Computer implemented digital filtering, scaling and addition for analysing the structure of early somatosensory...

Computer-implemented digital filters are used to separate the fast wave complexes which are superimposed on slower background waves in human short latency somatosensory evoked responses (SSERs). The choice of filter for picking out the fine structure of the fast wave is shown to be not critical. After scaling and adding digitally filtered SSERs from two electrode montages, the peaks believed to be of cortical origin are cancelled, leaving visible a repetitive wave which must be presumed to be generated subcortically. From this, a new interpretation of the origins of peaks in short latency SSERs is made.