TB9 - Action and Decision Flashcards
What is dystonia?
This is a movement disorder in which a person’s muscles contract uncontrollably
Where are upper motor neurons found?
The motor cortex
What occurs in the motor cortex?
Planning, initiating and directing voluntary movements
What occurs in the brainstem centres?
Basic movements and postural control
What does the cerebellum control?
Sensory motor coordination
Give examples of a simple reflex
Stretch reflex and knee jerk, mediated at the spinal cord
Give examples of posture and postural change
Standing and balancing
Give examples of locomotion
Walking and running
Give examples of sensory orientation
Head turning and eye fixation
Give examples of species specific action patterns
Ingestion, courtship, escape/defence, grooming
Give examples of acquired skills
dressing, painting, driving, sports, texting, instruments
What is leprosy?
What happens in leprosy and what are the effects?
A disease caused by a bacterium infection.
Peripheral nerves thicken, interrupting signals.
Thermal sensations, pain and touch slowly fade, which can result in severe limb damage.
When is a muscle known as a skeletal muscle?
When at least one end is connected to a bone through a tendon.
Where are smooth muscles found?
Around blood vessels, glands, the gut, and the bronchioles.
What are skeletal muscles made of?
They are composed of bands of the proteins actin (thin) and myosin (thick).
What is the name given to the basic unit of striated muscle tissue
A sacromere
What initiates voluntary muscle contractions?
Nerve impulses that start in the brain of spinal coloumn.
Where do nerve impulses travel to initiate muscle contractions?
Through the somatic division of the peripheral nerve system.
What is a motor neurone vs motor unit?
A motor neurone will control several muscle fibres, whilst a motor uni consist of the motor neurone and the fibres it controls.
What is curare toxin?
This blocks the acetylcholine receptor in muscle tissue. The muscle can then no longer respond to a motor nerve stimulus and there is no contraction of muscle fibre.
What is myasthenia gravis?
This is an abnormality of acetylcholine receptors, causing those with it to be very weak as they can only activate a few of the fibres in a muscle.
How do we make a movement?
Action potential travels to a lower motor neurone, which leads to a single twitch.
A train of action potentials spaced apart will lead to multiple twitches.
If action potentials arrive within 10-100ms of each other than they build up and give rise to large muscle contractions known as tetanic contractions.
What does the strength of a muscle contraction rely on?
How many motor neurones and muscle fibres are activated at approximately the same time, which is known as recruitment.
What can damage lower motor neurones?
A motor neurone disease, a trauma where a peripheral nerve is cut, by polio, or by alcohol.
What are symptoms of lower motor neurone syndrome?
Paralysis
Muscle wasting
Fatigue
No reflexes
Which neurones talk to lower motor neurones?
Upper motor neurones (voluntary)
Sensory neurones (Reflex)
Neurones that control posture (normally involuntary)
How are motor and sensory strips in the brain organised?
Somatotropically
What happens in premotor areas?
More abstract planning
What occurs in the primary motor cortex?
Executes all voluntary movements in the body, the ‘doing’ area.
What occurs in the posterior parietal cortex?
A ‘planning’ area - involved in spatial reasoning and attention
What occurs in the premotor cortex?
An ‘intention’ area - links action with visual objects and selects sequences of appropriate movements.
What occurs in the supplementary motor cortex?
Stores info on well learned actions
What are ‘Jacksonian March’ seizures?
A condition that leads to abnormal motor movements that begin in a restricted region then progress over extremities.
What did Mushiake (1991) find with regards to improvements in action?
After prior training participants performed better in a task and showed greater activity in the supplementary motor area.
What is apraxia?
An inability to carry out movements in response to commands.
It’s caused by damage to the posterior cortex and causes difficulty in motor planning.
What did Libet (1985) find with regards to action potentials?
They start building before the participant actually became aware of their intention