Describing consciousness as a physiological phenomenon has been a challenge for neuroscientists. In How Brain Arousal Mechanisms Work, neuroscientist Donald Pfaff presents his theoretical ideas on the organization of brain arousal systems that he names, “Generalized Arousal (GA)”. The main purpose of the book is to offer explanation of the mechanisms of brain arousal toward physical consciousness so that it can be applied for treatment purposes.
Pfaff criticizes Giulio Tononi’s “integrated information theory” of consciousness as lacking mechanisms of pathways in the CNS, and neither “information” nor “integration” mentioned in his theory are well defined. He further describes Tonini’s theory as a “top-down” approach in which overall abstract details of a system are established first so that experiments can be conducted within the framework. However, Pfaff approached his writing in a “bottom-up” fashion, which he describes as the conventional approach among neuroscientists: begins by extracting details from experiments, then these experimental details are grouped together into “subsystems,” then greater systems.
The order of chapters are arranged linearly so that brain arousal mechanisms are described in step-by-step fashion. Pfaff proposes the concept of “Generalized CNS Arousal” (GA) in which “low GA” and “high GA” are described similarly to physical phase transitions. He then introduces neurons essential for activating the arousal mechanisms (i.e., Nucleus Giganto Cellularis” (NGC) with experimental results from his own laboratory. Chapters progress to describe neuronal activities in the pons, midbrain, hypothalamus, and central thalamus. High and low arousal states are summarized in terms of GA concept, supported with studies from genetics, pharmacology, and biophysics, as well as patient diagnoses and observations. Towards the end of the book, discussions of arousal and consciousness as part of a complex “vertical” system are given to challenge philosophical explanations of consciousness. Pfaff argues brain arousal toward consciousness as a “neuronal phenomena” composed of a series of “observable, quantifiable behaviors” with evolutionary advantages for both humans and animals.
Although concise and reader-friendly, How Brain Arousal Mechanisms Works is targeted for experts and clinicians who study the brain, especially those pursuing topics of arousal, brain injury, deep sleep/anesthesia. The book has a practical merit in which quantitative assays for measuring GA activities based on operational definitions given in the book are described so that scientists may apply them in their own research. Ethical implications of clinically categorizing patients with disorders of consciousness may be useful to clinicians to think of better ways of clinically recognizing patient conditions by applying mechanisms introduced in the book. Extensive neurobiological and molecular explanations make the book appropriate to readers with solid understanding of Neuroscience, Neurology, and/or Psychiatry. It is most likely not a great book for those intending to seek philosophical or spiritual explanation of consciousness!