The lowest brain frequencies are Delta waves. Each of these has its distinct function and can be used to detect brain dysfunction. The raw EEG is usually described in terms of five frequency bands described below. Intensity, which is like the volume of brain wave activity, is measured in microvolts. Amplitude represents the power of electrical impulses generated by brain. If any of these frequencies are deficient, excessive, or difficult to access, our mental performance can suffer. It can be compared to the frequencies that you tune into on your radio. Frequency is measured in Hertz (Hz) it is the number of times a wave repeats itself within a second. The z refers to an electrode placed on the midline.Įlectrical activity is described by three characteristics frequency, amplitude and intensity. (Note that there is no “central lobe”, but this is just used for identification purposes.) Even numbers (2,4,6,8) refer to the right hemisphere and odd numbers (1,3,5,7) refer to the left hemisphere. The letters F, T, C, P, and O stand for Frontal, Temporal, Central, Parietal and Occipital. Each site has a letter (to identify the lobe) and a number or another letter to identify the hemisphere location. The “10-20 System” of Electrode PlacementĮach point on the skull is linked with an electrode position. The 10-20 system is based on the relationship between the location of an electrode and the underlying area of cerebral cortex.
![quantitative eeg quantitative eeg](http://neufydi.com/images/eeg-inspelning-ect.jpg)
The pattern we use is the international 10/20 standard for describing these positions. We record the EEG from many electrodes arranged in a particular pattern using a cap that is sized according to the circumference of the skull. The electrodes are fed into a sensitive amplifier. These potentials are recorded by an electrode that is attached to the scalp with non-toxic conductive gel. This electrical activity occurs at several different frequencies. These electrical voltages enter the membranes surrounding the brain and continue up through the skull and appear at the scalp where they are measured as microvolts. create voltages that are conducted through the brain tissues. Changes in membrane polarization, inhibitory and excitatory post-synaptic potentials, action potentials etc. The brain behaves like any other electrical system.
![quantitative eeg quantitative eeg](https://d3i71xaburhd42.cloudfront.net/07d5be3d95798dc4f81ddd40ffc94e34f3628d21/6-Figure2-1.png)
The brain map provides a baseline to work from while we retrain the brain and regulate metabolic and physiological problems in the body. This tool gives us the ability to view the dynamic changes taking place throughout the brain during processing tasks and assists in determining which areas of the brain are fully engaged and processing efficiently. Quantitative Electroencephalogram (qEEG) or Brain Mapping is a procedure that records electrical activity within the brain from 19 channels.