Block 4

Question 1

Cortical inputs to primary motor cortex

Answer 1

a. Somatosensory cortex
b. Premotor cortex
c. Supplementary motor area
d. Posterior parietal cortex (Areas 5 and 7)

Question 2

Output projections from primary motor cortex

Answer 2

1. Primarily from pyramidal neurons in different Regions
   a. Primary motor cortex (Area 4)
   b. Premotor and supplementary motor
   area (Area 6)
   c. Somatosensory (Areas 3, 1 and 2) and
   parietal cortex (Areas 5 and 7) d. Frontal eye fields (Area 8)

Question 3

Premotor cortex

Afferent projections

Answer 3

1. Prefrontal cortex
2. Supplementary motor area
3. Posterior parietal (Areas 5 and 7)
4. Cingulate motor area
5. Cerebellum and basal ganglia via
   thalamus

Question 4

Supplementary motor area

Afferent projections

Answer 4

1. Area 4
2. Prefrontal cortex/pre-SMA
3. Posterior parietal
4. Basal ganglia
5. Cerebellum

Question 5

Supplementary motor area

Efferent projections

Answer 5

1. Area 4
2. Striatum
3. Brainstem
4. Corticospinal

Question 6

Basic cerebellar circuit

Answer 6

a. Mossy fibers → granule cells → Purkinje cells
b. Climbing fibers → Purkinje cells
c. Purkinje cells → cerebellar nuclei and vestibular nucleus (medial and lateral)
d. Cerebellar nuclei → many targets in CNS

Question 7

Mossy fiber afferents

Answer 7

• Multiple spinal, brainstem sites of
  origination
• Synapse on granule cells (excitatory, glutamate) - Produce “simple spikes” in Purkinje cells
• High frequency discharge
• Can encode temporal and intensity information

Question 8

Premotor cortex

Efferent projections

Answer 8

1. Area 4
2. Supplementary motor area 3. Posterior parietal
3. Prefrontal areas
4. Basal ganglia
5. Brainstem, red nucleus
6. Corticospinal

Question 9

Climbing fiber afferents

Answer 9

• Solely from inferior olive
• Monosynaptic to Purkinje cells
• Powerful excitation
• Produce “complex spikes” in Purkinje cells - Low frequency discharge
• May encode “teaching signal”