Parkinson´s disease is a degenerative disorder produced by neuron death of the Substantia nigra or black substance, which are in charge of producing dopamine, one of the most important neurotransmitters within the basal ganglia system. This part of the brain, located within the brain lobes (subcortical nuclei), is formed by small structures closely related to movement.
Of these structures, the striatum is the most important, as it is in charge of receiving and processing cerebral cortex information, by activating neurons which codify it and transmit it to other structures of the brain for correct movement control.
Dr. Grecia López Ríos, Universidad Nacional de Colombia (UNal) in Manizales University Welfare Health Coordinator says that when there is a critical dopamine reduction, among other symptoms, the information of this aforementioned circuit is altered producing tremors, limb stiffness, movement sluggishness, unsteadiness of the body posture and lack of facial expression.
The World Health Organization (WHO) says that currently there are 6.3 million people that suffer from Parkinson´s Disease and also says that by the year 2030 the figure will climb to 12 million, turning into the second most prevalent neurodegenerative disease in the world after Alzheimer´s disease.
Although there are no specific statistics in Colombia, the Colombian Neurology Association estimates prevalence is between 0.12% and 0.47 %; therefore projecting this data to the current population, there could be more than 220,000 Parkinson’s cases in Colombia.
Considering that this is a chronic, incapacitating and not a preventable disease, which impacts mostly the elderly, every technological and scientific progress is esteemed, so for the near future, it will be possible to guarantee a better quality of life for people who suffer from the disease.
One of the most recent advancements produced in Colombia, specifically at UNal- Manizales, is a software program which imitates the activity of the striatum, through sequential neuron activation, allowing adequate motor coordination.
“For the striatum to work properly it needs the black substance and when it fails it is when Parkinson’s disease appears,” said David Angulo García, Researcher of the UNal-Manizales ABC Dynamics, and Intelligent Perception and Control Research Group (PCI for its Spanish acronym) and main author of the project. Therefore his proposal helps scientists understand what happens when the striatum begins to lack dopamine.
The innovation of the computer model is to reproduce the correct functioning of the striatum through a less number of parameters or possible features, including connectivity between neurons, connection strength (synapsis), and transmission speed. These three elements produce the essential mechanisms for the activity of said brain structure.
To develop the program, Angulo inputted levels or measurements of said parameters which have been referenced and researched by scientist all around the world. Regarding connectivity, they have verified that the connections between cells of the striatum are very disperse, in other words, the probability of interaction between two of them is very low (less than 10 %).
With respect to synapsis, evidence shows that when signals are transmitted between striatum cells, there is a change in receptor neuron membrane potential of 0.5 millivolts (mV). Regarding synapsis transmission speed, is 40milliseconds.
“The mathematical tools that we use show that inputting these measurements to the model, our neuron network not only reproduces the typical activity of the striatum but also maximizes the capacity of coding information of the simulated system,” said Angulo.
Understanding the function through the mechanisms that produce brain activity through models helps assess if the alteration of the dynamics may be explained through changes in critical parameters of the neuron network modification.
Taking this into account, another innovation of the computer program is that altering the interaction speed between two neurons –i.e. changing the 40-millisecond speed– it can produce serious alterations such as those encountered in Parkinson´s disease, while altering connectivity and connection speed parameters, they did not identify alterations of this type.
To verify this, Angulo, along with University of California, San Francisco Professor Alessandro Torcini –used statistical tools (standard deviation, probability distribution, coefficient of variation) to quantify the variability of the neuronal activity.
According to the researchers, the computer model results are part of the process to define possible new treatments for neurodegenerative diseases. For instance, they say that if the hypothesis that Parkinson´s is produced by a change in the interaction speed between neurons (i.e. lack of dopamine), pharmaceutical companies and governments should invest in drugs to help restore the synaptic transmission speed.
Therefore the computer models which simulate the functioning of any part of the body show how the alliance between science and technology contribute to health welfare in Colombia and the world.