ABSTRACT
The use of digital computers in neurophysiological laboratories requires analog to digital conversion. In the quantitative analysis of either the EEG or the evoked responses, similar technical problems arise that must be considered in detail. One extremely important aspect that should be taken into account during data acquisition is the change of the internal state of the subject, because such changes produce marked variations in brain electrical activity. The accuracy of the numerical representation of analog values is obviously limited by the number of quantizing levels—that is, the number of divisions into which the voltage range of the analog signal can be divided. Artifact rejection can be done by previous visual inspection and editing of the EEG data. The procedures just described are invaluable adjunct to automatic data acquisition, reducing the need for time-consuming editing by skilled personnel and permitting the recording of many cases in which it is impossible to obtain reliable data with routine techniques.
