The Human Brain : From Neurone to Nervous System

CLINICAL NEUROPHYSIOLOGY : Evoked Potentials


  1. Evoked Potentials are electrical events in regions of the brain that can be recorded following natural or electrical stimulation of a sensory nerve.

  2. Changes in the latency of these potentials allows the presence of lesions to be determined, and in some cases also the site of the lesion that gives rise to the abnormal changes.

  3. The Visual Evoked Potential can be recorded from the visual cortex following the sudden presentation of a visual to the eye, and follows that stimulus at a characteristic latency.

  4. The visual evoked potential cannot be easily recorded following a single visual stimulus; instead, a computer is used to reduce the background noise of the EEG and enhance to evoked activity by averaging the responses to many stimuli.

  5. The Auditory evoked potentials can also be averaged following presentaion of sudden sounds, such as clicks, to the ear. The complex waveforms of this evoked potential may allow the location of a lesion to be determined.

  6. Averaging computers can be used to identify somatosensory evoked potentials following electrical stimulation of sensory nerves in the limbs.

  7. Key Words: Sensory Evoked Potentials, visual, auditory, somatosensory evoked potentials.


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