Movement ( + Textbook Chapter 7 )

Question 1

Explain THREE things highlighting the relevance of the muscles in the context of biological psychology.

Answer 1

Muscles allow…
- Movement.
- Behavioural expression.
- Response to stimuli.

Question 2

Define:

The quantal theory of neurotransmitter release.

Answer 2

Neurotransmitters are released from vesicles typically containing a similar number of molecules in each.

Increased stimulation leads to increased release of fixed ‘packages’ (vesicles).

Question 3

List:

The THREE types of muscle cells.

Answer 3

• Smooth
• Striated
• Cardiac

Striated muscle cells are also known to be skeletal muscle cells.

Question 4

What function does smooth muscle tissue serve?

Answer 4

Mobility and motility of internal organs.

Question 5

What function does striated muscle tissue serve?

Answer 5

Support and movement of the skeletal system.

Question 6

What function does cardiac muscle tissue serve?

Answer 6

Enabling the pumping action of the organ to power blood circulation.

Cardiac muscle cells are similar to striated, but appear more like a tangled network.

Question 7

True or False:

One neuron can innervate multiple different skeletal muscle cells.

Answer 7

True

Question 8

True or False:

Each muscle fibre receives information from only one neuron.

Answer 8

True

Because although each neuron can innervate many different fibres for coordinated stimulation, each fibre should only be receiving input from a single source for specialised activation.

Question 9

State:

Each structural level of skeletal muscle.

In order from smallest unit to largest unit.

Answer 9

1. Myofilaments (actin and myosin).
2. Myofibrils (bundles of myofilaments).
3. Sarcomeres (segments end to end along myofibrils).
4. Muscle fibre (sarcomeres end to end).
5. Skeletal muscle (group of muscle fibres).

Question 10

What is the plasma membrane of a skeletal muscle cell more commonly referred to as?

Answer 10

Sarcolemma.

Question 11

What is the ER of a skeletal muscle cell more commonly referred to as?

Answer 11

Sarcoplasmic reticulum.

Question 12

Define:

Neuromuscular junction.

Answer 12

Where a neuron synapses with a muscle fibre.

Question 13

Which neurotransmitter is the most essential for muscle innervation and contraction?

Answer 13

Acetyl choline.

Question 14

What kind of receptors does acetyl choline typically bind to during muscle contraction?

Answer 14

Nicotinergic (ionotropic) receptors.

These lead to an influx of Na⁺ into the cell.

Question 15

Muscle fibre contraction is similar to action potentials in the sense that it is described as…

Answer 15

…an ‘all or nothing’ response.

The fibre will either contract or it won’t.

Question 16

What role does the sarcoplasmic reticulum serve during muscle contraction?

Answer 16

It releases stored Ca²⁺, which activates the sliding action of actin and myosin.

Question 17

Describe:

The sliding filament theory of muscle contraction.

Answer 17

Contraction of a muscle fibre arises when myosin filaments ‘slide past’ actin filaments and shorten the distance between sarcomeres.

Question 18

Motor neurons from which part of the spinal cord initiate contraction or movement of skeletal muscles.

(i.e. efferent neurons)

Answer 18

The ventral horn.

“Towards the belly”.

Question 19

Activation of muscle cells always initiates…

Answer 19

…contraction.

Question 20

Why is it important for the CNS to receive ‘feedback’ from the muscular system?

Answer 20

So that exact positioning may be known and subsequent appropriate activation.

Question 21

What are the TWO types of ‘sensory organs’ of the skeletal muscle system?

Answer 21

• Muscle spindle
  &
• Golgi tendon organs

Question 22

Describe the role of muscle spindle.

Answer 22

Sends ‘stretch response’ sensory information to the dorsal root of the spinal cord.

This signal then bypasses the brain to activate a contraction response.

An example is seen in the knee-jerk reflex.

Question 23

Describe the role of golgi tendon organs.

Answer 23

Provide sensory information for a tension response to help prevent over-contraction.

They synapse with inhibitory interneurons of the spinal cord.

Question 24

Describe:

The two types of muscle reflexes.

Answer 24

• Voluntary: involves conscious thought.
• Involuntary: does not involve conscious thought despite being driven by the nervous system.

There are few ‘purely’ involuntary movements.

Question 25

# List: TWO key features of **ballistic** movements.

Answer 25

- Short and **rapid**. - *Not* subject to **correction**. ## Footnote (e.g. saccadic eye movements or throwing a ball etc.) Such movements are typically performed at maximum velocity and acceleration.

Question 26

# List: TWO key features of **guided** movements.

Answer 26

- Usually **slower**. - Subject to **correction**. ## Footnote Note the corrections may be 'relatively automatic'.

Question 27

# Define: **Fixed motor programmes**.

Answer 27

**Sequences of movements** that are initiated by the brain but then are highly driven by the spinal cord and essentially 'run on their own'. ## Footnote They are a fixed routine from beginning to end, and also tend to have a set length. (e.g. yawning, smiling, frowning).

Question 28

# True or False: Many brain regions play a role in **muscle movement** but none directly innervate muscle cells.

Answer 28

**True** ## Footnote **Lower motor neurons** innervate muscle cells directly.

Question 29

Which TWO **brain regions** make up most of the **motor cortex** and crucial interrelated structures for movement?

Answer 29

**Frontal** and **parietal** regions. ## Footnote The somatosensory cortex is vital for knowing one's positioning and carrying out corresponding actions during movement.

Question 30

What is the 'last stop' for information in the brain before **executing a movement**?

Answer 30

The **primary motor cortex**.

Question 31

Which brain region receives visual and **sensory information** during movement processes first?

Answer 31

The **primary somatosensory cortex**.

Question 32

What unique feature do the **primary motor** and **somatosensory cortices** have in common?

Answer 32

They both have **representations** for each part of the body. ## Footnote The representations are not scaled according to size but rather **relevance** or **strength** of **sensation**. Hence the slightly disturbing 'homunculus' figures generated from these mappings.

Question 33

# True or False: The **primary motor cortex** controls individual muscles.

Answer 33

**False** ## Footnote However, **complex movements** may arise from its stimulation.

Question 34

# List: The SIX key brain regions comprising the **motor cortex**.

Answer 34

- **Primary motor cortex**. - **Primary somatosensory cortex**. - **Prefrontal cortex**. - **Premotor cortex**. - **Supplementary motor cortex**. - **Posterior parietal cortex**.

Question 35

# Fill-in-the-Blank: Movements appear to be '____ ____' .

Answer 35

'**outcome driven**'. ## Footnote Variations are made in order to achieve the 'final result'. (e.g. picking up a cup of coffee, and adjusting hand positioning etc.)

Question 36

What is the role of the **posterior parietal cortex** in movement? ## Footnote (Hint: TWO key things).

Answer 36

- Monitors **positioning** in relation to environment. - Associated with **intentions** to move. ## Footnote Some studies involving stimulation of this brain region have shown to cause people to think they've moved when they haven't.

Question 37

Describe the role of the **supplementary motor cortex** in relation to movement. ## Footnote (Hint: TWO key things).

Answer 37

- **Planning** or **organisation** of complex movements. - **Corrections** and/or **inhibition** of movements. ## Footnote **Inhibtion** would involve deciding the 'usefulness' of a movement *before* engaging in it.

Question 38

Which cortex is **most active** *before* a movement is made?

Answer 38

The **premotor cortex**.

Question 39

Which cortex evaluates the **outcomes** of actions and how to continue from them?

Answer 39

The **prefrontal cortex**. ## Footnote Interestingly, many psychiatric disorders involve reduced activity in this region.

Question 40

Where are the **soma** of neurons that activate muscles **located**?

Answer 40

In the **spinal cord**.

Question 41

Describe the TWO **nerve tracts** within the spinal cord.

Answer 41

**Lateral** and **medial** tracts corresponding to the positioning of the body part they innervate relative to the midline.

Question 42

# Define: The **pyramids of medulla**.

Answer 42

The point at which **pyramidal tracts** from the spinal cord ## Footnote It is at the base of the pyramids whereby the fibres decussate (cross). This allows for **contralateral control** of movement (i.e. the left-hand side of the brain controls the right leg).

Question 43

# Define: **Pyramidal tracts**

Answer 43

Efferent **motor nerve fibres** of (mostly) the **corticospinal tract**.

Question 44

Which brain region makes up only 10% of the organs total mass, but contains **~80% of the neurons**?

Answer 44

The **cerebellum**.

Question 45

What is the MAIN **function** associated with the **cerebellum**?

Answer 45

Fine motor **coordination**. ## Footnote More recent studies attribute broader-spanning roles to this region though, such as those involved in **learning** and **memory** (particularly movement-related).

Question 46

Which set of structures are associated with **switching between** different **motor programmes**?

Answer 46

The **basal ganglia**.

Question 47

Which brain regions make up the **basal ganglia**? ## Footnote (There is dispute on which regions/structures exactly constitute the basal ganglia, so the definition used here coincides with the course textbook by Kalat).

Answer 47

- **Putamen** - **Caudate nucleus** - **Globus pallidus** (lateral and medial) - **Subthalamic nucleus** - **Substantia nigra**

Question 48

What runs through the gap between the **caudate nucleus** and **putamen** in humans?

Answer 48

A **pyramidal tract**.

Question 49

Which two disorders involve damage or dysfunction in the **basal ganglia**?

Answer 49

**Parkinson's** and **Huntington's** disease. ## Footnote Parkinson's isreferred to as **cerebral palsy** when developed early in life (i.e. childhood).

Question 50

# True or False: Both **Huntington's** and **Parkinson's** disease have non-motor symptoms as well.

Answer 50

**True** ## Footnote These can include... **Parkinson's**: cognitive changes, fatigue, dizziness, pain, anxiety, insomnia, etc. **Huntington's**: attentional defecits, apathy, dysphagia, memory issues, depression falls, insomnia, urinary control issues, etc.

Question 51

What is **Parkinson's** often misdiagnosed as to begin with?

Answer 51

**Depression**. ## Footnote This may be contributed to by a loss of control over facial muscles and thus difficulty physically expressing emotions.

Question 52

What **neurophysiological change** is associated with **Parkinson's**?

Answer 52

Deterioration of **dopaminergic cells** in the **substantia nigra**.

Question 53

How **heritable** is **Parkinson's**?

Answer 53

Although **some genetic predispositions** exist, many cases have *no* hereditary history of the disease.

Question 54

Which type of **dopamine receptors** of the **caudate putamen** are involved in the **direct pathway** of the basal ganglia? ## Footnote And are they **excitatory** or **inhibitory**?

Answer 54

**D1** receptors. ## Footnote These are **excitatory**.

Question 55

Which type of **dopamine receptors** of the **caudate putamen** are involved in the **indirect pathway** of the basal ganglia? ## Footnote And are they **excitatory** or **inhibitory**?

Answer 55

**D2** receptors. ## Footnote These are **inhibitory**.

Question 56

What is the **importance** of **D1** and **D2** receptors of the **caudate putamen**?

Answer 56

They are **excitatory** and **inhibitory** dopamine receptors of the **direct** and **indirect** pathways for movement respectively, and thus play a vital role in **initiating** and **stopping** actions. ## Footnote This is why, in diseases like **Parkinson's**, sufferers have difficulty beginning or ending motor movements (e.g. hand tremors, difficulty walking).

Question 57

What is the role of the **direct pathway** of the **basal ganglia**?

Answer 57

It allows the **thalamus** to stimulate the **motor cortex** by ultimately *inhibiting* the **inhibitory effect** of the **globus pallidus** (GPi) and **substantia nigra reticulata** (SNr).

Question 58

What is the role of the **indirect pathway** of the **basal ganglia**?

Answer 58

It *prevents* the **thalamus** from stimulating the **motor cortex** by ultimately *stimulating* the **inhibitory effect** of the (internal) **globus pallidus** (GPi) and **substantia nigra reticulata** (SNr). ## Footnote It takes a few 'extra steps' compared to the direct pathway, which involve the (external) **globus pallidus** (GPe) and the **subthalamic nucleus** (STN).

Question 59

What does **SNc** stand for?

Answer 59

**Substantia nigra pars compacta** ## Footnote These are nuclei associated with **dopamine release**, with roles in reinforcement learning, reward, and motor control.

Question 60

What is **L-dopa**?

Answer 60

A **precursor** of **dopamine** that can pass through the blood-brain barrier and is used as a short-term treatment for **Parkinson's disease**. ## Footnote This is because fully formed dopamine *cannot* pass the blood-brain barrier. As more **dopaminergic cells deteriorate** though, this medication becomes less efficable.

Question 61

Which **alternative treatment** for **Parkinson's** seems to work well, in particular, for **severe tremors**?

Answer 61

**Deep-brain stimulation**. ## Footnote However, this is a very invasive technique, requiring surgery and so is used only in rare cases. But this can have long-lasting effects and allow patients to live up to years of relatively normal lives.

Question 62

Other than deterioration of dopaminergic cells, what is ONE other type of **dysfunction** associated with **Parkinson's**?

Answer 62

Reduction in **mitochondrial functioning**.

Question 63

Why are **stem cell implants** not truly effective in treating disorders like **Parkinson's**?

Answer 63

**Axon pathfinding** is determined by cell-signalling during **early development**. ## Footnote Therefore, it is difficult to get these implanted cells to fully develop in an appropriate way for the intended function.

Question 64

At what **age range** does **Huntington's** typically develop?

Answer 64

**20s** - **30s**

Question 65

# True or False: **Huntington's** is entirely **genetically determined**.

Answer 65

**True** ## Footnote It is caused by a single defective and dominant allele on Chromosome 4 which codes for the Huntingtin protein.

Question 66

What is the key **structural change** to a brain region that is associated with **Huntington's**?

Answer 66

Degeneration and atrophy of the **dorsal striatum**. ## Footnote This particularly affects the **indirect pathway** and so causes issues with **inhibition** of movements. Results in involuntary movement increase. We're not entirely sure yet why only these cells seem to experience the main effct despite the gene being expressed everywhere.

Question 67

What are THREE key **motor symptoms** associated with **Huntington's**?

Answer 67

- **Jerky movements**. - **Facial twitches**. - **Speech difficulties**. ## Footnote Eventually all coordinated motor skills are lost.