The general purpose of this research was to relate topographical mapping of brain electrical activity to performance on several tasks with different cognitive demands. A total of 35 subjects were studied. Fifteen subjects participated in a linguistic cognitive task. Eight subjects participated in exploratory studies of the Sternberg memory task. Based on these exploratory studies, twelve subjects participated in an experiment in which event related cortical potentials were recorded while they performed the Sternberg task. The overall results indicate that brain topography is a potentially powerful technique for relating brain functions to performance on tasks with varying cognitive demands. The present results with the Sternberg task, for example, not only confirmed past research results but also clearly indicated relationships between brain functions and performance on this task that had not previously been shown. One example was that a negative event related potential component (ERP) at 200 ms after the presentation of the stimulus was related to response set performance (positive vs. negative responses) primarily in the left hemisphere and more specifically in areas of the left temporal lobe often involved in memory and/or speech reception and articulation. These and other results are discussed in the report. Keywords: Electroencephalography psychophysiology. (aw).

Topographic Mapping of Brain Electrical Activity presents the state of topographic mapping. It discusses its contributions to brain research. It addresses its research and clinical applications. It also explains completely the brain electrical activity mapping as a tool used in the diagnosis and treatment of neurological dysfunction Some of the topics covered in the book are the color imaging of scalp somatosensory evoked potential fields; visual evoked potential topography; spatial analysis of EEG and evoked potential data; intra-individual changes in EEG during mental performance; and changes in transversal coherence. The event-related desynchronization mapping of visualization of cortical activation patterns is fully covered. The spatiotemporal mapping display is discussed in detail. The text describes in depth the physical aspects of EEG data as a basis for topographic mapping. The human scalp field injection experiments are presented completely. A chapter is devoted to the classification strategies for topographic mapping data. Another section focuses on the topological factors. The book can provide useful information to radiologists, neurologists, students, and researchers.

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.

"The study compared electrical brain activity of subjects in five different conditions: eyes-closed at rest, eyes-open at rest, looking at a flashing object, looking at apparent movement, and looking at real movement. Absolute theta and alpha power in the frontal and occipital areas were analyzed. Significant differences were found in the frontal area. Results suggest that perceived movement requires higher order cognitive processes outside the occipital area. Implications for education and cognitive research are discussed." --

From its discovery in 1929 by Hans Berger until the late 1960s, when sensory visual and auditory evoked potentials were dis covered and became popular, the EEG was the most important method of neurophysiological examination. W-ith the advent of computer technology in the 1980s, it became possible to plot the potential fields of the EEG onto models of the scalp. This plot ting of information as neuroimages followed the structural and functional techniques of Cf, MRI, PET and SPECf. The success of this method, which began in the early 1980s, has led to the brain mapping of EEGs and EPs being increasingly used for di agnosistic purposes in neurology, psychiatry and psychopharma cology. The pioneers of this method believed in it and were commit ted to its success. However, many traditionalists felt that it gave no new information and so regarded the method with scepticism. Some found both the coloured maps and the mapping technique misleading, which led to unnecessary conflict between mappers and their chromophobic oponents. Emotions have run so high that some professional bodies have justifiably adopted guidelines and warned of the misuse of the method.

It had been difficult to find appropriate teaching material for students and newcomers to this field of brain electromagnetic topography. In part, this is due to the many disciplines involved, requiring some knowledge of the physical sciences, mathematics, neurophysiology and anatomy. It is my hope that this book will be found suitable for introducing interested workers to this exciting field. Advanced topics will not be covered, as there are many excellent texts available. Peter K.H. Wong vii ACKNOWLEDGEMENT My co-authors, Hal Weinberg and Roberto Bencivenga, for their support; Richard Hamer, for all his early advice; Ernst Rodin and Gene Ramsay, for their encouragement; Wendy Cummings for her assistance; Technologists from the Department of Diagnostic Neurophysiology for collecting such excellent data; Bio-Logic Systems Corp. for permission to use some data as illustration; and all my friends and colleagues. My wife Elke, for putting up with me throughout this presumptuous endeavour. The manuscript was delivered in camera-ready form to the Publisher. Illustrations were created using Harvard Graphics and CorelDraw software. ix CONTENTS Part 1: Fundamentals. 1 1.1 Introduction . . . 1 1.2 Data Aquisition. . 3 Map Construction. 8 Interpolation . . . 12 1.3 Spatial Sampling . . 16 1.4 Reference and Reference-Dependence 20 1.5 Map Display Methods ..... . 27 Scaling and Floating Voltage Scales. 37 Summary Maps .......... . 37 1.6 Identification of Topographic Features 41 1.7 Spike Mapping .. . 51 1.8 Post-Processing 61 Analog Front-end. 62 Digital Filtering . 63 Reference Manipulation .. 65 Statistical Mapping .

"The study compared the brain electrical activity of two groups of gifted children between the ages of 9 and 13 years. The electroencephalogram (EEG) was recorded with eyes closed: "at rest" and during three simple cognitive tasks. Significant differences were found in absolute power in the resting state EEG between the gifted high achievers and non-gifted, age-matched peers. No significant differences were found between the gifted underachievers and age-matched peers. Significant differences were found in absolute and relative power during the word recognition task compared to the resting EEG. No significant differences were found in the comparisons of the topographic maps for the other cognitive tasks and the resting EEG. Results suggest that topographic mapping of brain activity may provide an educational method for discriminating among children of different cognitive abilities. Implications for education are discussed and suggestions for further research are given." --