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37 Cards in this Set

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Rythmic Frequency
EEg activity in consisting of waves of approximately constant frequency
Arrhythmic Frequency
EEG activity in which no stable rythms are present
Dysrhythmic Frequency
EEG activity that refers to patterns or rhythms that characteristically appear in patient groups and are rarely seen in healthy subjects
Attenuation (synonyms: suppression, depression)
Reduction of amplitude of EEG activity resulting from decreased voltage
increase in voltage and regularity of rhythmic activity, often in alpha, beta, theta range. The term implies an increase in the number of neural elements contibuting to the rhythm
Activity that emerges from background with a rapid onset, reaching usually quite high voltage, and ending with an abrupt return to lower voltage activity. This is associated with a change in frequency and morphology.
refers to the shape of the wave form. The shape of a wave or an EEG pattern is determined by the frequencies that combine to make up the waveform and by their phase and voltage relationships.
Surface polarity
is described as the negative or positive polarity of a particular activity or waveform at a particular electrode location.
EEG activity appearing to be composed of one dominant frequency
EEG activity composed of multiple frequencies that combine to form a complex waveform
Waves resembling sine waves. Monomorphic activity is usually sinusoidal.
An isolated wave or pattern that is distinctly different from background activity.
A transient with a pointed peak and a duration from 20 to under 70 msec
Sharp wave
A transient with a pointed peak and duration from 70-200 msec
A sequence of two or more waves, not necessarily of the same frequency, with a distinct form or pattern. IE. spike and wave complex, or a sharp and slow wave complex
Biphasic (diphasic)
A wave or complex having two distinct components, one surface positive and the oter surface negative
A wave or complex having 3 distinct component, such as negative-positive-negative.
Quantity refers to the ammount of a particular type of EEG activity with respect to percent time present and/or to voltage. There are 4 terms associated with quantity
Continuous: occuring without interpretation Discontinuous: appearing from time to time Regular and irregular.
Not limited to a specific area
Lateral (lateralized)
Coming from one side. ie. slow activity is present over the right temporal-frontal areas
Coming from both sides. ie. Bilateral spike activity in the left and right anterior areas
Coming from a local region
Equal distribution of EEG activity over homologous head areas. ie. Alpha activity is seen symetrically in the left and the right occipital areas.
is the simultaneous appearance or rhythmic or morphologically distinct patterns over different regions of the head, either on the same side (unilateral) or on both sides (bilateral)
refers to the distribution of patterns or elements in time (e.g. the appearance of a particular EEG activity at more or less regular intervals)
refers to the reaction of the EEG to stimulation or to a stimulus-related change in morphology.
Alpha activity
Range from 8 to 13 Hz about 85% range in 9.5-10.5 Hz 66% average between 20-60 uV with 28% less than 20 uV
Beta Activity
frequency faster than 13 Hz but in general range of 18-30 Hz Voltage is between 5 and 20 uV. Can be enhanced by tranquilizers and barbiturates.
Theta Activity
between 4-7 Hz voltage less than 15 uV with only 10% 15-25 uV if the amplitude of theta activity exceeds that alpha by more than 50% it may have pathological significance.
Mu Rythm
in central areas and about 9 Hz with a range of 7-11 Hz. Has a sharp element with a v;otage up to 80 uV. It can also be in perietal and is blocked by tactile stimulation, fist clenching, or thought of movement.
Lambda Waves
Sharp waves with variable polarity seen in the occipital areas when the subject intently scans a complex visual field with horizontal eye movements
Stage 1 Sleep (drowsiness)
Alpha attenuates, in the occipital areas, a series of surface positive transients which are called Positive Occipital Sharp Transients. POTS Cz C3 C4 will see a slow sharp transient called a vertex (V) waves
Stage 2 Sleep
11-15 HZ spindle bursts in central vertex area with voltages in 20-100 uV and high as 150 uV. Lasting 0.5- 3 seconds. K complexes are slow waves associated with spindle bursts. Can be seen with/without abrupt auditory stimuli.
Stage 3 Sleep
Delta activity with frequencies of 2 Hz or less are present in 20-50% of the time and there are still sleep spindles. K complexes and frontal slow transients may appear.
Stage 4 Sleep
Delta activity is present more than 50% with a voltage greater than 75 uV. Sleep spindles slow down to 10 Hz area you will have large regions of the brain appear to discharge synchronously
REM-Stage Sleep
EOG electro-oculogram picks up eye movemnt while an EMG electromyogram picks up decreased muscle tone in the chin. Sharp theta waves called saw tooth may appear in central areas. Occurs 5-6 times at intervals of 90 min
What are the 4 main changes seen in elderly persons?
1. decrease in frequency of alpha 2. increase in the amount of beta activity 3. increase in diffuse slow activity 4. development of focal dysrhythmias