Introduction to Neurolinguistics

attitude is lacking in patients with anomia (inability to name), since they cannot categorize, and in patients with agrammatism (difficulties using grammatical morphemes and function words), since they cannot use elements that “have no meaning in isolation.” In his description of abstract attitude, Goldstein mixes psychological factors, such as the ability to separate figure and ground, with physiological factors, like spreading and activation (i.e., the fact that stimuli can activate an abnormally large area in the cortex if thresholds of activation for neurons are changed by brain damage, which makes the patient unable to detect, for example, exactly where somebody is touching his skin). An abstract attitude is required for the fully efficient use of language and therefore the linguistic disorder arises secondarily. Words lose their function to organize the external world. Goldstein assumed different positions with respect to localization, but he was mainly an anti-localist. He claimed that the cortex could be separated into a “peripheral part” with structural localization and a “central part” which is equipotential and constructs “dynamic structures” against a “dynamic background.” Lesions in the central part cause a loss of abstract attitude. It was Karl Lashley (1933, 1950), a physiologist, who presented the theory of cerebral equipotentiality and mass effect. Equipotentiality means that all parts of the cortex have the same “ability” and mass effect means that functions are dependent on how much of the cortex is used. Lashley claimed that studies of humans were too unreliable, due to humans’ complex behavior, and therefore concentrated on experiments with rats in mazes. He accepted specified functions only for motor and sensory projection areas and objected to attempts to localize mental functions. He emphasized that psychological unity does not guarantee neurological unity; for example, many structures participate in intentional movements. Lashley tried to identify different integrative mechanisms, such as intensity, spatial orientation and serial ordering. Inspired by Marie, Bay (1962) suggested that speech is dependent on a large number of “extralinguistic” factors, which are disturbed by brain damage. In aphasia, the transmission of information is disturbed. This disorder always involves a reduced intellect. The aphasic patient’s concepts become pathologically distorted, which can be seen in tasks like drawing or sculpting. The same defect is noticed in speech: concepts become fuzzy, deformed, and poorly differentiated. Jason Brown’s theory of aphasia is inspired by Jackson, von Monakow, and Freud. It contains, among other things, evolutionary aspects and a regression hypothesis combined with a functional view of aphasia. He raises the connections between emotions, degree of consciousness and intentionality, creativity, and language. Brown’s theory is presented in several books, including Mind, brain and consciousness from 1977. (See also Chapter 10.) Chapter 2. The development of theories about brain and language 27 Localism and associationism Localism continued to survive but it did not attract much attention during the first half of the 20th century. Some examples are mentioned below. Swedish neurologist Salomon Henschen (1926) formulated a detailed model on the basis of all the clinical pathological cases of aphasia that had been described to that point. The model contained a large number of separate centers for different aspects of language function. Korbinian Brodmann (1909), another neurologist, divided the cortex into numerous histologically defined areas, each of which had a determined physiological function. His numbering system is still used to give exact references to areas of the brain (see Figure 14.6 in Chapter 14). Karl Kleist (1916) investigated war injuries from the First World War and tried to find a psychological explanation for each cytoand myeloarchitectonic (related to cellular patterns and myelinated nerve cell patterns, respectively) area. Speech and language were localized according to tradition. Johannes Nielsen (1947) devoted himself to the anatomical-physiological classification of cortical functions. He distinguished between receptive and afferent signals, and between primary identification through one sense and secondary identification via associations of different senses at a higher level. According to Nielsen, recognition means receiving impressions and comparing them to engrams (physical alterations of nerve tissue in response to stimuli). Remembering, on the other hand, is starting from the concept and identifying it with an engram, which takes place at a higher level. Two types of aphasia can then occur: (a) a type that changes the connection between language and recognition, and (b) a type that changes the “signification” (what Head called “semantic aphasia”). The latter is not localized in specific areas; rather, any lesion can affect the whole system. The destruction of a projection area causes a total loss of function, while the destruction of an adjacent zone causes agnosia (inability to recognize) and the destruction of association zones that are not localized results in memory disorders. Thus, this theory is strongly inspired by associationism. Associationism is rediscovered by Geschwind Associationism continues to be very influential today. It was Norman Geschwind who rediscovered associationism and made it known as “connectionism,” or the neoclassical school of neurolinguistics, in his 1965 book Disconnection syndromes in animals and man. (For more information, see Chapter 3.) Introduction to Neurolinguistics 28 Dynamic localization of function: Pavlov, Vygotsky, and Luria Dynamic localization of function is a tradition originating in Russia which developed during the 20th century in parallel with the other traditions. Today, it also has considerable influence in Western Europe and the U.S. The well-known physiologist Ivan Pavlov (1949) claimed that complex behavior could not be handled by isolated and fixed brain structures, but must emerge during the ontogenetic development of dynamic systems. These systems were said to consist of connected structures in different places within the nervous system. Psychologist Lev Vygotsky emphasized that it is necessary to first investigate what is to be localized, before asking the question where. Functions must be analyzed with respect to ontogenetic development. Vygotsky (1970) saw a function as a complex activity whereby the whole organism adapts to a task. The activity can be performed in different ways, because of the cooperation of several organs. This dynamic cooperation is controlled by neural structures that monitor different organs and are localized in different places. Vygotsky also formulated a theory about the development of language and thinking that became very influential. The noted psychologist and aphasiologist Alexander Luria studied aphasia within the framework of the theory of dynamic localization of function. Luria’s work has been extremely influential in aphasia research, and especially in clinical work. (It will be further discussed in Chapter 3.) The test psychological tradition Theodore Weisenburg and Katherine McBride investigated cognitive factors in persons with aphasia, persons with right-hemisphere lesions, and control subjects, using a large test battery of verbal and nonverbal tasks. Their methodology became the model for a large number of studies. The results showed that persons with aphasia varied a great deal cognitively. In general, aphasia was associated with a cognitive disorder, but there was no necessary correlation. Certain persons with severe aphasia had excellent results on nonverbal tests. Thus, there was no support for Head’s theories. Weisenburg and McBride claimed that the importance of language for thinking must differ in different individuals and that the intellect before the lesion must be determinant. Many psychologists were inspired by Weisenburg and McBride and by Goldstein and developed experiments for testing “symbolic thinking” in aphasics. Subjects with aphasia performed classification tasks, Raven’s matrices (analogy tests), and similar tests. The results most often showed considerable variability, and the general conclusion was that the cognitive disorder, where such a disorder existed, could not be attributed to the linguistic disorder. Nevertheless, certain types of cognitive disorders were often found in persons with aphasia, such as difficulties in discriminating faces and Chapter 2. The development of theories about brain and language 29 interpreting mimed actions, as well as construction apraxia (i.e., problems performing spatial construction tasks). Linguists and the linguistic influence on aphasiology Aphasia research was traditionally an area for neurologists, but philosophers and psychologists have also had considerable influence on the area. In the middle of the 20th century, linguists joined this group. They saw studies of aphasia as a means of testing general theories about language. By functionally analyzing different disorders using the descriptive methods of linguistics, they aimed to gain better understanding of the role of the brain in normal speech. The term neurolinguistics was eventually adopted for these studies. In 1941, Roman Jakobson published the book Kindersprache, Aphasie und allgemeine Lautgesetze (“Child language, aphasia and phonological universals”), in which he pointed out parallels between linguistic universals, children’s language development, and symptoms of aphasia. At this point, he was the only linguist to systematically describe aphasia within the structuralist framework. Jakobson applied Ferdinand de Saussure’s principle of paradigmatic and syntagmatic relations in language. If language consisted of two types of operations — choice of units and combination of units — then two types of aphasia should be possible: (a) a