In ancient times it was believed that the brain was only responsible for mucus production. Nowadays we know much more about its true functions. Allegedly, this knowledge is still a drop in the ocean, but on the basis of growing numbers of ways to examine the brain, in the future we are likely to get to know more and more.
How Do We Examine Brain Functions Now?
One technique is EEG – electroencephalography. EEG signals are spontaneous electrical brain activities. Unfortunately these signals are stochastic (random), dynamic, non-linear and non-stationary (constantly change over time). What makes their examination even more difficult is that EEG recordings vary greatly from one individual to another.
Fortunately, thanks to the use of suitable modern software, computers can analyze the characteristic features of brain activity to enhance the difficult visual inspections. Nevertheless, doctors must have extensive experience to interpret EEG recording visually, to isolate and identify clues in the data collected. Even though the interpretation of EEG data is highly complicated, EEG has become more and more popular among medical researchers dealing with fatigue detection. By measuring an individual’s brainwaves, the machine can distinguish between vigilance and sleep and to some extent, between the levels of vigilance within a state.
How Is This Done?
A special set of electrodes is placed on the subject’s head. The data collected (brainwaves of different lengths) is then subdivided into frequency ranges: α, β, γ, δ, and θ. During vigilance α and θ waves are the most important. When we are active and have our eyes open, the power of α waves is usually low unless the person is really tired. At the same time, when we rest with our eyes closed, and we are fully rested the α power is also high. When we change our state from rest with eyes closed to sleep, there is a gradual reduction of α power and an increase in θ power. This leads us to the conclusion that we can see if a person is beginning to feel tired enough to fall asleep, when there is reduced α and increased θ power during vigilance.
These observations are now being turned into hardware which can monitor the vigilance of people doing monotonous but attention demanding tasks, such as air traffic controllers or lorry drivers, in order to prevent them from falling asleep by, for example, using alarms to avoid potential accidents.
The only problem currently is the accuracy of such devices when compared to EEG examinations performed in hospital. There is new technology available which uses ‘wavelet transform’ to better discriminate the non-stationary waves, which are usually a considerable part of the data collected by EEG.
Perhaps in the future we will be able to see more clearly the full spectrum of opportunities given to us by EEG. Who knows, maybe the data which we now treat as “rubbish” will one day be properly understood, showing us new ranges of information to help us to further unravel the functions of the brain.