[The history of sleep research in the 20th century]

Not until the 19th century theories on sleep were based upon experimental findings in animal and humans. The so-called 'hypnotoxin theory' culminated, when Legendre and Piéron successfully induced sleep in a dog by transmission of cerebrospinal fluid from a dog deprived of sleep. The main discussion concerning the origin of sleep has been the question if sleep is a passive or an active state. Similarities with coma, the positive Babinski sign and pathoanatomical findings in patients who died after encephalitis lethargica were the arguments for the 'deafferentiation hypothesis'. Bremer's classical brainstem-transsections in cats confirmed this idea. Pavlov was the major representative of the idea that sleep was due to a general inhibition of the brain. Hess induced physiological sleep in cats by electrical stimulation of the diencephalon, proving the active nature of sleep. The introduction of the EEG in animals by Caton and in humans by Berger allowed for the first time the measurement of sleep depth without waking the sleeper. After discovery of the REM sleep periods by Aserinsky and Kleitman in 1953 and the demonstration of periodical sleep cycles by Dement and Kleitman, polysomnography with simultaneous whole night recording of EEG, EMG, electrooculogram and other physiological parameters was established as the major diagnostic tool in sleep disorders. One of the most important questions about the function of sleep is still unresolved. NREM sleep is believed to have a restorative function, whereas REM sleep might be involved in learning processes. According to the sleep interpretation of Sigmund Freud, the dream content represents endogenous wishes which cannot be expressed during wakefulness because of an internal 'sensor'. A more recent theory by Hobson explains the dreams by a very unspecific brainstem activity occurring during REM sleep which projects to the frontal brain and activates stored memory. The most important sleep disease of the 20th century is certainly the sleep-apnea syndrome. Charles Dickens described in his 'Pickwick Papers' subjects with this illness already 150 years ago. The pathogenetic significance of the apneas during sleep, however, were recognized in 1965 only by Gastaut and at the same time by Jung and Kuhlo. Treatment for insomniacs was restricted for many years to alcohol, opium and barbiturates. Following the horrible sequelae of thalidomide therapy in 1956, a more efficient treatment was available through the introduction of benzodiazepines after 1960.

[Electroencephalography and epileptology in the 20th century]

In 1875, Caton was already able to detect cerebral electric currents during experimental studies in animals. In 1914, Cybulski and Jeleńska-Macieszyna reported on the increase of current-intensity during a focal motor epileptic seizure. In 1929 in Jena, Berger revolutionized the study of epilepsy with his paper on the human electroencephalogram 'Uber das Elektrenkephalogramm des Menschen'. His discovery and further publications as well as later works of numerous researchers, especially F. and E. Gibbs, Lennox, Penfield and Jasper, made it possible to distinguish different forms of 'little' epileptic seizures and to separate them from nonepileptic paroxysmal disorders. New epileptic syndromes could be singled out, as e.g. the symptomatic epilepsy of childhood with variable clinical manifestations of seizures and slow spike-wave complexes in the EEG (Lennox-Gastaut syndrome) or the benign partial epilepsy of childhood with centrotemporal EEG spikes. In these fields, as well as for the epileptic seizures in newborns and babies and for the differentiation between epileptic and nonepileptic twilight states in later stages of life, the EEG remains an indispensable tool in the CT and MRI era. It also contributes largely to the diagnosis of nonepileptic cerebral illness such as herpes simplex encephalitis, subacute sclerosing panencephalitis van Bogaert and Creutzfeldt-Jakob disease. Since the introduction of phenobarbital by Hauptmann in 1912, the palet of effective drugs against epilepsy, such as phenytoin, carbamazepine, valproate and benzodiazepines used for status-epilepticus treatment, became essentially larger. The value of newer substances (vigabatrin, progabide, gabapentin, lamotrigin) can't be estimated actually.(ABSTRACT TRUNCATED AT 250 WORDS)

Berger lecture. Is Berger's dream coming true?

In the last quarter of our century technologies have been developed that permit us to measure and localize with previously unknown precision physiological concomitants of mental activities. Human in vivo cerebral psychophysiology has come of age, decades after the discovery of EEG. In part this has come about through the development of PET and most recently dynamic MRI. However, it is hardly known today that the concepts which underlie these modern methods of studying the physiological correlates of human mental activity were the focus of Berger's early research at the onset of his scientific career at the turn of the century. Indeed at that time he attempted to study human mental function through measuring cerebral blood flow by means of plethysmography applied to patients who had pulsating skull defects. He also measured intracerebral temperature changes during neurosurgical procedures in awake, locally anesthetized, patients in a quest of identifying metabolic concomitants of mental activity. He was thus well ahead of his time, but was forced to give up these methods because they were not commensurate to the task. Only at age 50 he turned to electrophysiology and discovered the EEG. At last he was able to identify some electrophysiological facets of human psychophysiology related to attention, sleep, wakefulness and coma. This essay will illustrate some examples of PET, functional MRI, computerized EEG and cerebral electrical stimulation studies that show that Berger's conceptual approaches to human psychophysiology, even though he could not effectively apply them himself, were correct and have become powerful tools of modern neuroscience.

Introduction and history of the use of electroencephalography in animal drug studies

A brief review of the development and the state-of-the-art of EEG methods used to study drug effects is presented. Classification systems based on drug effects in animals kept awake artificially, and based on drug effects on the sleep-wake state duration and distribution are discussed. It is concluded that the techniques are there and the time is ripe to develop animal EEG-based drug classification systems with high predictive ability.