Normal EEG & NormalEEG Variant Tracings

  Waking Adult  Adult Sleep     Adult Photic Stimulation

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Normal Adult EEG: Awake

Normal Adult Tracing
Normal Adult Tracing
These normal awake tracings contains Alpha rhythms, predominantly frontal Beta rhythms, and low voltage, predominantly central Theta rhythms. Some mu rhythms may be seen in normal adult awake tracings . 

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Normal Adult EEG: Sleeping Rhythms

Normal Adult Stage I (Drowsiness) This tracing shows normal adult drowsiness, or Stage I sleep. During this phase of sleeping, Alpha rhythms drop in amplitude, and Theta rhythms become prominent. Delta rhythms also become more pronounced, although at this stage of sleep, they are only abuot 10-20% of the tracing. 
Normal Adult Stage II During this stage of sleep frontal, enhanced, Beta rhythms make a come-back.  In addition, Theta rhythms become more pronounced, as do Delta rhythms.  Also during this phase, sleep spindles appear , which are 14-16 Hz waves which appear centrally.  K complexes appear, which are vertex waves (sometimes known as V waves), followed or preceeded by sleep spindles. Although V waves can be seen in Stage I sleep, they will be less than 75uV in amplitude. 

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Adult EEG Normal Variant:

Normal Photic Stimulation with Occipital Driving

Normal Adult Photic Driving
Normal Adult Photic Driving
This is a normal phenomena in which the occipital rhythms are taken over by the potentials created by the stimulation of the stobe light. In essence, one is seeing a large visual evoked potential. These rhythms keep exact time with the light, thus they are driven by the speed of the light. They can also occur in harmonics, during which the waves may match the lamp and be twice the frequency. 

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Telephone Ring Artifact


EEG Telephone Ring Artifact
This is an artifact created by a "land line" telephone.



 
 
















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