An electroencephalogram (EEG) is a medical procedure that records the electrical activity of the brain. It measures electrical signals generated by neurons as they communicate. This non-invasive method helps observe and understand brain function by detecting electrical impulses from the scalp.
Understanding the EEG Diagram Components
An EEG diagram visually represents the brain’s electrical signals over time. Small metal discs, called electrodes, are placed on the scalp to detect electrical charges. These electrodes are connected to a recording machine, which amplifies the signals from the brain. The diagram then displays these amplified signals as wavy lines.
The horizontal axis of the EEG diagram represents time, showing how brain activity changes moment by moment. The vertical axis indicates the amplitude of the electrical signals. The lines or waves seen on the diagram are the recorded electrical activity, reflecting the summed synchronized synaptic activity of neurons in the brain. Different patterns in these waves provide insights into various brain states and functions.
Decoding Brainwave Patterns
Brain activity is characterized by distinct types of waves, each defined by its frequency and amplitude. Frequency refers to how fast a wave oscillates, measured in Hertz (Hz), while amplitude describes the height or intensity of the wave. Five main types of brainwaves are commonly identified: Delta, Theta, Alpha, Beta, and Gamma waves.
Delta waves are the slowest and have the highest amplitude, ranging from 0.1 to 4 Hz. These waves are most prominent during deep sleep, indicating profound relaxation and physical recovery. Theta waves, which fall in the 4 to 8 Hz range, are associated with light sleep, daydreaming, and states of deep relaxation. These waves can also be observed during meditation and internal focus.
Alpha waves oscillate between 8 and 12 Hz. They are most noticeable during relaxed wakefulness, especially when a person has their eyes closed and is not actively concentrating. This brain state promotes mental resourcefulness and a general sense of calmness. Beta waves, ranging from 12.5 to 30 Hz, are characteristic of normal waking consciousness. These faster, smaller waves are present during active thinking, problem-solving, and states of alertness and focused attention.
Gamma waves are the fastest brainwave type, ranging from 30 to 100 Hz, though some classifications place them between 38 and 80 Hz. These waves occur during intense mental activities, such as concentration, learning, and problem-solving, reflecting rapid and complex information processing across different brain regions.
Common Uses of EEG
EEG is used in both medical diagnosis and research to understand brain function. It plays a significant role in identifying conditions such as epilepsy and seizure disorders by detecting abnormal brain activity patterns, including rapid spiking waves. Sleep disorders, like insomnia and sleep apnea, are also diagnosed by monitoring brainwave irregularities across sleep stages.
The test also assesses brain function following head injuries, strokes, or brain inflammation. It helps evaluate brain damage and monitor neurological conditions like encephalopathy or Creutzfeldt-Jakob disease. Beyond clinical applications, EEG is a tool in neuroscience research, providing real-time insights into cognitive processes, emotional responses, and the neural basis of mental health conditions.