Catatan

The brain contains over 100 known, or suspected, neu-
rotransmitter chemicals and probably as many that have not yet

been discovered. I have chosen to focus on those neurotransmit-
ter systems most commonly associated with the psychoactive

effects of drugs and nutrients that, in many cases, are regularly
consumed today. In general, I discuss mostly brain stimulants in
the fi rst half of the book and mostly depressants in the second
half, although, as you will see, this dividing line is far from hard
and fast, mainly because the brain does not always behave in
such a dichotomous manner. Therefore, some stimulants appear
later in the book; some depressants appear earlier; and some
substances that infl uence a given neurotransmitter discussed in
one chapter turn up again as they relate to neurotransmitters
discussed in other chapters. However, there is a constant across
these chapters: I’ve tried to organize much of the information
about specifi c neurotransmitter systems according to the action
of two types of substances—those that mimic these systems,
thereby acting as agonists, and those that block them, thereby
acting as antagonists. These and other fundamental concepts in

pharmacology, as well as information about the basic neurosci-
ence of the brain, are further explained in Chapter 1. In contrast,

I have deliberately paid little or no attention to substances that
have psychoactive effects on the brain but whose mechanism(s)
of action have not yet been adequately defi ned in the scientifi c

xii S PREFACE

literature, such as lithium. Furthermore, I have made no attempt
to detail the many, still poorly understood, additional roles
played by the neurotransmitters that I do discuss.