Editorial
There is probably no more exquisite a demonstration of anatomical arrangements and the physiological properties of conduction through myelinated axons than the slowing of adduction on attempted horizontal gaze, with preserved convergence, seen in a case of posterior internuclear ophthalmoplegia. This and many other aspects of normal and abnormal eye movements were summarized by David Cogan in his definitive 20th century monograph on the Neurology of the Ocular Muscles (1948). On March 20, 1823, Sir Charles Bell read a paper to the Royal Society entitled ‘The motions of the eye etc.’, concluding with a second account of ‘The nerves of the orbit’ on June 19. Bell described the pulleys and strings by which cranial nerves move the orbits. The supranuclear influences on these final common pathways were later mapped experimentally by Sir David Ferrier (The Functions of the Brain, 1876), and their projections described by many—including Constantin von Monakow, Sir Victor Horsley and Charles Beevor. And the various syndromes resulting from perturbation of the brainstem arrangements for control of conjugate gaze were systematically itemized in the latter half of the 19th century—a period caricatured by Lawrence McHenry as resulting ‘in a veritable tossed salad of eponymous neurological disorders’ (McHenry LC. Garrison's History of Neurology, 1969). In ‘A technical eye inspired by biology’, Thomas Brandt—himself no slouch when it comes to the elucidation of eye movements and their disorders—shows how Charles Darwin's grandfather, the polymath Erasmus Darwin, anticipated many aspects of this integrated anatomy and physiology (page 1070). Professor Brandt reviews ‘The Moving Tablet of the Eye’ by Nicholas Wade and Benjamin Tatler—a title taken from Erasmus Darwin—tracing progress in biology dependent on advances in technology, illustrated with apparatus old and new for modelling the organization of eye movements, and culminating in the development of an eye-movement driven camera that follows the surgeon's eyes as these roam the dark recesses of body cavities; it features a clever device for avoiding the artefacts of wobble resulting from rapid movements, with overshoot and corrective saccades. Thomas Brandt, Professor of Neurology at the Ludwig Maximilians University in Munich, brings his perspective to the honours list of those who illuminated the neurology of eye movements, adding names omitted by Wade and Tatler, including Sir Gordon Holmes who spoke on ‘Looking and seeing: movements and fixation of the eyes’ in his John Mallet Purser lecture to Trinity College, Dublin—his alma mater—on June 4, 1936, and on ‘The cerebral integration of ocular movements’ in his Victor Horsley lecture to University College, London, on July 12, 1938. Thomas Brandt gave the Gordon Holmes lecture, sponsored by the Guarantors of Brain, at the 2nd meeting of the European Neurological Society (Brighton, UK) in June 1990 (Brandt T. Historical and clinical aspects of vestibular function. Brain: 1991: 114; 2159–2174).Amongst five papers in the present issue using murine or rodent models to understand human disorders, Benjamin Underwood and colleagues from institutions in East Anglia and Manchester, UK, apply metabonomics of human samples and a mouse model to identify pro-catabolic signatures that may serve as biomarkers useful at a pre-clinical stage in the course of Huntington's disease (page 877). Gregory Pelka and a team from Sydney, Australia, describe the histological and behavioural phenotype of mice modelling the loss-of-function MECP-2 mutation that underlies Rett syndrome in children (page 887). William Zinnanti and collaborators from Penn State School of Medicine and the University of Colorado, USA, improve on previous attempts to model glutaric aciduria type 1 glutaryl-CoA dehydrogenase deficiency by combining GCDH double knockout mice with elevated dietary protein and lysine intake to reproduce the characteristic striatal injury attributed to altered mitochondrial function (page 899). Céline Dubé and colleagues from the University of California, Irvine, and the University of Pennsylvania, USA, apply a more sophisticated and prolonged videotelemetry assessment than heretofore to determine the nature and frequency of epileptic activity, and abnormal interictal electroencephalography, in a rodent model of febrile seizures (page 911).
Three papers deal with aspects of optic nerve function. Hanspeter Killer and a group from Basel and Aarau, Switzerland, and Johns Hopkins Hospital, Baltimore, USA, provide several lines of evidence supporting the view that the subarachnoid space of the optic nerve can become separated from remaining compartments of the cerebrospinal fluid in particular disorders, thus creating an optic nerve sheath compartment syndrome (page 1027). Vincent Pernet and Adriano Di Polo from the University of Montreal, Canada, test the hypothesis that repair in the CNS may need to combine strategies both for neuronal survival and axonal outgrowth by studying the synergistic trophic effects of brain-derived nerve growth factor and a stimulus for axonal growth; whereas axons grow better with the combined stimulus, they show signs of axonal dystrophy indicative of disordered axonal transport (page 1014; and see cover). Bertrand Audoin and collaborators from the Institute of Neurology and Moorfields Eye Hospital, London, and Marseille, France, explain the alteration in magnetization transfer ratio (MTR) seen in cortical grey matter after optic neuritis on the basis of trans-synaptic degeneration in the projection pathway of the optic nerve (page 1031): whilst reduced MTR is confined to the occipital cortex in cases with isolated optic neuritis, more widespread imaging abnormalities are observed in those who subsequently meet criteria for the diagnosis of multiple sclerosis. Ming-Tsung Tseng and a group from Taiwan and the University of California, Berkeley, USA, show that reduced intraepidermal nerve fibre density, correlating with altered thermal thresholds to hot and cold stimuli, is a marker of vasculitis and disease activity in systemic lupus erythematosus whether or not there is known to be overt sensory neuropathy (page 977). Inflammation of muscle is the focus of a paper by Dalia Dimitri and colleagues from Hôpital Pitié-Salpêtrière, Paris, and Rouen, France, who show that there is restriction both of the peripheral blood T-cell repertoire and of the infiltrating cells in inclusion body myositis, but with incomplete overlap of the oligoclonality, blood and muscle each evidently having undergone a priming stimulus in vivo, presumably also reflecting re-circulation of pathogenic T cells across these compartments (page 986).
Amongst three papers on aspects of behavioural neurology, and the regional specificity and circuitry underlying discrete cognitive functions, Lesley Fellows from the Montreal Neurological Institute, Canada, dissects in more detail the difficulty with decision making seen in lesions of the human ventromedial frontal lobe (page 944): specifically, its role in multi-attribute decision making under conditions of certainty. Compared with controls and patients not having ventromedial frontal lobe lesions, cases show a strategy for choosing which apartment to rent that focuses on alternatives rather than the particular attributes of a given hypothetical place to live. People with medial frontal lobe damage make bad residential choices because they lack critical decision-making abilities; thus, the consequences of ventromedial frontal damage need to be conceptualized in terms of taking decisions under conditions both of certainty and uncertainty. In From the Archives, we review an earlier paper—emotionally highly charged for the senior author—also written from the Montreal Neurological Institute that describes the neurology of frontal lobe lesions (Penfield and Evans. The frontal lobe in man: a clinical study of maximum removals. Brain 1935: 58; 115–133).
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