Understanding Brain Activity with Electroencephalography

Electroencephalography, commonly known as EEG, is a test used to record the electrical activity of the brain. An EEG can help detect abnormalities related to seizures, tumors, strokes, head injuries, and other brain conditions.

What is an EEG?

An electroencephalograph, or EEG machine, detects electrical changes on the scalp produced by the firings of neurons within the brain. Thin wire electrodes are placed non-invasively on the scalp, held in place by a special electrode cap. These electrodes pick up the subtle voltage changes as brain neurons communicate via electrical impulses and fire in patterns known as brainwaves. By measuring brainwave activity over time, the EEG records the brain's electrical patterns and activity in different areas.

How does an EEG work?

An EEG works by measuring, amplifying and recording spontaneous electrical currents flowing between neurons within the brain. During normal brain activity, pyramidal neurons in the cerebral cortex develop small positive and negative electrical changes across their cell membranes. This produces tiny fluctuations of electrical potential that can be detected from the scalp surface. These fluctuations are amplified many thousands of times by advanced biophysical instrumentation in the EEG machine. The amplified signals can then be recorded in graph form, with different brainwaves represented by characteristic wave patterns.

What does an EEG diagnose?

Abnormal or unusual patterns in Electroencephalograph recordings can help doctors diagnose various neurological conditions that affect brain function and structure. Some of the main diagnoses an EEG can provide include:

- Epilepsy - Spikes, sharp waves or periodic pattern changes can indicate seizure activity and help locate its origin point.

- Encephalopathies - Generalized slowing or abnormal rhythm patterns suggest diffuse brain dysfunction from conditions like trauma, infection, tumors or toxic/metabolic disorders.

- Stroke/TIA - EEG may show focal slowing over the area of injury from reduced blood flow.

- Dementia - Progressive slowing and generalized dysfunction seen in conditions like Alzheimer's disease.

- Head injuries - Abnormalities like bursts of high-voltage sharp waves localize injuries from trauma, lack of oxygen, etc.

- Sleep disorders - EEG records brainwaves to diagnose issues like narcolepsy during sleep stages.

Recent advances in EEG technology

Continuous improvements are allowing EEG to provide more detailed brain mapping capabilities. Advanced EEG systems now record from up to 256 channels simultaneously for highly localized readings. Digital data storage and computer analysis further aid diagnosis by quantifying changes over time. Ambulatory EEGs using portable recorders also allow monitoring patients while awake and asleep in their natural environments.

Newer modalities like magnetoencephalography (MEG) and functional MRI (fMRI) complement EEG by adding layer of precision of location. Combined EEG-fMRI now records both metabolic and electrical activity concurrently. Novel EEG paradigms also map brain networks involved in sensory, motor and cognitive tasks. All these latest developments continue enhancing EEG's role as an invaluable non-invasive window into the workings of the living human brain.

The future of EEG

As neural interface technologies evolve rapidly, EEG is paving the way towards direct brain-computer interfacing applications. Researchers are exploring use of EEG patterns to operate prosthetic devices or communicate through a "direct neural pathway." Other potential applications include enhanced lie detection through monitoring deceptive cognitive processes. EEG is also being incorporated into neurofeedback therapies allowing patients to train their own brainwaves. With its versatility, affordability and continued technical sophistication, EEG will undoubtedly keep empowering neuroscience research and improving neurological diagnostics and treatments for years to come.

Electroencephalography provides a safe, non-invasive way to study and monitor normal and abnormal electrical activity generated by the brain. As EEG technology and analysis methods progress, so does our understanding of the complex workings of the human brain in health and disease. EEG establishes a crucial foundation for advancing knowledge in neuroscience while delivering valuable clinical information about various neurological conditions. Its diagnostic power and future applications promise much more to come in serving both research and patient care applications.