These electrical oscillations are behind everything that happens in the activity of the brain.
The electrical activity of the neurons that populate the human brain forms part of the basis of all the thoughts, feelings and actions that we carry out. That is why it is so difficult to understand what neurons are doing at all times; everything that makes up our mental life consists of that inexplicable jump that goes from the frequency with which neurons send electrical impulses to the transformation of this very simple into mental processes in all its complexity.
That is, there is something in the way these nerve cells coordinate with each other that causes sensations, thoughts, memories, etc. to appear.
Of course, it is still very far from understanding in a detailed way what type of electrical signals in a part of the brain produce such a thought in a specific person and at a certain time, but there is something that is known about the functioning of the organ of the mind; It depends on something known as neuronal oscillatory activity, that is, firing frequencies of electrical impulses that generate what are known as the different types of brain waves.
Oscillations in neural electrical activity
The concept of oscillation in the activity of neurons refers to the different rhythms and frequencies expressed by electrical activity in the central nervous system. This idea is very broad, and applies both to refer to what an individual neuron does and a group of neurons working in a network.
For example, oscillation can refer to the degree of electrical activation of a single neuron over time, with the rate at which the appearance of a nerve impulse becomes more likely based on the degree of depolarization ; but it can also be used to refer to the frequency with which several neurons in a group send signals almost at the same time.
Be that as it may, in all cases these oscillations in electrical activity can be represented by waves by encephalography, in a similar way in which the heartbeat is measured by the electrocardiogram.
The types of brain waves
As we have seen, the activity of neurons in the brain is not absolutely chaotic, but rather follows a very complex logic in which it can be seen how different neurons fire electrical signals almost at the same time in a continuous way.
This frequency constituted by the activity of several neurons forms what is known as brain waves, activation patterns that, unlike what occurs with the activation frequency of a single neuron, are powerful and clear enough to be registered placing sensors outside the scalp (using encephalography, one of the most used technologies in research on the nervous system).
In turn, brain waves can be classified into different types according to their frequency, that is, the time that passes between the moments in which many neurons fire electrical signals at the same time.
These types of brain waves are called Delta waves, Theta waves, Alpha waves, Beta waves, and Gamma waves.
1. Delta waves (1 to 3 Hz)
Delta waves are the ones with the highest wave amplitude, that is, their frequency is very low. They are characteristic of the deep sleep phase, which is the one in which we rarely dream. However, that they represent the activation patterns of this deep sleep phase does not mean that the brain is relatively off. Although it is in a state of rest, it is no longer activated, yes, it is occupied with processes that do not depend on being in a state of consciousness.
2. Theta waves (3.5 to 7.5 Hz)
After Delta waves, Theta waves are the ones with the highest wave amplitude. You are associated with states of deep calm, relaxation and immersion in memories and fantasies, and also with the REM sleep stage, which is the one in which we dream. Consequently, when these waves appear, it is estimated that there is consciousness or that it is very likely that there is, although it is a consciousness disconnected from what is happening around us and focused on imaginary experiences.
3. Alpha waves (8 to 13 Hz)
Alphas are a type of brain wave that has more frequency than theta, although it is still related to states of relaxation. For example, they can appear during walks in a park, when lying on a beach or watching television. Thus, they are not typical of the dream state, but of deep calm, an intermediate step.
4. Beta waves (12 to 33 Hz)
Neural activity in Beta waves is intense. They are related to actions that require staying in a certain state of alert and agile management of care, such as a speech before a wide audience, the process of answering an exam question, etc.
Thus, this type of brain waves is linked to an agile management of the focus of attention, depending on the objectives, and with the concern about what is happening in the present, usually around us, since we have to react quickly to possible unforeseen.
5. Gamma waves (25 to 100 Hz)
These are the type of brain waves with the highest frequency and lowest amplitude. They appear in waking states and it is believed that their presence is related to the appearance of consciousness, with the expansion of the attention focus and with the management of memory.