Week 6B: Physiological foundation

Muscles controlling movements of the limbs typically come in pairs: the (…) and the (…)

agonist, antagonist

The strength of a muscle depends on its (…)

length

Hooke’s law formula

F = k* delta L

The group of muscle fibers that are innervated by a single motor neuron is called a (…)

Motor unit

The inverted U-shape of the length tension relation of active muscles follows from the way actin-myosin bridges are formed, why?

Fully stretched the filaments hardly overlap, only few bridges can be formed, fully contracted the different filaments compete for binding sites and there are less bridges. The u shape is optimal because this is the mid-range between stretched and contracted

The somatosensory system - Perception of body posture

Proprioception

The somatosensory system - Kinesthesis

Perception of force and motion

The somatosensory system - External forces

Cutaneous touch

Proprioception is mediated by three different types of mechanoreceptors

1. Joint receptors (joint position)

2. Golgi tendon organs (muscle tension)

3. Muscle spindles (muscle length)

1,2

1. Extrafusal fiber

2. Intrafusal fiber

Experiment: Vibration is given to the inside of the left elbow, stimulating the muscle spindles and Golgi tendon organs. The participant has to match the left and right elbow angle. What is the result

The muscle vibrated appears longer than it actually is

What is the contralateral crossed extensor reflex

Flexion of one side leads to extension on the contralateral side

A frog with the brain removed still shows a wiping reflex, this suggests

A spatial map encoded in the spinal cord

How can reflexes be suppressed

Drugs and diseases

Cerebellum is involved in regulation of (4 items)

1. Muscle tone

2. Coordination

3. Timing

4. Learning

Hypermetria

Overshooting targets

S

1,2,3,4,5,6

1. Cerebral cortex

2. Hypothalamus

3. Amygdala

4. Basal ganglia

5. Thalamus

6. Hippocampus

Main functions

1. Regulates body function

2. Emotion

3. Movement, reward

4. Sensory gateway

5. Memory

Which body parts controls the output and execution of movement plans

Basal ganglia

1,2,3

1. Unsupervised

2. Reinforcement

3. Supervised

Which part of the brain is most relevant during 1. Unsupervised learning 2. Reinforcement learning 3. Supervised learning

1. Cerebral cortex

2. Basal ganglia

3. Cerebellum

Symptoms of Huntington’s disease and what is causing these symptoms

Uncontrollable ballistic movements due to abnormal production of GABA neurotransmitters

Symptoms of Parkinson’s disease and what is causing these symptoms

Tremors and slow movement initiation due to dopamine deficit

What is supplementary motor area involved in

High-level planning of movement sequencing and coordination

Function premotor cortex

Orienting the body

Function parietal cortex

Processing sensory information, spatial awareness, and movement

Disorder: ideational apraxia

Problems in sequencing movements

Disorder: ideomotor apraxia

Inability to imitate

What is response chaining

Each motor act causes a (sensory) stimulus that triggers a subsequent motor act

The name of skill acquisition through refinement of perceptuomotor feedback loops and the name of it if based on motor plans

Closed-loop theory, open loop theory

Why is mirror-symmetric tapping of sequences transferring more easily from one hand to the other than symmetric patterns

Because the muscle activations are symmetric

Three stages of skill acquisition

1. Cognitive stage

2. Associative stage

3. Automatic stage

Novices (…) their joints to (…) DoF, experts (…) their joints in order to (…)

lock, reduce, unlock, improve skills further

Ideomotor theory

Ideas are tightly linked to motor actions and as such mental activities automatically trigger actions