A History of Neuropsychology. Группа авторов

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Fig. 1. Kussmaul’s 1877 diagram [25] of centers and tracks involved in spoken and written language (labeling added). J, ideational (concept) center. B, center for the sound images of words. B’, center for the visual, or text, images of words. C,motor center for spoken words. C’, motor center for written words. a, acoustic (auditory) nerve. o, optic nerve. o–p–q–p–r,pathway for copy of written text. o–p–r, pathway for copying words that are not understood. q–p–r, pathway for writing spontaneously. c–x–q, pathway for writing to dictation by associating sound images with text images within the concept center. Pathway p–q–p is obstructed in word blindness (alexia) with agraphia. Pathway p–q is obstructed in word blindness without agraphia. Original image modified by V.W. Henderson.

Born in Russia in 1852 and working in Paris, Nadine Skwortzoff wrote a medical thesis on word blindness (alexia) and word deafness in 1881 [26]. Word blindness represented the “failure to comprehend signs of thoughts represented by writing” (p 33). Her thesis included 14 cases with prominent reading impairments. She was influenced by the Scottish neurologist and physiologist David Ferrier (1843–1924). Working in England, Ferrier had mistakenly identified the angular gyrus of the parietal lobe as the primate visual center [27], and Skwortzoff suggested that the angular gyrus in the inferior left parietal lobe was damaged in cases of word blindness.

Also in 1881, Sigmund Exner (1846–1926) in Vienna reviewed literature cases where clinical and autopsy findings permitted inferences on cortical localization [28]. In his chapter on cortical fields for speech, 4 cases mentioned writing disturbances; lesions in these cases included the posterior part of the left middle frontal gyrus. This region is immediately in front of the part of the motor cortex involved with hand movement and immediately above Broca’s area in the inferior frontal gyrus. In one patient, only this area was involved. Exner suggested that this region, later referred to as Exner’s area, played a role in written expression similar to that played by Broca’s area in spoken expression.

The identification of specific centers for reading and writing were a logical extension of ideas advanced by Broca and Wernicke. Bastian, in 1887, produced a new brain diagram that now included “word centres” for auditory impressions, visual impressions, “glosso-kineasthetic” impressions (based on speech movements; Broca’s area), and “cheiro-kinaesthetic” impressions (based on writing movements; Exner’s area) [29]. Damage of the visual word center led to word blindness, and damage of the cheiro-kinaesthetic center led to isolated agraphia. Word blindness and agraphia occurred together when the visual word center and the white matter pathway connecting it to the cheiro-kinaesthetic center were affected all together. Agraphia resulted when this pathway was damaged in isolation.

Jean-Martin Charcot (1825–1893), first recipient of the chair in Clinical Diseases of the Nervous System at the Salpêtrière hospital in Paris, was intensely interested in problems of aphasia [19]. His center-pathway model was based on component memories. Word memories consisted of an auditory image, a visual image, a motor image for articulatory movements, and a motor image for movements required for writing (Fig. 2) [30]. Charcot was interested in partial forms of memory loss, which he believed provided convincing evidence for the existence of independent cerebral centers. Charcot used word blindness (alexia) and agraphia to illustrate 2 of the partial forms of aphasia [31].