The Factor Structure Of Human Handedness

Illustrates important fundamental aspects of cerebral lateralization, explaining how decreased language lateralization can facilitate psychotic symptoms in the human brain.

Handedness, or manual laterality of function, is thought to be both universal and unique to humans, making it a highly derived trait, based on an equally specialized neural substrate. By contrast, in various non-human species, both living and extinct, extent of lateralization varies. All known populations of living human beings apparently favor the right hand, motorically, culturally, and symbolically, thus right-handedness is species-typical, as well as species-specific. This laterality of function is correlated with asymmetry of structure, that is, neural, skeletal and muscular, for example as manifest especially in skilled movement, such as handwriting. Human brains are lop-sided, and sagitally-paired organs (hand, foot, eye, ear, etc.) are skewed in their use, usually biased to the right; explaining this variation appears to require both cultural and environmental causal variables. To tackle these questions and advance our knowledge of this basic human trait requires genuinely multi-disciplinary input by scholars willing to think inter-disciplinarily. Thus, participants in this Annals volume come from anthropology, archaeology, genetics, neurosciences, palaeo-anthropology, primatology, psychology, and psychiatry. NOTE: Annals volumes are available for sale as individual books or as a journal.

Brain asymmetry for speech is moderately related to handedness but what are the rules? Are symmetries for hand and brain associated with characteristics such as intelligence, motor skill, spatial reasoning or skill at sports? In this follow up to the influential Left, Right Hand and Brain (1985) Marian Annett draws on a working lifetime of research to help provide answers to crucial questions. Central to her argument is the Right Shift Theory - her original and innovative contribution to the field that seeks to explain the relationships between left-and right-handedness and left-and right-brain specialisation. The theory proposes that handedness in humans and our non-human primate relations depends on chance but that chance is weighted towards right-handedness in most people by an agent of right-hemisphere disadvantage. It argues for the existence of a single gene for right shift (RS+) that evolved in humans to aid the growth of speech in the left hemisphere of the brain. The Right Shift Theory has possible implications for a wide range of questions about human abilities and disabilities, including verbal and non verbal intelligence, educational progress and dyslexia, spatial reasoning, sporting skills and mental illness. It continues to be at the cutting edge of research, solving problems and generating new avenues of investigation - most recently the surprising idea that a mutant RS+ gene might be involved in the causes of schizophrenia and autism. Handedness and Brain Asymmetry will make fascinating reading for students and researchers in psychology and neurology, educationalists, and anyone with a keen interest in why people have different talents and weaknesses.

Ronald Reagan and Barack Obama have both signed bills into law with their left hands. And being left-handed certainly did not hold back the artistic achievements of Michelangelo or Raphael. And the dexterous guitar playing of Jimmi Hendrix may only have been aided by his southpaw tendencies. Left-handedness, in fact, would appear to be no big deal. Yet throughout history, it has been associated with clumsiness and generally dubious personality traits like untrustworthiness and insincerity. Even the Latin word for left, sinister, has ominous connotations. In The Puzzle of Left-handedness, Rik Smits uncovers why history has been so unkind to our lefthanded forebears. He carefully puts together the pieces of the puzzle, presenting an array of historical anecdotes, strange superstitions, and weird wives’ tales. Smits explains how left-handedness continues to be associated with maladies of all kinds, including mental retardation, alcoholism, asthma, hay fever, cancer, diabetes, insomnia, depression, and criminality. Even in the enlightened twenty-first century, left-handedness still meets with opposition—including from one prominent psychologist who equates it with infantile negativism, similar to a toddler’s refusal to eat what’s on his plate, and another who claims that left-handed people have average lifespans that are nine years shorter than those who favor the right hand. As Smits reminds us, such speculation is backed by little factual evidence, and the arguments presented by proponents of right-handedness tend to be humorously absurd. The Puzzle of Left-handedness is an enlightening, engaging, and entertaining odyssey through the puzzles and paradoxes, theories and myths, of left-handed lore. Chock full of facts and fiction, it’s a book to be read with both hands.

This book has brought together leading investigators who work in the new arena of brain connectomics. This includes ‘macro-connectome’ efforts to comprehensively chart long-distance pathways and functional networks; ‘micro-connectome’ efforts to identify every neuron, axon, dendrite, synapse, and glial process within restricted brain regions; and ‘meso-connectome’ efforts to systematically map both local and long-distance connections using anatomical tracers. This book highlights cutting-edge methods that can accelerate progress in elucidating static ‘hard-wired’ circuits of the brain as well as dynamic interactions that are vital for brain function. The power of connectomic approaches in characterizing abnormal circuits in the many brain disorders that afflict humankind is considered. Experts in computational neuroscience and network theory provide perspectives needed for synthesizing across different scales in space and time. Altogether, this book provides an integrated view of the challenges and opportunities in deciphering brain circuits in health and disease.

Laterality in Sports: Theories and Applications summarizes recent research on the neurophysiological foundations of handedness, and how left or right lateralization (affecting primary hand use, foot use, and eye use) affects motor control, performance outcome, skill acquisition, and achievement of sports expertise—both for one-on-one sports and team sports. As laterality research has matured, greater focus has been given to applications in human endeavours and, in particular, sport. The book examines performance within individual sports, and discusses the coaching ramifications of coaching to a specific lateralization preference. Describes the neurophysiological foundations of handedness Discusses the origins and development of laterality in humans Summarizes the impact of laterality on motor control and sports performance Encompasses research on both individual and team sports Includes research on skill acquisition, coaching, and development of expertise Covers research on laterality in preferred hand, foot, and eye use in sports

McManus considers evidence from anthropology, particle physics, the history of medicine, and the notebooks of Leonardo to answer questions like: Why are most people right-handed? Why does European writing go from left to right, while Arabic and Hebrew go from right to left? And how do we know that Jack the Ripper was left-handed?