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37 Cards in this Set
- Front
- Back
Rythmic Frequency
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EEg activity in consisting of waves of approximately constant frequency
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Arrhythmic Frequency
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EEG activity in which no stable rythms are present
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Dysrhythmic Frequency
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EEG activity that refers to patterns or rhythms that characteristically appear in patient groups and are rarely seen in healthy subjects
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Attenuation (synonyms: suppression, depression)
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Reduction of amplitude of EEG activity resulting from decreased voltage
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Hypersynchrony
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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
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Paroxysmal
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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.
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Morphology
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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.
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Surface polarity
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is described as the negative or positive polarity of a particular activity or waveform at a particular electrode location.
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Monomorphic
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EEG activity appearing to be composed of one dominant frequency
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Polymorphic
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EEG activity composed of multiple frequencies that combine to form a complex waveform
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Sinusoidal
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Waves resembling sine waves. Monomorphic activity is usually sinusoidal.
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Transient
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An isolated wave or pattern that is distinctly different from background activity.
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Spike
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A transient with a pointed peak and a duration from 20 to under 70 msec
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Sharp wave
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A transient with a pointed peak and duration from 70-200 msec
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Complex
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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
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Biphasic (diphasic)
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A wave or complex having two distinct components, one surface positive and the oter surface negative
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Triphasic
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A wave or complex having 3 distinct component, such as negative-positive-negative.
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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
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Continuous: occuring without interpretation Discontinuous: appearing from time to time Regular and irregular.
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Generalized
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Not limited to a specific area
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Lateral (lateralized)
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Coming from one side. ie. slow activity is present over the right temporal-frontal areas
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Bilateral
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Coming from both sides. ie. Bilateral spike activity in the left and right anterior areas
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Focal
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Coming from a local region
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Symmetry
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Equal distribution of EEG activity over homologous head areas. ie. Alpha activity is seen symetrically in the left and the right occipital areas.
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Synchrony
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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)
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Periodicity
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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)
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Reactivity
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refers to the reaction of the EEG to stimulation or to a stimulus-related change in morphology.
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Alpha activity
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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
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Beta Activity
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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.
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Theta Activity
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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.
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Mu Rythm
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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.
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Lambda Waves
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Sharp waves with variable polarity seen in the occipital areas when the subject intently scans a complex visual field with horizontal eye movements
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Stage 1 Sleep (drowsiness)
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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
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Stage 2 Sleep
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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.
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Stage 3 Sleep
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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.
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Stage 4 Sleep
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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
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REM-Stage Sleep
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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
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What are the 4 main changes seen in elderly persons?
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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
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