Twins present special problems for the study of lateralisation, both psychological and biological. Central to both areas is the common observation that identical (monozygotic) twins can differ in their laterality. In the case of hand preference, this is most obvious in the one in five twin pairs where one is right-handed and the other left-handed. A similar problem can be found morphologically, not only in normal anatomical traits, such as hair whorls, which can be in opposite direction, but also in the rare condition of conjoined twins, where it is frequently the case that one twin has its heart and viscera in the normal orientation (situs solitus) and the other is mirror reversed (situs inversus). This special issue of Laterality brings together papers on these different aspects of twinning. Two of the papers are biological, one providing a detailed analysis of the laterality of artificially conjoined twins created by fusing two different species of newt, and the other overviewing the recent developments in understanding the molecular biology of visceral lateralisation in relation to twinning. The other papers concern aspects of cerebral lateralisation in twins, one providing a much needed meta-analysis and critical overview of the twin literature, another providing detailed data from a large study of handedness in twins, a third asking about the almost neglected question of footedness, earedness and eyedness in twins, and the fourth looking at lateralised cognitive processing. Between them these papers extend the literature on lateralisation in twins, and reinforce the need to consider the lateralisation of twins from biological, neurological and psychological perspectives.

Left-right asymmetries of structure and function are a common organization principle in the brains of humans and non-human vertebrates alike. While there are inherently asymmetric systems such as the human language system or the song system of songbirds, the impact of structural or functional asymmetries on perception, cognition and behavior is not necessarily limited to these systems. For example, performance in experimental paradigms that assess executive functions such as inhibition, planning or action monitoring is influenced by information processing in the bottom-up channel. Depending on the type of stimuli used, one hemisphere can be more efficient in processing than the other and these functional cerebral asymmetries have been shown to modulate the efficacy of executive functions via the bottom-up channel. We only begin to understand the complex neuronal mechanisms underlying this interaction between hemispheric asymmetries and cognitive systems. Therefore, it is the aim of this Research Topics to further elucidate how structural or functional hemispheric asymmetries modulate perception, cognition and behavior in the broadest sense.

The Lateralized Brain: The Neuroscience and Evolution of Hemispheric Asymmetries is an up-to-date teaching resource for neuroscience faculty members that teach courses concerning hemispheric asymmetries. The book provides students with all relevant information on the subject, while also giving aspiring researchers in the field an up-to-date overview of relevant, previous work. It is ideal for courses on hemispheric asymmetries, that is, the functional or structural differences between the left and the right hemispheres of the brain, and also highlights how the widespread use of modern neuroimaging techniques, such as fMRI and DTI has completely changed the way hemispheric asymmetries are currently investigated. According to the preface, the main aim of The Lateralized Brain is to provide "an up-to-date teaching resource on hemispheric asymmetries ... [and] to introduce undergraduate students of all levels to the fascinating topics of hemispheric asymmetries" (p. xv)... (Sebastian Ocklenburg and Onur Güntürkün) have succeeded admirably in their stated aim and are to be congratulated on undertaking the mammoth task they set themselves. They can be proud of what they have accomplished.~ Alan A. Beaton, Department of Psychology, Swansea University, Swansea, UK, in Laterality: Asymmetries of Body, Brain and Cognition, July, 2018. Includes references to key articles, books, protocols and online resources for additional, detailed study Presents classic studies that helped define the field Covers key concepts and methods that are explained in separate call out boxes for quick overview Provides introductory short stories (e.g. classic clinical cases) as a starting point for each chapter

Journalist Abigail Pogrebin is many things—wife, mother, New Yorker—but the one that has defined her most profoundly is “identical twin.” As children, she and her sister, Robin, were inseparable. But when Robin began to pull away as an adult, Abigail was left to wonder not only why, but also about the very nature of twinship. What does it mean to have a mirror image? How can you be unique when somebody shares your DNA? In One and the Same, Abigail sets off on a quest to understand how genetics shape us, crisscrossing the country to explore the varied relationships between twins, which range from passionate to bitterly resentful. She speaks to the experts and tries to answer the question parents ask most—is it better to encourage their separateness or closeness? And she paints a riveting portrait of twin life, yielding fascinating truths about how we become who we are.

Neurolinguistics is a young and highly interdisciplinary field, with influences from psycholinguistics, psychology, aphasiology, and (cognitive) neuroscience, as well as other fields. Neurolinguistics, like psycholinguistics, covers aspects of language processing; but unlike psycholinguistics, it draws on data from patients with damage to language processing capacities, or the use of modern neuroimaging technologies such as fMRI, TMS, or both. The burgeoning interest in neurolinguistics reflects that an understanding of the neural bases of this data can inform more biologically plausible models of the human capacity for language. The Oxford Handbook of Neurolinguistics provides concise overviews of this rapidly-growing field, and engages a broad audience with an interest in the neurobiology of language. The chapters do not attempt to provide exhaustive coverage, but rather present discussions of prominent questions posed by given topics. The volume opens with essential methodological chapters: Section I, Methods, covers the key techniques and technologies used to study the neurobiology of language today, with chapters structured along the basic divisions of the field. Section II addresses the neurobiology of language acquisition during healthy development and in response to challenges presented by congenital and acquired conditions. Section III covers the many facets of our articulate brain, or speech-language pathology, and the capacity for language production-written, spoken, and signed. Questions regarding how the brain comprehends meaning, including emotions at word and discourse levels, are addressed in Section IV. Finally, Section V reaches into broader territory, characterizing and contextualizing the neurobiology of language with respect to more fundamental neuroanatomical mechanisms and general cognitive domains.

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

This volume is about an ongoing long-term research initiative led by researchers from the School of Dentistry at the University of Adelaide. The aim of this book is to provide an overview of the studies of the teeth and faces of Australian twins and their families that have extended over more than thirty years.