What Is Brain Mapping (QEEG)?
EEG (or electroencephalogram) is a recording of brainwave activity. QEEG (Quantitative EEG), popularly known as brain mapping, refers to a comprehensive analysis of brainwave frequencies, the amount of the frequencies, the connectivity, and time signal processing takes for the brain to do its work. After the brainwaves are recorded, editing is completed to insure only brainwaves and not movements are analyzed. After the editing is complete, the recording is analyzed in a digital database to create color-coded maps.
These maps show three things: 1) If the brain has too much or too little of a frequency—there are no BAD frequencies. 2) How well or how poorly the regions of the brain are connected—this is called regional information flow, 3) The time it takes for a signal to travel between the regions of the brain—too fast or too slow makes the brain operate inefficiently.
Physical injury to the brain, such as concussion, disrupts normal flow of information in the brain. Similarly, stress, anxiety, toxic injury, seizure disorder, Alzheimer’s disease, anoxia and brain infection (e.g., chronic Lyme encephalitis) alter brainwave activity. ADD, OCD, anxiety, depression and Learning Disability have distinct patterns. These patterns can be re-trained by Neurofeedback.
While other brain imaging techniques (CT, MRI, PET, and SPECT) measure physical properties such as structure and blood flow. QEEG measures electrical activity of the brain. It provides an in depth analysis of such brainwave characteristics as power, information flow, and time across the regions of the brain. In order for the division of labor in the brain to be efficient, all these parameters must be in sync.
LORETA (Low Resolution Electromagnetic Tomography Analysis) is actually HIGH RESOLUTION. It was developed by Roberto Paschal D. Pascual-Marqui in the early 1990s. He is a multi-lingual Swiss scientist who choose the word “low” to mean DEEP in the brain. This technique allows viewing of 3-dimentional electrical current sources in the brain. It uses data obtained in the QEEG recording and employs standard MRI atlas images with anatomical Talairach coordinates for 3-dimentional gray matter modeling.
The QEEG and LORETA findings are then compared to a normative database. This database consists of brainwave recordings of hundreds healthy individuals. Comparisons are displayed in Z scores which are “standardized” standard deviations.
How Is It Done?
An elastic cap with 20 sensors is placed on the head and the sensors are connected to the recording equipment. A special conductive gel is into 21 sensors in the cap. This preparation takes approximately 15 minutes. Two recordings are made: eyes open and eyes closed. The actual recording length is from 5 to 10 minutes. The recordings are analyzed to determine if the brain makes the proper transitions between each condition.
Reading The Maps
The QEEG results are displayed in colorized Z scores charts which represent standard deviations from the mean and span from +3 to -3. That is to say, a Z score of +2 means that the result is 2 standard deviations higher than the norm. Higher scores are shown in warmer colors such as orange and red. A Z score of 0 represents the norm and is color-coded white. A Z score of -2 means the result is 2 standard deviations below the norm. The cooler colors, blue and green show levels of low activity below the norm. It is important to know that when it comes to brainwave activity, more does not mean better. Both excessive and diminished activity may be equally problematic.