Selective averaging of the intracerebral click evoked responses in man: an improved method of measuring latencies and amplitudes.

Individual click evoked responses recorded in the right and left frontal lobe in man have been correlated with different templates, that is, particular wave shapes of evoked responses, and from the maxima of the cross correlation functions individual estimates were obtained of amplitude and latency. Averages were then made of evoked responses having particular amplitude and/or latency values. Using such selected trials for averaging, better results were obtained and artificial amplitude damping avoided. It was found for example that the component N90 varied in latency between 75 and 100 msec and was linked with the behaviour of the contralateral recorded potential amplitude of P150. Furthermore it was found that the biphasic potential N230 P430 was very unstable in latency and the amplitude of the averaged potential using all trials was about 30% too small.