1. Review: General Control Theory
-Cortex
-Basal Ganglia
-Cerebellum

2. Review: Primary M. Cortex
Directionality:
yellow = one cell’s firing vectors (broad)
red = “best” vector
No one (1) cell can generate an appropriate directional code!
Population Tuning

3. Motor Cortex
Topographical Orientation
…great question from last time

4. Current Research Topics
Conserved Topographical Organization?
(Bizzi E):

5. PreMotor Cortex PreMotor Cortex - Rostral Pre-Central Gyrus
- Activated by cues for well-learned events (monkey)

6. PreMotor Cortex Continued
Lateral PreMotor elements
conditional tasks
fire before action
external cues (in monkey anyway)
damage = inability to select appropriate response movements
Medial PreMotor elements
initiate internally / voluntarily driven motor tasks
internal cues
damage = reduced spontaneous movements

7. - Somatosensory Cortex
Primary vs. PreMotor
Inputs:
- Premotor Cortex
- Somatosensory Cortex
Inputs:
- Pre-Frontal Cortex
- Areas 5 and 7

8. Review
Be familiar with the contribution of each particular anatomical structure / region:
Cortex
2 regions discussed
Brainstem
the 3 nuclei discussed & pathways
-Spinal Cord
spatial significance / distribution
Local Circuitry / MNs / Muscle
those properties discussed

9. Basal Ganglia (Group #3)

11. Anatomical Components:
Globus Pallidus
Corpus Striatum (striped)
caudate nucleus
putamen
ventral striatum
Associated Nuclei
substantia nigra
subthalamic nuclei *

12. Basal Ganglia Function Direct Pathway: interrupt tonic inhibition
- Active before and during movements
Inputs: majority of cortex
multiple parallel pathways
Output: thalamus, superior colliculus, cortex…
“Upper Motoneurons”
- High levels of efferent tonic inhibition
- GABAergic output
Direct Pathway: interrupt tonic inhibition
Indirect Pathway: internal loop increases inhibition

13. Basal Ganglia Continued
Cerebral Cortex 
Corpus Striatum
(caudate & putamen)
Medium Spiny Neurons
Globus Pallidus &
Substantia Nigra
Upper MNs
Medium Spiny Neurons
majority of cells in striatum
75,000,000 (!)
labeled line
occur in patches: striosomes
normally not tonic
Globus Pallidus
1/100 number of m. spiny neurons
750,000
INTEGRATOR
high level tonic output
GABAergic
Primary pathway back to motor
cortex is via internal G. P.

14. Direct Pathway (tonic only)
Normal activity of the direct pathway = hypokinesia

15. Direct Pathway (phasic activation)
Reduced activity of the direct pathway (GP) = hyperkinesia

16. Enhanced activity in the indirect pathway = hypokinesia

17. Parkinson’s Disease damage to Nigrostriatal cells
medium spiny neurons
damage to Nigrostriatal cells
- increased thalamic inhibition
- seldom can coordinate movements
bursts of activity

18. Parkinson’s Disease treatments
Must attenuate activity in the Globus Pallidus
- l-Dopa (there are several pharmacological treatments)
- thalamotomy
- pallidotomy

19. Huntington’s Disease sequence is known, protein function is not - yet
medium spiny neurons
sequence is known, protein
function is not - yet
genetic test is available
- excessive excitability
involuntary movements
eventual loss of mental cohesion

20. Huntington’s Disease treatments
Must augment activity in the Globus Pallidus
- ACh (acetylcholine)
- Striatal tissue implants
genetic treatments (?)

21. Cerebellum (Group #4)

22. Cerebellum Anatomical Components: Cerebellar Cortex: - Spinocerebellum
gross movt’s
vermis
Cerebrocerebellum
complex movt’s
Vestibulocerebellum
posture / balance
nodulus
flocculus

23. Cerebellum Anatomical Components Cerebellar Deep Nuclei:
continued:
Cerebellar Deep Nuclei:
(All receive input from the
cerebellar cortex – though
functionally distinct)
Dentate (invaginations)
Fastigial
Interposed (2)
Cerebellar Peduncles
Superior
efferent pathways
Middle
afferent pathways
Inferior
Both afferent & efferent

24. Cerebellum General Function (still not completely understood)
- measure motor error
motor learning
output to cortex (via thalamus) and vestibular nucleus
Modify activity pattern of “Upper MNs”
- inputs from:
pre-motor, primary motor,
primary / secondary
somatic, anterior parietal,
secondary visual (not primary)
behavior modulation inputs: “learning”
inferior olive
locus coruleus

25.  Cerebral Cortex Pontine Nuclei Cerebellar Cortex
[Report what’s happening] 
Pontine Nuclei
[Relay / Process]
Cerebellar Cortex
[Compute error(?)]
Deep Cerebellar Nuclei
Thalamus (Cortex) &
Vestibular Nucleus
[Tell control centers]
middle peduncle

26. Cerebellar Cell Types Purkinje Cells: (inhibitory)
If there were a brain of the cerebellum, it would be the Purkinje cells
Mossy Fibers: (excitatory)
From: - pontine nuclei (via middle peduncle)
- other pons / brainstem loci
To: - deep cerebellar nuclei
- granule cells
Granule Cells: (most abundant in brain)
From & To: cerebellar cortex… ~unipolar
Give rise to: Parallel Fibers: (excitatory)
Climbing Fibers: (excitatory)
From: - inferior olive
To: - Purkinje shaft
Local Interneurons:
Basket Cells
Stellate Cells
Golgi Cells
(inhibitory)
“control the flow of information through the cerebellar cortex”

27. Cerebellar Cell Types
Extraordinary
branching
integrative properties

28. Clinical Implications
Normal Function (to reiterate):
Smooth motor functions (reduce error)
Coordinate target acquisition
Lesion or Degeneration:
Loss of smooth movements
Rarely stop on target

29. CONCLUDING ADMONITION
The ability to successfully complete an organized sequence of movements requires the appropriate coordination of MANY elements.
Spatial organization
(rubrospinal pathways, spinal signals, cerebellar integration)
Temporal organization
(cortical planning)
Accuracy and uniformity
(error measures, sensory integration)
Sequencing
(spinal circuitry)