Nervous system connectivity Flashcards
Name and describe the areas that control speech. Then say what happens if you damage each area
Broca’s area
- Motor speech area
- Cannot physically speak
Wernicke’s area
- Sensory speech area
- Cannot understand language
Linked by arcuate fasciculus
- Cannot repeat back what you just said
Give an example of a simple behavior (spinal reflex)
Knee jerk reflex:
- Receptor senses stretch of the quadriceps and tendon (mimicking knee bend)
- Afferent sensory fibre synapses directly onto motor neuron
- Quads contract.
Why are simple behaviors important?
They are fast and do not involve the brain.
Eg. important in muscle tone
Give an example of a complex behavior
Visual information is combined with proprioceptive information in the parietal and visual association cortices.
Information is passed to the premotor cortex to calculate the movement necessary
Primary motor cortex initiates the swing, also sending a copy of the plan to the cerebellum
During the swing there’s a constant flow of sensory information
The cerebellum compares the proprioceptive feedback with the motor plan and makes any adjustments necessary to ensure the arm is where it’s meant to be.
What is the striatum and what is it made up of?
It is the input portion of the basal ganglia
Made up of caudate and putamen
What are the output components of the basal ganglia?
Internal segment of globus pallidus
Substantia nigra pars reticulata
What do the basal ganglia output to?
The thalamus which projects to the motor cortex
What do the internal part of the globus pallidus and substantia nirgra pars reticularis normally ‘say’ to the thalamus?
“NO!” - They inhibit movement
What are the pathways which determine the activity of the basal ganglia?
Indirect pathway: The striatum inhibits GPe, which releases the inhibition of Subthalamic nucleus (STN). STN stimulates Gpi and SNpr, resulting in inhibition of movement.
Direct pathway: Dopamine from the SNpc causes the striatum to inhibit the GPi and SNpr, thereby facilitating movement.
What happens in parkinson’s disease?
Loss of dopaminergic neurons in the substantia nigra
Underactivity of direct pathway, resulting in bradykinesia.
What happens in HD?
Loss of medium spiny neurons in the striatum, resulting in underactivity of the indirect pathway.
What leads to a similar condition to HD?
Overtreatment of PD with Ldopa
Except that’s due to overactivity of direct pathway.
What is the part of the striatum that makes dopanime?
Substantia nigra pars compacta
