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What is Brain Mapping?
By Victor Zelek, Ph.D., Director of Neuropsychological Services
Northeast Center for Special Care
Diplomate, National Registry of Neurofeedback Providers
What is Brain Mapping ?
Physical injury to the brain, such as concussion,
disrupts normal flow of electrical impulses in the brain tissue.
Similarly, 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 brainwave “signatures.”
EEG (or electroencephalogram) is a recording of
brainwave activity. QEEG (Quantitative EEG), popularly known as brain
mapping, refers to a comprehensive analysis of brainwave frequency
bandwidths that make up the raw EEG. QEEG is recorded the same way as
EEG, but the data acquired in the recording are used to create
topographic color-coded maps that show electrical activity of the
cerebral cortex.
While other brain imaging techniques (e.g., CT, MRI,
PET, SPECT) measure such properties as cerebral blood flow, metabolism
or structural integrity, QEEG measures electrical activity of the
brain. It provides complex analysis of such brainwave characteristics
as symmetry, phase, coherence, amplitude, power and dominant
frequency. In fact, subtle disruptions of electrical
connectivity and flow in the brain sometimes may be the only or the early
signs of a problem.
The QEEG findings are then compared to a normative
database. This database consists of brain map recordings of
several hundred healthy individuals. Comparisons are displayed
as Z scores, which represent standard deviations from the norm.
The primary use of QEEG is to examine patterns of
brainwaves and help determine whether a person is an appropriate
candidate for Neurofeedback, a treatment that normalizes brainwaves.
QEEG does not render a diagnosis, but is designed to help the
clinician to make a diagnosis. QEEG is not a substitute for EEG; it is
a different process than that carried out by the neurologist when he
or she performs an EEG assessment. Medical illness of the brain, such
as seizure disorder, dementia, encephalopathy, brain tumor, lesion,
haematoma and aneurysm should be diagnosed by a physician.
How is it Done?
An elastic cap with 19 sensors is placed on the
head and the sensors are connected to the recording device. A special
conductive gel is squeezed into each of the 19 sensors in the cap.
This preparation takes approximately 15 minutes. The actual recording
might take from 10 to 30 minutes.
A patient may be instructed to keep his eyes open or closed during
parts of the recording, or asked to perform a mental task, such as reading
or simple math. It is important to sit very still during the recording.
Reading the Maps
QEEG results are presented as Z scores. Z scores
represent Standard Deviations (SD) from the norm and span from -3 to
+3. Thus a Z score of +2 means that the result is 2 Standard
Deviations higher than the norm (+2SD) and exceeds 98% of the
age-matched people in the normative sample. A Z score of 0 represents
the norm and is color-coded green. Red and blue colors on the maps
show brainwave activity that is 3 SDs above or below the norm.
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Green - Normal Red =
Excessive Blue = Diminished Activity |
The following examples show different ways in which
QEEG can be useful in diagnostics and treatment, as well as evaluation
of treatment effectiveness.
Example 1
Excessive Theta waves (4-8 Hz) at the central
& left parietal area due to traumatic brain injury, presented in 1 Hz
slices. The red color represents increased slow wave activity at the site of
the injury.
Before Neurofeedback Treatment:
After
Neurofeedback Treatment:
Example
2
Diminished coherence in the left hemisphere after a concussion to the left
frontal area. Blue lines show reduced neural connectivity.
Example 3
Typical ADD signature: excessive generalized Theta and diminished Beta.
Example 4
QEEG combined with LORETA (Low Resolution Electromagnetic Tomography)
enables examining of deep structures of the brain slice by slice, as well
as viewing 3-dimentional models of the brain. Here is asymmetrically
increased slow wave activity typical of depression: too much Alpha and
Theta (red) on the front left side.
Example 5
Increased slow wave (Theta) activity in the Frontal Lobes commonly seen in
ADD.
Example 6
Seen here are diminished fast Beta waves in the Frontal lobes (blue) and
excessive slow Theta waves in the Hippocampus (red), indicative of the
early stages of Alzheimer’s disease.
Some
Technical Considerations
Although
QEEG may render lots of useful information it has its limitations and
possible pitfalls. For example, it is important that raw data that are
digitized and analyzed by the computer are free from artifacts, which are
electrical signals produced by something else than the brain, such as
muscles or improper electrode placement. Therefore, the person that
performs the recording and data analysis should be well trained in
artifact recognition. There is also some debate about the several
normative databases that are currently on the market. Some of them have
larger sample size or age span than others. They also use somewhat
different inclusion criteria for “normalcy” and different mathematical
procedures for data analysis.
Clinicians that are considering QEEG in their practice are often faced
with complex choices of multi-channel EEG recoding devices, data analysis
software programs and normative databases. Internet resources such as the
International Society for Neuronal Regulation www.insr.org
may be helpful in
providing information or journal articles describing relative merits of
various systems.
At Northeast Center for Special Care we use Mindset 24 recording
device. We found it to be a reliable and sensitive instrument that
produces very clean recordings. For data analysis we use Neuroguide
software with Dr. Robert Thatcher’s Lifespan normative database, which
consists of 625 subjects from two months of age to 82.3 years of age. We
also use LORETA (Low Resolution Electromagnetic Tomography) which allows
for 3-dimentional electrical source localization analysis.
The Place of Brain Mapping in the Overall Assessment
It is important to remember that QEEG is just one part of the overall
assessment. QEEG, along with MRI, SPECT or CT scans is an imaging
technique and, as such, it does not describe cognitive or emotional
problems in functional terms. While very good at pinpointing problem
locations in the brain it cannot say how much cognitive functioning is
diminished at that location. For example, QEEG may show reduced electrical
activity in the Hippocampus area, which is associated with memory storage
and retrieval. Neuropsychological testing, on the other hand, may reveal
that an individual’s short term auditory memory is at the 9th
percentile of functioning.
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this article was helpful why not download our podcast:
Brain Mapping and Neurofeedback.
Listen on your iPod® or Mp3
player. Click Here
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