There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
A new type of EEG derivation has been investigated. This derivation, constituting
a practical implementation of the Laplace operator, detects source activity as it
appears at the surface level of the scalp. It is realized in the 10-20 system of electrode
placement basically as an analogue superposition of four bipolar derivations, forming
a star-like configuration around each electrode. Visual estimation of the topographical
origins of a pattern, is thus replaced by a more efficient on-line process, which
derives the source activity at the position of each individual electrode. Practical
correlation tests have shown that the separation of adjacent derivations is improved
by a factor of between two and four, compared to the corresponding bipolar and common
reference derivations. Any feature of local origin will therefore have a correspondingly
increased signal-to-noise ratio prior to the stage of visual or automatic interpretation.
As a consequence of the partition of the scalp field into 19 source zreas, instead
of utilizing an arbitrary number of potential differences, one fixed montage with
19 recorder channels is sufficient to present the total surface activity, within the
limits of resolution of the electrode system.