Course Handout - Neuropsychology Timeline

Copyright Notice: This material was written and published in Wales by Derek J. Smith (Chartered Engineer). It forms part of a multifile e-learning resource, and subject only to acknowledging Derek J. Smith's rights under international copyright law to be identified as author may be freely downloaded and printed off in single complete copies solely for the purposes of private study and/or review. Commercial exploitation rights are reserved. The remote hyperlinks have been selected for the academic appropriacy of their contents; they were free of offensive and litigious content when selected, and will be periodically checked to have remained so. Copyright © 2010, High Tower Consultants Limited.

 

First published online 12:14 BST 28th August 2002, Copyright Derek J. Smith (Chartered Engineer). This version [HT.1 - transfer of copyright] dated 18:00 14th January 2010

 

An earlier version of this material appeared in Smith (1996; Appendices A to C). It is repeated here with minor amendments and supported with hyperlinks.

1 - Neuroscience Before 1861

The following early contributions to neuroscience are worth noting:

Anonymous - The "Ebers" Papyrus: This ancient Egyptian document dates from about 2500BC, and describes a case of head injury who had lost his ability to speak without paralysis of his tongue (cited in Hecaen and Albert, 1978, p13).

Anonymous - The "Edwin Smith" Papyrus: This ancient Egyptian document (named after the archeologist who dug it up in 1862) dates from about 2500BC, and has been called the oldest medical "textbook" on earth. It presents 48 case studies, including head injuries and broken bones. It includes the first recorded use of the word "brain" (Breasted, 1930), and records both lateralised skeletomuscular impairments and loss of speech. [For more on this, see the Cyber Museum of Neurosurgery.]

Alcmaeon (Greek physician): According to Williams and Warwick (1975), the first to describe the optic nerves (ca 500BC).

Hippocrates (Greek physician: 460-370BC): Apart from introducing the Hippocratic Oath, Hippocrates stated that the brain (and not the heart, as many thought at that time) was the seat of sensation, thought, and the emotions. He also noted a variety of conditions - epilepsy, etc. - where speech was likely to suffer.

Erasistratus (Alexandrian physician: ca 300-250BC): Began human dissection and equated the gyri of the brain with various facets of intelligence (a suggestion described by Warwick and Warwick, 1975, as "remarkably prophetic").

Pliny the Elder (Roman archivist: 27-79AD): In 77AD noted the selective loss of memory with head injury. For example, a man who when struck by a stone forgot how to read (Pliny, 77AD; Book VII, Stanza 24.)

Claudius Galen (Roman physician: 129-199AD): Physician from 170AD to the Roman emperor Marcus Aurelius, and author of over 400 early treatises on anatomy and physiology. Served when young as resident surgeon at the gladiator school in Pergamum on the Turkish side of the Aegean Sea (hence the knowledge of anatomy). Since it was officially forbidden at that time to dissect human corpses, Galen instead conducted dissections on apes, other animals, and "at least one elephant" (Spillane, 1981). His human anatomy diagrams thus contain various errors, although he was very much on the right lines when he taught that the blood contains "vital spirits" released into it by the brain, because this is much how the hypothalamus-pituitary gland does control the body via the endocrine system. Galen's works were the standard authority on anatomy for the 1400 years until Vesalius (below).

Gregor Reisch: (1467-1525): Located the faculty of memory in the fourth ventricle.

Andreas Vesalius (Flemish physician: 1514-1564): Vesalius was a renaissance anatomist. Since it was still officially forbidden to dissect human corpses, he bought bodies from grave robbers and conducted the first systematic dissections. These included dissections of the NS. He recorded his findings in his textbook On the Structure of the Human Body (Vesalius, 1543). This was a printed rather than a hand-written book, and so was able to make anatomical drawings and diagrams widely available at low cost and without transcription error. Many of Galen's long-standing errors were exposed. Nevertheless Galen's works remained the conventional wisdom, and for a while Vesalius suffered establishment vilification and accusations of body snatching. In the end, however, his ideas caught on and he is today credited with being the "father of modern anatomy".

Rene Descartes (French philosopher-mathematician: 1596-1650): Speculated on the relationship between the mind and the brain, even going so far as to locate the seat of the soul in the pineal gland. Used as his definition of human existence the Latin maxim cogito ergo sum - "I think, therefore I am".

Robert Hooke (British physicist): In 1665 published Micrographia, one of the early sources for the concept of the biological cell.

Sir Thomas Willis (British physician: 1621-1675): Published Anatomy of the Brain (1664), Pathology of the Brain (1667), and The Mind of Animals (1672), describing the NS and its blood supply. Declared the cerebellum to be an organ for the execution of involuntary movements.

Johann Schmidt (German physician): In 1673 described a case of acquired alexia with preserved ability to write, thus making him one of the first to record a dissociation of function [Neuropsychology Glossary]. Particularly fascinating was the fact that this patient could successfully write to dictation, but could not then read back what he had written.

Peter Rommel (German physician): In 1683 published a detailed description of a motor aphasia [Neuropsychology Glossary], terming it "a rare aphonia". The patient's understanding was intact, but conversationally she was poor and unable to repeat even short phrases to command. Curiously, though, she retained the ability to recite long and well-learned Biblical passages.

Abbé Jean-Antoine Nollet (French priest: 1700-1770): Used electrical current from "Leyden Jar" batteries (then only recently invented) to induce muscle twitchings in newly hanged corpses and in the living. In one demonstration he linked the hands of 180 men in a chain and sent a shock from one end to the other. (Note that Nollet also discovered the phenomenon of osmotic pressure, one of the factors involved in maintaining the neural resting potential.)

Emanuel Swedenborg (Swedish mathematician-physiologist: 1688-1772): In the period 1740-1744, collated and reviewed the sum total of neurological knowledge to that date, and, in so doing, noted the importance of the cerebral cortex as the top level of the sensory and motor systems. He described it as the site of the "soul's faculty of understanding, thinking, judging, willing". Also correctly identified the pituitary gland as the "arch-gland" of the body, and placed the production of CSF in the choroid plexuses.

Johann Gesner (German physician): In 1770 reviewed a number of case descriptions of patients with various language defects. Gesner made an important contribution to aphasiology, thus:

"He attributes aphasic disorders not to a general intellectual decline or a general loss of memory, as had been done so often by earlier writers, but to a specific impairment in verbal memory. This impairment in memory consists in the inability of the patient to associate images or abstract ideas with their conventional linguistic signs. [These] "associationist" theoretical conceptions, which are admittedly rather vague, might well be considered as being the first statement of a modern theory of the aphasic disorders." (Benton, 1964, pp319-320; emphasis original.)

Francesco Gennari (Italian anatomist: 1750-1795): According to Spillane (1981) was the first (in 1776) to note the tiny laminations in the visual cortex, thus laying the groundwork for later investigations by Baillarger (see 1840) and Brodmann (see 1909).

Luigi Galvani (Italian chemist: 1737-1798): Demonstrated in 1780's-90's that the muscle tissue of a "dead" animal could be caused to twitch by the application of electric current (Galvani, 1791). This, of course, smacked of "reanimating the dead", and the experiments caused intense public interest, even entering mainstream literature in the form of Mary Shelley's novel "Frankenstein" in 1818.

Albrecht von Haller (Swiss physiologist: 1708-1777): In a series of textbooks published in the period between 1747 and 1776, described the circulation of the blood and the control of muscles by nerves. He described the contraction of muscle under nervous influence as "irritability". He regarded the cerebral cortex to be important, but located the soul in deeper centres.

Franz-Joseph Gall (Austrian physician: 1758-1828): Lectured from 1802 on the "science" of phrenology, claiming (a) that different parts of the brain have different functions (some truth), (b) that different individuals could be differently endowed with these abilities (probably true, although great caution is needed), and (c) that the individual extent of these abilities could be gauged from the shape of one's skull (probably untrue). These ideas were published in 1805 under the title On the Activities of the Brain. Gall's position comes out well in the following quotation:

"I would often divide [the lower classes] into three classes. The first would include the thieves; the second, those who had an abhorrence of theft; and the third, those who regard it with indifference. On examining their heads, I was astonished to find that the most inveterate thieves had a long prominence, extending from the organ of cunning, almost as far as the [] supraciliary ridge; and that this region was flat in all those who showed a horror of theft. [These cases] conclusively prove that the propensity to steal is not the result of moral depravement, nor of a defective education, but is an inherent quality in human nature." (Gall, 1805; emphasis added)

While phrenology is now generally accepted as being little more than charlatanism (Gray, 1948, calls it a "preposterous notion" and a "persistent nonsense"), Gall and his associate Spurzheim (1776-1832) were actually quite accomplished neuroanatomists, and should not be dismissed out of hand.

Sir Charles Bell (Scottish physician: 1774- 1842): Published New Anatomy of the Brain in 1811. In it he analysed the organisation of the spinal cord and proposed a fundamental distinction between sensory and motor functions. The motor tracts, he claimed, ran ventrally.

Francois Magendie (French physiologist: 1783-1855): In 1822 confirmed Bell's analysis and added that the sensory tracts ran dorsally. The principle has since become known as the Bell-Magendie Law. Magendie's work comes out well in the following description of an experiment upon a puppy:

"I was able with the help of a very sharp scalpel to expose the posterior half of the spinal marrow. I was able to cut the posterior roots of the lumbar and sacral pairs on one side. [] I reunited the wound by a suture, and then observed the animal. I at first thought the member was paralysed because it was insensible to the strongest prickings and pressures. But soon, to my great surprise, I saw it move. I began to think it probable that the posterior roots of the spinal nerves might have different functions from the anterior roots. It naturally occurred to the mind to cut the anterior roots, leaving the posterior untouched. As in the preceding experiment, I made the section on one side only, in order to have a point of comparison. The member was completely immovable and flaccid, at the same time preserving its sensitivity. Finally, that nothing might be neglected, I cut the anterior and posterior roots at the same time. There ensued absolute loss both of sensibility and of motion." (Magendie, 1822)

Marie-Jean-Pierre Flourens (French anatomist: 1794-1867): [Selected Internet biography] Was very critical of phrenology, arguing that it was not possible to localise brain function too precisely because many of its functions were complex and all-embracing. Flourens' position comes out well in the following quotation:

"Each part of the nervous system [] has a proper function; and that is what makes it a distinct part: but the activity of each of these parts affects the activities of all the others; and that is what makes them parts of a particular system. [What matters] is the way each distinct part of this system contributes to the common activity." (Flourens, 1824)

Modern neuropsychology is still vigorously debating this very issue, which remains to be resolved. Flourens also located the respiratory centres of the medulla and demonstrated by inflicting cerebellar lesions upon dogs that the cerebellum was involved in muscular control. His method is illustrated in the following quotation:

"I made a lesion in the cerebellum of a young and healthy dog by means of incisions which extended deeper and deeper. The animal gradually lost the power of ordered and regular movement, and when the mid-region of the cerebellum was reached he could only totter along with a zigzag motion. [] The animal was in full possession of his intellectual facilities and his senses and there was no trace of convulsion; he was merely deprived of the power to control and regulate his movements. When I extended the lesion to the innermost layer of the cerebellum the animal lost the power of motion and of equilibrium completely." (Ibid.)

Flourens also helped shape our opinions on the relationship between the mind and the body. Consider:

"The function of the cerebral lobes is to will, to judge, to remember, to see, to hear, or - in a word - to feel. [They] wish and feel; that is their proper action. The suppression of these lobes weakens the activity of the entire nervous system." (Flourens, 1824; in Herrnstein and Boring, 1965, p221; italics original)

Jean-Baptiste Bouillaud (1796-1881) [WhoNamedIt Biography

]: In 1825 gave an early description of a motor aphasia [Neuropsychology Glossary], thus:

"It is evident that the movements of the organs of speech must have a special centre in the brain, because speech can be completely lost in individuals who present no other signs of paralysis. [From these observations I believe] that the principal lawgiver of speech is to be found in the anterior lobes of the brain." (Bouillaud, 1825; cited in Head, 1926, p15.)

Despite having a background in phrenology, Bouillaud's methods and conclusions were generally sound. Benton (1964) credits him with distinguishing pure expressive aphasia, apraxia, and amnestic aphasia many years before Broca, Liepmann, and the like. And so certain was he of the role of the frontal lobes, that he even offered 500 francs to anyone who could bring him a case of a frontal lesion not accompanied by a speech disorder.

Nobele: In 1835 reported on the attempted suicide by gunshot wound to the head of a psychotic patient. The patient survived, but, perhaps anticipating the work on prefrontal lobotomy by Moniz a hundred years later, was apparently cured of his mental illness.

Marc Dax (French physician): In 1836 was one of the first to record that when a stroke paralysed the right side of a right-handed person, the patient usually suffered speech loss as well. Thus:

"It was known from anatomic dissection that the nervous pathways of the left hemisphere cross over in the brain stem and pass on to the muscles in the right side of the body. From this Dax reasoned that the speech centre must lie in the left hemisphere." (Gray, 1948, p5.)

Dax's paper, sadly, was not properly published until 1865, when its impact was dwarfed by the controversy over Broca's (1861) report (see below).

Richard Owen (British Anatomist: 1804-1892): In May 1837 presented a series of seven lectures on comparative anatomy to the Royal College of Surgeons. Topics included embryology and comparative neuroanatomy.

Jules Baillarger (French neurologist: 1809-1890): In 1840 published investigations of the layered nature of the cerebral cortex.

Jacques Lordat (French army surgeon: 1773-1870): In 1843 described a priest who became aphasic after a stroke. Consider the following account by Benton (1964):

"At first he showed an almost complete motor aphasia but steadily improved until he reached a static condition in which he could say hardly a word in French but could express himself fluently in his native provincial dialect of Languedoc. This is, so far as I know, the first explicit description of a clear dissociation of language loss in a polyglot, although Bouillaud in 1825 had already made reference to a patient who retained some words of patois within the setting of complete inability to speak French." (Benton, 1964, pp321-322.)

Lordat also coined the term paramnesia to describe partial, as opposed to total, memory recall problems. Lecours, Nespoulos, and Pioger (1987) rate Lordat's contribution to aphasiology and neuropsychology very highly, especially insofar as he points to what we nowadays would call "processing stages".

Henry J. Bigelow (American physician: 1818-1890): Reported in 1850 on the case of a 25 year old railroad worker named Phineas P. Gage, the victim of a blasting accident in 1848 which had driven a four-foot long iron bar in through his left cheek and out through the top of his skull. The injury destroyed much of the left frontal lobe, together with the medial elements of the right. Nevertheless it did not prevent the victim walking part of the way to the surgery, nor his survival for another twenty years. What was equally noteworthy were the changes to the man's personality which resulted. Whilst his general intellectual level remained more or less unaffected, his injury changed him from a well-respected and competent foreman to a state of indifference, carelessness, and frequent profanity. [The Phineas Gage case turned out to be one of the classics of the neuropsychological literature. To see how it fits into modern interpretations of frontal lobe function, see our e-paper on "From Frontal Lobe Syndrome to Dysexecutive Syndrome".]

Guillaume Duchenne (French physician: 1806-1875): In the period 1855-1875, documented a variety of neuromuscular deficits, including poliomyelitis and progressive atrophy.

2 - Neuroscience 1861-1926

The following contributions to neuroscience were made following an initial impetus given by Broca (1861), who showed that localisation of brain function could be successfully investigated scientifically. Considerable progress at localisation was made for a few years (say until Ferrier, 1876), but then gradually bogged down. There were two reasons for this loss of impetus. The first barrier was that the imaging techniques were technologically poor. The second barrier was the sheer complexity of the NS. Many of the most important functions (like memory, for example) seemed to be literally unlocatable. The first barrier began to lift in 1926, when Berger developed the EEG as a non-invasive imaging technique. The second is with us still. The workers to note are:

Pierre-Paul Broca (French physician: 1824-1880) In 1861, in one of the top ten most influential scientific reports of that century, described the autopsy of a brain tumour patient named Leborgne. Prior to his death, Leborgne had displayed a reasonably intact understanding of the world, including the ability to respond appropriately to both written and spoken instructions. Despite being able to understand speech, however, his ability to produce it was grossly impaired, although even then it was necessary to differentiate the voluntary production of speech (which was non-existent) from the production of emotional and/or overlearned utterances (curses, expletives, rhymes, days of the week, etc.) which was intact. Having seen similar cases before where there had been damage to the lower regions of the left frontal lobe, Broca predicted that Leborgne's autopsy would reveal a similarly located lesion, and this prediction was duly borne out. Leborgne died on 17th April 1861, and Broca reported the results of the autopsy to the Societe d'Anthropologie (of which he was secretary) the very next day. Leborgne's tumour, the size of a hen's egg, was centred on the posterior third of the left inferior frontal gyrus, the area known to this day as "Broca's Area". Broca called the deficit aphemia. Broca should also be credited with introducing the term limbic lobe in 1878. He used this term to refer to the oldest areas of the telencephalon, ie. those anatomically closest to the diencephalon.

Armand Trousseau (French physician: 1801-1867): In 1864 substituted the term aphasia [Neuropsychology Glossary] for aphemia. (Head, 1926, laments this unnecessary interference, and credits Trousseau with having added nothing else deserving to be remembered; and since Lecours, Nespoulos, and Pioger, 1987, tell us that Trousseau's treatment of aphasics included applying leeches around the anus, Head might well have been right.)

Otto Deiters (German anatomist: 1834-1863): In 1865 sketched the first reasonably accurate diagrams of the neuron.

Theodor Meynert (Austrian physician: 1833-1892): Meynert (1867) is credited by Freud (1891) with having played an important part in shaping the turn-of-century understanding of brain function, especially the model of an all-powerful cortex, divided into many projection areas, and presiding over a variety of ascending and descending fibre tracts. The fact that this model remains the standard more than a century after Freud makes this tribute doubly deserved.

Henry Charlton Bastian (British physician): In 1869 claimed (a) that we think in words, and thus (b) that if the auditory comprehension centres are damaged, the faculty of thought will be degraded as well. Also produced an early flow diagram showing the language centres and the communication routes between them.

J.W. Ogle: In 1869 coined the term agraphia to apply to acquired disorders of writing, although it was not until Exner (1881) that the brain area responsible was identified.

Gustave Fritsch (1838-1927) and Julius Hitzig (1838-1907) (Prussian army surgeons): Immediately after the Battle of Sedan (Franco-Prussian War, 1870), they toured the battlefield looking for head-injuries among the casualties. They carried a portable generator which they then used to apply electrical stimulation to the exposed brain tissue. Their observations of the resulting muscle twitchings helped them locate the motor part of the cortex. They found that limb movements could be induced by stimulating small areas of brain and that the mapping of cerebrum to limb was very specific and reliable.

Silas Weir Mitchell (American army surgeon: 1829-1914): Did much the same as Fritsch and Hitzig, but using American battle injuries during the American Civil War. In 1872 he published his findings in Injuries of Nerves and their Consequences.

Vladimir Betz (Russian anatomist: 1834-1894): In 1874 published his description of the pyramidal cells in the motor area, later to become known as the great cells of Betz.

Robert Bartholow (American neurologist): According to Penfield and Boldrey (1937) was the first (in 1874) to directly stimulate the human cortex electrically. Applied a faradic (AC) current to the exposed dura of patient Mary, a 30 year old domestic, producing contralateral muscle twitchings and hallucinatory sensations, and thus initiating the major experimental tradition subsequently carried through by the likes of Ferrier, Cushing, and Penfield.

Carl Wernicke (German physician: 1848-1905): In Wernicke (1874) he described the "opposite" syndrome to Broca's, that is to say one in which verbal comprehension was severely impaired but the ability to produce speech was intact. Patients with Wernicke's aphasia [Neuropsychology Glossary] were found to have left hemisphere lesions affecting the first temporal convolution (at the junction of the left temporal and parietal lobes), far enough away from the primary auditory area, therefore, for hearing per se to be intact. Wernicke accordingly placed auditory comprehension in this area, and held it to be the store of "sound images" (Klangbilder), the basis of understanding spoken words. Wernicke's aphasia is readily demonstrated in such patients by asking them verbally to perform a target task, the request falling not upon deaf ears, but upon a brain which simply cannot decode the incoming message. Wernicke was subsequently criticised by Freud (1891) and Head (1926) for being too ready to rely on simplistic diagrammatic explanations of language difficulties.

John Hughlings Jackson (British physician: 1835-1911): Lectured and wrote on aphasiology in the period from 1864, taking a strong stand against the wave of "localisationists". Like Flourens before him he argued that localisation successes were of restricted value because of the complex nature of the system being investigated.

"To locate the damage which destroys speech and to localise speech [itself] are two different things." (Jackson, 1864; cited in Head, 1926, p50; emphasis added.)

Jackson also noted the motor-sensory split between the frontal and post-central areas of the cortex. Jackson also warned that to understand speech disturbances you needed to distinguish between automatic speech - speech which is more or less a reflex response, characterised by being rapid, of constant form, and more or less meaningless (things such as cliches, rhymes, and curses) - and propositional speech - speech which is voluntary, meaningful, and constructed to order. Thus:

"Emotion uses propositions in a largely interjectional manner, that is to say, reduces them to or towards inferior speech. Emotion, as it were, appropriates and subordinates an intellectual utterance." (Jackson, 1864; cited in Head, 1926, p38; emphasis added.)

"Loss of speech is, therefore, the loss of power to propositionise." (Ibid, p41; emphasis added.)

The topic of propositional speech lay dormant for many years, but has recently re-emerged in modern cognitive science, where it is used to distinguish propositional knowledge [Memory Glossary] from procedural knowledge as part of the study of epistemology (ie. the science of knowledge itself). This resurrection of what is essentially a philosophical debate has been prompted by computer science's ongoing drive towards intelligent computers.

William Hammond (American Surgeon-General: 1828-1900): In 1871 published the first American textbook of neurology drawing upon his experiences organising treatment for head injuries during the American Civil War. In this textbook, he coined the term athetosis to describe a condition where there was an inability to retain the fingers/toes in a fixed position. Instead there was an uncontrollable state of continuous motion, which he tentatively attributed to basal ganglia lesions.

Richard Caton (British physiologist): In 1875 was the first to demonstrate that the brain produced electric currents detectable by a scalp-surface electrode. Although this predated Berger's (1926) development of a working EEG by some 50 years, Caton was unable to make much progress because the electrical signals involved were too small to be detected by the monitoring equipment available at the time.

Sir David Ferrier (British physiologist: 1843-1928): Published several papers in the period 1872-1876, culminating in The Functions of the Brain in 1876. In these he reviewed earlier findings and added clinical and experimental evidence of his own which he used to map the functions of the cerebral hemispheres. Unlike Fritsch and Hitzig he applied a "Faradic" as opposed to a "Galvanic" electrode voltage (i.e. AC rather than DC). His experimental subjects included a variety of animals - birds, frogs, fishes, and mammals - and he found, for example, that an electrode applied to the auditory cortex of a monkey's brain would cause the contralateral ear to be pricked up, accompanied by head turning to that side.

Adolph Kussmaul (German physician: 1822-1902): Suggested in 1877 that verbal expression goes through three stages, namely preparation, internal diction, and articulation (compare Lordat, 1843). Kussmaul also proposed the terms (a) agrammatism for disorders of word order, and (b) pure word deafness for the (rare) syndrome where the patient is unable to understand the spoken word but has intact reading comprehension and speech (for more on which see Auerbach, Allard, Naeser, Alexander, and Albert, 1982, if interested). Another who recognised the true complexity of the underlying system, and thus the inherent futility of simplistic localisation models. Thus:

"We turn away with a smile from all those naive attempts to seek a 'seat of speech' in this or that cerebral convolution." (Kussmaul, 1877; cited in Head, 1926, p64.)

Ernst Haeckel (German zoologist: 1834-1919): Suggested in 1866 that "ontogeny recapitulates phylogeny", that is to say, that the developing embryo passes through the same stages in days and hours that the mother species did as it evolved in geological time.

Camillo Golgi (Italian histologist: 1843-1926): In 1878 perfected the Golgi stain, a technique of staining neural tissue so that individual neurons would stand out better under the microscope.

Sir William Broadbent (British physician: 1835-1907): In 1878 gave one of the first accounts of "jargoning" aphasia, and postulated auditory and motor speech centres united by a commissure. Also separated naming and propositionising as higher cognitive functions (because he had observed patients who could quite happily have ideas, but could not name the objects in those ideas correctly).

Siegmund Exner (Austrian physiologist: 1846-1926): In 1881 identified Exner's area, a secondary motor area situated at the foot of the second frontal convolution (just above Broca's area), which he claimed helped organise the motor behaviour necessary for fluent writing. Damage to this area induces the agraphia described earlier by Ogle (1869).

J.B. Charcot (French physician: 1825-1893): In 1883 published a diagram of the language centres known as "Charcot's bell". In 1887 went on to propose that a word has four fundamental elements: an auditory image, a visual image, and two motor images, one articulatory and one graphic. Like Wernicke before him and Lichtheim after him, he saw these as being subject to damage individually or in various permutations, each with characteristic results.

Ludwig Lichtheim (German physician: 1845-1928): In 1885 added to the aphasia-localisation debate by drawing a set of explanatory diagrams showing how the language centres as he saw them were connected up. These diagrams placed auditory memories and motor memories in different centres (the "A" and "M" centres respectively), thus: "We may call 'centre of auditory images' and 'centre of motor images' respectively, the parts of the brain where these memories are fixed" (Lichtheim, 1885, p435). A third concept centre (the "B" centre - from the German word Begriffe) took care of the semantic element of the equation. The beauty of the resulting diagram - affectionately known as "Lichtheim's house" and shown at Figure 3.6 - is that a different aphasic syndrome naturally follows damage to any single pathway or any single centre (compare Charcot above). Lichtheim was also one of the first to recognise the diffuseness of higher-order cognitions (or what we today term the "semantic system" or the "central executive"). In his Figure 7, he placed these in a set of distributed "conceptual centres". His work was subsequently described by Head (1926 - see below) as being "the high-water mark" of the diagram-making approach to language localisation.

H. Grashey (German neurologist): In 1885 added to the modularity of processing debate with a diagram more complex than those of Charcot or Lichtheim.

Sergei Korsakoff (Russian neurologist: 1853-1900): In 1887 described a neuropathic disorder associated with severe confusional state and anterograde amnesia, yet with preserved consciousness and general intellectual capacity.

Sigmund Freud (Austrian physician: 1856-1939): Long before he achieved fame with his theory of psychoanalysis, Freud was a competent neuropsychologist, having published an influential monograph on aphasia in 1891. Consider:

"Freud's monograph on aphasia [] is an incisive analysis of the so-called diagram-makers, those aphasiologists who would reduce brain and language to simple schemes of circumscribed cortical centres linked by unidirectional subcortical pathways. Chief architects of the diagram-maker school were Wernicke and Lichtheim, and their formulations of conduction aphasia and the transcortical aphasias were particular targets of Freud's trenchant criticism." (Henderson, 1992, p19.)

The monograph includes a penetrating analysis of the neuropsychology of semantics - that is to say, of the relationship between a word and its referent, and generally has much in common with modern transcoding models.

Gottlieb Burckhardt (Swiss neurologist: 1836-1907): In 1891 reported six cases of unilateral frontal lesions carried out in the period from 1888 to alleviate psychiatric rather than organic disease. Became thereby "the first modern psychosurgeon" (Whitaker, Stemmer, and Joanette, 1996).

Friedrich Goltz (German physiologist: 1834-1902): In 1892 noted that decorticate dogs could be aroused to "sham" rage by the most trivial stimuli. Nor (cited in Blakemore, 1977) do they have experiences "for only he who has memories can have experiences".

Santiago Ramon y Cajal (Spanish neurophysiologist: 1852-1934): From 1890 began to published detailed observations of the microstructure and microstructural development of the cerebral cortex of a wide range of species.

Pierre Marie (French physician): In 1906 coined the term anarthria to describe articulatory disorders not resulting from a defect of the articulators themselves. Also scathingly criticised diagram-making - the tendency to propose precisely localised cortical lesions to explain aphasic deficits.

Georg Elias Müller (German psychologist: 1850-1934): [Optionally Mueller or Muller.] [Selected Internet biography] In 1900, in cooperation with Pilzecker, developed the consolidation theory of memory. This postulates an electrically based short term memory (see both Lorente de No and Hebb below) which gradually consolidates itself into a structurally based long term memory.

Hugo Liepmann (German physician: 1863-1925): In 1900 and 1905 described the defect known as apraxia .....:

"This he defined as inability to act or to move various parts of the body in a purposeful manner, although the power of movement is intact. There is no paralysis and the patient understands what is required of him; yet he cannot execute the action he wishes to perform. The apraxic possesses a sufficient sensori-motor apparatus, but he cannot employ it at will in certain directions....." (Head, 1926, p94.)

Sir Charles Sherrington (British physiologist: 1857-1952): Studied the spinal cord and its reflexes. Published The Integrative Action of the Nervous System in 1906 in which were contained many useful concepts, for example that of the final common pathway.

Sir Victor Horsley (British physician: 1857-1916): Pioneered neurosurgery in May 1886. In 1909, developed the stereotaxic frame, a contraption fitted externally to the head to allow needle electrodes to be guided very precisely in through the skull. This technique allowed mapping of very small subcortical structures such as the thalamic and hypothalamic nuclei.

Korbinian Brodmann (German neurologist: 1868-1918): Departed from the traditional "naked eye" description of the brain, and turned instead to microscopic considerations as a basis for cortical mapping. Found under the microscope that the cerebral cortex contains six distinct layers (or "laminae"). Also that in different areas of the cortex the relative predominance of each layer is different, reflecting the different nature of the neural processing required. Brodmann allocated numbers to these different areas, and his numbering schema is still in use (Brodmann, 1909).

Harvey Cushing (American neurosurgeon: 1869-1939): In 1909 performed the first open-skull cortical stimulation on conscious humans, a method later popularised by Penfield.

K. Kleist (German psychiatrist): In 1912 described the deficit of constructional apraxia, in which the ability to organise actions in space is affected. He regarded this as another disconnection syndrome; a loss of the ability to transmit information between the processes of spatial analysis and those of voluntary action. (There are various tests of constructional apraxia nowadays, for details of which see McCarthy and Warrington, 1990, pp107-109.) (See also separate entry for 1934.)

Von Monokow (Russian physiologist): In 1914 resurrected Jackson's (1874) arguments and argued that the more complex processes of memory involve the successful coordination of many diverse sensory and motor processes supported by different parts of the cortex. (See also Anokhin, 1935.)

Gordon Morgan Holmes (1876-1965) (Irish neurologist): In 1917 studied the behaviour of war wounded, focusing on lesions of the cerebellum. Coined the term "decomposition" to describe the resulting inability to control more than one joint at a time.

Henry Head (British physician): Investigated the role of the thalamus in emotional behaviour and consciousness. Wrote extensively on aphasia, including the 1926 classic text Aphasia and Kindred Disorders of Speech, and recognised the importance of the brain as a representational system, coining the term schema to refer to the end-result of perceptual abstraction. Here are some of his major points:

"The processes which underlie an act of speech run through the nervous system like a prairie fire from bush to bush; remove all inflammable material at any one point and the fire stops. So, when a break occurs in the functional chain, orderly speech becomes impossible, because the basic physiological processes which subserve it have been disturbed." (Head, 1926, p474; emphasis added.)

"The site of such a breach of continuity is not a 'centre for speech', but solely a place where it can be interrupted or changed." (Ibid, p474; emphasis added.)

"There are no centres for speaking, reading, writing or other forms of behaviour comprised in the normal use of language. On the other hand, there are areas of the brain within which structural injury can produce disorders of symbolic formulation and expression." (Ibid, p478.)

"Cortical and subcortical mechanisms participate in every act of language. The deeper a lesion extends from the surface into the substance of the brain, the more definite and permanent will be the disorders of speech." (Ibid, p478.)

3 - Neuroscience From 1926

We break at 1926 for two reasons. Firstly, as just noted, it was the year of Head's monograph on Aphasia, and secondly, as we now note, it was the birthyear of the first modern scanning techniques .....

Hans Berger (German psychiatrist: 1873-1941): In 1926, following experiments carried out on his young son, Klaus, perfected pen-tracing machinery sensitive enough (a) to detect, and (b) to display, brainwaves from the surface of the scalp (that is to say, non-invasively). Here was the first technique of measuring brain activity in normal subjects. (NB: Berger's technique was a major methodological milestone in the neurosciences.)

Walter Cannon: In 1927 expounded the "thalamic theory" of the emotions. This proposed that emotional feeling is the result of stimulation of the dorsal thalamus, whereas emotional expression results from activity of the hypothalamus. One key prior observation was that "sham" behaviour could be elicited in decerebrated animals, but only if the thalamus remained intact. Cannon also coined the term homeostasis to describe the processes maintaining the body's internal environment in a stable state.

C.U. Äriens Kappers (Dutch comparative anatomist): In 1929 published The Evolution of the Nervous System in Invertebrates, Vertebrates, and Man, one of the classics of comparative neuroanatomy. Also reviewed various earlier methods of calculating the "cephalisation coefficient"

J.W. Papez (American neuroanatomist: 1883-1958): In 1937 named the limbic system, comprising Broca's (1878) limbic lobe, plus elements of the diencephalon, as the centre of motor and emotional behaviour.

Karl Lashley (American neuropsychologist: 1890-1958): In 1929 published Brain Mechanisms and Intelligence in which he laid out his theory of mass action. This holds that there is very little localisation of function in the cerebral cortex, but a lot of generalised, or "diffuse", neural activity. He gave this principle the name equipotentiality, because it meant that each part of the brain was equally capable (at birth, at least) of doing any given job.

Lorente de No: Postulated in 1933 that neural reverberatory loops might be able to function as physiological substrates of the engram (ie. a neural circuit, properly interconnected, would continue to stimulate itself for a length of time after the disappearance of the originating stimulus.)

Karl Kleist (German psychiatrist:1879-1960): [Selected Internet biography] In 1934 published a detailed analysis of a large sample of head wounds from World War I, and, contrary to Lashley's cautionary advice, added further areas to the cortical localisation maps. Kleist's (1934) cortical map remains of considerable value to this day. McCarthy and Warrington (1990, p186) also credit Kleist with expanding Hughlings Jackson's earlier distinction between automatic and propositional speech, adding nominalising speech - or naming - to the debate. (See separate entry for 1912.)

Anokhin (Russian physiologist): Pursued Jackson's (1864) and Von Monokow's (1914) arguments as to the complexity of neural coordination, arguing strongly (1935) that to understand cognition properly you had had to see the brain as a system.

Egas Moniz (Portuguese psychiatrist: 1874-1955): In 1935 resurrected and improved Burckhardt's psychosurgical operations (see Burckhardt's entry for 1891, as well as Chapter 3).

Wilder Penfield (Canadian neurosurgeon: 1891-1976): Continued work with Cushing's open skull stimulation method. In 1937 published a detailed localisation map summarising these findings. This included areas where electrical stimulation could momentarily induce aphasic signs in previously normal subjects. Thus one patient, when shown a picture of a foot, could only answer: "That's what you put in your shoes." When the electrode was withdrawn, however, the ability to answer "foot" returned immediately. Another line of investigation concerned the location of episodic memory. Typical findings here were that electrical stimulation of the temporal lobe could produce vivid "flashback" memories of past incidents, even though these had been long forgotten and were, in themselves, usually quite trivial. What is challenging is that at the age of 84, after decades of investigation, Penfield (1975) admitted one significant failure in his searches: "There is no room or place," he concluded, "where consciousness dwells."

Von Wagenen & Herren (1940)/Akelaitis (1941): First reports of deliberate section of the corpus callosum to prevent interhemispheric propagation of epileptic seizure.

Bodamer: In 1947 described patients with disproportionate impairments in recognising faces as opposed to objects. He termed this defect prosopagnosia, and saw face recognition as distinct from object recognition because it was biologically more primitive.

Walter Hess (Swiss physiologist: 1881-1973): Demonstrated in 1949 that specific emotional or instinctive behaviours could be elicited by stimulation of specific subcortical areas. (NB: Hess's technique was a major methodological milestone in the neurosciences.)

Donald Hebb (Canadian psychologist): In 1949 published The Organisation of Behaviour in which he extended Lorente de No's concept of reverberatory neural circuits and proposed what he termed the cell assembly. This he saw as a set of neurons which became synaptically inter-associated as the result of experience, and this, in turn, he saw as the structural basis of the engram.

Various: Between 1949 and the mid-'fifties, a small group of researchers, primarily Bernard Katz, Alan Hodgkin, Andrew Huxley, Lord Adrian, and Herbert Gasser, analysed the microbiology of neural transmission, and discovered the nature of the resting potential and the action potential.

David Hubel: In 1957 developed a microelectrode capable of recording the activity of single neurons from the grey matter of the cerebral cortex. In cooperation with Torsten Wiesel, he used this method to analyse the functional microarchitecture of the visual cortex.

4 - Where To Next?

By the 1950s, the pace of neuroscientific discovery was beginning to hot up. For the more recent discoveries we therefore refer you to a number of separate resources, as follows .....

·         For more on frontal lobe pathology and assessment, see our e-paper on "From Frontal Lobe Syndrome to Dysexecutive Syndrome".

·         For more on the neuroanatomy of mathematical cognition, see our e-paper on "The Psychology of Numeracy".

·         For more on the neuroanatomy of dyslexia, see our e-paper on "Dyslexia and the Cognitive Science of Reading and Writing".

·         For more on the neuroanatomy of memory, see our Memory Glossary.

5 - References

See the Master References List

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