Nervous system: Parkinson's disease Flashcards
Label the diagram
What is the condition called when there is a lesion near the upper regions of the corticospinal tract?
Spastic paralysis
What are the symptoms of a spastic paralysis?
They would be stiff and an over exaggerated response to a stimulus
What causes the symptoms of a spastic paralysis?
Because the corticospinal tract is damaged and not transmitting neural signals from the upper motor neurons to the spinal cord, the lower motor is not controlled and lower motor neurons tend to fire neural signals that are too strong resulting in exaggerated responses in muscles
What is the condition called when there is a lesion in the spinal cord?
Flaccid paralysis
What are the symptoms of a flaccid paralysis?
There is no muscle activation (i.e. limp limbs)
What causes the symptoms of a flaccid paralysis?
When a lesion occurs in the spinal cord it causes all the motor neuron from the lower motor neurons up to be unable to transmit signals to the muscle resulting in little/no stimulation of the muscle resulting in no muscle tone
What is the main issue associated with Parkinson’s disease?
Initiating motor neurons
What is bradykinesia?
A reduced ability to move
What is the nick name for a condition for Parkinson’s patients that involves facial muscles?
Wooden face
What is wooden face?
It is the condition where parkinson’s patients are unable to create facial expressions that match their actual feelings
Why do Parkinson’s patients get wooden face?
The face has a homunculus representation of about half the neurons of the primary motor cortex and due to the inability to initiate muscles quickly, it is difficult for the to change facial emotions quickly
What kind of neurotransmitter is the striatum activated by?
Dopamine
The dopamine activated cells in the striatum are kept in what kind of state?
They are always kept in a state where they are ready to produce an action potential for the slightest change in neurotransmitter
Why are the striatum cells kept in a constant state of being ready to fire?
So that if there is even the slightest change in the neural input they will produce an action potential
What happens to the striatum’s ability to produce an action potential if the dopaminergic pathway is damaged? Why?
It is greatly reduced
The striatum cells are not kept in a state where they can fire at the slightest change of neurotransmitter
How does a damage dopaminergic pathway impact motor planning? Why?
It reduces it’s ability to contribute to motor planning, i.e. difficulties in initiating movement, tremors, decrease movement refining
The striatum is less able to produce an action potential so it can’t drive the basal ganglia system
What parts of the brain are feed information into the lower part of the striatum? What kind of actions are associated with this part of the striatum?
The frontal parts of the brain
Mood and impulse
When the dopaminergic pathway is damaged, what are the impacts?
Loss of fine movement, initiating movement and loss of mood and impulse
What condition is caused by the damage of the dopaminergic pathway?
Hypokinesis
Explain the pathway for hypokinesis
Dopaminergic pathway is damaged which means that the GABA pathways (which are inhibitory) are not controlled by the striatum resulting in their overstimulation. This overstimulation of the inhibitory pathway at the thalamus causes the glutamatergic pathway from the thalamus to eh cerebral cortex to become inhibited resulting in under stimulation of the cerebral cortex = hypokinesis
What is hypokinesis?
A lack of planning of movements
How can you treat Parkinson’s disease?
Levo-dopa
What is levo-dopa?
The precursor of dopamine
What does levo-dopa do?
It is a substitute for dopamine which allows the striatum to function normally
Is levo-dopa a full proof treatment for parkinson’s? Why/why not?
No
It only works for ~8years before either the disease gets worse or the body develops tolerance for levo-dopa which means treatment no longer effective
What does extremes of dopamine do to a person’s movement and behaviour?
Very low = Catatonia, stiffness/rigidity
Very high = Wild movements, psychosis and depression
What is very low dopamine associated with?
Parkinson’s disease
What is very high dopamine associated with?
Schizophrenia
What is a difficultly in treating Parkinson’s disease with levo-dopa?
It causes very large fluctuations in dopamine in your system which results in large mood and behaviour changes throughout the day
