Brain stimulation to improve functions: the proposal of CICS UDD researchers for patients with cognitive impairments

Miércoles, 21 Abril, 2021 | NEWS, PROJECTS

Have you ever wondered what would happen if we could have control over our brain and, why not, improve some of its functions? This is precisely the question that a group of researchers from the Research Center in Social Complexity (CICS) led by Dr. Pablo Billeke, director of the Laboratory of Social Neuroscience and Neuromodulation, asked themselves. After the award of the Fondecyt 1181295 “Modulation of proactive cognitive control through prefrontal oscillatory training” in 2018, the focus was on discovering how to improve very concrete things – some function – through a mechanism that is “hidden” in our brain and that, for this, there would be to “train” as it happens, for example, when we learn to play a musical instrument.

Understanding that the brain functions as a machine or mechanism, a large part of its operations can be understood as the transformations made by a computer or a CPU. Taking this premise, can we effectively understand the brain as a computer that makes transformations and thus be able to intervene it externally?

Since 1665, and thanks to the observation of the English scientist Robert Hooke – who subsequently started a revolution in biology – we know that we are made of cells and, moreover, that all living units are made of cells. In the late 1800s and early 1900s, the Italian physician Camillo Golgi began to investigate whether the brain was made in the same way, conducting studies to increase the contrast, to see how the tissue was made and thus be able to distinguish its structure. At the same time, the Spanish physician and scientist, Santiago Ramón y Cajal – using the technique described by Golgi – began to study the structures of the brain and described that the brain was also composed of cells, which were later called neurons. In 1906, both received the Nobel Prize for Medicine

A century earlier, there had already been discussions about how living beings use and transform electrical impulses. In the 1700s, two scientists, Galvani and Volta, were discussing two different approaches to the investigation of electrical phenomena in living organisms. While Volta doubted about a form of electricity intrinsic to the animal, and assumed that it derived instead from the metals used to connect nerve and muscle in experiments on frogs. Galvani countered by providing a series of experiments showing that muscle contractions occurred even in the absence of any metal, and also through direct contact between nerves. For his part, Volta was able to demonstrate that the contact of two different metals could produce an electrical effect (see Piccolino, M. and Bresadola, M., 2013).

Following this line, the membrane of a neuron can be understood as an electrical circuit. In neurons, what moves are small atoms that are electrically charged (ions), and they move across membranes. The circuit occurs in the membrane of a neuron, on a very small scale, but circuits are also formed between different neurons that communicate with each other. This communication is called synapse and causes these circuits to generate transformations that, over time, become a code. So, we are talking about a series of instructions over time. Depending on the circuit that each neuron has in particular, the transformations it makes will be different, because they will generate different codes. Likewise, there are neurons that generate their own activity, that is to say, their own transformation generates a code.

Brain and Functions
To better understand, it works like this: the cerebral cortex has layers and each part of a cortex has columns, a functional unit. Each column comprises many types of neurons. The membrane of a neuron is a circuit, which generates action potential transformations with certain rhythms. A group of neurons also forms a circuit and, therefore, transformations that show oscillatory activity. Groups of neurons can form large networks of macro circuits. Two groups of neurons can also communicate and form another circuit, large, small or on a large scale. How they influence each other depends on their history, that is, on the process of neuroplasticity, which is the conversation between neurons, generating patterns of activity. If a neuron sends messages with a certain frequency, the way the neuron responds to the previous message is different, it changes its intensity.

To improve some function, we must understand it as a transformation. These transformations are distributed at different scales, in groups of neurons that make different transformations each, in different circuits. For example, there are lesions that can alter certain functions and not others, such as what happened to the American railroad worker Phineas Gage in 1848, who suffered severe brain damage after an accident that specifically affected part of the frontal lobe, resulting in notorious changes in his personality and temperament. So, there are parts of the brain that can be “removed” and the command is altered, but the circuit continues to function.

The question is: Can we directly intervene in the activity of any brain circuit?

To answer this question, we need to use several tools. We start with the fact that there is a relationship between magnetic fields and electric fields, a relationship that can be measured. That said, one technique is the use of magnetic fields as a form of non-invasive brain stimulation. What it does is, through the magnetic field, induce in the brain an electric field sufficient to intervene in the circuits of the neurons and generate a brain response, for example, to move the hand. With this, it is possible to intervene on a certain scale, to interrupt or improve a specific function. In this case, the function to be improved is proactive cognitive control, at a more macro level.

However, certain conditions are necessary:

Knowing the context where that function is elicited or required.
– To have some idea or notion of the “place”, i.e., in which brain regions are involved in that function.
– To have some idea or notion of the “neural transformation” required for that function. In other words, what pattern of activity is related to the application of that function.
After conducting tests with two groups of healthy subjects in experimental sessions with MRI and EEG (Go-Nogo)-TMS, carried out by the team of the Laboratory of Social Neuroscience and Neuromodulation together with students of the PhD in Sciences of Social Complexity, some results were obtained:

Non-invasive brain stimulation techniques, give the possibility to intervene a brain function if there is enough knowledge about the mechanism of it, as mentioned: context, place (brain area network) and transformation (brain activity pattern). In addition, these techniques will help to establish the (causal) roles between them.

An important fact to keep in mind is that research has provided evidence that lateral prefrontal areas are involved in proactive cognitive control. And that these areas, through the oscillatory activity in theta band (transformation or pattern of brain activity), apply this function of proactive cognitive control. This would open the possibility of designing interventions to improve these processes in patients with neuropsychiatric diseases who present cognitive alterations.