The term ‘Neurodynamics’ was coined in the 1940s, and denotes the field of study which specialises in monitoring neural activity in the brain – and more specifically the neural oscillations, or frequency signatures, which characterise different patterns of thought and behaviour. In this way it could be seen as a discipline which concerns itself with finding 'neural correlates of consciousness' (or NCCs), and thereby forming a theoretical link across the mind-body divide.
Put simply, it involves working out what happens in our brain when we're thinking, and how consciousness actually 'works'.
This is going to be the first in a series of posts. I’ll start by explaining the scientific background of neurodynamics, but after that, we’re going to have some fun. As we look at each of the typical human brain frequencies in turn, I’ll be offering free audio downloads. These are sound files known as binaurals, which modulate brain frequencies, and can have the effect of producing altered states of consciousness in the listener.
Before that though, we need to cover some of the background... and explain exactly how these brain frequencies work.
The Nature of Consciousness
The study of neurodynamics aims to relate cognitive functions (such as logic, imagination or memory) to specific, dynamic patterns in the brain – in other words, to offer us some kind of a link between what a brain is physically doing, and the nature of self-awareness that is experienced by the brain’s owner.
For many years the principles of mind and matter have remained separate entities, and explaining the relationship between the two has been one of the ultimate goals of psychology since its inception. While many theorists have suggested that there may be some particular region of the brain in which thoughts happen (a so-called ‘seat of conscious’), neurodynamics is more interested in relating conscious states to the overall function of the brain, and to the pattern of interactions between its different parts.
The clearest indicators of brain activity are the tiny electrical signals fired by our neurons. These are the basic cells that form the vast, interconnected web of nerves in our brain, and it is believed that there may be as many as one hundred billion neurons in the average human brain. Each one communicates with its neighbour by transmitting a tiny electrical charge, known as an ‘action potential’.
We can read these electrical signals using methods such as electroencephalography (EEG), or even by taking a closer look – on a cellular level, it is possible to observe the movement of tiny electrical charges across the subthreshold membrane of individual cells.
Much more telling than monitoring individual action potentials however, is a look at the larger patterns in which these neurons fire. It is possible to monitor the charge differential between different regions of the brain, in much the same way that you might use a potentiometer to measure the voltage across an electronic circuit. These signals are known as 'local field potentials' (LFPs), and it has been demonstrated that localised synchronisation seems to occur more often in those modules of the brain that are currently ‘in use’. For example, the neurons in the visual cortex may begin firing in neatly coordinated waves, when the subject is reading.
Then, a revelation came in 2009... when a group of French researchers led by the neuroscientist Raphaël Gaillard, took advantage of a unique opportunity.
Galliard's team were researching one of the more extreme treatments for drug-resistant epilepsy, which is conducted by implanting a series of intercranial electrodes directly into the patient’s brain. By sending microscopic electrical charges into specific regions of the cerebral cortex, it is possible to counter, offset and even cancel-out the chaotic build-up of electrical charge which contributes towards the seizures suffered by epileptics.
While they had ten patients prepared in this manner, Galliard and his colleagues noticed a couple of strange phenomena – firstly, on presenting the subject with a series of different stimuli, the electrodes would report higher voltages in the corresponding sensory regions… the same localised effect that was described above.
More importantly though, they noticed a synchronised pattern of firing between neurons spread all across the cortex. The electrical charges transferred between neurons in one part of the brain would trigger chain reactions during periods of conscious thought, resulting in co-ordinated electrical waves that covered the whole brain. Galliard’s findings seemed to suggest that consciousness occurs as a dynamic process across the brain, as it literally pulses with electrical charge - much like a beating heart.
Altered States
One of the useful results of neurodynamics has been to define the different frequencies of neural oscillation which appear to indicate different levels of conscious activity. Through observation of amplitude, frequency and phase, it has been possible to link a range of different cognitive states with their corresponding frequencies of brain activity.
Five different frequencies are usually referred to when describing the full spectrum of human conscious states;
This is the slowest of normal brain frequencies, and typically associated with deep sleep, or other states of lost consciousness - such as comas. Delta frequencies can also be achieved by those profoundly skilled at meditation, and are sometimes associated with deep dissociation and near death experiences.
This is where the magic happens. Theta activity represents a state below the normal functioning of the conscious mind, in which the subconscious is left unhindered. It is commonly experienced through rich imagination work, lucid dreaming and the hypnogogic states we sometimes pass through on the way to sleep. It is the trance-like daze that can sometimes accompany well-rehearsed, repetitive actions; this is the frequency that hypnotists work with, and the depth that experienced meditators often reach. It is in the Theta frequency that we are most open to suggestion.
Associated with a state of relaxed wakefulness, this is the basic resting state for the human brain. Your neurons will typically be synchronised in this frequency range when you are focussed inwardly; you could be remembering something, or in a basic meditative state. The Alpha frequency is relaxation, inspiration, memory and daydreams.
Taking it up a notch from our resting state, Beta activity is usually seen during interaction with the outside world. It represents the kind of focus necessary for speech, where we maintain an awareness of turn-taking the the changing flow of a conversation. Any intellectual activity is likely to promote this frequency of brain activity (or higher), including problems of logic, arithmetic and visual focus.
Heightened consciousness characterises this frequency of brain activity, which is typically associated with advanced mental functions such as perception and self-awareness. Gamma activity is the first frequency to disappear in states of anaesthetic or hypnosis. It is also believed to be responsible for coordinating signals across the cortex; in this respect, it has been suggested that the Gamma frequency may represent the brain’s very own ‘operating system’.
Next Time...
So, that more or less covers the nature and history of neurodynamics, including an overview of the most typical brain frequencies. However, while this system of brainwave definition allows us to make useful inferences as to the nature of an individual’s private cognitive world at any given time, the reverse effect also applies – somewhat more dubiously, by manipulating the frequency of neural oscillations in the individual's brain, it becomes possible to forcibly alter their state of consciousness.
In Part 2, we’re going to be looking at the different ways that these frequencies can be artificially modified, in order to bring about altered states… and in Part 3, we’ll be moving onto some exciting practical experiments which you can try out for yourself!
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