THE ORGANIZING POWER OF EXPERIENCE STEWART WOLF and RICHARD C. STROHMAN* Experience, the universal Mother of Sciences.—Miguel de Cervantes (1547-1616) [1] Introduction The central processing of sensory information from within and without the organism has turned out to be far more complex than suspected. The mechanisms of visceral regulation—involving, as they do, myriad neuronal interactions that assemble stored information from highly individual learning and memory—are nonlinear and highly individualized [2]. However, the use of chaos theory to study such complex biological processes is affording access to forebrain regulatory activities that determine somatic and visceral behaviors, behaviors that depend on the unique experiences and characteristics of individuals [3-5]. Indeed, measurements in low dimensional chaos are sufficiently deterministic to predict clinical outcomes including, in some instances, sudden cardiac death [6]. The striking feature of all this is that individual somatic and visceral behavior is powerfully modulated by specific past experiences and prevailing circumstances through a vast interactive neuronal circuitry . The output of such a system can be accessed by non-invasive recording and analysis of oscillatory patterns ofobservable visceral functions . The idea that intangible, but powerfully moving sensory input from life experience participates in the control of bodily systems has been proposed for centuries. The work of Pierre Gassendi [7] andJohn Locke [8] in the seventeenth century greatly influenced the eighteenth-century Adapted from an address at the Center for Frontier Sciences, Temple University, Philadelphia , April 1993, and the Roy C. Swan lecture at Cornell, New York Hospital, New York City, May 1993. *Totts Gap, RD#1, Box 1120 G, Bangor, Pennsylvania 18013-9716.© by The University of Chicago. All rights reserved. 003 1-5982/94/3801-0889$0 1 .00 106 Stewart Wolf and Richard C. Strohman ¦ The Power ofExperience philosophers in France, and notably the physician-scientistJean Georges Cabanis. Cabanis studied the effects of adverse life experiences on gastrointestinal function. In 1802 he wrote, "according to one's state of mind and according to the different nature of the ideas and of the moral affections, the activity of the organs can, by turns, be stimulated, suspended or entirely reversed" [9]. Such findings have been pursued and confirmed in the present century with the aid of increasingly more sophisticated techniques of exploration, but only recently have the mechanisms whereby the brain stores information and evaluates experience begun to be accessible. Early evidence regarding the storage of experiences in the brain became available in the work of Wilder Penfield. Studying patients with temporal lobe epilepsy, he found that sights, sounds, and happenings in the long past of their lives could, by appropriately applied electrical stimulation to the brain, be vividly reexperienced [10]. Current technical refinements have made it possible to explore, stimulate, and record from fairly precisely identified structures in the brain. From such studies it has become evident that while the basic neuronal structures and their distribution in the brain are species-specific (and to some extent specific to the individual), their fine dendritic development is epigenetic and largely determined by experience [11]. Scheibel and colleagues analyzed pyramidal neurons in various cortical receptive zones in the brains of individuals with differing levels of education and types of occupation. They revealed that the richness and patterns of dendritic development corresponded roughly to the cortical localization of the body parts most involved in the individuals' daily activities [12]. Scheibel recalled observations Oscar and Cecile Vogt had made in 1954. In autopsy specimens, the Vogts had observed an unusual thickness of the primary auditory receptive cortex of a violinist who in life had had perfect pitch. They also had observed an enhancement of the primary visual cortex in an artist with extraordinary eidetic powers, and comparable developments in the cortices of other highly talented individuals. Although such findings do not distinguish between genetic and developmental changes, Hubel and Weisel have shown that visual experience is essential to the development of the visual cortex, and furthermore , that such sensory exposure must occur during a critical period in infancy [13, 14]. Although the techniques of measuring and tracing dendritic branching need a great deal more development, refinement , and precision before their physiological consequences and explanatory power can be stated, they nevertheless...