The investigation of the cortical structure of stimulus-response pathways is the central subject of this book. The investigation comprises measurement of reaction times and recording of event-related potentials, the computer assisted evaluation of these empirical data and the mathematical description of these pathways. The investigation is completed by a hypothetical neural interpretation and a comparison of the pathways of healthy subjects, patients with brain tumors, and patients with schizophrenia. The author has chosen a completely new approach by describing the structure of the stimulus-response pathways by mathematical equations and by presenting a hypothetical neural interpretation of this structure, and by simulating these pathways in computer programs. This volume presents a neural theory of simple mental processes like stimulus-response sequences. Knowing the neural correlate of decision making would have far reaching consequences for the neurosciences. The readers will benefit from new insights into the physical substrate of mental processes.