1. Huntingtons Disease
early symptoms include cognitive dysfunction, memory problems, depression, clumsiness or motor incoordination
first described syndrome in 1872
usually first symptoms emerge between 30 and 45 years of age
characterized by progressive degeneration of CNS
genetic basis –
offspring has 50% of inheriting disorder if parent has it

3. tremendous progress in genetics of HD
4th chromosome
CAG repeats
sequence replicated up to 26 times in normal adults;
HD to over 100X – more replicates usually the earlier and more severe the onset of disease
still not sure why CAG repeats cause HD

4. Brain injury and recovery
responses that can occur as a consequence of neuronal damage
1. neural degeneration
anterograde degeneration
retrograde degeneration

5. peripheral axon gets severed –
both sections of axon will begin to die (or degenerate)

6. retrograde degeneration
anterograde degeneration

7. if a myelinated axon is in the PNS -
each segment of myelin is a
separate Schwann cell

8. What can happen to allow nerves in the PNS to sometimes regrow?
importance of glial cells
Schwann cells in PNS – each segment of the myelin sheath is a different Schwann cell
oligodendroglia in CNS – a single glial cell provides for multiple myelin sheath segments

10. something (or things) about the environment in the CNS does NOT allow for axonal regrowth and something (or somethings) about the environment in the PNS ALLOWS for axonal regrowth
WHAT?

11. Schwann cells multiply at the site of injury
release neurotrophic factors
one of the consequences is axonal sprouting

13. schwann cells
multiply
this part of the
axon dies
branches of axon sprouts

15. SO Schwann cells can help guide axons; oligodendroglia cannot
astroglia – in CNS – produce scar tissue which also might block axonal sprouting

16. Neuronal reorganization
somatotopic maps –
plasticity

17. Neuronal reorganization
somatotopic maps –
plasticity
how might it happen?
new local collateral sprouting

18. Recovery of function understanding this is the million dollar question
rehabilitation