ABSTRACT
This chapter addresses the ‘simpler’ question: what can the electroencephalogram (EEG) recordings tell us about the underlying brain activity? Or just as importantly what cannot it tell us? It discusses how the volume conductor changes the measurement is important for understanding the EEG. EEG measurements at the scalp, cortex or elsewhere in the head are also affected by the electrical properties of the surrounding medium, known as the volume conductor. This is because the many biological tissues each alter the electric fields generated within the brain differently. Macro-scopic potentials measured intra-cranially are predominantly dependent on the location and activity of mesosources. Macro-scopic potentials measured at the scalp are also dependent on source location and activity, but must consider the volume conducting properties of the tissues between source and recording site.
