El tracto cortico espinal: perspectiva histórica / The corticospinal tract: historical perspective

RESUMEN: La neuroanatomía y la neurofisiología han permitido en gran parte entender de forma más integrada las estructuras que conforman el sistema nervioso y los mecanismos asociados con la transmisión de los potenciales de acción, relacionados con la vía corticoespinal en la ejecución de movimientos voluntarios. Se realizó una revisión histórica sobre la vía corticoespinal, desde el punto de vista neuroanatómico y neurofisiológico mediante una revisión de literatura en distintas bases de datos y libros de texto dedicados a estas vías nerviosas. La información obtenida se ordenó cronológicamente, seleccionando los datos más relevantes que desde el punto de vista neuroanatómico y neurofisiológico han permitido comprender su mecanismo funcional. Actualmente se tiene un conocimiento muy depurado de los distintos elementos que componen la vía corticoespinal, lo que permitirá su aplicación en el campo de la salud y resolver múltiples problemas de la función motora.

SUMMARY: Neuroanatomy and Neurophysiology have, in large part, permitted a more thorough understanding of those structures that conform the nervous system and mechanisms associated with the transmission of action potentials associated with the corticospinal tract. This assertion is made based upon a literature review of various databases and textbooks dedicated to said nerve tracts. The information obtained was ordered chronologically, and data was selected that, from the neuroanatomical and neurophysiological viewpoints, were most relevant and have permitted the comprehension of its functional mechanism. The thorough understanding of those elements that compose the corticospinal tract will permit its application in the health field and resolve multiple motor function problems.

Luigi Luciani (1840-1919) - the Italian Claude Bernard with German shaping, and his studies on the cerebellum with projections to nowadays / Luigi Luciani (1840-1919) - o italiano Claude Bernard com formação alemã, e seus estudos sobre o cerebelo com projeções na atualidade

Luigi Luciani (1840-1919) was an illustrious Italian citizen and physiologist whose research scope covered mainly cardiovascular subjects, the nervous system, and fasting. He published in 1891 a modern landmark of the study of cerebellar physiology - "Il cervelletto: nuovistudi di normal and pathología physiology" / "The cerebellum: new studies on normal and pathological physiology." In his experiment, a dog survived after cerebellectomy, reporting a triad of symptoms (asthenia, atonia, and astasia). In this way, the eminent neurophysiologist improved the operative technique and sterile processes to redirect the issue of cerebellar symptoms. Luciani died at age 78, a hundred years ago, and left mainly the understanding of the role of the cerebellum in regulating postural tone and muscle strength, which represented a step forward in understanding cerebellar motor physiology. In recent decades, cognitive / affective function has been added to the cerebellar motor, and there has also been a better understanding of cerebellar circuits.

Luigi Luciani (1840-1919) foi um ilustre cidadão e fisiologista italiano, cujo escopo de pesquisa abrangia principalmente assuntos cardiovasculares, sistema nervoso e jejum. Ele publicou em 1891 um marco moderno do estudo da fisiologia do cerebelo - "Il cervelletto: nuovistudi di fisiologia normale and patologica" / "O cerebelo: novos estudos sobre fisiologia normal e patológica". Em seu experimento, um cão sobreviveu após a cerebelectomia, com o relatório de uma tríade de sintomas (astenia, atonia e astasia). Dessa maneira, o eminente neurofisiologista aprimorou a técnica operatória e os processos estéreis para redirecionar a questão dos sintomas cerebelares. Luciani morreu aos 78 anos, cem anos atrás, e deixou principalmente a compreensão do papel do cerebelo na regulação do tônus postural e da força muscular, o que representou um passo adiante na compreensão da fisiologia motora cerebelar. Nas últimas décadas, a função cognitivo / afetiva foi adicionada à motora cerebelar e, também, houve uma melhor compreensão dos circuitos do cerebelo.

Aristides Leão: a birth centennial homage with comments on his spreading depression.

The year of 2014 is the birth centenary of Aristides Azevedo Pacheco Leão (1914-1993), and also marks seventy years of the publication of his discovery of the novel electrophysiological phenomenon, named by him "spreading depression" (SD), soon designated "Leão's wave" or "Leão's spreading depression". This was a remarkable scientific milestone, and the author must be celebrated for this achievement, as the studies he triggered proceeded worldwide, with new concepts, as spreading depolarization, until the present days. Robust experimental and clinical evidence emerged to suggest that these and related electrophysiological phenomena are involved in the mechanisms of migraine aura, acute cerebrovascular diseases, traumatic brain injury, transient global amnesia, epileptic seizures, and their pathophysiological characteristics come to offer new therapeutic perspectives. He was a remarkable and complex personality, and the authors remit the readers to a paper where his personal life is contemplated.

Aristides Leão: a birth centennial homage with comments on his spreading depression / Aristides Leão: homenagem ao centenário de nascimento com comentários sobre sua depressão alastrante

The year of 2014 is the birth centenary of Aristides Azevedo Pacheco Leão (1914-1993), and also marks seventy years of the publication of his discovery of the novel electrophysiological phenomenon, named by him “spreading depression” (SD), soon designated “Leão’s wave” or “Leão’s spreading depression”. This was a remarkable scientific milestone, and the author must be celebrated for this achievement, as the studies he triggered proceeded worldwide, with new concepts, as spreading depolarization, until the present days. Robust experimental and clinical evidence emerged to suggest that these and related electrophysiological phenomena are involved in the mechanisms of migraine aura, acute cerebrovascular diseases, traumatic brain injury, transient global amnesia, epileptic seizures, and their pathophysiological characteristics come to offer new therapeutic perspectives. He was a remarkable and complex personality, and the authors remit the readers to a paper where his personal life is contemplated.

O ano de 2014 é o centenário de nascimento de Aristides Azevedo Pacheco Leão (1914-1993), e também assinala setenta anos da publicação de sua descoberta, que ele denominou “depressão alastrante” (DA), logo designada “onda de Leão” ou “depressão alastrante de Leão”. Foi um notável marco científico e o autor deve ser celebrado por esse feito, considerando que estudos que desencadeou continuaram no mundo todo, com novos conceitos, como a despolarização alastrante, até os dias atuais. Evidência experimental e clínica robusta emergiram sugerindo que esses fenômenos eletofisiológicos e outros relacionados encontram-se envolvidos nos mecanismos da aura da enxaqueca, doenças cerebrovasculares agudas, lesão cerebral traumática, amnésia global transitória, crises epiléticas, sendo que suas características fisiopatológicas vêm oferecer novas perspectivas terapêuticas. Foi uma personalidade complexa e notável, e os autores remetem os leitores para um artigo no qual sua vida pessoal é contemplada.

Humphrey Ridley (1653-1708): forgotten neuroanatomist and neurophysiologist.

Humphrey Ridley is a little known character in the history of anatomy and physiology. Born in 1653, Ridley was a physician and anatomist who followed the research done by Willis, Vieussens, and Galen. Outside of a cursory knowledge of his birth and death, readers have only two remnants of his contributions to science: The Anatomy of the Brain, containing its Mechanism and Physiology and Observationes Quaedam Medico-Practicae et Physiologicae de Asthmate et Hydrophobia. The former text was the first book in the English language written on the human brain. Ridley's studies using cadavers executed by hanging provided him with a novel view of the venous drainage and lymphatic system not seen as accurately by those before him. Since the study of the brain was still largely in its infancy, he was not without his errors of deduction as to the purpose of parts of the brain and its pathologies. With his dissections, however, Ridley was able to build on the collective knowledge of neuroanatomy and provided new insight into brain structure and function. The current paper reviews what is known of Ridley's life and contributions to neuroanatomy and neurophysiology.

Claude Bernard: bicentenary of birth and his main contributions to neurology.

Claude Bernard (1813-1878) followed two main research paths: the chemical and physiological study of digestion and liver function, along with experimental section of nerves and studies on sympathetic nerves. Curare studies were, for example, of longstanding interest. His profound mental creativity and hand skillfulness, besides methodology quality, directed his experiments and findings, mainly at the Collège de France. His broader and epistemological concerns were carried out at the Sorbonne and later at the Muséum national d'Histoire naturelle. His insight gave clues to define the " milieu intérieur", later known as "homeostasis", and grasp the brain complexity. Bernard followed and surpassed his master François Magendie who also fought against dogmas and laid the foundations of experimental medicine, and its main heinous tool - vivisection. Bernard created the methodological bases of experimental medicine, and collected honors as a renowned researcher.

Claude Bernard: bicentenary of birth and his main contributions to neurology / Claude Bernard: bicentenário do nascimento e suas principais contribuições à neurologia

Claude Bernard (1813-1878) followed two main research paths: the chemical and physiological study of digestion and liver function, along with experimental section of nerves and studies on sympathetic nerves. Curare studies were, for example, of longstanding interest. His profound mental creativity and hand skillfulness, besides methodology quality, directed his experiments and findings, mainly at the Collège de France. His broader and epistemological concerns were carried out at the Sorbonne and later at the Muséum national d'Histoire naturelle. His insight gave clues to define the “ milieu intérieur”, later known as “homeostasis”, and grasp the brain complexity. Bernard followed and surpassed his master François Magendie who also fought against dogmas and laid the foundations of experimental medicine, and its main heinous tool – vivisection. Bernard created the methodological bases of experimental medicine, and collected honors as a renowned researcher.

Em suas pesquisas, Claude Bernard (1813-1878) seguiu dois caminhos principais: o estudo fisiológico e químico da digestão e da função hepática; a seção experimental de nervos e os estudos sobre nervos simpáticos. Estudos sobre curare, por exemplo, foram de interesse duradouro. Suas profundas criatividade mental e habilidade manual, além da qualidade metodológica, conduziram às suas experiências e descobertas, principalmente no Collège de France. Seus interesses sobre temas epistemológicos mais amplos foram conduzidos na Sorbonne e, posteriormente, no Muséum national d'Histoire naturelle. Seu discernimento deu subsídios para definir o “ milieu intérieur ”, mais tarde conhecido como “homeostase”, e para ajudar a compreender a complexidade do cérebro. Bernard seguiu e superou seu mestre François Magendie. Este também lutou contra dogmas e lançou os fundamentos da medicina experimental, utilizando sua principal ferramenta hedionda – a vivissecção. Bernard ampliou estes estudos e criou as bases metodológicas da medicina experimental, tendo colecionado honrarias como renomado pesquisador.

Emil du Bois-Reymond on "The Seat of the Soul".

The German pioneer of electrophysiology, Emil du Bois-Reymond (1818-1896), is generally assumed to have remained silent on the subject of the brain. However, the archive of his papers in Berlin contains manuscript notes to a lecture on "The Seat of the Soul" that he delivered to popular audiences in 1884 and 1885. These notes demonstrate that cerebral localization and brain function in general had been concerns of his for quite some time, and that he did not shy away from these subjects.

John Hughlings Jackson: um neurologista inglês / John Hughlings Jackson: a British neurologist

John Hughlings Jackson tornou-se médico e neurologista por uma via atípica e sem frequentar qualquer universidade. Entretanto, sua mente brilhante e a admirável capacidade de trabalho levaram-no a produzir conhecimentos que repercutem até os dias de hoje, nas áreas do diagnóstico neurológico, epilepsia, localização cerebral, níveis evolucionários do sistema nervoso e sua hierarquia, entre outros. Diversas das condições que descreveu foram designadas com seu nome. É admirável que essa produção médico-científica tenha sido baseada inteiramente na sua aguçada capacidade de observação clínica. Foi a personalidade que mudou a neurologia inglesa, dando-lhe um status que carecia no meio nacional e internacional. É considerado o "pai" da neurologia inglesa.

John Hughlings Jackson became a physician and neurologist through an atypical way, and without attending any university. However, his brilliant mind and amazing capacity for work led him to produce knowledge that resounds until the present days, in areas of neurological diagnosis, epilepsy, brain localization, evolutionary levels of the nervous system and their hierarchies, among others. Several conditions that he described were named after him. It is admirable that this medical-scientyphic production was founded entirely in his sharp ability of clinical observation. He was the personality that changedthe English neurology providing a status it lacked in the national and international milieu. He is considered the "father" of the English neurology.

Coming to grips with a "new" state of consciousness: the study of rapid-eye-movement sleep in the 1960s.

The recognition of rapid-eye-movement sleep (REM) and its association with dreaming in 1953 by Aserinsky and Kleitman opened a new world to explore in the brain. Discussions at two major symposia in the early 1960s reveal that a state with characteristics resembling both wakefulness and sleep was overturning accepted views of the regulation of the two states. Participants grappled with the idea that cortical activation could occur during sleep. They struggled with picking a name that would capture the essence of REM without focusing on just one aspect of the state. Questioning whether REM in cats could be homologous with that of humans suggested an anthropocentric focus on human dreaming as the essence of the state. The need for biochemical studies was evident given that deprivation of REM caused a rebound in the amount of subsequent REM, which indicated that simple synaptic activity could not support this phenomenon.

Letters from Dom Pedro II to professor Brown-Séquard: imperial correspondence and neurophysiology.

The authors have analyzed the content of a selection of letters written by Dom Pedro II, the Emperor of Brazil, and sent to Doctor Charles Brown-Séquard, the famous neurologist, between 1876 and 1885. The content of those letters focuses mainly on his wife's, Princess Thereza Cristina, health issues and Dom Pedro's personal desire to foster the research into the physiological study of the nervous system.

Resuscitation great. Luigi Galvani and the foundations of electrophysiology.

Luigi Galvani became one of the greatest scientists of the 18th century with his research and the development of his theory on animal electricity. His work was appreciated by many scientists. Nevertheless, it gave rise to one of the most passionate scientific debates in history when Alessandro Volta postulated that Galvani had confused intrinsic animal electricity with small currents produced by metals. This debate would result in the creation of electrophysiology, electromagnetism, electrochemistry and the electrical battery. Galvani responded to each of the postulated theories of Volta giving irrefutable proof of the involvement of electricity in the contraction of muscles. However, his work was subsequently abandoned and silenced for many years but his ideas and theories were finally confirmed by the creation of new instruments and the interest of new scientists who helped position Galvani as the father of electrophysiology.