World Health Organization 2016 Classification of Central Nervous System Tumors

The recent update of the World Health Organization (WHO) classification of tumors of the central nervous system represents a paradigm shift. Previous iterations of the classification relied on morphologic features for classification. In the 2016 update, the definitions of specific neoplastic entities tumors now include precise molecularly defined entities. This article discusses this paradigm shift, and focuses on the refinements in classification criteria, relations to previous editions, and their implication to neuropathology and neuro-oncology practice. The authors distinguish the criteria that were used to determine why molecular changes were included.

Neurosurgery of the future: Deep brain stimulations and manipulations

Important advances are afoot in the field of neurosurgery-particularly in the realms of deep brain stimulation (DBS), deep brain manipulation (DBM), and the newly introduced refinement "closed-loop" deep brain stimulation (CLDBS). Use of closed-loop technology will make both DBS and DBM more precise as procedures and will broaden their indications. CLDBS utilizes as feedback a variety of sources of electrophysiological and neurochemical afferent information about the function of the brain structures to be treated or studied. The efferent actions will be either electric, i.e. the classic excitatory or inhibitory ones, or micro-injection of such things as neural proteins and transmitters, neural grafts, implants of pluripotent stem cells or mesenchymal stem cells, and some variants of gene therapy. The pathologies to be treated, beside Parkinson's disease and movement disorders, include repair of neural tissues, neurodegenerative pathologies, psychiatric and behavioral dysfunctions, i.e. schizophrenia in its various guises, bipolar disorders, obesity, anorexia, drug addiction, and alcoholism. The possibility of using these new modalities to treat a number of cognitive dysfunctions is also under consideration. Because the DBS-CLDBS technology brings about a cross-fertilization between scientific investigation and surgical practice, it will also contribute to an enhanced understanding of brain function.

A half century of change in diagnostic neuropathology: from the giants of yore to current brain tumor classification

The first issue of Human Pathology contains a laudatory review of one of the most treasured books in the history of neuropathology: Neurological Clinicopathological Conferences of the Massachusetts General Hospital, a collection of neurological cases that appeared first in the New England Journal of Medicine in the 1940s, 1950s, and 1960s. Each patient history is discussed by well-known neurologists, neurosurgeons, and neuropathologists. Review of these cases provides a framework to explore diagnostic shifts that have occurred over the past half century. Importantly, while the discussants of these cases were great diagnosticians, they were somewhat limited by the methods available to them at the time; subsequent novel technologies provided opportunities for new insights that were made by the next generation of experts. Today's pathologists (whether neuropathologists or any other pathology subspecialists) are similarly skilled at diagnosis, although their diagnoses are now more often made on biopsies (rather than autopsies) and informed by pre-operative imaging studies as well as post-operative molecular analyses. In turn, one would conclude that, even in the face of future technological changes brought about by disruptive innovations like artificial intelligence and deep molecular analyses, a need will continue for the expertise of pathologists and other clinical diagnosticians.

Connectomics and other novel methods for examining neural systems

Novel approaches for studying the brain and relating its activities to mental phenomena have come into use during the past decade (Bargmann, 2015). These include both new laboratory methods - involving, among others, generation of isolated cells which retain neuronal characteristics in vivo; the selective stimulation of neurons by light in vivo; and direct electrical stimulation of specific brain regions to restore a system's balance of excitation and inhibition - and a new organizing principle, "connectomics", which recognizes that networks, and not simply a key nucleus or region, underlie most brain functions and malfunctions. Its application has already improved our comprehension of how the brain normally functions and our ability to help patients with such poorly treated neurologic and psychiatric diseases as Alzheimer's disease.

The future of psychiatry: brain devices

Recent advances in deep brain stimulators and brain-machine interfaces have greatly expanded the possibilities of neuroprosthetics and neuromodulation. Together with advances in neuroengineering, nanotechnology, molecular biology and material sciences, it is now possible to address fundamental questions in neuroscience in new, more powerful ways. It is now possible to apply these new technologies in ways that range from augmenting and restoring function to neuromodulation modalities that treat neuropsychiatric disorders. Recent developments in neuromodulation methods offer significant advantages and potential clinical benefits for a variety of disorders. Here we describe the current state of the art in neuromodulation methods, and some advances in brain-machine interfaces, describing the advantages and limitations of the clinical applications of each method. The future applications of these new methods and how they will shape the future of psychiatry and medicine, along with safety and ethical implications, are also discussed.

Pediatric Neuropathology-Keeping Pace with Progress

Recent strides in pediatric neuropathology have revolutionized the field. The integration of advanced technologies like next-generation sequencing and methylation arrays have refined the diagnosis and classifications of pediatric brain tumors, epilepsy, and central nervous system vascular anomalies, though full clinical integration remains a challenge. Emerging technologies and genomic discoveries, particularly in the field of pediatric brain tumors, promise to further enhance diagnostic precision and patient care, underscoring the need for adaptable, forward-thinking practices.

Large-scale neurophysiology and single-cell profiling in human neuroscience

Advances in large-scale single-unit human neurophysiology, single-cell RNA sequencing, spatial transcriptomics and long-term ex vivo tissue culture of surgically resected human brain tissue have provided an unprecedented opportunity to study human neuroscience. In this Perspective, we describe the development of these paradigms, including Neuropixels and recent brain-cell atlas efforts, and discuss how their convergence will further investigations into the cellular underpinnings of network-level activity in the human brain. Specifically, we introduce a workflow in which functionally mapped samples of human brain tissue resected during awake brain surgery can be cultured ex vivo for multi-modal cellular and functional profiling. We then explore how advances in human neuroscience will affect clinical practice, and conclude by discussing societal and ethical implications to consider. Potential findings from the field of human neuroscience will be vast, ranging from insights into human neurodiversity and evolution to providing cell-type-specific access to study and manipulate diseased circuits in pathology. This Perspective aims to provide a unifying framework for the field of human neuroscience as we welcome an exciting era for understanding the functional cytoarchitecture of the human brain.

Recent developments in multiple sclerosis neuropathology

PURPOSE OF REVIEW

Neuropathological studies in human brain tissue are indispensable for our understanding of disease mechanisms in multiple sclerosis (MS). They inform concepts of lesion evolution, tissue regeneration and disease progression, and ideally reveal new disease mechanisms and therapeutic targets. Here we review recent neuropathological studies that have advanced our knowledge of MS pathogenesis.

RECENT FINDINGS

Recent cohort studies support the notion that different clinical MS disease phenotypes share underlying pathological features, and that clinical and pathological heterogeneity is derived from a variable combination of innate and adaptive inflammation, demyelinating activity, and neuroaxonal loss. Importantly, emerging technologies for spatial transcriptome analysis enable an unprecedented glimpse into the cellular composition and molecular mechanisms involved in lesion evolution. These promising technologies will help identify the identification of molecular hubs governing tissue damage and regeneration.

SUMMARY

Recent neuropathological studies helped to identify tissue correlates of disability and disease progression. Substantial progress in molecular brain tissue analysis revealed the complexity of MS-related tissue features. Close collaboration between tissue-based, molecular, bioinformatic, pharmacologic, imaging and clinical experts is needed to continue to advance the field, particularly for the benefit of people with progressive MS.