L15. Higher Functions of the Brain Pt.1

Question 1

Initiating movement?

Answer 1

Primary motor cortex –> motor neuron –> NMJ

Question 2

Basal ganglia in movement?

Answer 2

Premotor cortex to striatum –> output from globus pallidus to thalamus inhibits unwanted movement –> dopamine is released from substantia nigra to striatum –> striatum inhibits globus pallidus to allow activation of thalamus

Question 3

Basal ganglia?

Answer 3

Monitors and helps plan cortical activity involved in movement

Needed for initiation of movement

Cycle through loop (cortex-basal ganglia-cortex) occurs several times during preparation for movement

Helps cortex select combinations/sequences of muscle activation

Question 4

Parkinson’s disease?

Answer 4

Death of dopamine neurons
- Difficulty beginning movements, slowed movements, tremor
- Cause uncertain, genetic and environmental, trauma

Treatments:
- Dopamine replacing drugs (precursors for dopamine, taken up and released by surviving substantia nigra cells)
- Deep brain stimulation and (possibly) transplantation of dopamine cells

Question 5

The cerebellum?

Answer 5

Largest number of neurons and synapses of any structure in the CNS
(10% brain volume - 1/2 of all neurons)

Roles of the cerebellum:
- Coordination = integrates sensory information with planned motor programs
- Timing = organises timing of individual muscle contractions around joints
- Correction = compares the intended result of a planned movement with the actual result, and modifies ongoing activity, for smooth and accurate muscle control
- Memory = stores movement memory for progressively more accurate and timed movements

Question 6

Sleep wake cycle?

Answer 6

Suprachiasmatic nucleus generates sleep waking cycle of about 24 hours (clock neurons)
Intrinsic pacemaker
Accurate “entrainment” to day length via input from retinal cells
Can maintain sleep/wake cycles even in constant darkness

Question 7

What is the striatum made up of?

Answer 7

Caudate nucleus and putamen

Question 8

What does the substantia nigra contain?

Answer 8

Dopamine producing neurons

Question 9

What happens if the cerebellum is damaged?

Answer 9

Disruption of coordination and balance, and difficulties with fine motor control

Question 10

Sleep cycle EEG?

Answer 10

• EEG measures the postsynaptic potentials in the cortex; which are the signals received by the cortex
• Wake and alert states: high cortical activity produce fast EEG waves, which have smaller amplitudes
• Sleep states: low cortical activity produce slow EEG waves, which are larger in amplitudes