To understand the human brain is unquestionably one of the most difficult tasks of modern science. A leading approach for most of the past 200 years has been to link brain functions to different areas or even separate neurons (brain cells). But recent studies increasingly point to the fact that we can move in a completely wrong way, trying to understand the human mind.
The idea that the brain consists of numerous regions that perform specific tasks is called “modularity.” At first it seemed quite successful. For example, it can give an explanation of how we recognize faces by activating a chain of certain areas of the brain in the occipital and temporal lobes. The bodies, however, are treated with a completely different set of brain regions. And scientists believe that other areas – areas of memory – help combine these perceptual stimuli to create holistic ideas about people. The activity of certain areas of the brain has also been associated with specific conditions and diseases.
The reason why this approach was so popular, in part in the technologies that provide us with an unprecedented cut of the brain. Functional magnetic resonance imaging (fMRT), which tracks changes in blood flow in the brain, allows scientists to see how the brain regions activate in response to actions – allowing them to apply functions to the map. Meanwhile, optogenetics, a method that uses the genetic modification of neurons, so that their electrical activity is controlled by light pulses, can help us to explore their specific contribution to brain function.
Although both approaches produce extremely interesting results, it is unclear whether they will ever be able to provide us with a meaningful understanding of the brain. A neurophysiologist who finds a correlation between a neuron or a brain region and a specific but basically arbitrary physical parameter, such as pain, can conclude that this neuron or this part of the brain is controlling pain. And this is ironic, because even the brain itself has the task of finding correlations in everything that it does.
But what if we instead consider the possibility that all brain functions are distributed throughout the brain and that all parts of the brain contribute to all of these functions? If this is so, then the correlations found can be an ideal trap of the intellect. And then we need to solve the problem of how the region or type of neuron with a specific function interacts with other parts of the brain to form meaningful integrated behavior. Until now, there is no general solution to this problem – only hypotheses for specific cases, for example, recognizing people.
This problem can be well illustrated by a recent study, which showed that a psychedelic LSD preparation may violate a modular organization that explains vision. Moreover, the level of disorganization is related to the degree of “personality disorder” that people have at the time of taking the drug. The study showed that the drug affects how several areas of the brain interact with the rest of the brain, increasing their level of connectivity. So if we ever want to understand what our self-perception really is, we will have to understand the connections that lie deep between the brain regions as part of a complex network.
The way forward?
Today, some researchers believe that the brain and its diseases as a whole can only be understood as the interaction between a huge number of neurons distributed throughout the central nervous system. The function of any single neuron depends on the functions of all the thousands of neurons with which it is connected. They, in turn, depend on others. The same region or the same neuron can be involved in a large number of contexts, but have different specific functions depending on the context.
Perhaps it is the tiny disturbances of these interactions between neurons that cause avalanche effects in networks that lead to the development of depression or Parkinson’s disease. In any case, we need to understand the mechanisms of these networks in order to understand the causes and symptoms of these diseases. Without a full picture, we are unlikely to be able to successfully cure these and many other conditions.
In particular, neuroscience should begin to explore how network configurations emerge from continuous brain attempts to comprehend the world. We also need to get a clear picture of how the cortex, the brain stem and the cerebellum interact with the muscles and tens of thousands of optical and mechanical sensors throughout our body, creating a single picture.
The connection with physical reality is the only way to understand how information is represented in the brain. One of the reasons that we have a nervous system, first of all, is that the evolution of mobility requires a control system. Cognitive, mental functions – and even thoughts – can be seen as mechanisms that evolved to better plan the consequences of movements and actions.
Thus, the pathway of neurology may be more focused on common neuronal records (using optogenetics or fMRI), when it is not the goal to anchor each neuron or brain region for a specific function. This can be used in theoretical network studies that take into account various observations and provide an integrated functional explanation. But the theory should help us design experiments, and not just walk around the bush.
The main obstacles
It will not be easy. Modern technologies are expensive – they put in large financial resources, as well as national and international prestige. Another obstacle is that the human mind tends to prefer simpler solutions to more complex ones, even if the former can not explain the results as widely as the latter.
All relationships between neuroscience and the pharmaceutical industry are also built on a modular model. Typical strategies when it comes to common neurological and mental illnesses are to identify one type of receptor in the brain that can be targeted by the medicine to solve the entire problem.
For example, SSRIs (selective serotonin reuptake inhibitors) blocking the absorption of serotonin in the brain, so that more are freely available, are currently used to treat a number of different mental health problems, including depression. But they do not work for many patients and can create a placebo effect.
Similarly, epilepsy is now considered a separate disease and is treated with anticonvulsant drugs that inhibit the activity of all neurons. Such drugs do not work for everyone. Any instantaneous disturbance in the system of brain circuits – and each patient can have a thousand unique triggers – can send the brain into an epileptic state.
From this point of view, the neuroscience gradually loses the compass needle on the way to understanding the brain. We absolutely need to change this. Not only can this be the key to understanding a number of the most serious puzzles known in science, for example consciousness, but it will also help in treating a variety of various illnesses and health problems, both physical and mental.