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
Who completed research with regards to prosthetic limbs?
Hochberg (2012)
What did Roitman and Shadlen (2002) and Gold and Shadlen (2004) find with regards to monkeys and brain activation?
Monkeys show a build up of graded activation when following moving dots, and activation occurred jut when the frontal eye fields were stimulated. Exposure to a stimulus increase change of eye movement in monkeys.
Which area is involved with hand movements?
Supplementary motor area
What ha been found with regards to motivation and movement?
Participants are more likely to do movements that they find rewarding, with more activation in motor areas that correspond to the rewarding movement.
Which areas are involved in reaching for objects?
The parieto-occipital extra-striate area and the dorsal promotor area.
Which areas are involved in grasping objects?
Dorsal extra-striate cortex and ventral premotor area.
Which cortex helps sensory motor coordination?
Parietal cortex, as parietal cells represent locations of visual stimuli.
What is the supplementary motor area essential for?
Generating linked self-generated movements.
What did Tanji and Shima (1994) find with regards to the supplementary motor area?
Deactivation produces severe disruption of learned sequences.
Where is the cerebellum located?
What does it do?
Above the brainstem towards the back of the brain.
It is involved in coordination, balance and rapid movements.
What are ballisitc movements?
These are rapid movements that occur so rapidly one cannot depend on sensory feedback for control.
EG: Running, typing, writing, talking
What happens when we are exposed to errors?
Vestibular receptors send signals to the vestibulo-cerebellum, which initiates correct signals. The vestibular nuclei then adjusts necessary muscles.
How are motor and cognitive error correction different?
Motor involves the motor cortex, spinal cord, and muscular-skeletal system. It produces motor output and sensory consequence.
Cognitive involves the prefrontal cortex which produces an informative output and cognitive consequences.
What is cerebella ataxia?
Errors in range and direction of movement. Uncontrolled eye movements and slurred speech.
What is Disdiadocho Kinesia?
An impaired ability to perform rapid alternating movements
What are hypometria and response delays?
Responses are delayed and often fall short of the intended goal
What is the main role of the basal ganglia?
Action selection, influenced by decisions in the prefrontal cortex.
What is hypokinesia vs hyperkinesia?
Hypo - Insufficient direct pathway output, with an excess of an indirect pathway output
Hyper - Insufficient indirect pathway output, with an excess of an direct pathway output
What is the direct pathway to movement?
Cortex stimulates the striatum > Inhibits Nr and Gpi > Less inhibition of the thalamus > Cortex is stimulated more> Spinal tract stimulated via upper motor neurones to lower motor neurones > movement.
What is the indirect pathway to movement?
Cortex stimulates the striatum > Inhibits Gpe > Less inhibition of STN > Stimulates the SNr - Gpi complex > inhibits the thalamus > less stimulation of cortex > less stimulation of neurones leading to less movement.
What are the effects of lobotomies?
A general impairment of higher mental functions Judgement Future Planning Social Awareness Creativity Emotional relatability Dull and apathetic
What do we use executive control for?
Planning Time Management Sustained attention Working memory Task switching Goal Orientation Inhibition Organisation
What did Bianchi find with regards to frontal cortex damage?
It led to problems such as an inability to use past experience to guide behaviour and a general lack of coherence.
What is inhibition used for in prefrontal control?
To overcome automatic processes
What is initiation/task-switching used for in prefrontal control?
To facilitate selection of new behaviour
What are simulation and rehearsal used for in prefrontal control?
Being mindful of outcomes, judging behaviours
What are the four types of inhibition?
Restraining potentiated behaviour
Preventing information from interfering with processing
Restraining inappropriate actions
Removing irrelevant info from working memory.
What did Schreuder (2017) find with regards to iniation?
A spike in prefrontal activity was seen 300ms arfter participants spotted a ball of a target colour, so this is known as a P300 spike.
What is the orbitofrontal cortex important for?
It is a part of the vmPFC, with the lateral part of the OFC important for establishing links between stimuli and actions. It is critical for adaptive learning.
What can damage to the OFC cause?
Impairments in the ability to interact with objects and others. It can lead to acquired sociopathy, so they are unconcerned about punishment or consequences.
What can damage to the medial PFC cause?
Impairs the need for goals and the ability to initiate actions. Patients become lethargic and quiet and cannot sustain movement
What can be used to test cognitive flexibility in infants?
The looking in A not B cup test. They start to pass around the age of one.
What is the Wisconsin Card Switching task used to test?
Task switching, abstract reasoning, and problem solving.
What causes involuntary imitative behaviour?
Dysfunction in the frontal lobe
What is utiity?
This can be a measure of reward, based on a psychological value rather than an objective one.
What is diminished utility?
When a reward does not have much relative value.
What do normative theories claim with regards to rewards?
That people take risks based on the concept of probability and expected value.
What does prospect theory claim with regards to rewards?
Decision making is made based on judgements that already exist.
What is anchoring?
When you judge relative value based on the first piece of information you receive.
What are primary and secondary reinforcers?
Primary - Water, food, sex, pleasure
Secondary - When this can be used to gain other rewards, so it has no actual value itself. For example, money.
What is dopamine important for and what is it associated with?
Motivation, exploring, habits, learning
Reward seeking behaviours and addiction
Where is dopamine produced?
The substantia nigra.
What are the two routes for the production of dopamine found in the VTA?
Mesolimbic: The amygdala and hippocampus
Neocortical: All of the cortex but especially the medial parts of the frontal lobe.
What was found with regards to rats and the release of dopamine?
When stimulating the VTA via pressing a lever there was not the same amount of dopamine release compared to when the VTA is unexpectedly stimulated.
What does mentalising refer to?
Representing the feelings and thoughts of others as if they were your own
What are the main symptoms of Parkinson’s?
Dyskinesia: abnormality of voluntary movement
Akinesia: absence of movements
Hypoekinesia: slowness of movements
Which areas are affected in Parkinson’s?
The basal ganglia, and areas with many dopaminergic neurons.
The nigro-striatal pathway damage leads to a depletion of striatal dopamine.
What is hemisballimus?
A movement disorder characterised by dance like movements. It features hyperkinetic movements - patients cannot stop them.
What cause hemisballimus?
A decreased activity in the sub-thalamic nucleus of the basal ganglia due to stroke or brain injury.
What is tourettes?
This is characterised by motor tics, typically preceded by an unwanted urge or sensation in the affected muscle.
Which brain areas are affected in tourettes?
The basal ganglia is thought to be involved since it involves movement, as well as connection failures in the cortex.
What can abnormal dopamine levels cause?
Impulse control disorders such as over eating, shopping addiction and hyper sexual activity.
Is there treatment for dopamine abnormalities?
L-DOPA enters the brain through the blood and is converted into dopamine. However, this may cause severe side effects.
What does deep brain stimulation do?
Stimulation is applied to the sub-thalamic nucleus. It improves slowness of movements and tremors. However, it can cause side effects such as hallucinations and depression, as well as potential personality changes.
