Quantitative Electroencephalography (qEEG) is a highly advanced, non-invasive, safe and cost effective method for assessing brain wave activity and functioning. While other brain imaging techniques measure cerebral blood flow, metabolism or structural integrity (fMRI/CT), qEEG tracks brain functioning by measuring the electrical activity (neural network activity) of the brain. Specifically, qEEG is recorded the same way as EEG but the data acquired in the recording is used to create topographical color coded maps that show the electrical activity of a brain's cerebral cortex organized according to symmetry, phase, coherence, amplitude, power and dominant frequency (view sample brain maps). This is important as the qEEG gives us information about whole brain functioning as well as defining localized areas of concern influencing the client's symptoms and/or behavior.
A standard QEEG assessment takes approximately an hour to complete. An elastic cap with 19 sensors is placed on the head and the sensors are connected to the receiving amplifier. We measure the head and use caps appropriate to the circumference of the child or adult's head so that there is correct placement of the electrodes. These positions are standardized so that data from different laboratories or clinics can be compared more easily to one another.
The skin at each location is then cleaned and prepared to ensure good electrode contact and therefore, good conductance of electrical signals from the brain to the electrodes. A small amount of paste or gel is applied between the electrode and the scalp to further enhance signal conductance. This process may take 15 - 30 minutes. During this time your child can watch a video or play with hand held devices. However, during the recording process it is important to sit very still in order to obtain data, free of artifact. Recordings are taken with eyes open as well as closed.
The first part of the analysis involves inspection of the raw EEG waveforms. Abnormal shapes, amplitudes or frequencies of brainwaves can provide significant clues to the existence of specific nervous system disorders including epilepsy. In some cases, information from this part of the analysis may be essential in diagnosing the patient's problem and determining the best course of action. It is also necessary for eliminating "artifacts" (various forms of interference to the EEG signal) prior to the quantitative analysis. We analyze the QEEG in a number of ways.
qEEGData is obtained in the form of "Z-scores" or standard deviations from the norm. Red and blue color displayed on the maps below show brain wave activity that represent three (3) standard deviations from the norm. In addition to these topographical maps we specifically analyze data obtained in terms of Absolute and Relative power, Coherence, Asymmetry and Loreta.
This term refers to the amount of activity within a specific frequency band of brain waves. The activity in each frequency band is shown in the examples below in order of slowest (left)-Delta to fastest (right) Beta. Activity in each frequency band is compared to a normative database to determine the presence of suspected abnormalities. The results for each frequency band are shown with the topographic activity maps. In the example shown below, green is the color representing average activity. Red means there is a large increase in activity, yellow-moderate increase in activity when compared to the normative database, while blue means there is a large decrease.
This term refers to the relative amount of activity within a specific frequency band compared to all the other frequency bands. Relative activity in each frequency band is compared to a normative database to determine the presence of suspected abnormalities. The results for each frequency band are shown with the topographic activity maps. In the example shown below, green is the color representing average activity. Red means there is a large increase in activity, yellow-moderate increase of activity when compared to the normative database, while blue means there is a large decrease.
This term refers to the similarity in EEG waves over different areas of the brain i.e., the timing of activity in one area compared to another. Coherence in each frequency band is compared to a normative database to determine the presence of suspected abnormalities. The results for each frequency band are shown with the topographic connection maps. Thick lines represent larger deviations from "normal" – red refers to increased coherence, while blue refers to decreased coherence.
This term refers to the relationship between the amounts of activity in one area of the brain compared to another. Inter-hemispheric-means differences between each side of the brain, while intra-hemispheric mean differences between areas on the same side of the brain.
Asymmetry in each frequency band is compared to a normative database to determine the presence of suspected abnormalities. The results for each frequency band are shown with the topographic connection maps. Thick lines represent larger deviations from "normal" – red refers to increased asymmetry, while blue refers to decreased asymmetry.
3-D source localization using LORETA (Low Resolution Electromagnetic Tomographic analysis) produces 3 dimensional images that reflect patterns of activity in your brain. Each image demonstrates activity in different regions of the brain at different frequencies. The big advantage of LORETA testing when compared to QEEG only is the ability to find functional abnormalities in the deeper structures of the brain-very similar to functional magnetic resonance (fMRI) of the brain but at much lower cost.
An Informed Consent detailing the process required for the qEEG recording will be part of the intake process. In addition, you will be asked to complete a medical history form and symptom checklist. If Sensory Integration concerns are present, our Clinical Director, Linda Marshall-Kramer, OTR/L BCN, will perform Occupational Therapy related evaluations. Following the qEEG, the data will be analyzed as explained above, by our Medical Director, Dr. Kramer, MD. A report will be generated and you will receive this 40+ document in the form of a CD. A written report is also provided; this interprets the full qEEG and suggests the training protocol. In addition, a visit can be scheduled in order to go over the results of the qEEG in more detail with Dr. Kramer.
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Different brain wave frequencies, called bandwidths, relate to different mental states. They are named after letters of the Greek alphabet. Neurofeedback therapy is used to reduce or increase specific brainwave frequencies depending upon the clinical symptoms presented and the results of standardized testing and the Quantitative EEG or Brain Map.
DELTA is the slowest frequency of brain wave activity. Frequency is a measurement of the oscillations, or the cycles per second, of the brain waves. This electrical activity is hypothesized to emerge from large aggregates of neurons as they communicate and process information. The source of this activity is considered to be the postsynaptic changes in electrical potential along the membrane of the dendrites. Delta is the slowest brain wave and is measured from .5 to about 4 cycles per second. Delta is only seen in the adult EEG in the deep sleep state that occurs within the first two hours of the sleep cycle. If it is seen in the waking state in an adult, it could indicate some type of abnormality.
THETA occurs between 4 and 8 cycles per second. Theta in the adult EEG can indicate drowsiness, it can also indicate some abnormalities. Sometimes people with head injuries will show excessive Theta activity either at the site of the injury or other areas of the brain. Theta has also been found to be outside the norm in some children with ADD and ADHD and sometimes in children with learning disabilities.
ALPHA is similar to putting the clutch in before shifting gears; it is an idling or holding pattern. Approximately 95% of the population has a peak Alpha frequency with eyes closed and that is considered very normal. Alpha predominance essentially represents a brain that is quiet and at rest. An important point is that Alpha ranges from 8-12 cycles per second.
BETA is anywhere from 13 cycles per second all the way on up to 32 cycles per second. Low Frequency Beta, between 13 and 15 cycles per second, has also been referred to as "sensory motor rhythm" and it seems to be a very important rhythm. It has the ability to organize the brain in terms of biofeedback. It is being used for ADD and Learning Disabilities, as well as a variety of emotional problems and for Peak Performance. It has to do with the coordination of many areas of the brain. By teaching an area of the brain to make more low frequency Beta activity, it actually effects many pathways within the brain in may different ways. We use it often for sleep disorder. From 15 hertz on up, we speed up in frequency so the brain becomes more focused, more concentrated, up to about 20 hertz. From 20 hertz on, too much Beta activity can backfire. What starts to happen is that there is too much activity, too much electrical noise occurring in the brain. You actually see functioning and organizational concentration abilities start to deteriorate.