D4 Evoked potentials

Title

Evoked potentials extract, by averaging multiple trials, the specific neuronal response to a sensory stimulus from the background EEG activity (direct extension of the D1 recording), since the average of random signals not correlated with the stimulus tends to zero while the evoked response, consistent trial after trial, is preserved and reinforced. The improvement in the signal-to-noise ratio scales with the square root of the number of averaged trials. The clinically relevant characteristics are the latency (time to the peak of a specific component) and the amplitude of said peak; In brainstem evoked potentials, the interval between spikes allows estimation of the central conduction velocity, a conceptual extension of the axonal conduction velocity defined in E3. A delay with respect to normative values suggests an alteration of the sensory pathway studied (for example, demyelination as in A4), while cognitive components such as the P300 depend on the subjective probability of the stimulus, not only on its physical properties.

ID:4300