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My
name is Arianna Tucci.
I am a Clinical Research Fellow
at UCL Institute for Neurology,
and I work on the genetics basis
of neurodegenerative diseases.
Today I'm going to
talk about the genetics
of hereditary spastic paraplegia.
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Hereditary spastic
paraplegia, or HSP,
refers to a clinical designation
for neurological syndromes
characterized by bilateral
lower limb spasticity,
or stiffness and weakness, which
are caused by gene mutation
and therefore they are inherited.
HSP was first described
by Strumpell in 1880
as an upper motor neuron syndrome.
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Upper motor neurons are part of
the pyramidal motor system, which
controls human voluntary movements.
This system is arranged
into two main stages.
First, axons of the upper
motor neurons originating
in the cerebromotor cortex
call through the brain stem
and descend as the lateral
corticospinal tract
within the spinal cord.
In the spinal cord
the upper motor neuron
axons establish synapses directly
with lower motor neurons.
Or with a spinal interneuron,
which in turn established
a connection with
lower motor neurons.
In the second stage lower
motor neurons terminate
in specialized synapses at
the neuromuscular junction
throughout the body to
regulate muscle contraction.
So for example at
the cervical level,
the upper motor neurons establish
synapses with lower motor
neurons that control
muscles of the arms.
While down at the lumbar level
upper motor neurons control neurons
that in turn control
the muscles of the legs.
On the right side of the slide is
an illustration of the spinal cord
in a transverse section, showing
the lateral corticospinal tracts.
The corticospinal tracts are made
up by the axons of the upper motor
neurons originating from
the cerebral cortex.
