Editorial
Anyone wishing to trace the history of anatomical discovery in the nervous system ends up considering observations that pre-date by many centuries the launch of modern macroscopic and microscopic anatomy in the 16th and 18th centuries, respectively. Thus, the study of form and function starts in Antiquity. But, as separate structures were accurately described, and the neuron doctrine firmly established, so it became necessary accurately to map and interpret axonal connections and fibre pathways of the brain and spinal cord. These are beautiful arrangements, visually and in organisational terms, and the artistry that first stimulated their study in the Renaissance period is no less evident today in the depictions based on autoradiography, diffusion-weighted imaging and immunocytochemistry. In his review of Fibre pathways of the brain by Jeremy Schmahmann and Deepak Pandya, Mitchell Glickstein brings a professional lifetime of studying anatomy in the monkey and man, and scholarship in the history of neuroscience, to his account of how post-Galenic knowledge on connections in the nervous system accumulated through the work of Anton van Leeuwenhoek, Jan Evangelista Purkyn
and Theodor Schwann dealing with normal structures, and the evidence that accumulated later—using increasingly sophisticated techniques—from the study of fibres degenerating in response to injury (page 875). Especially valuable is Professor Glickstein's identification of the critical contributions since 1906 when Santiago Ramon y Cajal and Camillo Golgi received the Nobel Prize for Physiology or Medicine for their discoveries in neuronal and axonal anatomy. We also publish work from Jeremy Schmahmann and colleagues in Boston (USA) that uses diffusion spectrum imaging to overcome the problem of how to visualize cortico-cortical association fibres that have intersecting trajectories in the simian brain (page 630, and see cover): comparing structures defined using autoradiographic tracers and diffusion-based imaging, they identify ten long pathways emerging from the parietal, occipito-parietal, temporal, occipital-temporal and cingulate regions to propose new interpretations for the putative functions of these tracts based on the connections they make. The opportunity to define functional connections in primates that may illuminate the neurology of disconnection syndromes in man, and the need generally for anatomical studies in the normal brain, are argued by Marco Catani in his commentary on this paper (page 602): he, too, starts with Aristotle, and the Renaissance artist-anatomists, in tracing the scientific roots of modern hodology and the neurology of the disconnection syndromes described by Carl Wernicke, Jules Déjérine and, subsequently, Norman Geschwind (see Brain 2005: 128; 2224–2239). Jon Skranes and investigators from Trondheim, Arendal and Tromsø (Norway) and La Jolla (California, USA) use diffusion tensor imaging to correlate differences in fractional anisotropy of specific brain fibre pathways with perceptual, cognitive, motor, social and mental health impairments, 15 years after perinatal white matter injury (page 654); and Deanne Thompson and a team from Melbourne (Australia) and Washington University, St Louis, and Harvard Medical School, Boston (USA) provide additional evidence indicating the selective vulnerability of cortical and deep nuclear grey matter regions and non-myelinated and myelinated white matter—to some extent varying with precipitating factors—in preterm infants studied at ‘term equivalent’ and compared with infants delivered at full-term, thus providing an anatomical substrate for impaired developmental outcomes in children born prematurely (page 667).
Three papers on neurogenetics focus on childhood encephalopathy. Louise Harkin and colleagues from Adelaide, Melbourne and Sydney (Australia), Wellington (New Zealand), Glasgow (UK), Montreal and Vancouver (Canada) and Maryland (USA) describe a large series of infants with epileptic encephalopathy screened for mutations of the sodium channel alpha 1 subunit (SCN1A): these are present more frequently in severe myoclonic epilepsy of infants (SMEI) than the borderland syndrome (SMEB), and also in cryptogenic generalised epilepsy and cryptogenic focal epilepsy—especially the variant with severe infantile multi-focal epilepsy (page 843). Elsebet Ostergaard and investigators from Copenhagen, Hillerod and Glostrup (Denmark), Torshaven (Faroe Islands) and Reykjavik (Iceland) describe the clinical, neuroimaging and biochemical features of autosomal recessive mitochondrial encephalopathy with elevated methylmalonic acid (page 853): they confirm that the defect maps to the region of 13q14, SUCLA2 encoding the ATP-forming ß subunit of succinyl-CoA ligase, and show that a novel splice site mutation that alters exon 4 leads to the accumulation of succinyl-CoA and its metabolite methylmalonc acid. Rosalba Carrozzo and a team from Rome (Italy), Torshaven (Faroe Islands), Nijmegen (The Netherlands) and Hamburg (Germany) add to the literature on methylmalonic aciduria, Leigh-like encephalomyopathy, dystonia and deafness identifying three novel SUCLA2 mutations and characterising biochemical abnormalities in the carnitine ester pathway (page 862). As Patrick Chinnery (Associate Editor of Brain) sets out in his commentary on these papers (page 606), both draw attention to the founder effects and high gene frequency of this disorder in the Faroe Islands, and suggest local opportunities for screening and managing an inborn error of metabolism. Neurological disease in specific geographic regions is also the focus of the paper by Annie Lannuzel and colleagues from Guadeloupe (FWI), Paris (France) and Marburg (Germany) who compare clinical and laboratory features to distinguish regular Parkinson's disease from the progressive supranuclear palsy-like, parkinsonism-dementia and parkinsonism-related syndromes seen in Guadeloupe (page 816): they suggest that the atypical forms, as defined, may be related to ingestion of ‘soursop’ containing annonacin, a mitochondrial complex 1 inhibitor present in the leaves of Annona muricaata.
The biological and neuropathological basis for many neuropsychiatric disorders is no longer much in dispute and Brain periodically publishes articles describing abnormalities of brain structure in autism and the psychoses. In the present issue, Pawel Kreczmanski and investigators from Maastricht (The Netherlands), Würzberg, Rostock and Aachen (Germany), London (UK), Rome (Italy) and New York (USA) describe reduced volume and fewer neurones in the putamen and lateral nucleus of the amygdala, studied by high-precision stereological techniques, in schizophrenics (page 678). Motoaki Nakamura and a team from Harvard Medical School and the University of Massachusetts, Boston (USA) characterise the ‘H-shaped’ sulcus, which forms the boundaries of major orbitofrontal gyri, also in schizophrenics: normal hemispheric asymmetries are lost and the so-called type III pattern (interrupted rostral and caudal portions of the medial and lateral orbital sulci) over-represented in patients having more severe and socially disabling symptoms—perhaps reflecting a neuro-developmental abnormality (page 693). These anatomical correlates with psychiatric disease were not always so evident. In the 19th century, concepts on mental disorders were largely dominated by psychodynamic views, whereas the principle of biological psychiatry was less clearly formulated. The housing of inmates in asylums, providing care and support in exchange for clinical documentation and (eventual) neuropathological examination promoted a more emancipated understanding of mental disorders. In From the Archives, we review an early evaluation of brain structure in the context of insanity: On the weight of the brain and its component parts in the insane, by J. Crichton-Browne. Brain 1879: 1; 514–518 and 1879: 2; 42–67.
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