Lecture 16 : Higher Brain Function 1 Flashcards
Describe the basic overall initiation of movement:
Initiation of movement -> primary motor cortex -> motor neuron -> NMJ
What are the 4 structures of the basal ganglia?
- Striatum
- Substantia nigra
- Globus pallidus
- Thalamus
What is the striatum?
Made up of the caudate nucleus and putamen
What is the substantia nigra?
Contains dopamine producing neurons
What is the globus pallidus?
Exerts tonic inhibition on the thalamus to prevent unwanted movement
What is the thalamus?
A relay station between basal ganglia and motor cortex
Explain the process of initiating movement:
- Input from premotor cortex for movement to striatum
- Dopamine release from substantia nigra to striatum to activate striatal neurons
- Striatum inhibits globus pallidus, which leads to activation of thalamus
- Thalamus sends signals to motor cortex, leading to execution of intended movement
Describe the hierarchical organisation of movement control:
- Basal ganglia monitors and helps plan cortical activity involved in movement
- Needed for initiation of movements
- Cycle through loop (cortex – basal ganglia – cortex) occurs several times during preparation for movement
- Helps cortex select combinations/sequences of muscle activation
- Look a slide diagram
What causes Parkinson’s disease?
- The death of dopamine-producing neurons in the substantia nigra produces Parkinson’s disease
Describe the characteristics of the cerebellum:
- Largest number of neurons and synapses of any structure in the CNS
- 10% brain volume - 1/2 of all neurons
What are the roles of the cerebellum?
Coordination, timing, correction, and memory
- Receives information regarding intended and actual movement
- Makes corrections and adjust ongoing movement for accuracy, precision, and coordination
- Sends correction signals to the thalamus, which relays to the motor cortex
- Stores movement memories – “muscle memory”
What does cerebellar injury result in?
- Movements that are slow and uncoordinated
- Individuals tend to sway and stagger when walking
What is the suprachiasmatic nucleus?
- Body’s internal pacemaker that generates sleep waking cycle of about 24 hours (clock neurons)
- Receives input from retina
- Light entrainment synchronises the suprachiasmatic nucleus with the 24hr light-dark cycle
- This allows the sleep/wake cycle to continue even in constant darkness
What is the reticular formation/activating system?
- Regulates wakefulness/arousal
- Filters sensory information to draw attention to important stimuli
