Brain concepts

Conventional human thinking today is in harmony with The Self and Its Brain conception as described so elegantly and delightfully as interaction between Worlds 1,2, and 3 (Popper and Eccles, 1977). In the light of the operation of mesencephalic and cortical enhancer regulation, the opposite conception, with The Brain and Its Self approach, deserves serious consideration. 

As we have seen in this chapter steroids have a number of functions in human physiology Cholesterol is a component part of cell mem branes and is found in large amounts in the brain Derivatives of cholic acid assist the digestion of fats in the small intestine Cortisone and its derivatives are involved in maintaining the electrolyte balance in body fluids The sex hormones responsible for mascu line and feminine characteristics as well as numerous aspects of pregnancy from conception to birth are steroids... 

The aroma of fmit, the taste of candy, and the texture of bread are examples of flavor perception. In each case, physical and chemical stmctures ia these foods stimulate receptors ia the nose and mouth. Impulses from these receptors are then processed iato perceptions of flavor by the brain. Attention, emotion, memory, cognition, and other brain functions combine with these perceptions to cause behavior, eg, a sense of pleasure, a memory, an idea, a fantasy, a purchase. These are psychological processes and as such have all the complexities of the human mind. Flavor characterization attempts to define what causes flavor and to determine if human response to flavor can be predicted. The ways ia which simple flavor active substances, flavorants, produce perceptions are described both ia terms of the physiology, ie, transduction, and psychophysics, ie, dose-response relationships, of flavor (1,2). Progress has been made ia understanding how perceptions of simple flavorants are processed iato hedonic behavior, ie, degree of liking, or concept formation, eg, crispy or umami (savory) (3,4). However, it is unclear how complex mixtures of flavorants are perceived or what behavior they cause. Flavor characterization involves the chemical measurement of iadividual flavorants and the use of sensory tests to determine their impact on behavior. 

Strobel et al. (101) reported a unique approach to delivery of anticancer agents from lactide/glycolide polymers. The concept is based on the combination of misonidazole or adriamycin-releasing devices with radiation therapy or hyperthermia. Prototype devices consisted of orthodontic wire or sutures dip-coated with drug and polymeric excipient. The device was designed to be inserted through a catheter directly into a brain tumor. In vitro release studies showed the expected first-order release kinetics on the monolithic devices. 

Unfortunately transplants require 6-7 foetal brains to obtain enough transplantable material for one patient, which itself raises ethical considerations, and as the tissue cannot diffuse its influence is restricted, even with multiple injection sites, and only a fraction (approx. 20%) of the neurons survive. Also without knowledge of the cause of PD the transplant could meet the same fate as the original neurons. The concept, however, demands perseverance and a number of variants are being tried. 

It has been known for many years that aversive stimuli increase serotonergic transmission (reviewed by Chaouloff 1993) and so it was inevitable that exaggerated serotonergic transmission in a hypothetical brain punishment system became linked with anxiety. Unfortunately, much of the evidence for this idea was gleaned from unreliable measures of changes in 5-HT concentration in rodent brain tissue postmortem after experience of moderately severe forms of stress in vivo. Nevertheless, this concept was encouraged by reports that a reduction in 5-HT transmission, following administration of either the 5-HT synthesis inhibitor, p-chloroamphetamine (pCPA),... 

Raisman G. (1972). An experimental study of the projection of the amygdala to the accessory olfactory bulb and its relationship to the concept of a dual olfactory system. Exp Brain Res 14, 395-404. 

McGeer E., McGeer P. (1973). Some characteristics of brain tyrosine hydroxylase. In Mandel A., editor. New Concepts in Neurotransmitter Regulation. New York Plenum Press pp. 53-68. 

Laubichler, M. and Sarkar, S. (2002), Flies, genes, and brains Oskar Vogt, Nikolai Timofeeff-Ressovsky, and the origin of the concepts of penetrance and expressivity , in L. S. Parker, and R. Ankeny (Eds), Medical Genetics, Conceptual Foundations and Classic Questions, Kluwer, Dordrecht, The Netherlands, in press. 

Basic Concepts Underlying the Pharmacogenomics of the Blood-Brain Barrier... 

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