The interdisciplinary approach so popular today is more than a matter of fashion. It is, in fact, a reflection of the recognition that a good many areas once considered ade­ quately treated by one or the other of the traditional disciplines straddle the boundaries of several. Interdisciplinary research then is, by definition, a coop­ erative venture by several autonomous branches of science into areas incompletely accessible to anyone of them. By stimulating cooperation among several related disciplines, such research may serve to enrich each of them; but, on the other hand, the existence of these border areas occa­ sionally serves as Ii, pretext for postponing the solution of seemingly insurmountable problems. Brain research seems to have become such a border area of science. The fortress of classical psychology is being assaulted before our very eyes, its peripheral and even its more integral areas being invaded by physiology, morphol­ ogy, physics, and chemistry. Neurophysiology, too, has ceased to be an autonomous and self-governing field, and has come increasingly to rely on the help proffered by gen­ eral psychology, epistemology, and logic, as well as exact sciences such as mathematics and physics. These border assaults have undoubtedly been beneficial for all involved. 9 Within the traditional boundaries of their stuffy principles most classical disciplines are today facing a methodological and epistemological crisis. The breaching of their walls may at least hold out some hope of a renaissance.

I Perception-Information Uptake of the Mind.- 1 The biology of perception.- Experimental techniques.- Generation and conduction of impulses.- Functional unity of analyzers.- Once more about the problem of methods.- Connection between stimulus and perception.- Physiological characteristics of perception.- 2 Perception of electromagnetic waves: vision.- The receiving end: the retina.- The thalamus-a central relay station.- The cortical decoding center.- The central control of vision.- The perception of patterns.- Visual perception of depth and distance.- 3 Perception of mechanical vibrations: hearing.- Structure of the auditory analyzer.- Coding and decoding in the auditory system.- Perception of acoustic configuration and direction of sounds.- Cerebral control in the auditory system.- 4 Perception of the mechanics of body position.- Structure and encoding activity of proprioceptors.- Cortical decoding of information on body position.- The gamma-efferent mechanism: central control of muscle receptors.- 5 Senses of indefinite classification: cutaneous and chemical receptors.- Physiological analysis of sensations arising from cutaneous receptors.- Encoding and decoding mechanisms in the sensation of taste and smell.- 6 Interoception -sensory function without perception.- Structure of the visceral sensory apparatus.- Encoding of interoceptive impulses.- Decoding of visceral impulses.- II The Energetics of Mental Processes: The Waking State, Sleep, Attention, and Consciousness.- 7 Alert neurons in the brain-waking and attention.- The brainstem reticular activating system.- Electroencephalography.- Attention and habituation.- 8 The sleeping brain.- Dreams.- Hypnosis.- 9 The conscious state and the unconscious.- Unconscious physiological processes.- The biology of the conscious state: an unknown field.- III The Experience of the Mind: Learning and Memory.- 10 Contiguity of cerebral processes: learning.- Type I. Learning by classical conditioning.- Type II: Instrumental (operant) learning.- The process of conditioning.- Structural organization of conditioned reflexes.- The negative reflection of learning: inhibition.- Learning in the living organism.- 11 The other aspect of cerebral plasticity: the fixing and storing of information.- Short-term (labile) memory.- Long-term (permanent) storing based on synaptic rearrangement-the first alternative.- Qualitative molecular changes-another alternative of long-term memory.- Further Readings.