Week 3-4 (Motor Control) Flashcards

Question 1

Q

Why is motor control important to study?

Answer

A

The ultimate function of the nervous system is to control behaviour (move muscles).

Question 2

Q

Examples that the brain is essential for behaviour? (3)

Answer

A

1.) Locked in Syndrome

<ul> <li>Paralyised, butawake &cognitively intact</li> <li>Caused by brainstem stroke</li></ul>

2.) Sea Squirt

<ul> <li>Larvae: Brain in head and big tail for swimming</li> <li>Adult: Eat its own brain after attaching to a rock</li> <li>Suggests brain is useless once the need to move is lost</li></ul>

3.) Blindsight

<ul> <li>Ability of cortically blind people to respond to visual stimuli that they don’t consciously see.</li> <li>unable to consciously process</li></ul>

Question 3

Q

What are the 3 kinds of muscle cells/fibres

Answer

A

Voluntary

<ul> <li>Skeletal (Straited)</li></ul>

Involuntary

<ul> <li>Smooth: Gut and Lungs</li> <li>Cardiac: Heart</li></ul>

Question 4

Q

Kinds of skeletal muscles?

What kind of movements do they make?

Answer

A

<ul> <li>Agonist/Antagonist (Flexor/Extensor)</li> <li>They can only make one movement (i.e. contract)</li></ul>

Question 5

Q

What are the types of muscle contractions (2) and what is its underlying mechanisms (1)

Answer

A

Isometric contraciton: Length of muscle stays the same

<ul> <li>e.g. Trying to lift table</li></ul>

Isotonic contraction: Tone of muscle stays the same

<ul> <li>e.g. Picking up a ball</li></ul>

Sliding Filament Theory is the underlying mechanism

Question 6

Q

What is the anatomy of skeletal muscle? Fine vs Gross motor control?

Answer

A

<ul> <li>Many muscle fibres in each muscle</li> <li>Each muscle fibre isinnervated by only one motor neuron, but one motor neuron innervates many muscle fibres <ul> <li>Fine motor control: Few muscle fibres in onemotor unit</li> <li>Gross motor control: Many muscle fibres in one motorunit</li> </ul> </li></ul>

Question 7

Q

What is the anatomy of the muscle fibre?

Answer

A

Myofibrils

Main work force that causethe muscle contraction. They contain thick filaments (myocin) and thin filamenets (actin)

T-Tubules

Folded cell membranes outside the muscle fibre

Sarcoplasmic Reticulum

Modified endoplasmic reticulum and is full of calcium.

Question 8

Q

What are differences between synaptic trasmission and muscle contraction (3)

Answer

A

In muscle contraction,

<ul> <li>AP always causes muscle twitch (no threshold)</li> <li>AP propogrates in all directions</li> <li>Only Acetylcholine is released</li></ul>

Question 9

Q

How is force modulated in muscles?

Answer

A

Force is modulated by:

<ul> <li>Number of motor neurons activated</li> <li>Rate of firing of motor neuron</li></ul>

An AP ALWAYS result in muscle twitch

Question 10

Q

What is the sliding filament theory?

Answer

A

<ul> <li>Motor neuron from the spinal cord synapses on a muscle fibre at the neuromuscular junction (NMJ), releasing acetylcholine(Axon-to-Membrane)</li> <li>Acetylcholine depolarises membrane by opening sodium-gated channels, creating AP</li> <li>AP propagatesin all directions and including going down the t-tubules <ul> <li>Sarcoplasmic reticulum releases calcium</li> <li>causeMyocin (Thick) and Actin (Thin) filaments in myofibrils to slide over each other, causing contradction</li> </ul> </li> <li>WhenAP is gone,calcium is gradually taken up by the sarcoplasmic reticulum <ul> <li>Muscle relaxes and goes back to its resting position (the filaments goes back to its resting position)</li> </ul> </li></ul>

Question 11

Q

What are the 2 kinds of reflexes?

Answer

A

Muscle Spindles/ Intrafusal Fibres

<ul> <li>Located in muscle</li> <li>Detect muscle length</li></ul>

Golgi Tendon Organs

<ul> <li>Located in tendons</li> <li>Detect muscle stretch (or rather, tension and force because of the stretch)</li></ul>

Question 12

Q

What is the difference between extrafusal and intrafusal muscle fibres

Answer

A

Extrafusal Muscle Fibres

<ul> <li>Voluntary movement</li> <li>Innervated by alpha motor neuron</li></ul>

Intrafusal Muscle Fibres

<ul> <li>Involuntary movement</li> <li>Innervated by gamma motor neuron</li></ul>

Question 13

Q

How does the intrafusal fibres/muscle spindles work?

Answer

A

<ul> <li>Signal from brain telling muscle to contract <ul> <li>AP generated in alpha and gamma motor neurons</li> <li>Extrafusal fibres contract and intrafusal fibres contract a bit (not as much)</li> </ul> </li> <li>Whenintrafusal fibrescontract <ul> <li>Afferent fibre detects small change in length and sends information back to the alpha motor neuron in spinal cord (via. monosynaptic connection)</li> </ul> </li></ul>

Question 14

Q

What is the gorgi tendon reflex. What is the function and give an example.

Answer

A

Golgi Tendon Reflex

<ul> <li>Bundle of nerves located in tendons, at the ends of the muscle</li> <li>Prevent muscle damage and a polysynaptic reflex <ul> <li>e.g. Increasing tension in muscle to hold more weight. Golgi tendon organ sends information tospinal cord and an inhibitory interneuron sends an inhibitory signal to alpha motor neuron so that the muscle relaxes a little</li> </ul> </li></ul>

Question 15

Q

How is M1 distributed?

Answer

A

<ul> <li>Each area of M1 correspond to a particular region of the body (Somatotropic Distribution)</li> <li>Majority of nerves projecting to our spinal cord for body movements starts here</li></ul>

Question 16

Q

What are the nerves that take information from M1 to muscles (i.e., what are the descending motor tracts)?

Answer

A

Descending Motor Tracts

<ul> <li>Lateral tracts: <ul> <li>Control peripheral muscles for fine, precise, discreet movements</li> </ul> </li> <li>Ventromedial (Medial) tracts <ul> <li>Control core muscles for postural movements and bilateral movements</li> </ul> </li></ul>

Question 17

Q

Elaborate on descending motor tracts (lateral)

Answer

A

Lateral Tracts:

<ul> <li>Independent limbs movements</li> <li>Axons from M1 and red nucleus (midbain area involved in arm movements) project to spinal cord and cranial nerves</li> <li>Axons cross over to contralateral sides in bulges of medulla (pyramids)</li> <li>Axons also project to cranial nerves directly</li></ul>

Question 18

Q

Elaborate on descending motor tracts (ventromedial)

Answer

A

Ventromedial Tracts:

<ul> <li>Coordinated movements</li> <li>Axons from many parts of cerebral cortex (not just M1).</li> <li>Axons go to BOTH sides of spinal cord (unlike lateral, don't cross-over in medella)</li></ul>

Question 19

Q

Explain the brain processess in planning and producing a movement

Answer

A

<ul> <li>PPC (7-10s) <ul> <li>Location of item in space</li> </ul> </li> <li>PFC (2-3s) <ul> <li>Action Plan; Inhibition</li> <li>Damage results in illogical disorganised movement</li> </ul> </li> <li>SMC and PMC (???) <ul> <li>SMC: Sequences (e.g., key-in-lock); Inhibiting habitual motions</li> <li>PMC: Complex; Receives arbitrary ("when I clap jump" and non-arbitrary ("where my arm is") information</li> </ul> </li> <li>M1 (0.5s) <ul> <li>Sends via. descending tracts</li> </ul> </li> <li>Desision Conscious (0.2s)</li> <li>Sensory stimuli (0.03-0.05)</li> <li>Movement (0s)</li></ul>

Question 20

Q

What is the basal ganglia (including input, outputs)

Answer

A

<ul> <li>Large group of structures in the forebrain that forms loops with motor regions. <ul> <li>Input <ul> <li>M1, Somatosensory</li> </ul> </li> <li>Output <ul> <li>M1, SMC, PMC, Brainstem</li> </ul> </li> </ul> </li></ul>

Question 21

Q

What are the pathways of basal ganglia? (2) What is the function of the basal ganglia? (3)

Answer

A

Pathways

<ul> <li>Direct: excitatory effect on movement</li> <li>Indirect: inhibitory effect on movement</li></ul>

Function

<ul> <li>Regulate the vigour of movement (Force modulation)</li> <li>“Self initiated” movements</li> <li>Movement inhibition (e.g., "Don't touch this")</li></ul>

Question 22

Q

What brain structures are important when inhibiting a movement

Answer

A

PFC and Basal Ganglia

(That's why before age 5, poor inhibition due to slow maturation of PFC)

Question 23

Q

What is the function of cerebellum?

Answer

A

Cerebellum

<ul> <li>Originally thought for balance and coordination</li> <li>Important for rapid, repetitive movements where aim is important (e.g., basketball; start-stop initiated movement)</li> <li>Continous movements (e.g., cycling) unaffected by cerebelluar damage</li></ul>

Question 24

Q

What does the lateral zone of the cerebellum do? (2)

Answer

A

Lateral Zone

<ul> <li>Receives information about movement plan (e.g,, location of limbs)and send to M1 for modification</li> <li>Damage results in decomposition ofmovements</li></ul>

Question 25

Q

Summarize motor control

Answer

A

Movements are initiated in cerebral cortex, but assisted and modified by cerebellum and basal ganglia

Question 26

Q

What does motor imagery activate? And what happens when imagining a demanding task and and exhaustion task?

Answer

A

Motor imagery

<ul> <li>Imagining a movement activates many of the brain regions involved in the early stage of motor control. <ul> <li>SMC</li> <li>PPC</li> <li>Basal Ganglia</li> <li>Cerebellum</li> </ul> </li> <li>If imagining demanding task, cardiovascular and respiration increase and the muscles used have increased activity.</li> <li>If imagine performing a task to exhaustion then the muscles involve fatigue more quickly.</li></ul>

Question 27

Q

Apraxia: Symptoms (2)

Answer

A

Apraxia

Symptoms:

<ul> <li>"Without Action" but not paralysed</li> <li>Inability to imitate or perform actions to vocal instructions</li></ul>

Question 28

Q

Apraxia: Types

Answer

A

<ul> <li>Limbs: Kicking, etc.</li> <li>Oral (Speech/Muscle): Facial muscles and vocalization</li> <li>Constructional agraphia (rare): Imitating a picture/ Legos</li> <li>Apraxic agraphia (rare): Can spell word (understand) but cannot write</li></ul>

Question 29

Q

Apraxia: Causes and Treatment

Answer

A

Causes

<ul> <li>Parietal Lobe Lesions <ul> <li>Limb: Left frontal and parietal</li> <li>Constructional: Right parietal</li> </ul> </li></ul>

Treatment

<ul> <li>Physical/occupational/speech therapy</li></ul>

Question 30

Q

Ataxia: Symptoms

Answer

A

Symptoms

<ul> <li>"Without coordination"</li> <li>Poor coordination, speech change, unsteady walking, difficulty swallowing</li></ul>

Question 31

Q

Ataxia: Causes

Answer

A

Causes

<ul> <li>Cerebellar damage <ul> <li>Alcohol abuse</li> <li>Stroke & Tumour</li> <li>Multiple Sclerosis</li> <li>Hereditary forms</li> <li>Virus</li> </ul> </li></ul>

Question 32

Q

Ataxia: Treatment/Management

Answer

A

Ataxia: Treatment

<ul> <li>Treat underlying cause (e.g. alcohol consumption)</li> <li>Virus may reverse spontaneously</li></ul>

Ataxia: Management

<ul> <li>Physical/Speech/Occupational therapy</li> <li>Devices to aid mobility when untreatable</li></ul>

Question 33

Q

PD: Symptoms

Answer

A

PD: Symptoms

<ul> <li>Muscle tremor, slow movement, rigidity <ul> <li>"Freezing gait"</li> </ul> </li> <li>Cognitive difficultiies, memory loss, depression</li> <li>Loss of oflaction (early)</li></ul>

Question 34

Q

PD: Causes

Answer

A

PD: Cause

<ul> <li>Neuronal death in substantia nigra which have dopamine releasing axons to basal ganglia</li> <li>Genetics and environmental contributions</li></ul>

Question 35

Q

PD: What are the 2 pathways of dysfunction? What does it mean for the pathways when there is no DA

Answer

A

1.) Direct

<ul> <li>Overall excitatory</li></ul>

2.) Indirect

<ul> <li>Overall inhibitory</li></ul>

No DA > Both pathways are inhibitied > Everything is dampaned (Inhibitory)

Question 36

Q

What is freezing gait. Which disease is it related to and how does one avoid it?

Answer

A

Freezing gait in PD:

Involuntary inability to move at unpredictable times

Avoiding

<ul> <li>Marching: Stepping rhythmically</li> <li>Stepping over an imaginary line</li></ul>

One can cycle but cannot walk

Question 37

Q

PD: Treatment

Answer

A

PD: Treatment

<ul> <li>Behavioural (Exercise)</li> <li>Dopamine Agonists and Mao-B inhibitors (inhibit dopaine breakdown)</li> <li>Deep Brain Stimulation (Advanced disease)</li></ul>

Question 38

Q

Polio: Prevalance and Symptoms

Answer

A

Polio: Viral disease.

Asymptomatic in 90-95%; Symptomatic in 5-10%

Symptoms

<ul> <li>Symptomatic: Flu-like, full recovery</li> <li>Non-Paralytic (1%): Headache, pain, full recovery</li> <li>Paralytic (0.5%): Muscle paralysis, weakness, not all recover</li> <li>Post-polio syndrome (25-50% of all): Weakeness years after</li></ul>

Question 39

Q

Polio: Causes. What is paralyptic polio

Answer

A

Polio

<ul> <li>Viral infection spread through faeces-mouth.</li> <li>Paralytic Polio <ul> <li>Virus attacks the spinal alpha motor neurons.</li> </ul> </li></ul>

Question 40

Q

Polio: Treatment

Answer

A

Treatment:

<ul> <li>None <ul> <li>Focus on prevention via vaccination (Booster vaccination recommended if travelling to active areas (Afghanistan, Pakistan, Nigeria))</li> </ul> </li></ul>

Question 41

Q

Myasthenia Gravis: Symptoms and Causes

Answer

A

Symptoms

<ul> <li>Muscle weakness and fatigue, usually starting with head muscles (often eyelids).</li></ul>

Cause

<ul> <li>Bodies own immune system creates antibodies that bind to Acetylcholine receptor.</li></ul>

Question 42

Q

Myasthenia Gravis: Treatment

Answer

A

Treatment

<ul> <li>Immunosuppressant’s that slow antibody production.</li> <li>Acetycholinesterase inhibitors to increase the time that Ach is present in the neuromuscular junction.</li></ul>

Question 43

Q

Anarchic hand (Alien hand syndrome). Definition and Cause

Answer

A

Definition

<ul> <li>Rare disorder of involuntary, yetpurposeful, hand movements.</li></ul>

Causes

<ul> <li>Anterior cerebral artery strokes, midline tumors, and neurodegenerative illnesses.</li></ul>

Question 44

Q

What are the variants of Anarchic hand and what are the brain parts implicated?

Answer

A

Frontal variant:

<ul> <li>Groping movements</li> <li>SMC, prefrontal cortex, corpus callosum</li></ul>

Posterior variant:

<ul> <li>Levitating hand, withdrawal.</li> <li>PPC, thalamic, occipital lobe damage.</li></ul>

Question 45

Q

Tourette Syndrome: Symptoms and What are the simple and complex variants

Answer

A

Tics: Rapid, repetitive, “involuntary” muscle movements and vocalisations

<ul> <li>Commonly associated with OCD and ADHD</li></ul>

Simple

<ul> <li>Motor: eye blink, head jerk, nose twitch, shrugging.</li> <li>Vocal: grunts, sniffs, throat clearing, barking noise</li></ul>

Complex

<ul> <li>Motor: jumping, twirling, pulling at clothes</li> <li>Vocal: words or phrases, coprolalia, echoalia, palilalia</li></ul>

Question 46

Q

Tourette Syndrome: Causes

Answer

A

Cause:

Unclear pathophysiology but

<ul> <li>Abnormal activity in the cortico-basal ganglia loops.</li> <li>Genetic involvement assumed</li></ul>

Question 47

Q

Tourette Syndrome: Treatment

Answer

A

Treatment

<ul> <li>Mild: Nothing</li> <li>Comorbid conditions (ADHD, OCD, anxiety)</li> <li>Problematic: Antipsychotics (haloperidol, pimozide)deep brain stimulation.</li></ul>

Question 48

Q

What arepsychogenic movement disorders

Answer

A

<ul> <li>Abnormal movements not attributable to an organic neurologic disorder.</li> <li>Considered to be psychologically mediated (conversion disorder)</li> <li>Many patients lack clear psychological distress and don’t believe there is a psychological cause of abnormality.</li> <li>CBT can be useful.</li></ul>

Question 49

Q

What is target muscle reinnervation?

Answer

A

Targeted muscle reinnervation

<ul> <li>Nerves for missing muscles are reattached to existing muscles to prevent neuroma</li> <li>Nerves activate new muscles when attempting 'old' function</li> <li>Electrical activity generated in re-innervated muscle (fromold nervesforming new NMJ with existing muscles)can be mapped out and usedby the prosthetic andto make 'natural' movement</li></ul>

Question 50

Q

What is quadriplegia?

What did prosthetics demonstrate?

Answer

A

Quadriplegia: No signal going through to spinal cord and to muscles

Prosthetic

<ul> <li>Microelectrode planted over M1 and connected to computer</li> <li>Electrodes can be stimulated by computer and computer can control/receive information</li> <li>Can move muscle <ul> <li>Showed that motor cortex is still able to function over a decade after loss of descending motor outputs</li> </ul> </li></ul>

Question 51

Q

Aflalo (2015): Other than M1, where else could electrodes be implanted to enable movement control?

What is the issue?

Answer

A

Anywhere in the pathway but PPC (Think) + M1 (Move)

Issue

No feedback – there is no sensation arising back from the arm etc (eggshell)

Question 52

Q

How does somatosensory feedback work

Answer

A

<ul> <li>Different forms of stimuli will activatedifferent receptors, but</li> <li>Strech/pressure/chemical on receptors open Na+ channels in axons, causing AP</li> <li>AP sends to brain via. spinal nerves which have different characteristics for different receptors <ul> <li>Dermatome: Area of body each spinal nerve innervates</li> </ul> </li></ul>

Question 53

Q

How does sensory information reachthe brain?

Answer

A

<ul> <li>Receptors > Spinal cord > Somatosensory cortex (behind M1)</li></ul>

Question 54

Q

How is somatosensory cortex organised?

How is it different from M1?

Answer

A

Somatotropic organization

<ul> <li>All the information about sensation from the face come in right next to the region of the motor cortex that corresponds to the face.</li></ul>

Difference

<ul> <li>You feel tooth pain but you can’t move your teeth</li> <li>You have lots of sensory information from the genitals but not much control over it.</li></ul>

Question 55

Q

Other than somatosensory cortex, where is information sent to?

What happens if there is damage to one region

Answer

A

Somatosensory information is also sent to insula, which is also involved in emotions

<ul> <li>Feather = Nice</li> <li>Hard harshake = Unpleasant</li></ul>

Damage to one region can cause separation of emotional content versus sensation

Question 56

Q

When sensory nerves are damaged, what can be useful and why?

What are some criticisms

Answer

A

Sensory feedback with prostheses:

<ul> <li>Microarrays placed over somatosensory cortex <ul> <li>Mimics natural biology</li> <li>Adaption/Learning (e.g picking up egg)</li> </ul> </li></ul>

Critics

<ul> <li>Some scientists argue that sensory feedback not essential with visual feedback and practice</li></ul>

Question 57

Q

What is the efference copy?

What is the advantage?

Answer

A

Efference Copy (corollary discharge)

A copy of the motor command sent to sensory regions (instead of muscles).

Advantage

<ul> <li>Enables planned movement to be compared with actual movement</li> <li>Enables sense of self-generated movement</li></ul>

Question 58

Q

Explain why when we copy someone's force, it gets stronger?

How does it relate to tickle

Answer

A

Efference Copy

<ul> <li>We pay more attention to externally generated information than internally generated sensations (because we cannot anticipate)</li> <li>So if you push someone else you think that you’re not doing it as hard as it feels to them</li></ul>

Becausewe know the tickle is coming (efference copy), it doesn't work

Question 59

Q

What are the 2 kinds of tickles? And what does it activate

Answer

A

Tickle

<ul> <li>Light feather touch "itch type" <ul> <li>light touch + Itch</li> <li>Somatosensory and ACC (pleasure)</li> </ul> </li> <li>Deeper laughter provoking type <ul> <li>Pain + Deep Pressure</li> <li>Anterior SMC</li> </ul> </li></ul>

Question 60

Q

Self-tickle with delay. What are the results?

Answer

A

<ul> <li>If there is a delay between thinking and action, one can self-tickle <ul> <li>100ms: More ticklish</li> <li>200ms: About the same as when someone else does it</li> </ul> </li></ul>

Question 61

Q

Explain the link between tickle and schizophrenia

Answer

A

SZ may result from faulty efference copies of speech and movement

<ul> <li>SZ don't reognise speech/movement as self-geneated, attirbuting it to external sources.</li></ul>

Tickle

<ul> <li>SZ without hallucinations = Same as controls</li> <li>SZ with hallucinations = Equally ticklish regardless of delay</li></ul>

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Week 3-4 (Motor Control) Flashcards

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