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“It’s more important to know who you’re talking to than where you sit.”
Neuron talk.
INTRODUCTION
Why can’t we link a brain region to a specific function?
In a previous article we returned to the myth of the right and left brain. One would be the seat of creativity and global thinking, while the other would be the seat of analytical, organized thinking. This approach, which attempts to link a brain region to a specific function, is found in many conferences and popular articles. Thus, the amygdala is said to be the seat of emotions, the prefrontal cortex the seat of complex thought, etc… Even if neuroscience has enabled us to clearly identify the function of certain areas, such as vision in the occipital lobe (at the back of the skull), language in the air de broca (within the left hemisphere) and, more recently, language in the air de broca (within the right hemisphere), we can still identify the function of these areas. recently selective attention in the ventro-lateral prefrontal cortex, we feel it’s important to restore some perspective to the popularization of science.
Indeed, scientists often refer to brain areas (see Brodmann’s areas) to understand how the brain works. But the brain can be broken down into numerous, even infinite, regions, and it’s very difficult, if not futile, to remember their location and function. Unless you’re a researcher, working on a particular function or region of interest, most of the time it’s pointless trying to remember this kind of information. On the other hand, we think it’s more interesting to pursue a “network” approach. You may have heard of the ” default” network, which includes neurons that are active when we do nothing in particular, neurons that are “active by default”. While it’s generally accepted that we all have this network, some of its regions may differ slightly from one individual to another. This hypothesis of the brain organizing itself into networks rather than regions was defended in an article published by Ed Bullmore in the journal Nature in 2012.
In this article, the author argues that this networked organization enables better energy management (for an organ that consumes over 20% of the body’s energy) and, above all, greater adaptability.
This is because the brain is adaptable, “plastic”, and in the event of damage, a function can develop in another region. So, even in neurosurgeries requiring the removal of vast areas of the brain, it is possible to keep certain functions intact, as neurosurgeon Hugues Duffau has demonstrated.
WHICH NETWORK FOR WHICH FUNCTION?
This approach makes it easier to identify the main brain networks and their functions. We’ve decided to present three of them here:
The default network:
It’s activated when we’re doing nothing in particular, and is thought to be linked to wandering of the mind, periods of daydreaming and imagination. This is THE network most studied by scientists today. It may be directly involved in disorders such as attention deficit disorder, schizophrenia and depression.
=> To activate it, simply wait a few minutes without doing anything in particular. You will then see thoughts and images emerge naturally from the activity of this network.
The executive functions network :
It enables us to complete a task and reach our goals. They help us think and adapt to situations by adjusting our level of attention. Executive functions are well known to neuropsychologists, as they are involved in attention disorders, obsessive disorders (OCD) and autism.
=> To activate it, you need to do the opposite of the default mode, i.e. set yourself a task and a goal.
The network of salience:
It enables us to identify what’s important in our environment. We can easily notice food on the corner of our table, or a beautiful object. But we can also look to our inner world and highlight a sensation or a thought.
=> To activate it, look around you. Scan your surroundings without a specific objective, and pay attention to what your attention is naturally drawn to.
NETWORKS THAT INTERACT
Although these networks are differentiated, they constantly interact according to our activities.
This first example illustrates how these three networks work together: on your daily commute to work, you generally take the same route, with a few minor adjustments, saving you the trouble of having to plan a new route every morning and conserving energy for other activities. Now your mind can wander, the default network is activated. Let’s imagine that one day, you come across a work zone that you hadn’t anticipated: at this point, activation of the executive functions network will enable you to draw up a plan to get to work anyway, as efficiently as possible. Following this new itinerary, you are alerted by the sight and smell of thick smoke on your left: the salience network is activated, enabling you to pick up important information and avoid the burnt-out area on your way. You arrive at work a few minutes late, but you can see how the collaboration of these networks has enabled you to adapt to the situation.
The previous example shows how these networks complement each other. The default network and the executive functions network, for example, are antagonistic. And this seems logical: one requires us to do nothing in particular, while the other enables us to achieve a goal. But studies carried out by R. Beaty of the University of Pennsylvania have shown that during periods of creativity, these two networks tend to activate at the same time (the default network enables us to make links with our past experiences, and the executive functions network could apply them to the task in hand). In fact, just as with the right and left brain, it’ s the connection and communication between neurons that counts.
In the end, when an orchestra plays, some instruments are in front, others at the back, some play as soloists, some form groups, but they all follow the same beat, and it’s the synergy of all these instruments that brings the score to life.
AUTHORS
Mathilde Maillebuau, neuropsychologist & Nicolas Bassan, psychologist and co-founder of Open Mind Neurotechnologies
SOURCES
Beaty, R. E., Benedek, M., Silvia, P. J., & Schacter, D. L. (2016). Creative cognition and brain network dynamics. Trends in cognitive sciences, 20(2), 87-95.
Bullmore, E., & Sporns, O. (2012). The economy of brain network organization. Nature Reviews Neuroscience, 13(5), 336-349.
Duffau, H. (2016). Broca’s error. Michel Lafon.
Rudie, J. D., Brown, J. A., Beck-Pancer, D., Hernandez, L. M., Dennis, E. L., Thompson, P. M., & Dapretto, M. J. N. C. (2013). Altered functional and structural brain network organization in autism. NeuroImage: clinical, 2, 79-94.
