Topographic Mapping Of Brain Electrical Activity

Topographic Mapping of Brain Electrical Activity

Topographic Brain Mapping of EEG and Evoked Potentials

Imaging procedures have been used for many years and are becoming increasingly important in a number of medical disciplines. This is due to recent technological advances, primarily computerization. The meth ods employed in CNS diagnostics are collectively referred to as "neu roimaging" and include procedures for investigating both cerebral morphology and cerebral function, such as computed tomography (CT), magnetic resonance imaging (MRI), positron emission tomogra phy (PET), and single-photon emission computed tomography (SPECT). Topographic mapping of electroencephalograms (EEG) and evoked potentials represents one of the functional procedures and per mits topographic imaging of EEG, evoked potentials, and magnetic fields. The latter application includes not only magnetic fields evoked by stimuli relating to different sensory modalities, but also endogenous and motor fields resulting from spontaneous brain magnetic activity, as recorded by magnetoencephalograms (MEG), the magnetic comple ment of the EEG. The advantage of recording electric and magnetic fields over other neuroimaging procedures is that these techniques are completely noninvasive and have extremely short analysis times (in the millisecond range). The aim of this book is to clarify the current state of this emerging technology, to assess its potential for substantive contributions to brain research, to delineate areas for further research and, over all, to envis age clinical applications in disciplines such as psychiatry, neurology, and neuropsychology.

Clinical Electroencephalography and Topographic Brain Mapping

Electroencephalography is truly an interdisciplinary endeavor, involving concepts and techniques from a variety of different disciplines. Included are basic physics, neuro physiology, electrophysiology, electrochemistry, electronics, and electrical engineer ing, as well as neurology. Given this interesting and diverse mixture of areas, the train ing of an EEG technician, a neurology resident, or an EEG researcher in the basics of clinical electroencephalography presents an uncommon challenge. In the realm of technology, it is relatively easy to obtain a technically adequate EEG simply by learning to follow a protocol and by correctly setting the various switches on the EEG machine at the right time. But experience has shown that the ability to obtain high-quality EEGs on a routine, day-to-day basis from a wide variety of patients requires understanding and knowledge beyond what is learned by rote. Likewise, knowledge above and beyond what is gained by simple participation in an EEG reading is necessary to correctly and comprehensively interpret the record. Such knowledge comes from an understanding of the basic principles upon which the practice of clinical EEG is founded - principles that derive from the various disciplines cited.