Lecture 8(AIver) - Motion

What did Dan Wolpert argue is the main reason humans have brains?

To produce adaptable and complex movements

What structure sits at the lowest level of the motor hierarchy?

Spinal cord

What are effectors?

Parts of the body that can move

What type of neurons produce muscle contractions?

Alpha motor neurons

What determines the force generated by a muscle?

Number/frequency of alpha motor neuron action potentials and number of muscle fibres

What do muscle spindles detect?

How much a muscle is stretched

What are pyramidal tracts?

Motor tracts travelling directly from cortex to spinal cord

What are extrapyramidal tracts?

Motor tracts originating in subcortical regions and projecting to the spinal cord

What are three major functions of the cerebellum?

Balance/posture, timing of movements, and coordination

What disorder results from cerebellar damage?

Ataxia

What are the main inputs to the basal ganglia?

Striatum (caudate + putamen)

What tract carries axons from motor cortex to spinal cord?

Corticospinal tract

What is another name for the primary motor cortex?

BA4 or M1

What type of organisation does M1 contain?

Somatotopic representation

Why do fingers occupy large areas in M1?

They perform fine motor movements

What are the two subdivisions of BA6?

Premotor cortex and supplementary motor area

What disorder is associated with lesions in the dorsal-dorsal stream?

Optic ataxia

What disorder is associated with lesions in the ventral-dorsal stream?

Apraxia

What are central pattern generators?

Spinal neurons producing sequences of movement without brain input

What does the endpoint control hypothesis propose?

Movements are planned based on their final goal

What method records activity from individual neurons?

Single-cell recording

What did Georgopoulos et al. (1995) demonstrate?

Motor neurons show directional tuning

What is a population vector?

The summed preferred movement directions of many neurons

What does the affordance competition hypothesis propose?

Action selection and specification occur simultaneously

What are affordances?

Opportunities for action defined by the environment

What are mirror neurons?

Neurons active during both action performance and observation

Who discovered mirror neurons?

Rizzolatti and colleagues

What are the three main components of a brain-machine interface (BMI)?

Brain recording method, decoding algorithm, and prosthetic effector

What disease is caused by degeneration of indirect pathway neurons?

Huntington’s disease

What symptom characterises Huntington’s disease?

Hyperkinesia

What disease results from loss of dopamine neurons in the SNc?

Parkinson’s disease

What symptom characterises Parkinson’s disease?

Hypokinesia

What is bradykinesia?

Slowed movement

What does the direct basal ganglia pathway do?

Facilitates movement and increases cortical excitation

What does the indirect basal ganglia pathway do?

Suppresses movement and decreases cortical excitation

How does dopamine affect the direct pathway?

Excites it via D1 receptors

How does dopamine affect the indirect pathway?

Inhibits it via D2 receptors

What did Kawai et al. (2015) investigate?

Whether motor expertise depends on cortex or subcortex