Publications

Abstract

This chapter introduces the origins and development of our current anatomical terminology. It scrutinizes the historical evolution and etymological significance of the over 1900 official anatomical terms in the current nomenclature, underscoring their impact on the contemporary comprehension of cognitive neuroanatomy. The chapter traces unification efforts from the Basel Nomina Anatomica in 1895 to the 1998 Terminologia Anatomica, noting challenges arising from outdated terminology in light of recent anatomical advancements.

Highlighting the influence of terminologies on interpretations of brain anatomy, the chapter explores several anatomical mapping methods such as surface, sectional, connectional, and functional anatomy. It illuminates discrepancies and controversies, exemplified by divergent interpretations of the number of brain lobes and the definitions of 'Broca' and 'Wernicke' areas.

The chapter explores anatomical terms' historical and cultural underpinnings, encompassing mythonyms, eponyms, and cultural influences on nomenclature. It critically examines the implications of these terminologies on contemporary research and shows that Large Language Models mirror these discrepancies. It underscores the need for more inclusive and culturally sensitive approaches in anatomical education.

Lastly, we advocate for updating anatomical nomenclature, suggesting that a deeper understanding of these terminologies could provide insights and aid in resolving ongoing debates in the field. This examination sheds light on historical knowledge and emphasizes the dynamic interplay between language, culture, and anatomy in shaping our comprehension of the neurobiology of the brain and how we navigate neuroanatomy in the 21st century.

Abstract

The human brain is an intricate network of cortical regions interconnected by white matter pathways, dynamically supporting cognitive functions. While cortical asymmetries have been consistently reported, the asymmetry of white matter connections remains less explored. This chapter provides a brief overview of asymmetries observed at the cortical, subcortical, cytoarchitectural, and receptor levels before exploring the detailed connectional anatomy of the human brain. It thoroughly examines the lateralization and interindividual variability of 56 distinct white matter tracts, offering a comprehensive review of their structural characteristics and interindividual variability. Additionally, we provide an extensive update on the asymmetry of a wide range of white matter tracts using high-resolution data from the Human Connectome Project (7T HCP www.humanconnectome.org). Future research and advanced quantitative analyses are crucial to understanding fully how asymmetry contributes to interindividual variability. This comprehensive exploration enhances our understanding of white matter organization and its potential implications for brain function.

Abstract

The brain is the most magnificent structure, and we are only at the cusp of unraveling some of its complexity. Neuroanatomy is the best tool to map the brain's structural complexity. As such, neuroanatomy is not just an academic exercise; it serves our fundamental understanding of the neurobiology of cognition and improves clinical practice. A deepened anatomical understanding has advanced our conceptual grasp of the evolution of the brain, interindividual variability of cognition in health and disease, and the conceptual shift toward the emergence of cognition. For the past 20 years, diffusion imaging tractography has dramatically facilitated these advances by enabling the study of the delicate networks that orchestrate brain processes (for review, see Thiebaut de Schotten and Forkel, 2022). Several steps are consistent across all studied populations and brain states (health/disease) when analyzing tractography data. We discuss various considerations for dissections across populations and give practical tips on common pitfalls and features to improve the visualization of the dissections. We briefly discuss specific considerations for manual dissections in nonhuman primates. Lastly, we provide an atlas of regions of interest (ROIs) for the most commonly delineated white matter connections in the human brain.

Abstract

Brain tumors are classified as rare diseases, with an annual occurrence of 300,000 cases and account for an annual loss of 241,000 lives, highlighting their devastating nature. Recent advancements in diagnosis and treatment have significantly improved the management and care of brain tumors. This chapter provides an overview of the common types of primary brain tumors affecting language functions—gliomas and meningiomas. Techniques for identifying and mapping critical language areas, including the white matter language system, such as awake brain tumor surgery and diffusion-weighted tractography, are pivotal for understanding language localization and informing personalized treatment approaches. Numerous studies have demonstrated that gliomas in the dominant hemisphere can lead to (often subtle) impairments across various cognitive domains, with a particular emphasis on language. Recently, increased attention has been directed toward (nonverbal) cognitive deficits in patients with gliomas in the nondominant hemisphere, as well as cognitive outcomes in patients with meningiomas, a group historically overlooked. A patient-tailored approach to language and cognitive functions across the pre-, intra-, and postoperative phases is mandatory for brain tumor patients to preserve quality of life. Continued follow-up studies, in conjunction with advanced imaging techniques, are crucial for understanding the brain's potential for neuroplasticity and optimizing patient outcomes.

Abstract

Over the past two decades, the study of resting-state functional magnetic resonance imaging has revealed that functional connectivity within and between networks is linked to cognitive states and pathologies. However, the white matter connections supporting this connectivity remain only partially described. We developed a method to jointly map the white and grey matter contributing to each resting-state network (RSN). Using the Human Connectome Project, we generated an atlas of 30 RSNs. The method also highlighted the overlap between networks, which revealed that most of the brain’s white matter (89%) is shared between multiple RSNs, with 16% shared by at least 7 RSNs. These overlaps, especially the existence of regions shared by numerous networks, suggest that white matter lesions in these areas might strongly impact the communication within networks. We provide an atlas and an open-source software to explore the joint contribution of white and grey matter to RSNs and facilitate the study of the impact of white matter damage to these networks. In a first application of the software with clinical data, we were able to link stroke patients and impacted RSNs, showing that their symptoms aligned well with the estimated functions of the networks.

Abstract

Aberrant anatomical brain connections in attention-deficit/hyperactivity disorder (ADHD) are reported inconsistently across
diffusion weighted imaging (DWI) studies. Based on a pre-registered protocol (Prospero: CRD42021259192), we searched PubMed,
Ovid, and Web of Knowledge until 26/03/2022 to conduct a systematic review of DWI studies. We performed a quality assessment
based on imaging acquisition, preprocessing, and analysis. Using signed differential mapping, we meta-analyzed a subset of the
retrieved studies amenable to quantitative evidence synthesis, i.e., tract-based spatial statistics (TBSS) studies, in individuals of any
age and, separately, in children, adults, and high-quality datasets. Finally, we conducted meta-regressions to test the effect of age,
sex, and medication-naïvety. We included 129 studies (6739 ADHD participants and 6476 controls), of which 25 TBSS studies
provided peak coordinates for case-control differences in fractional anisotropy (FA)(32 datasets) and 18 in mean diffusivity (MD)(23
datasets). The systematic review highlighted white matter alterations (especially reduced FA) in projection, commissural and
association pathways of individuals with ADHD, which were associated with symptom severity and cognitive deficits. The meta-
analysis showed a consistent reduced FA in the splenium and body of the corpus callosum, extending to the cingulum. Lower FA
was related to older age, and case-control differences did not survive in the pediatric meta-analysis. About 68% of studies were of
low quality, mainly due to acquisitions with non-isotropic voxels or lack of motion correction; and the sensitivity analysis in high-
quality datasets yielded no significant results. Findings suggest prominent alterations in posterior interhemispheric connections
subserving cognitive and motor functions affected in ADHD, although these might be influenced by non-optimal acquisition
parameters/preprocessing. Absence of findings in children may be related to the late development of callosal fibers, which may
enhance case-control differences in adulthood. Clinicodemographic and methodological differences were major barriers to
consistency and comparability among studies, and should be addressed in future investigations.

Abstract

The parietal lobe has a unique place in the human brain. Anatomically, it is at the crossroad between the frontal, occipital, and temporal lobes, thus providing a middle ground for multimodal sensory integration. Functionally, it supports higher cognitive functions that are characteristic of the human species, such as mathematical cognition, semantic and pragmatic aspects of language, and abstract thinking. Despite its importance, a comprehensive comparison of human and simian intraparietal networks is missing.

In this study, we used diffusion imaging tractography to reconstruct the major intralobar parietal tracts in twenty-one datasets acquired in vivo from healthy human subjects and eleven ex vivo datasets from five vervet and six macaque monkeys. Three regions of interest (postcentral gyrus, superior parietal lobule and inferior parietal lobule) were used to identify the tracts. Surface projections were reconstructed for both species and results compared to identify similarities or differences in tract anatomy (i.e., trajectories and cortical projections). In addition, post-mortem dissections were performed in a human brain.

The largest tract identified in both human and monkey brains is a vertical pathway between the superior and inferior parietal lobules. This tract can be divided into an anterior (supramarginal gyrus) and a posterior (angular gyrus) component in both humans and monkey brains. The second prominent intraparietal tract connects the postcentral gyrus to both supramarginal and angular gyri of the inferior parietal lobule in humans but only to the supramarginal gyrus in the monkey brain. The third tract connects the postcentral gyrus to the anterior region of the superior parietal lobule and is more prominent in monkeys compared to humans. Finally, short U-shaped fibres in the medial and lateral aspects of the parietal lobe were identified in both species. A tract connecting the medial parietal cortex to the lateral inferior parietal cortex was observed in the monkey brain only.

Our findings suggest a consistent pattern of intralobar parietal connections between humans and monkeys with some differences for those areas that have cytoarchitectonically distinct features in humans. The overall pattern of intraparietal connectivity supports the special role of the inferior parietal lobule in cognitive functions characteristic of humans.