Functional electroencephalography, or fEEG, is a non-invasive method that uses sensors on the scalp to record brainwave patterns in real time. It is used to see how the brain functions when responding to specific triggers or performing a task. This technique provides a direct measurement of neural activity with high temporal resolution, tracking changes as the brain processes information. The data offers insights into how different parts of the brain communicate and helps in understanding cognitive processes like attention, memory, and language.
How Functional EEG Differs from Standard EEG
A standard electroencephalogram (EEG) is administered while a patient is in a resting state. The objective is to identify irregularities in brain waves when the individual is relaxed, drowsy, or asleep. This makes a standard EEG useful for investigating conditions that present with abnormal brainwave patterns independent of a specific cognitive task, such as epilepsy.
In contrast, a functional EEG (fEEG) is an active assessment designed to measure brain function in response to controlled activities or stimuli. During the procedure, the patient engages in tasks like listening to sounds or solving problems. While a standard EEG provides a snapshot of the brain’s general electrical state, an fEEG offers a dynamic view of the brain at work. It reveals how brainwave patterns change when specific cognitive systems are engaged, showing how efficiently different brain regions are processing information and communicating.
This active evaluation provides objective data on brain function that can be tied to performance on cognitive tests. The information helps create a more comprehensive picture of an individual’s cognitive strengths and weaknesses.
The Functional EEG Procedure
For preparation, patients are asked to wash their hair the night before or the day of the test but to avoid using conditioners, sprays, or gels. Caffeine should be avoided for 12 to 24 hours before the procedure. It is also important to inform the clinician of any medications being taken.
The procedure is painless and non-invasive. A technician fits a cap containing small electrodes onto the patient’s scalp and applies a conductive gel to each electrode to ensure a clear signal is received. Once the cap is in place, the patient is seated in a quiet room to minimize distractions.
During the test, the individual is presented with auditory or visual stimuli or asked to complete cognitive tasks on a computer. These tasks are designed to elicit specific brain responses related to functions like attention or memory. The electrodes record the brain’s electrical signals for later analysis, and a session lasts between 60 to 90 minutes.
After the test is complete, the cap is removed, and the conductive gel is washed out of the patient’s hair. There are no lasting side effects, and individuals can return to their normal daily activities immediately. The recorded data is then processed and analyzed.
Analyzing the Brain’s Electrical Activity
After the procedure, the collected data undergoes analysis to interpret the brain’s electrical responses, primarily by examining event-related potentials (ERPs). ERPs are the measured brain responses that are the direct result of a specific sensory, cognitive, or motor event. By averaging the EEG signals from repeated stimuli, background brain activity is filtered out, isolating the brain’s reaction.
This process identifies specific ERP components, which appear as voltage peaks in the waveform linked to different stages of information processing. For example, some components reflect initial sensory registration, while others are associated with attention or memory. The timing and amplitude of these components provide information about how effectively the brain is processing information.
The analysis is also enhanced by Quantitative EEG (qEEG), which is the statistical analysis of the digital EEG data. This process creates a “brain map” by converting the electrical data into a visual format. This map highlights areas of the brain with typical or atypical activity levels during the tasks.
The individual’s brainwave patterns are compared to a normative database for an objective measure of brain function. Resulting maps show which brain regions are overactive, underactive, or communicating inefficiently, helping to pinpoint the neural basis of symptoms.
Clinical Applications of Functional EEG
Functional EEG provides objective data that assists in the diagnosis and management of various neurological and developmental conditions. This information is useful for tailoring treatment plans, such as neurofeedback, medication, or lifestyle interventions.
- Attention-Deficit/Hyperactivity Disorder (ADHD): The test measures brain activity related to attention and impulse control during tasks that require sustained focus. This data can help identify biomarkers associated with the condition and guide more targeted interventions.
- Autism Spectrum Disorder (ASD): It is used to assess how the brain processes sensory information and social cues. The technique can reveal differences in brain connectivity and the timing of neural responses, providing a basis for developing supportive therapies.
- Traumatic Brain Injury (TBI) and concussions: It can detect subtle changes in brain function not apparent on structural imaging tests like MRI or CT scans. By measuring processing speed and cognitive efficiency, fEEG can help track recovery from an injury and inform decisions about returning to activities.
- Learning disabilities: By examining the brain’s electrical activity during reading or problem-solving tasks, fEEG can help identify the neural basis of these difficulties. This information can be used to develop personalized educational strategies.