Ions, their transport across membranes, and their flow through specialized ion channels are central to the understanding of brain function, normal and pathological. The first part of this book deals with the regulation of ions in brain extra- and intracellular fluids. Regulation is effected by the blood-brain barrier, and by membrane ion pumps and other transport mechanisms of neurons and glial cells. Normally adjusted for optimal neural function, ion levels can change and alter the excitability of neurons and influence synaptic transmission in healthy and diseased brains. After an introduction to the electrophysiology of epilepsy, and a description of experimental seizure models, the second part discusses the roles of the faulty regulation of ions and of the diseases of ion channels in generating epileptic seizures. The mechanisms of action of various anticonvulsant drugs are also considered. The third part is devoted to the phenomenon of spreading depression and its likely role in human diseases. The final chapters of the book deal with the role of ions in the devastation caused by lack of oxygen and by insufficient blood flow to brain tissue, and the reasons for the exceptional vulnerability of certain classes of central neurons in hypoxia and stroke. The book will be of interest to neuroscientists, neurobiologists, neurophysiologists, neurologists, neurosurgeons, and to their students and trainees.