Brain functions, basics

Brain structure below the thalamus and main portion of the ventral region of the diencephalon, controlling homeostatic and nonhomeostatic basic body and brain functions, including circadian and feeding rhythms, energy metabolism, thermogenesis, sympathoadrenal, and neuroendocrine outflow (secretion of hormones by the pituitary gland), behavioral state and memory functions. 

After an overview of neurotransmitter systems and function and a consideration of which substances can be classified as neurotransmitters, section A deals with their release, effects on neuronal excitability and receptor interaction. The synaptic physiology and pharmacology and possible brain function of each neurotransmitter is then covered in some detail (section B). Special attention is given to acetylcholine, glutamate, GABA, noradrenaline, dopamine, 5-hydroxytryptamine and the peptides but the purines, histamine, steroids and nitric oxide are not forgotten and there is a brief overview of appropriate basic pharmacology. 

We have no such pretensions in this book but we do hope to help you to understand how neurotransmitters may be involved in brain function and more particularly how their activity is modified by disease and drugs. As the above quotation implies, this will mean considering the synaptic characteristics of each neurotransmitter, but before we do so, it is important to consider some more general and basic aspects of neurotransmitter function. Thus ... 

To understand the chemical-imbalance theory, it will be helpful to first review some basic aspects of how the brain functions. The human brain contains about ioo billion nerve cells called neurons. Each neuron is like an electrical wire with many branches. When a neuron fires, electrical impulses travel along its length from one end to the other. When an impulse reaches the end of a branch, it may stimulate the next neuron, influencing whether or not it fires. 

In this chapter we will focus on two basic principles of neurotransmission that may help to understand normal brain function on the one hand, and the current practice of clinical psychopharmacology on the other. First, the anatomic organization of neurotransmitter systems determines their behavioral affiliation. Second, neurotransmitter receptors modulate the electrical properties (via ion channels) or the biochemical properties (via second messenger systems) of neurons. We will then review these two basic principles for some of the neurotransmitter systems relevant to the practice of neuropsychopharmacology. 

Basic nitrogen compounds similar to the plant alkaloids also occur in animals, although the description animal alkaloid seldom is used. Certain amines and ammonium compounds play key roles in the function of the central nervous system (Figure 23-3) and the balance of amines in the brain is critical for normal brain functioning. Also, many essential vitamins and hormones are basic nitrogen compounds. Nitrogen bases also are vital constituents of nucleic acid polymers (DNA and RNA) and of proteins (Chapter 25). 

The question of personal survival of death is no longer automatically nonsensical. It could be that basic awareness, even though different from brain functioning, could exist only in conjunction with a living brain. But it is also possible that basic awareness could exist on its own. Because the question of whether individuals will survive bodily death and go on to some other sort of existence makes a tremendous difference in what people do with their lives, intensive research on the possibility of survival of deadi becomes one of our highest priorities. 

This is the conservative or orthodox view of the mind discussed briefly at the beginning of this book. It does not really explain what consciousness is, but, citing good evidence that physically affecting the brain alters consciousness, asks not further questions and simply believes that consciousness itself is a product of brain functioning. The consequence of this view is that for an ultimate explanation of consciousness, the phenomena of consciousness must be reduced to those of brain functioning brain functioning must be reduced to basic properties of nervous systems, which must be reduced to basic properties of live molecules, which in turn must be reduced to basic properties of molecules per se, which must be reduced to properties of atoms, which must finally be reduced to properties of subatomic parti cles. 

By increasing the activity of the neurotransmitter serotonin, Ritalin affects both higher human activities and basic physiological functions. In fact, increasing serotonin levels affects every brain function described in Table 3.1 on page 47. Some researchers believe that Ritalin produces more extreme mental... 

The first four principles are the heart of the brain-disabling concept basically, that all psychiatric drugs cause a generalized impairment of brain function that reduces overall mental and emotion function that this disabling effect occurs, as well, in normal volunteers and that the effect has no specificity for any psychiatric disorder. 

First, awareness is. Our basic ability to have experiences, to know that we are, to be aware of things, has never been satisfactorily explained in terms of anything else. Current Western science likes to assume that awareness will be explained as an aspect of brain functioning, reduced to nothing but some action of the brain, but this assumption is an item of current faith and fashion, not good science. Indeed, science itself can be seen as one among many derivatives of the action of awareness, such that we wouldn t expect the part ever to be able to explain the whole. 

The answer to this question offers both good news and bad news. Most experts in brain functioning believe that the changes created by lengthy cocaine abuse will alter the brain in certain basic ways. These changes may be permanent. 

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