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Neurobiology and Neurology

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New Essays on Its Nature and the Methodology of Its Study
Edited by Murat Aydede

What does feeling a sharp pain in one's hand have in common with seeing a red apple on the table? Some say not much, apart from the fact that they are both conscious experiences. To see an object is to perceive an extramental reality—in this case, a red apple. To feel a pain, by contrast, is to undergo a conscious experience that doesn't necessarily relate the subject to an objective reality. Perceptualists, however, dispute this. They say that both experiences are forms of perception of an objective reality. Feeling a pain in one's hand, according to this view, is perceiving an objective (physical) condition of one's hand. Who is closer to truth?

Because of such metaphysical issues, the subjectivity of pains combined with their clinical urgency raises methodological problems for pain scientists. How can a subjective phenomenon be studied objectively? What is the role of the first-person method (e.g., introspection) in science? Some suggest that the subjectivity of pains (and of conscious experiences in general) is due to their metaphysical irreducibility to purely physical processes in the nervous system. Can this be true?

The study of pain and its puzzles offers opportunities for understanding such larger issues as the place of consciousness in the natural order and the methodology of psychological research. In this book, leading philosophers and scientists offer a wide range of views on how to conceptualize and study pain. The essays include discussions of perceptual and representationalist accounts of pain; the affective-motivational dimension of pain; whether animals feel pain, and how this question can be investigated; how social pain relates to physical pain; whether first-person methods of gathering data can be integrated with standard third-person methods; and other methodological and theoretical issues in the science and philosophy of pain.

A Foundation for Motor Learning

Neuroscience involves the study of the nervous system, and its topics range from genetics to inferential reasoning. At its heart, however, lies a search for understanding how the environment affects the nervous system and how the nervous system, in turn, empowers us to interact with and alter our environment. This empowerment requires motor learning. The Computational Neurobiology of Reaching and Pointing addresses the neural mechanisms of one important form of motor learning. The authors integrate material from the computational, behavioral, and neural sciences of motor control that is not available in any other single source. The result is a unified, comprehensive model of reaching and pointing. The book is intended to be used as a text by graduate students in both neuroscience and bioengineering and as a reference source by experts in neuroscience, robotics, and other disciplines.

The book begins with an overview of the evolution, anatomy, and physiology of the motor system, including the mechanisms for generating force and maintaining limb stability. The sections that follow, "Computing Locations and Displacements," "Skills, Adaptations, and Trajectories," and "Predictions, Decisions, and Flexibility," present a theory of sensorially guided reaching and pointing that evolves organically based on computational principles rather than a traditional structure-by-structure approach. The book also includes five appendixes that provide brief refreshers on fundamentals of biology, mathematics, physics, and neurophysiology, as well as a glossary of relevant terms. The authors have also made supplemental materials available on the Internet. These web documents provide source code for simulations, step-by-step derivations of certain mathematical formulations, and expanded explanations of some concepts.

The folk belief that the left brain hemisphere is dominant for language and the right for visuospatial functions is incomplete and even misleading. Research shows that asymmetries exist at all levels of the nervous system and apply to emotional as well as to higher cognitive processes. Going beyond the authors' previous book, Brain Asymmetry, this book reflects the most recent thinking on functional asymmetries and their structural correlates in brain anatomy. It emphasizes research using new neuroimaging and neurostimulation techniques such as magnetic resonance imaging (MRI and fMRI), positron emission tomography (PET), magnetoencephalography (MEG), and transcranial magnetic stimulation (TMS). It also considers clinical applications of asymmetry research. The book contains sections on animal models and basic functions, neuroimaging and brain stimulation studies, visual laterality, auditory laterality, emotional laterality, neurological disorders, and psychiatric disorders.

The Collected Papers of Wilfrid Rall with Commentaries

Wilfrid Rall was a pioneer in establishing the integrative functions of neuronal dendrites that have provided a foundation for neurobiology in general and computational neuroscience in particular. This collection of fifteen previously published papers, some of them not widely available, have been carefully chosen and annotated by Rall's colleagues and other leading neuroscientists. It brings together Rall's work over more than forty years, including his first papers extending cable theory to complex dendritic trees, his ground-breaking paper introducing compartmental analysis to computational neuroscience, and his studies of synaptic integration in motoneurons, dendrodendritic interactions, plasticity of dendritic spines, and active dendritic properties.

Today it is well known that the brain's synaptic information is processed mostly in the dendrites where many of the plastic changes underlying learning and memory take place. It is particularly timely to look again at the work of a major creator of the field, to appreciate where things started and where they have led, and to correct any misinterpretations of Rall's work. The editors' introduction highlights the major insights that were gained from Rall's studies as well as from those of his collaborators and followers. It asks the questions that Rall proposed during his scientific career and briefly summarizes the answers.

The papers include commentaries by Milton Brightman, Robert E. Burke, William R. Holmes, Donald R. Humphrey, Julian J. B. Jack, John Miller, Stephen Redman, John Rinzel, Idan Segev, Gordon M. Shepherd, and Charles Wilson.

Allostatic Regulation in Physiology and Pathophysiology

Homeostasis, a key concept in biology, refers to the tendency toward stability in the various bodily states that make up the internal environment. Examples include temperature regulation and oxygen consumption. The body's needs, however, do not remain constant. When an organism is under stress, the central nervous system works with the endocrine system to use resources to maintain the overall viability of the organism. The process accelerates the various systems' defenses of bodily viability, but can violate short-term homeostasis. This allostatic regulation highlights our ability to anticipate, adapt to, and cope with impending future events.

In Rethinking Homeostasis, Jay Schulkin defines and explores many aspects of allostasis, including the wear and tear on tissues and accelerated pathophysiology caused by allostatic overload. Focusing on the concept of motivation and its relationship to the central nervous system function and specific hormonal systems, he applies a neuroendocrine perspective to central motive states such as cravings for water, sodium, food, sex, and drugs. He examines in detail the bodily consequences of the behavioral and neuroendocrine regulation of fear and adversity, the endocrine regulation of normal and preterm birth, and the effects of drug addiction on the body. Schulkin's presentation of allostasis lays the foundation for further study.

Chemically Altered States of Consciousness

In this book J. Allan Hobson offers a new understanding of altered states of consciousness based on knowledge of how our brain chemistry is balanced when we are awake and how that balance shifts when we fall asleep and dream. He draws on recent research that enables us to explain how psychedelic drugs work to disturb that balance and how similar imbalances may cause depression and schizophrenia. He also draws on work that expands our understanding of how certain drugs can correct imbalances and restore the brain's natural equilibrium.

Hobson explains the chemical balance concept in terms of what we know about the regulation of normal states of consciousness over the course of the day by brain chemicals called neuromodulators. He presents striking confirmation of the principle that every drug that has transformative effects on consciousness interacts with the brain's own consciousness-altering chemicals. In the section called "The Medical Drugstore," Hobson describes drugs used to counteract anxiety and insomnia, to raise and lower mood, and to eliminate or diminish the hallucinations and delusions of schizophrenia. He discusses the risks involved in their administration, including the possibility of new disorders caused by indiscriminate long-term use. In "The Recreational Drugstore," Hobson discusses psychedelic drugs, narcotic analgesia, and natural drugs. He also considers the distinctions between legitimate and illegitimate drug use. In the concluding "Psychological Drugstore," he discusses the mind as an agent, not just the mediator, of change, and corrects many erroneous assumptions and practices that hinder the progress of psychoanalysis.

Until recently, the vast majority of memory research used only university students and other young adults as subjects. Although such research successfully introduced new methodologies and theoretical concepts, it created a bias in our understanding of the lifespan development of memory. This book signals a departure from young-adult-centered research. It views the lifespan development of memory as a continuous process of growth and loss, where each phase of development raises unique questions favoring distinct research methods and theoretical approaches. Drawing on a broad range of investigative strategies, the book lays the foundation for a comprehensive understanding of the lifespan development of human memory.Topics include the childhood and adulthood development of working memory, episodic and autobiographical memory, and prospective memory, as well as the breakdown of memory functions in Alzheimer's disease. Of particular interest is the rich diversity of approaches, methods, and theories. The book takes an interdisciplinary perspective, drawing on work from psychology, psychiatry, gerontology, and biochemistry.

A Union of the Senses

For decades, scientists who heard about synesthesia hearing colors, tasting words, seeing colored pain just shrugged their shoulders or rolled their eyes. Now, as irrefutable evidence mounts that some healthy brains really do this, we are forced to ask how this squares with some cherished conceptions of neuroscience. These include binding, modularity, functionalism, blindsight, and consciousness. The good news is that when old theoretical structures fall, new light may flood in. Far from a mere curiosity, synesthesia illuminates a wide swath of mental life.In this classic text, Richard Cytowic quickly disposes of earlier criticisms that the phenomenon cannot be "real," demonstrating that it is indeed brain-based. Following a historical introduction, he lays out the phenomenology of synesthesia in detail and gives criteria for clinical diagnosis and an objective "test of genuineness." He reviews theories and experimental procedures to localize the plausible level of the neuraxis at which synesthesia operates. In a discussion of brain development and neural plasticity, he addresses the possible ubiquity of neonatal synesthesia, the construction of metaphor, and whether everyone is unconsciously synesthetic. In the closing chapters, Cytowic considers synesthetes’ personalities, the apparent frequency of the trait among artists, and the subjective and illusory nature of what we take to be objective reality, particularly in the visual realm.The second edition has been extensively revised, reflecting the recent flood of interest in synesthesia and new knowledge of human brain function and development. More than two-thirds of the material is new.

The traditional model of synapses as fixed structures has been replaced by a dynamic one in which synapses are constantly being deleted and replaced. This book, written by a leading researcher on the neurochemistry of schizophrenia, integrates material from neuroscience and cell biology to provide a comprehensive account of our current knowledge of the neurochemical basis of synaptic plasticity.

The book presents the evidence for synaptic plasticity, an account of the dendritic spine and the glutamate synapse with a focus on redox mechanisms, and the biochemical basis of the Hebbian synapse. It discusses the role of endocytosis, special proteins, and local protein synthesis. Additional topics include volume transmission, arachidonic acid signaling, hormonal modulation, and psychological stress. Finally, the book considers pharmacological and clinical implications of current research, particularly with reference to schizophrenia and Alzheimer's disease.

Perceptual learning is the specific and relatively permanent modification of perception and behavior following sensory experience. It encompasses parts of the learning process that are independent from conscious forms of learning and involve structural and/or functional changes in primary sensory cortices. A familiar example is the treatment for a "lazy" or crossed eye. Covering the good eye causes gradual improvement in the weaker eye’s cortical representations. If the good eye is patched too long, however, it learns to see less acutely.

This book presents advances made in the last decade in this rapidly growing field. The first part examines neuronal changes caused by lesions or external influences. It discusses the effects of these changes on behavior and the extent to which plasticity in sensory systems is possible. Taking a broader view, the second part looks at how more conscious or systemic stimuli cause cortical changes. Clinical trials in which subjects are taught to recognize visual and auditory stimuli demonstrate the relationship between perceptual and cognitive learning. The final sections offer general models of perceptual learning and discuss the future of the field.

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