The final project to the course "Understanding the Brain: Neurobiology of Everyday Life".

1. Distonia
Two years ago my cousin G.L. began to feel tremors in his hands. These tremors started
suddenly and without apparent cause. He consulted with three doctors, but none could
find the cause of the tremors.
In the second week of the course, Dr. Mason talked a little bit about dystonia. I realized
that the symptoms of this disease were consistent with what my cousin G.L. has. So I
decided to research more about this disease and make the final project about it in order
to understand more about it.
1. Dystonia
Dystonia is a hyperkinetic nervous system movement disorder that causes
involuntary and repetitive muscle contractions in one or more parts of the body.
1.1. Causes
The main causes are: congenital; genetic; idiopathic (with no apparent
cause); and acquired from other problems such as stroke, encephalitis, lack of
oxygen, head trauma, side effect of medicines, repetitive strain injury and
intoxication by some heavy metal or carbon monoxide.
1.2. Symptoms
The main symptoms are: cramps, tremors, spasm, writing problems, difficulty
holding objects, pain, muscle enlargement (hypertonia) and unusual postures.
1.3. Types
• Focal: occurs in only one part of the body, as only in the neck, or only in
the hand, or only in the feet.
• Specific work: manifests itself in the performance of specific actions. Ex.:
writer’s cramp and musician’s dystonia.
• Segmental: this type of dystonia is not restricted to only one part of the
body, such as the hand, or only the neck. In this case, it is common to
affect two parts at once, such as Oromandibular dystonia and spasmodic
dystonia.
• Generalized: it is the most uncommon type of dystonia among the others
already mentioned. The symptoms usually take a long time to appear, but
are progressive. They may appear during childhood, with contractions in
the foot(s) when walking and even standing.
2. Dystonia and the nervous system
2.1. Basal ganglia
Dystonia is a base ganglia disorder.
The basal ganglia is one of the oldest structures in the central nervous system
and are a deep part of the telencephalon. Its main function is to select which
action to perform. We are capable of very complicated choices with what

2. movements we make and what movements we don't and the ultimate selector is
the basal ganglia.
2.2. How the basal ganglia select movements
There are two main parts of the basal ganglia: the striatum and the pallidum.
Pallidum is always active, even at rest. Its neurons inhibit the movements.
The striatum makes it possible to move. When it receives an excitatory
information from the cerebral cortex it inhibits the performance of the pallidum, it
inhibits pallidum’s inhibition. This allows the realization of a movement.
It is through these inhibitions that the basal ganglia select the movements. When
there is a compromise of this structure this selection is impaired, causing
problems that cause loss or increase of movements (extra movements) - such as
in dystonia.
In dystonia some movements are not inhibited, which causes involuntary and
repetitive contractions.
3. How botox can be used to treat dystonia
Botox (botulinum toxin) can be used to treat focal dystonia because it inhibits the
release of neurotransmitters and consequently prevents dystonia’s typical
repetitive muscle contractions.
3.1. Muscle contraction
Muscle contraction occurs when a motor neuron releases acetylcholine
(neurotransmitter) into the synaptic cleft between itself and the motor unit it
innervates.
3.2. Vesicles
Neurotransmitters are packaged in vesicles. Three proteins (the snare complex)
hold them in the membrane of the axon terminal. When an action potential
reaches the axon, calcium ion channels are opened and these ions enter the
cell. Because of the increased concentration of Ca2+
in the cell, the vesicle
membrane fuses to the cell membrane, releasing the neurotransmitters in the
synapse.
3.3. Botox
As stated earlier, the vesicle is held in the cell membrane by three proteins. Botox
cuts one of them, which prevents the membranes fusion and thus the release of
the neurotransmitter does not occur.
Botox can be used as a treatment for focal dystonia. It is injected at a very low
dose, very locally. As it prevents the release of the neurotransmitter, the typical
contractions of dystonia do not occur.

3. 4. How this course has allowed me to better analyze the events and
phenomena around me
The course "Understanding the Brain: The Neurobiology of Everyday Life"
showed me the beauty and complexity of the brain and how it is present in
everything we do. I was able to identify examples of everything I learned in the
course in my daily life: I explained to my mother about the hot flashes she feels
because of menopause, I understood how Alzheimer’s interferes with my best
friend’s grandmother’s memory, I learned how my brain turns what I learned in
the course into knowledge.
I became more observant; I watch my godson learning to walk and I think of all
the parts of the nervous system involved in this learning and how challenging it
is for him; I watch my mother trying to learn a new language and remember all
the language mechanisms that we have; I saw that the symptoms of dystonia
were consistent with what my cousin G.L. has and now I’m learning more about
that disease to try to help him.
This course didn’t just teach me about the brain, it taught me about life and how
it works.
SOURCES
Understanding the Brain: Neurobiology of Everyday Life; Dr. Peggy Mason
Jinnah, H A, and Stewart A Factor. “Diagnosis and treatment of
dystonia.” Neurologic clinics vol. 33,1 (2015): 77-100.
doi:10.1016/j.ncl.2014.09.002
Karp, Barbara Illowsky, and Katharine Alter. “Muscle Selection for Focal Limb
Dystonia.” Toxins vol. 10,1 20. 29 Dec. 2017, doi:10.3390/toxins10010020
Batla, Amit. “Dystonia: A review”. Neurol India. March 2018, doi: 10.4103/0028-
3886.226439