Parkinson's is a progressive (it becomes worse over time) neurodegenerative (lost the degeneration of neurons in the brain) disease.
In Parkinson's disease the individual loses the Dopamine neurons that Produces the Dopamine. Dopamine neurons live in the part of the brain called Substantia Nigra.
The Substantia Nigra is a nucleus located about the spinal cord and midbrain and its part of Basal Ganglia. The Substantia Nigra is actually made up of two parts with different functions: Pars compacta and Pars reticulata and the Dopamine neurons are located in Pars compacta (SNc) region.
Dopamine is a neurotransmitter. a chemical released by nerve cells (Dopamine neurons) to send signals to other nerve cells and its have a serious role in controlling the movements, it helps us to have smooth, coordinated muscle movements, it's like a motor oil for human body and it will facilitate the Direct pathway of the Basal Ganglia. Decrease amount of Dopamine leads to symptoms of Parkinson's disease.
Actually the couse of PD is mostly Unknown, Parkinson's is a Idiopathic disease which means the uncertain or unknown origin.
However there are many idea that says maybe genetic is one of the PD causes and also there are some clues that environmental factors (toxins, chemicals and heavy metals) may cause the PD.
What are the Parkinson's symptoms?
Parkinson's has four main motor symptoms:
Bradykinesia, Rigidity, Tremor, and Problem with Balance
PD also has common Non-motor symptoms which includes autonomic dysfunction, neuropsychiatric problems.
Parkinson's disease doesn't affect everyone in the same way, so each person with Parkinson's will experience movement and non-movement symptoms differently.
I find an example of PD in Youtube and there is an individual who talks about his life with PD on medication and out of medication.
Martin Parker has been diagnosed with PD about 2 years, he uses 4 medication to help him for normal life. (more information about his medications)
Martin mentions in his video that his left hand is very affected and his right hand is less affected. Symptoms of PD often start on one side of the body and as the disease progresses, it ultimately affects both sides. However, the symptoms may still be more severe on one side than on the other.
After not having medications, Martin showed us that he cannot use his left foot and also his left arm is slow.
Martin:“ when I'm trying to move my left arm off from my leg now, I can't do it ”
This is one of the PD symptoms and we call it Slow Down Movements or Bradykinesia. It results from a failure of Basal ganglia. Bradykinesia exists in all cases of Parkinson's. An individual with Bradykinesia can feel weakness, fatigue or they have hesitation in initiating movement, a feeling like they can't move there body parts.
In a part of video Martin's wife asked him "how is your left arm?" and Martin seemed to have a lack of concentration. Trouble with concentration is one of the Cognitive problems and a non-movement symptoms of the PD.
Rigidity is another movement symptom of PD. an individual with Rigidity feels like having stiff muscles and movements which are not smooth anymore. Movements are going to be more like cogwheels that are moving together.
Martin: “it feels like my bones are punching my skin and I can't stop pushing against the subjects”
Martin is feeling like this because of all the stiffness that he feels in his muscles therefore he starts to bend over because axial rigidity also can effect on posture.
We can see that when Martin is trying to button up his shirt the movements are slowly and cogwheel-like and he have to put much effort and focus on his action to reach his goal of movement.
“In a situation of Parkinson's there is a need for deliberate movement of every component action. It's as though all the possibilities of habit were taken away and everything had to be done deliberately with thought. This makes for very slow moving.” Prof. Peggy Mason
In Martin's case there is no sign of Tremor. Tremor is present in most PD patients but not all. The Tremor in PD is a resting Tremor which means that it happens when the body parts are in rest and tremor will be stopped when individual moves that part of his body. The cause of Tremor is not well understood.
Problem with Balance is a Symptom that the Person is feeling Unbalanced while standing or walking and it happens because Postural Reflexes stopped working.
Basal Ganglia
The Basal Ganglia is a collection of nuclei, and the main components of the BG are:
Striatum, Globus Pallidus (GPi - GPe), Substantia Nigra (SNc - SNr), Subthalamic Nucleus (STN)
The main function of Basal Ganglia is to control of voluntary motor movements, and it does this by two pathways process signals:
A) Direct Pathway → The Direct Pathway goal is to exciting Thalamic neurons and results in less inhibition of Thalamus ( Thalamus is normally under inhibition) and aim of the direct pathway is to making movement and reach the goal of movement.
The Direct Pathway starts with an excitatory signal (a stimulate) from Cerebal Cortex going to striatum → inhibitory neurons in striatum that they going to GPi become more active and this leads to inhibition of the GPi (GPi is normally what keeps the Thalamus activity down) so the result is that Thalamus will be more active to communicate with Cortex (to excite the cortex). This is the neurobiological form of “double negative”.
SNc and STN are working togather to facilitate the direct pathway via Dopamine.
STN is exciting The SNc and this allows the SNc to send Dopamine to striatum (D1 receptors) so the Dopamine makes these inhibitory neurons in striatum more excited and this results more inhibition of the GPi.
The Dopamine is critical in facilitating the direct pathway. Without Dopamine the Direct pathway is suppressed and the indirect pathway is favored and that results the poverty of movement in PD.
B) Indirect pathway → the aim of indirect pathway is to prevent unwanted movements by inhibiting thalamic neurons.
The normal functioning of the Basal ganglia apparently involves a proper balance between the activity of these two pathways.
"Take care of your Brain and your Brain will take care of you" Prof.Peggy Mason
Hossein Koofi - May 21, 2015
