{"title":"Sex/gender differences in hemispheric asymmetries.","authors":"Sophie Hodgetts, Markus Hausmann","doi":"10.1016/B978-0-443-15646-5.00014-2","DOIUrl":"10.1016/B978-0-443-15646-5.00014-2","url":null,"abstract":"<p><p>This chapter will critically review evidence across 40 years of research, covering both early and contemporary studies that have investigated sex/gender differences in hemispheric asymmetries, including both structural and functional asymmetries. We argue that small sex/gender differences in hemispheric asymmetry reliably exist, but there is significant overlap between the sexes and considerable within-sex variation. Furthermore, we argue that research to date is limited in its consideration of sex/gender-related factors, such as sex hormones and gender roles. Moreover, we highlight a critical limitation stemming from the lack of universal agreement on the definitions of \"sex\" and \"gender,\" resulting in the majority of studies interested in sex/gender differences in hemispheric asymmetry involving the separation of participants into dichotomous male/female groups based solely on self-identified sex. Future research involving sex/gender should adopt a biopsychosocial approach whenever possible, to ensure that nonbinary psychologic, biologic, and environmental/social factors related to sex/gender, and their interactions, are routinely accounted for. Finally, we argue that while the human brain is not sexually dimorphic, sex/gender differences in the brain are not trivial and likely have several clinically relevant implications, including for the development of stratified treatment approaches for both neurologic and psychiatric patient populations.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"255-265"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Large-scale genetic mapping for human brain asymmetry.","authors":"Zhiqiang Sha, Clyde Francks","doi":"10.1016/B978-0-443-15646-5.00029-4","DOIUrl":"10.1016/B978-0-443-15646-5.00029-4","url":null,"abstract":"<p><p>Left-right asymmetry is an important aspect of human brain organization for functions including language and hand motor control, which can be altered in some psychiatric traits. The last 5 years have seen rapid advances in the identification of specific genes linked to variation in asymmetry of the human brain and/or handedness. These advances have been driven by a new generation of large-scale genome-wide association studies, carried out in samples ranging from roughly 16,000 to over 1.5 million participants. The implicated genes tend to be most active in the embryonic and fetal brain, consistent with early developmental patterning of brain asymmetry. Several of the genes encode components of microtubules or other microtubule-associated proteins. Microtubules are key elements of the internal cellular skeleton (cytoskeleton). A major challenge remains to understand how these genes affect, or even induce, the brain's left-right axis. Several of the implicated genes have also been associated with psychiatric or neurologic disorders, and polygenic dispositions to autism and schizophrenia have been associated with structural brain asymmetry. Knowledge of developmental mechanisms that lead to hemispheric specialization may ultimately help to define etiologic subtypes of brain disorders.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"241-254"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614615","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Foreword.","authors":"Michael J Aminoff, François Boller, Dick F Swaab","doi":"10.1016/B978-0-443-15646-5.09997-8","DOIUrl":"https://doi.org/10.1016/B978-0-443-15646-5.09997-8","url":null,"abstract":"","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"xi"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614371","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Definitions, diagnostic criteria, and clinical assessment scales in disorders of consciousness.","authors":"Bei Zhang, Nathan Darji, Joseph T Giacino","doi":"10.1016/B978-0-443-13408-1.00011-7","DOIUrl":"10.1016/B978-0-443-13408-1.00011-7","url":null,"abstract":"<p><p>Disorders of consciousness (DoC) are neurologic conditions characterized by severe alteration in level of consciousness. Categories of DoC may include coma, unresponsive wakefulness syndrome/vegetative state, minimally conscious state (MCS; can be further categorized into MCS+ and MCS- based on the presence or absence of language-related behaviors), emergence from MCS, confusional state or delirium, and cognitive motor dissociation (CMD). CMD is a recently defined condition in which the patient fails to demonstrate observable behavioral responses on bedside assessment but demonstrates covert cognitive processing on functional imaging or EEG studies. Accurate differential diagnosis in DoC is aided by adherence to basic principles of assessment, including use of standardized assessment scales. Clinicians should serially administer standardized assessment tools to ensure valid interpretation of results and optimize diagnostic accuracy. Among standardized scales, the Coma Recovery Scale-Revised is most widely used and has the strongest psychometric validity in assessing DoC. The Neurocritical Care Society's Curing Coma Campaign has proposed a slate of DoC common data elements that is expected to improve the consistency and precision of DoC research.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"207 ","pages":"1-13"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143476448","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hemispheric asymmetries, paleoneurology, and the evolution of the human genus.","authors":"Emiliano Bruner","doi":"10.1016/B978-0-443-15646-5.00026-9","DOIUrl":"10.1016/B978-0-443-15646-5.00026-9","url":null,"abstract":"<p><p>Brain asymmetries are a distinctive feature of Homo sapiens and are associated with key evolutionary functions including language and handedness. Nonetheless, differences between humans and apes could be just a matter of degree and size and not the expression of unique traits of our species. In this chapter, I introduce paleoneurology and the study of brain morphology in fossil hominids, reviewing the anatomic factors that can influence the main asymmetries of the endocranial cavity (cortical volumes, sulcal patterns, and craniovascular features). The paleoneurological evidence suggests that most extinct human species displayed a pattern of gross endocranial asymmetries similar to modern humans. In addition, the behavioral information on handedness also points to a similar degree of laterality in archaic species of the human genus and in Neandertals. At present, there is therefore no evidence suggesting that the brain asymmetries in H. sapiens are part of a derived set of features. Of course, even a simple proportional change due to brain size increase can anyway prompt crucial cognitive changes, mostly if threshold effects are considered. Nonetheless, we still lack much information in basic anatomy to support consistent hypotheses on the biologic factors involved in endocranial asymmetries in fossil hominids. This missing information concerns endocranial morphogenesis and topology, spatial conflicts and constraints, the biomechanical balance between cerebral tissues, and the actual histologic changes associated with encephalization.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"231-240"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614434","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
George F Michel, Iryna Babik, Eliza L Nelson, Claudio L Ferre, Julie M Campbell, Emily C Marcinowski
{"title":"Development of handedness and other lateralized functions during infancy and early childhood.","authors":"George F Michel, Iryna Babik, Eliza L Nelson, Claudio L Ferre, Julie M Campbell, Emily C Marcinowski","doi":"10.1016/B978-0-443-15646-5.00003-8","DOIUrl":"10.1016/B978-0-443-15646-5.00003-8","url":null,"abstract":"<p><p>Using a historical or \"development from\" approach to study the development of hand-use preferences in infants and children, we show how various sensorimotor experiential events shape the cascade from initial to subsequent hand-use preferences. That cascade represents, creates, and shapes the lateralized asymmetry of neural circuits in the cerebral hemispheres. The control of the preferred hand requires neural circuits in the contralateral hemisphere that are capable of processing the organization of finely timed, sequentially organized movements and detecting haptic information derived from high-frequency transitions in the stimulus. We propose that the lateralized differences in these neural circuits underlie processes contributing to the development of other forms of hemispheric specialization of function. We show how the development of hand-use preferences contributes to the development of language skills, tool use, spatial skills, and other cognitive abilities during infancy and early childhood. Such evidence supports the proposal of Michael Corballis that the phylogeny of human language emerged during the evolution of hominins from the co-option of those neural circuits employed in the expression of manual skills involved in tool use, tool manufacture, and communication. Finally, we summarize evidence from children with cerebral palsy, which shows that their difficulties with sensorimotor processing, visuomotor coordination, anticipatory motor planning, and other cognitive abilities may stem from disturbances in the development of their hand-use preferences and hence the functional specialization of their hemispheres.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"181-194"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Michael B Miller, Lukas J Volz, Jessica M Simonson, Michael S Gazzaniga
{"title":"Split-brain patients: A clinical vs experimental perspective.","authors":"Michael B Miller, Lukas J Volz, Jessica M Simonson, Michael S Gazzaniga","doi":"10.1016/B978-0-443-15646-5.00015-4","DOIUrl":"10.1016/B978-0-443-15646-5.00015-4","url":null,"abstract":"<p><p>For more than 80 years, the clinical perspective on the behavioral outcome of split-brain surgery suggested that it \"may be carried out without any untoward effect on the patient,\" despite some initial and transient disconnection effects. The last 60 years of experimental studies, however, have shown quite the opposite. Using lateralized testing procedures, split-brain patients have demonstrated profound disconnection effects that can last a lifetime. This experimental work has transformed our understanding of hemispheric specializations and cerebral asymmetries. It paints a picture of patients with two distinct neural systems processing and operating independently with, nevertheless, a seemingly unified conscious experience. This chapter tracks how these two divergent perspectives have coexisted for so long and offers some explanations for why these patients appear normal from a clinical and social perspective.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"155-166"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Metabolic control of microglia in health and disease.","authors":"Gloria Colombo, Katia Monsorno, Rosa C Paolicelli","doi":"10.1016/B978-0-443-19104-6.00009-7","DOIUrl":"10.1016/B978-0-443-19104-6.00009-7","url":null,"abstract":"<p><p>Metabolic states within cells are tightly linked to functional outcomes and finely regulated by nutrient availability. A growing body of the literature supports the idea that various metabolites can influence cellular functions, such as cell differentiation, migration, and proliferation in different contexts, with ample evidence coming from the immune system. Additionally, certain functional programs can trigger significant metabolic changes within cells, which are crucial not only to meet high energy demands, but also to produce intermediate metabolites necessary to support specific tasks. Microglia, the resident innate immune cells of the central nervous system, are constantly active, surveying the brain parenchyma and providing support to neighboring cells in the brain. They exhibit high metabolic flexibility, capable of quickly undergoing metabolic reprogramming based on nutrient availability and functional requirements. In this chapter, we will discuss the major metabolic pathways within cells and provide examples of how relevant enzymes and metabolites can impact microglial function in physiologic and pathologic contexts.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"209 ","pages":"143-159"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143691700","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Sara B Festini, Grace Kegler, Patricia A Reuter-Lorenz
{"title":"Hemispheric organization of the brain and its prevailing impact on the neuropsychology of aging.","authors":"Sara B Festini, Grace Kegler, Patricia A Reuter-Lorenz","doi":"10.1016/B978-0-443-15646-5.00004-X","DOIUrl":"10.1016/B978-0-443-15646-5.00004-X","url":null,"abstract":"<p><p>Age differences in brain hemispheric asymmetry have figured prominently in the neuropsychology of aging. Here, a broad overview of these empirical and theoretical approaches is provided that dates back to the 1970s and continues to the present day. Methodological advances often brought new evidence to bear on older ideas and promoted the development of new ones. The deficit-focused hypothesis of accelerated right-hemisphere aging is reviewed first, followed by subsequent accounts pertaining to compensation, reserve, and their potential hemispheric underpinnings. Structural and functional neuroimaging reveal important and consistent age-related patterns, including indications of reduced brain asymmetry in older relative to younger adults. While not mutually exclusive, different neuropsychologic theories of aging offer divergent interpretations of such patterns, including age-related reductions in neural specificity (dedifferentiation) and age-related compensatory bilateral recruitment [e.g., Hemispheric Asymmetry Reduction in Older Adults (HAROLD); Compensation-Related Utilization of Neural Circuits Hypothesis (CRUNCH)]. Further, recent neurobehavioral evidence suggests that the right hemisphere plays a unique role in resisting the neurocognitive effects of aging via brain reserve. Future advances in human cognitive neuroscience, including neurostimulation methods for targeted interventions, along with analytic techniques informed by machine learning promise new insights into the neuropsychology of aging and the role of hemispheric processes in resilience and decline.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"169-180"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614613","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Handedness.","authors":"Sebastian Ocklenburg, Onur Güntürkün","doi":"10.1016/B978-0-443-15646-5.00016-6","DOIUrl":"10.1016/B978-0-443-15646-5.00016-6","url":null,"abstract":"<p><p>This chapter offers an overview of the literature on human handedness and its assessment in clinical neurologic practice and research. There are two major forms of handedness: hand preference, which describes a subjective preference to use one hand over the other for skilled motor activities like writing, and hand skill, which describes objectively measured mother skill. This chapter gives an overview of widely used questionnaires and tests to assess hand preference and hand skill, as well as suggestions on how to determine handedness categories such as left-handed, right-handed, and mixed-handed based on the results of these questionnaires and tests. Handedness is just one form of hemispheric asymmetry in the human motor system, and the chapter also provides an overview of its association with other motor asymmetries such as footedness. Moreover, the associations of handedness with functional brain activation as well as with structural markers on the cortical, subcortical, cerebellar, and spinal levels are discussed. Furthermore, the potential relevance of handedness retraining for clinical neurologic research and the association of handedness and cognitive abilities are discussed. The chapter concludes with an outlook on the critical importance of including handedness in clinical neurologic research and practice.</p>","PeriodicalId":12907,"journal":{"name":"Handbook of clinical neurology","volume":"208 ","pages":"379-391"},"PeriodicalIF":0.0,"publicationDate":"2025-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143614382","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}