Cerebral Activity – The Electroencephalogram (EEG)

In any field of medicine, the knowledge of the practitioner is critical for providing the best quality of care. The invention of the electroencephalography has played an important role in gaining new insights into electrophysiological phenomena associated with brain function.

The German scientist Hans Berger, was the first to use the electroencephalogram or EEG in 1924, he also discovered the alpha wave rhythm, also known as the "Berger wave". During an EEG, various pairs of electrodes are typically attached to the scalp to detect cerebral electrical potentials, which are recorded by a specifically engineered device. Essentially, the EEG is a graphic display of a difference in voltages from two sites of brain function recorded over time.

Neurones within the brain generate these electrical potentials, which fluctuate rhythmically in distinct patterns. This signal consists of rhythmical voltage fluctuations, which is shown as peaks and troughs on a line graph by the recording channel. Cerebral bioelectrical phenomena comprise action potentials that are brief and produce circumscribed electrical fields, and slower, more widespread, postsynaptic potentials. It should be considered that the interpretation of EEG is one art within the vast field of clinical neurophysiology.

The EEG enables to study the electrical activity of the brain in different conditions. For instance, EEG recording of a healthy adult in a fully conscious but relaxed state is composed of regularly recurring oscillating alpha waves. These alpha waves are replaced by low-voltage rapid irregular waves, when a person is excited or startled. During sleep or deep coma, the brain waves become extremely slow. It appears that irregular slow delta waves arise from the vicinity of a localised area of brain damage. In addition to investigating brain function, the EEG is also utilised to study and trace connections between one part of the central nervous system and another.

The EEG is a unique and valuable measure of the brain’s electrical function, and in modern clinical practice, it is used as a diagnostic aid in cases of brain infections, serious head injuries, brain tumours, epilepsy and various degenerative diseases of the nervous system.

Since their invention and development, medical devices have changed the way we see living organisms, including the human body, inviting us to interpret the various physiological functions in a novel way. The use of investigative technology has the power to transform the unknown into knowledge, and therapeutic medical devices can help make the incurable treatable.