Lecture 10 Flashcards
Where does the interaction between the motor unit and the muscle fibres occur?
At the neuromuscular junction
The spinal motor circuitry system is a complicated system with a lot of feedback connections, why is this?
Because the motor system needs to excite and inhibit different muscles at together and separately.
Name the two different types of descending (cortex to muscle) motor pathways. What is each of there functions?
The Dorsolateral tracts and the ventromedial tracts. The Dorsolateral tracts control independent movements of limbs e.g. Reaching for objects. The ventromedial tracts control limb movements as a whole e.g. Posture.
Name the two pathways within the Dorsolateral pathway. And what is there difference.
Direct- corticospinal tract
Indirect- corticobruspinal tract
The difference between them is that the indirect pathway crosses over earlier in the spinal cord at the red nucleus
What’s the difference between the indirect and direct pathways in the ventromedial pathway?
The indirect pathway splits into two at the tectum. Both direct and indirect pathways travel ipisilatetally down the spinal cord.
In the ventromedial pathway which sub pathway (eg direct or indirect) would have greater plasticity?
The indirect pathway because there are two identical pathways so if one breaks the other is there as backup.
What is the function of the cerebellum?
Is involved in balance, speech, coordination and the learning of motor sequences
Where does the cerebellum receive it’s input from?
Primary and secondary motor cortexes
Where does the cerebellum receive feedback from ?
Somatosensory and vestibular systems
What is cerebellar ataxia?
Poor control of gate (walking)
What is the role of the basal
Ganglia?
Modulates movement and cognitive functions such as habitual responses and implicit learning
Fill in the blanks for the basal ganglia pathway: basal ganglia- ……….. - supplementary motor cortex (secondary)- ……… - feedback
Thalamus
Primary motor cortex
What do the direct and indirect pathways of the basal ganglia do? And why are they important?
The direct pathway- excites
The indirect pathway- inhibits
The balance is important to be maintained between direct and indirect pathways otherwise over and under movement behaviours may occur . E.g. Parkinson’s
What neural disruption is apparent in Parkinson’s patients?
The loss of dopamine found in the substantia nigra and straitum
What is administered to reduce Parkinson’s symptoms? And why?
L-Dopa. Dopamine cannot be administered to patients as it is not taken up by the brain because of the blood brain barrier
What are some problems associated with L-Dopa?
L-Dopa can cause serious side effects such as disorientation, confusion and hallucinations. The brain also builds up a tolerance to the drug and will eventually stop working.
What are some positive symptoms of Parkinson’s?
Tremors- particularly resting tremors
Rigidity- stiffness of muscles and joints
What are some negative symptoms of Parkinson’s?
Reduction in spontaneous movement - hypokinesia
Slow initiation of movement- akinesia
Freezing or slowing during movement
Reduced scale of movement
What did Huntington say the 3 peculiarities of huntingtons disease are?
- it’s heredity and found on chromosome 4
- manifests in adults
- tendency for insanity and suicide
Explain the progression of signs in huntingtons.
Begins with personality changes- depression, aggression, impulsivity and then progresses to effect the motor system where a lot involuntary movements occur
Describe the movement disruption huntingtons patients have ?
Jerky, rapid, uncontrollable movements that come and go randomly. They can resemble voluntary movements
Where is the primary motor cortex located?
Precentral gyrus in the frontal lobe.
If damage is obtained to this area, what is likely to happen? What is the name for this?
The homunculus is damaged therefore motor performances for particular body parts may be impaired. which is called a hemiplegia
What three areas does the secondary motor cortex contain?
Cingulate motor areas, supplementary motor area and the premotor cortex.
PCS.
Explain the role of the sensorimotor association area.
The sensorimotor area takes information from the senses and uses it to locate objects and body parts in space.
Where is the sensorimotor area?
Posterior parietal lobe
If damage is obtained to the input of the sensorimotor area, what is the called and describe it?
Ataxia- the inability to Use visual information to guide hand movements particularly in the peripheral vision.
If damage is obtained to the output of the sensorimotor cortex what is this called and explain it?
Apraxia- the inability to pull movements together in an action sequence
What is the function of the Dorsolateral prefrontal association cortex and where does it receive information from?
It’s involved in the making of a decision to act. It receives it’s information from the association cortex.
Explain the sequence of motor information from the association cortex to the primary motor cortex.
Sensorimotor Association cortex- Dorsolateral prefrontal association cortex/secondary motor area - primary motor area
What is ideational apraxia?
Ideational apraxia is the inability to perform complex sequences and actions. Although it can be performed generally in an illogical manner or incorrect order.
Ideomotor apraxia is….
The inability to mentally envision and act upon an action.
What case study supported the function of the posterior parietal lobe to be those of body part awareness and intrinsic spatial coding?
The case study of a woman who received damage to her parietal lobe and claimed that her arm and leg drifted when they were out of sight
Explain the 3 basic components/ states of the motor control system diagram.
The desired or goal state
The actual state (now)
The predicted state (how is should feel)
Describe what affordances mean in the motor control system diagram.
Affordances are all the possible stimuli in an environment that can be acted upon. It is the choosing of the correct actions that is important.
Why, according to the motor control system diagram, can’t people tickle themselves?
Because people can predict (predicted state) how the tickling will feel so there is no reaction or element of surprise.
What is compromised in the alien hand syndrome in the motor control system?
The affordances take over. So all stimuli are reacted upon in the environment. Random grabbing and reaching would occur.
What is meant by the mirror neurone system?
When an action is observed, thought of or envisioned the part of the brain that would be stimulated in the performance of the action would also be stimulated.
Where is this activation of mirror neurones found?
In the parietal lobes, in the premotor cortex, in the inferior frontal lobe (Broca’s area) and in the superior temporal gyrus.
What is the function of these mirror neurone systems?
To understand how to do an action, to understand why others do an action and to plan actions.
