Historia de la neurologia clinica, Apuntes de Neurociencia

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Clinical Neuropsychology: A

Brief

History

A.L. Benton and A.B. Sivan

Clinical Neuropsychology is the discipline that investigates the interrelations of the human brain with thinking and behavior on the basis of the variations in brain function produced by injury or disease. That such injury caused mental impairment must have been apparent even to primitive man who resorted to trephining in an attempt to alleviate its pernicious effects. Interestingly, emphasis was placed not only on the brain substance itself but also on the fluids, which it enclosed, ie, the ventricles. Early Greek physicians (eg, Nemesius ca. 400 A.D.) placed sensation and perception in the lateral ventricles, reasoning in the third ventricle, and memory in the fourth ventricle. This ventricular concept accorded well with the doctrine of the circulation of animal spirits. Moreover, it provided a structural basis for a dynamic process wherein sensations were integrated into perceptions in the lateral ventricles, moved to the third ventricle to be reflected upon, and consolidated as memories in the fourth ventricle. In the absence of better alternatives, “ventricular” theory survived for a remarkably long time. It was displaced definitively by “brain substance” concepts only in the 17th and 18th centuries. It is also worth recalling that Aristotle, the greatest natural scientist of the ancient world, maintained that the heart was the seat of thinking and emotion, assigning the brain only the function of cooling the heat generated by the heart. His conclusions were based on sound empirical study. He noted that the exposed brain of animals was cold to the touch and that poking the brain surface did not elicit movements or signs of feeling. In contrast, the heart was warm and active; it accelerated during excitement and was slower during periods of calm. Aristotle’s cardiocentric concept of the seat of mental life had many supporters during the Middle Ages, the Renaissance, and even as late as the 17th century. That it was widely accepted is reflected in our language today. We still “learn by heart”; we offer “heartfelt sympathy”; and we “lose our heart” when we fall in love. Dis Mon 2007;53:142- 0011-5029/2007 $32.00 0 142 DM, March 2007

the effect of broadening the concept of left hemisphere dominance to include DM, March 2007 cognitive functions. Thus, the left hemisphere became, in the minds of many clinicians, the “intellectual” hemisphere. The demonstration by Gustav Fritsch (1838–1927) and Eduard Hitzig (1835–1907) in 1870 that electrical stimulation of the precentral gyrus produced movement in the contralateral limbs was as revolutionary in its way as Broca’s discovery of the role of the left hemisphere in speech had been. It provided the impetus for intense efforts during the ensuing decades to localize the functional properties of each and every gyrus in the cerebral cortex, a period called the “golden age” of cerebral localization. In 1873, Roberts Bartholow, a Cincinnati physician, took advantage of the circumstance that one of his patients had a skull defect that permitted stimulation of the exposed cortex to confirm the Fritsch–Hitzig finding in a human subject. Bartholow was censured for what was considered to be unethical conduct for this initiative. Today, such stimulation of the exposed human cerebral cortex during the course of neurosurgery is commonplace. Yet during this “golden era” of localization, there were thoughtful students of the nervous system who objected to this placement of numerous cognitive capacities in sharply delimited cortical centers. They found it inconceivable that a restricted aggregate of nerve cells could be the seat of a complex intellectual function. Hughlings Jackson (1835– 1911), who was well aware of the facts of clinical localization and applied them in his neurological practice, cautioned that identifying the lesion that leads to an aphasic disorder was not the same as identifying the locus of speech. In short, he accepted the concept of centers for its clinical utility, but not as a neuropsychological theory. Jackson’s conception of the nature of aphasic disorder was also incompatible with the notion of cortical centers. He maintained that aphasia always entailed an impairment in intellectual functioning, a position that was diametrically opposed to that of Carl Wernicke (1848–

1904. who insisted that there was no intrinsic connection between aphasia and intelligence. One or another of Jackson’s ideas was later expressed in the 1880s and 1890s by the physiologist, Jacques Loeb (1859–1924), by Sigmund Freud (1856–1939), who was then a neurologist as well as a psychiatrist, and by the philosopher Henri Bergson (1859–1941). Their approach to 144 DM, March 2007

the problem of localization in turn influenced the thinking of some early 20th century neurologists such as Arnold Pick (1851–1924), Henry Head (1861–1940), and Kurt Goldstein (1878–1965). On the whole, however, mainstream neurology remained wedded to the doctrine of cerebral centers and interconnected conduction pathways, the “telephone system” conception of the functional organization of the brain. No doubt many neurologists regarded the concept of centers as a fiction, although it was a convenient and useful fiction. For example, H. Charlton Bastian (1837–1915), a leading 19th century authority on aphasia, believed that the cerebral substrates of speech were, as he phrased it, “diffuse but functionally unified nervous networks.” Nevertheless, he wrote that, although he did not accept the common conception of a neatly defined center “.. .for the sake of brevity it is convenient to retain this word and refer to such networks as so many centers.” Thus, the concept of centers was of some heuristic value in clinical practice in that it pointed to the probable locus of a suspected focal lesion.

Hemispheric Cerebral Localization

As has been mentioned, following Broca’s discovery that the left hemisphere was endowed with a broader significance, encompassing cognitive functions beyond the realm of speech, it became indeed the dominant hemisphere in all respects. During this period, when the left hemisphere was assigned importance for cognitive function, there were scattered attempts to suggest that the human right hemisphere possessed its own distinctive cognitive capacities, particularly those expressed in visuospatial performances, in route finding and in geographic orientation. In the face of neurosurgical findings that the whole right hemisphere could be extirpated without causing major cognitive disability, however, these suggestions were ignored. The most that could be said was that the right hemisphere might possess left hemisphere abilities in latent form, capacities that under some circumstances could be brought into play when the left hemisphere was damaged. The empirical studies of the British psychologist Oliver Zangwill (1913–1986), and the French neurologist Henry Hecaen (1912–1983), initiated during and shortly after World War II, demonstrated conclusively that patients with right hemisphere disease did show a very high frequency of specific visuosperceptual, visuospatial, and constructional defects. 145

order on the internal and external world and reach at least a partial view of the nature of the real world. Given the complexity and varied nature of the stimuli and events with which the brain must deal, this is a truly daunting task. It is not surprising that it often makes mistakes. That, in fact, it often makes mistakes is amply documented by the innumerable false conclusions reached through observation and experimentation over the centuries. What then accounts for the advances in knowledge and control that have been achieved over the centuries? We could say that it is the creativity which is reflected in the tools of investigation that have been developed: the microscope, the x-ray, current neuroimaging procedures. Without the microscope there would be no histology and hence no histopathology. Without x-ray we would have no direct knowledge of the status of the brain in living patients. Our understanding is made possible by (and limited by) our remarkable neuroimaging procedures. No doubt these procedures will be displaced by even more informative techniques that permit deeper insight into the nature of brain function and brain-behavior relationships. The future of the discipline of neuropsychology should be very bright. If you wish to further explore the history of neuropsychology, the following references are available for your examination:

1. Akert K, Hammond HP. Emmanuel Swedenborg (1688-1772) and hiscontributions to neurology. Med Hist 1962;6:255-66.
2. Benton AL. Exploring the History of Neuropsychology. New York,NY: Oxford University Press, 2000.
3. Benton AL, Tranel D. Historical notes on reorganization of functionand neuroplasticity. In: Levin HS, Grafman J, eds. Cerebral Reorganization of Function after Brain Damage. New York, NY: Oxford University Press, 2000:1-23.
4. Clarke E. Aristotelian concepts of the form and function of the brain.Bull Hist Med 1963;37:1-14.
5. Finger S. Origins of Neuroscience. New York, NY: Oxford UniversityPress, 2001.
6. Head H. Aphasia and Kindred Disorders of Speech. London: Cambridge University Press, 1926.
7. Pagel W. Medieval and renaissance contributions to knowledge of thebrain. In: Poynter FN, ed. The Brain and Its Functions. Oxford: Blackwell, 1958. 147

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