2. Middle level
3. Lowest level

Question 2

The central motor system (what are the levels, what are their functions and what brain areas are involved?)

Answer 2

1. Highest level: Strategy: the goal of movement (brain areas: areas of the neocortex (frontal and parietal lobes) and the basal ganglia)
2. Middle level: Tactics: the sequence of muscle contractions (brain areas: Motor cortex and cerebellum)
3. Lowest level: Execution: activation of the motor neuron and interneuron pools that generate the goal-directed movement (brain areas: Brain stem and spinal cord)

Question 3

What is the highest level of the central motor system for?

Answer 3

Strategy: the goal of movement

Question 4

Which brain areas are involved in the highest level of the central motor system?

Answer 4

1. Areas of the neocortex (frontal and parietal lobes)
2. Basal ganglia

Question 5

What is the middle level of the central motor system for?

Answer 5

Tactics: the sequence of muscle contractions

Question 6

Which brain areas are involved in the middle level of the central motor system?

Answer 6

Motor cortex and cerebellum

Question 7

What is the lowest level of the central motor system for?

Answer 7

Execution: activation of the motor neuron and interneuron pools that generate the goal-directed movement

Question 8

Which brain areas are involved in the lowest level of the central motor system?

Answer 8

Brain stem and spinal cord

Question 9

To know the positions of your own body in space and how it relates to the positions of others, the mental body image is generated by (3)?

Answer 9

1. Somatosensory input (touch, pressure, pain, temperature, position, movement, and vibration)
2. Proprioceptive input (sensory input to activate the joints and muscles to become more responsive)
3. Visual input (sight)

to the posterior parietal cortex

Question 10

The … and … make a tactical decision and issue instructions to the brain and spinal cord

Answer 10

Motor areas and cerebellum

Question 11

Which areas activates the neurons to cause the movement to be executed?

Answer 11

Brain stem and spinal cord

Question 12

Which of the control levels has a sensory motor system that makes tactical decisions based on memory of sensory information form past movements?

Answer 12

Middle level
(motor cortex and the cerebellum)

Question 13

Axons from the brain descend through the spinal cord trough which two major pathways?

Answer 13

Lateral pathways and ventromedial pathways

Question 14

Which pathways are involved in voluntary movement and under direct cortical control?

Answer 14

Lateral pathways

Question 15

What is the pyramidal decussation?

Answer 15

Junction of the medulla and spinal cord

Question 16

What are the different tracts?

Answer 16

1. Corticospinal tract (the major neuronal pathway providing voluntary motor function)
2. Vestibulospinal tract (maintain head and eye coordination, upright posture and balance, and conscious realization of spatial orientation and motion)
3. Tectospinal tract (orienting the eyes and the head towards sounds as part of the auditory and visual reflex)
4. Pontine (medial) reticulospinal tract (extending the joint)
5. Medullary (lateral) reticulospinal tract (flexing/tightening the joint)

Question 17

Which tract originates in the neocortex, 2/3 of axons in the tract originates in the motor cortex and remaining axons derive from somatosensory areas?

Answer 17

Corticospinal tract (the major neuronal pathway providing voluntary motor function)

Question 18

Which pathways are involved in control of posture and locomotion and are under brain stem control?

Answer 18

Ventromedial pathways

Question 19

Which tract of the ventromedial pathway keeps the head balanced on the shoulders as the body moves?

Answer 19

Vestibulospinal tract (maintain head and eye coordination, upright posture and balance, and conscious realization of spatial orientation and motion)

Question 20

Which tract of the ventromedial pathway directs the head and eyes to move so that the appropriate point of space is imaged on the fovea and helps control muscles of the neck, upper trunk and shoulders?

Answer 20

Tectospinal tract (orienting the eyes and the head towards sounds as part of the auditory and visual reflex)

Question 21

Where does the tectospinal tract originate from and was does this area do?

Answer 21

Superior colliculus
Constructs a map of the world around us

Question 22

Which tract of the ventromedial pathway enhances the antigravity reflexes of the spinal cord and helps maintain a standing posture by resisting gravity?

Answer 22

The pontine (medial) reticulospinal tract
(inhibit the limb flexors and stimulate the extensors -> extending the joint)

Question 23

Which tract of the ventromedial pathway liberates the antigravity muscles from reflex control?

Answer 23

The medullary (lateral) reticulospinal tract
(stimulate the limb flexors and inhibit the extensors -> flexing/tightening the joint)

Question 24

Voluntary movements: … pathways
Reflex control: … pathways

Answer 24

Voluntary: lateral
Reflex: ventromedial

Question 25

The motor cortex consists of area 4 and 6, what do they refer to?

Answer 25

Area 4: primary motor cortex (M1) Area 6: premotor area (PMA) and supplementary motor area (SMA)

Question 26

A mental body image seems to be generated by the posterior parietal lobe, it gets input from area 5 and 7, what do they refer to?

Answer 26

Area 5: primary somatosensory cortical areas Area 7: higher order of visual cortical areas

Question 27

Which lobes are important for abstract thoughts, decision making and anticipating the consquences of action?

Answer 27

Anterior frontal lobes

Question 28

Area 6 converges axons from the PFC and parietal cortex, in what does it play an important role?

Answer 28

In planning of movement (particularly complex movements sequences of far muscles)

Question 29

Which neurons may be part of an extensive brain system for understanding actions and intentions of others also for copying behaviour?

Answer 29

Mirror neurons

Question 30

Which brain part consists of the caudate nucleus, putamen, globus pallidus, the subthalamic nucleus (and substantia nigra)?

Answer 30

The basal ganglia

Question 31

Which structures together are called the striatum?

Answer 31

The caudate and putamen

Question 32

Which pathway allows the basal ganglia to enhance the initation of desired movements?

Answer 32

Direct (excitatory)

Question 33

Which pathway of the basal ganglia is involved in the inhibition of movement?

Answer 33

Indirect pathway (inhibitory)

Question 34

Increased inhibition of the thalamus by the basal ganglia leads to?

Answer 34

Hypokinesia (lack of movement)

Question 35

Decreased basal ganglia output leads to?

Answer 35

Hyperkinesia (excess of movement)

Question 36

What is bradykinesia and akinesia?

Answer 36

**Bradykinesia**: slowness of movement and speed (or progressive hesitations/halts) as movements are continued **Akinesia**: difficulty in initiating willed movements Both in Parkinson's disease

Question 37

What happens within the basal ganglia in Parkinson's disease?

Answer 37

Degeneration of the substantia nigra neurons and their inputs to the striatum

Question 38

Which neurotransmitter facilitates the direct motor loop by activating the cells in the putamen?

Answer 38

Dopamine

Question 39

Which disorder is characterised by hyperkinesia, dyskinesias (involuntary, erratic, writhing movements of the face, arms, legs or trunk), dementia and disorder of personality?

Answer 39

Huntington’s disease

Question 40

What is chorea?

Answer 40

Spontaneous, uncontrollable and purposeless movements

Question 41

What happens within the basal ganglia in Huntingtons?

Answer 41

Loss of neurons in the caudate nucleus, putamen and globus pallidus

Question 42

What disorder can be caused by damage to the subthalamic nucleus?

Answer 42

**Ballism** - involuntary hurling/flinging, irregular, frequently violent movements of the shoulder and arm (on one side of the body) while the patient is awake

Question 43

The larger the population of neurons presenting a type of movement, the finer the possible control, is called the?

Answer 43

Malleable motor map - leads to a prediction

Question 44

Critical motor functions belong to which brain area?

Answer 44

Cerebellum

Question 45

Lesions in the cerebellum can lead to which kind of movement disorders?

Answer 45

**Ataxia** (= without coordination) or **dyssynergia** (disturbance of muscular coordination, resulting in uncoordinated and abrupt movements)

Question 46

What is ataxia?

Answer 46

Degenerative disease of the nervous system, giving trouble with coordination (symptoms are slurred speech, stumbling, falling, inaccurate movements and incoordination)

Question 47

What is Dyssynergia?

Answer 47

Disturbance of muscular coordination, resulting in uncoordinated and abrupt movements

Question 48

What is the vermis in the cerebellum?

Answer 48

The vermis separates the two lateral cerebellar hemispheres and sends output to the brain stem structures

Question 49

How much premotor areas in addition to the primaray motor cortex do we have?

Answer 49

Six (seven in total)

Question 50

Cortical inputs to the primary motor cortex arise from which areas (2)?

Answer 50

1. Frontal premotor areas 2. Parietal somatosensory areas

Question 51

Some aspects of higher order processes such as reward value, context and motor goals are presented in which area?

Answer 51

A premotor area

Question 52

Which areas are involved in the control and initiation/genesis of movement disorders?

Answer 52

The basal ganglia and cerebellum

Question 53

Which basal ganglia structure is important in planning complex sequences?

Answer 53

Striatum (the caudate and putamen)

Question 54

Sequences with greater planning requirements appear to be associated with greater activation only in which side/areas?

Answer 54

Left parietal and premotor areas

Question 55

Damage in the … lobe disrupts the ability to maintain internal representations and produces deficitis in motor imagery

Answer 55

Parietal

Question 56

Left/right hemisphere damage produces deficits in planning, refelected as impaired control of movements direction

Answer 56

Left

Question 57

Left/right hemisphere damage causes problems achieving and stabalising the arm at a desired goal location

Answer 57

Right

Question 58

The explicit learning system relies on … memory and … control, whereas the implicit system relies more on the …

Answer 58

Working memory, executive attentional control, basal ganglia

Question 59

Damage of the (left/right) ... cortex disrupts motor adaption, what suggests that it is critical for motor planning and updating new internal representations

Answer 59

Left parietal

Question 60

What is apraxia?

Answer 60

Difficulty with motor planning to perform tasks or movements

Question 61

Limb praxis is most commonly associated with …. regions on the (left/right) hemisphere

Answer 61

Fronto-parietal regions, left

Question 62

What is ideomotor apraxia?

Answer 62

1. Planning deficits 2. Impaired ability to update motor plans trough learning (intact understanding of what task requires but loss of access to kinetic memory)

Question 63

What does the vestibular system do?

Answer 63

Gives us information of motion, head/body position and orientation

Question 64

What are the three stages of motor learning?

Answer 64

1. Early/cognitive – declarative, verbal selftalk 2. Associative – detect and eliminate errors, link components 3. Autonomous – automatic, frees up conscious working memory

Question 65

In Huntington's disease, the indirect pathway becomes more/less active leading to over-/understimulation of the thalamus In Parkinson’s disease, the indirect pathway becomes more/less active leading to over-/understimulation of the thalamus

Answer 65

Huntington's disease: **less, overstimulation** (too little inhibition leading to more movement) Parkinson's disease: **more, understimulation** (too much inhibition leading to stiffening up of the person)

Question 66

What is Ideation Apraxia?

Answer 66

Wrong execution of an action because they don’t know what to do. They have lost the perception of the object’s purpose

Question 67

Which apraxia is associated with left frontoparietal damage?

Answer 67

Ideomotor apraxia

Question 68

Basal ganglia dysfunction is associated with motor learning deficits in implicit/explicit learning

Answer 68

Implicit