Illiteracy and brain damage. 2. Manifestations of unilateral neglect in testing "auditory comprehension" with iconographic materials

Right unilateral spatial neglect in aphasic patients

To investigate spatial responses by aphasic patients during language tasks, 63 aphasics (21 severe, 21 moderate, and 21 mild) were administered two kinds of auditory pointing tasks-word tasks and sentence tasks-in which the spatial conditions of the stimuli were controlled. There were significantly fewer correct responses on the right side of a space than on the left side in both the word and sentence tasks, but the left deviation of correct responses was more prominent in the sentence task than in the word task. Additionally, the severe aphasics exhibited a prominent leftward deviation that may have been the result of deficits in rightward attention controlled by the left hemisphere. This phenomenon also seems to reflect the directional attention that is subserved by the right hemisphere, which attends to the left side of a space and, less predominantly, the right side of a space.

Effect of literacy level on cognitive and language tests in Korean illiterate older adults

AIM

Illiterate individuals represent a significant proportion of the world's population. Acquisition of reading and writing skills influences the functional status of the brain, and consequently alters the performance on cognitive and language tests. Thus, it is important to identify the degree of the impact of levels of both illiteracy and education as potential confounders on test performance in people with neurological communication disorders.

METHODS

A total of 203 community-dwelling older adults aged 65 years and older were recruited for the present study. Participants were classified into four groups based on the literacy level; pure illiterate (n=29), semi-illiterate (n=67), literate (n=75) and high-level literate (n=32). The participants completed the Mini-Mental State Examination, Boston Naming Test, Controlled Oral Word Association Test (animal), verb naming, and sentence comprehension tests.

RESULTS

The pure illiterate group showed the lowest performance on all five tests. Regression analysis showed that literacy level was the variable that best predicted the performance on cognitive and language tests.

CONCLUSIONS

These findings suggest that literacy in performance on cognitive and language tests is an important factor in neuropsychological evaluations for older adults.

Impact of phonological processing skills on written language acquisition in illiterate adults

Illiteracy remains a world-wide problem not only for children but also for adults. Phonological processing has been defined as a crucial factor for the acquisition of written language, which usually occurs in childhood. However, it is unclear to what extent phonological processing is necessary in order for adults to acquire written language skills. We tested 47 illiterate adults before and after a one-year alphabetization course in several cognitive domains relevant to phonological processing and compared their results to 41 matched controls who did not take part in the alphabetization course. Phonological awareness in the narrower sense (e.g., phoneme association) was a stronger predictor of alphabetization outcome than demographic variables such as years of education. In addition, despite improvement of illiterate individuals in phonological awareness, short-term memory, and visual attention from before to after the alphabetization course, they did not reach the phonological processing level of literate controls. Our results confirm that the alphabetization of adults requires and enhances phonological processes similar to those of children. Nevertheless, specific aspects, such as improvements in short-term memory or visual attention, need to be considered in order to improve and optimize alphabetization programs for adults.

Cultural values underlying psychometric cognitive testing

It is proposed that culture (values, beliefs, styles of behavior) can affect neuropsychological testing. Cognitive testing represents a social situation that-as any social situation, it is one governed by implicit cultural rules. At least eight different culture-dependent values underlie cognitive testing: (1) One-to-one relationship, (2) Background authority, (3) Best performance, (4)Isolated environment (5) Special type of communication, (6) Speed, (7) Internal or subjective issues, and (8) The use of specific testing elements and strategies. In addition, it is proposed that"the distance" (e.g., gender, age, ethnicity) between the examiner and the examinee may potentially impact the testing situation. A special analysis regarding the function of instruction in cognitive tests is also presented emphasizing that test instruction interpretation is also culture-dependent. Some potential avenues of research are finally proposed.

Language processing modulated by literacy: a network analysis of verbal repetition in literate and illiterate subjects

Previous behavioral and functional neuroimaging data indicate that certain aspects of phonological processing may not be acquired spontaneously, but are modulated by learning an alphabetic written language, that is, learning to read and write. It appears that learning an alphabetic written language modifies the auditory-verbal (spoken) language processing competence in a nontrivial way. We have previously suggested, based on behavioral and functional neuroimaging data, that auditory-verbal and written language interact not only during certain language tasks, but that learning and developing alphabetic written language capacities significantly modulates the spoken language system. Specifically, the acquisition of alphabetic orthographic knowledge has a modulatory influence on sublexical phonological processing and the awareness of sublexical phonological structure. We have suggested that developing an orthographic representation system for an alphabetic written language, and integrating a phoneme-grapheme correspondence with an existing infrastructure for auditory-verbal language processing, will result in a modified language network. Specifically, we suggest that the parallel interactive processing characteristics of the underlying language-processing brain network differ in literate and illiterate subjects. Therefore, the pattern of interactions between the regions of a suitably defined large-scale functional-anatomical network for language processing will differ between literate and illiterate subjects during certain language tasks. In order to investigate this hypothesis further, we analyzed the observed covariance structure in a PET data set from a simple auditory-verbal repetition paradigm in literate and illiterate subjects, with a network approach based on structural equation modeling (SEM). Based on a simple network model for language processing, the results of the present network analysis indicate that the network interactions during word and pseudoword repetition in the illiterate group differ, while there were no significant differences in the literate group. The differences between the two tasks in the illiterate group may reflect differences in attentional modulation of the language network, executive aspects of verbal working memory and the articulatory organization of verbal output. There were no significant differences between the literate and illiterate group during word repetition. In contrast, the network interactions differed between the literate and illiterate group during pseudoword repetition. In addition to differences similar to those observed in the illiterate group between word and pseudoword repetition, there were differences related to the interactions of the phonological loop between the groups. In particular, these differences related to the interaction between Broca's area and the inferior parietal cortex as well as the posterior-midinsula bridge between Wernicke's and Broca's area. In conclusion, the results of this network analysis are consistent with our previously presented results and support the hypothesis that learning to read and write during childhood influences the functional architecture of the adult human brain. In particular, the basic auditory-verbal language network in the human brain is modified as a consequence of acquiring orthographic language skills.

A calculation and number processing battery for clinical application in illiterates and semi-literates

Ten simple tasks assessing counting, number processing, elementary calculation and quantity estimation were proposed to 122 normal Brazilian adults aged between 18 and 58 years with 0, 1, 2, 3 or 4 years of education. Tasks such as counting the number of elements in small sets were almost perfectly mastered by these illiterate or semi-literate normal subjects; however in other tasks (e.g. those assessing knowledge of the correspondence between numbers and banknotes) a sizeable proportion of the sample showed errors. The pattern of errors was analysed to identify difficulty factors. A strong gender effect with better performance in men than women was observed, which was even greater than the expected effect of educational level. Results in normals allowed to propose cut-off scores for neuropsychological assessment in brain-damaged patients with very low levels of education, which were tested in a small sample of illiterate or semi-literate patients with cerebrovascular accident. It is argued that the relatively neglected area of neuropsychological assessment in illiterates is of great practical and theoretical interest.

Effective auditory-verbal encoding activates the left prefrontal and the medial temporal lobes: A generalization to illiterate subjects

Recent event-related FMRI studies indicate that the prefrontal (PFC) and the medial temporal lobe (MTL) regions are more active during effective encoding than during ineffective encoding. The within-subject design and the use of well-educated young college students in these studies makes it important to replicate these results in other study populations. In this PET study, we used an auditory word-pair association cued-recall paradigm and investigated a group of healthy upper middle-aged/older illiterate women. We observed a positive correlation between cued-recall success and the regional cerebral blood flow of the left inferior PFC (BA 47) and the MTLs. Specifically, we used the cued-recall success as a covariate in a general linear model and the results confirmed that the left inferior PFC and the MTL are more active during effective encoding than during ineffective encoding. These effects were observed during encoding of both semantically and phonologically related word pairs, indicating that these effects are robust in the studied population, that is, reproducible within group. These results generalize the results of Brewer et al. (1998, Science 281, 1185-1187) and Wagner et al. (1998, Science 281, 1188-1191) to an upper middle aged/older illiterate population. In addition, the present study indicates that effective relational encoding correlates positively with the activity of the anterior medial temporal lobe regions.

Influence of educational level of non brain-damaged subjects on visual naming capacities

Educational level of subjects is a variable often neglected in neuropsychological studies. However, there are pieces of evidence to suggest that illiterate subjects may perform worse than literate subjects in some tests. Visual naming is one of the tasks where a poor performance was reported in illiterate populations. The present study addresses this problem of comparing the performance in visual naming tasks of non-brain-damaged patients of different educational levels. The test materials were composed of three subtests: naming real objects, their photographs, and line drawings of the same objects. Results revealed that there is a clear influence of educational level on the ability to name photographs and line drawings of the objects. Naming line drawings is particularly difficult for the lower educated non-brain-damaged subjects. Visual analysis of two dimensional representations is a task that requires special learning. These results have to be taken into consideration in test selection for poorly educated populations.

Attentional load and visual neglect

Ten subjects suffering from left unilateral neglect carried out a letter cancellation task under normal conditions, while counting forward, and when generating random numbers, respectively. The index of neglect increased with each of these conditions, though only the normal-random difference was statistically significant. In a second study, four left unilateral neglect subjects and four right brain-damaged controls carried out a simple reaction time task, with stimuli appearing randomly to the left and right, with and without the simultaneous performance of a secondary task (counting backward in threes from 100). The discrepancy between left versus right latencies increased significantly in the secondary task condition for two patients in the neglect group but not for the other two. None of the control group showed this effect. Theoretical implications of these findings for understanding neglect are discussed.

Digit span and visual neglect: a puzzling relationship

Weinberg et al. found a relationship between the presence of extinction and the discrepancy between backward and forward digit span among left hemiplegic patients. The present study replicates this finding in a group of 37 patients suffering from unilateral left visual neglect, demonstrating a strong relationship between degree of neglect and digit span discrepancy. A principal components analysis of a neurospychological examination revealed three main independent components--Neglect, Verbal Memory and Non-verbal Memory respectively. Digit Span Discrepancy had one of the highest loadings on the neglect factor, and loaded significantly on no other factor. Multiple regression analysis showed that the relationship of Digit Span Discrepancy with Degree of Neglect exists independently of visuo-spatial ability, and this is also true for paced auditory serial addition (PASAT) scores for one of the two main indices of neglect. The implications of this for understanding neglect are discussed.

Neuropsychological assessment in illiterates: visuospatial and memory abilities

A basic neuropsychological battery of visuospatial and memory abilities was administered to extreme educational groups (illiterates and professionals). Subjects were matched according to sex and age. The following visuospatial tasks were included: figure copy (cube, house, and Rey-Osterrieth complex figure), telling time, recognition of superimposed figures, recognition of a map, and drawing of the plan of the room. The following memory tasks were used: basic information, digit retention (forward and backward), memory curve, delayed verbal recall, sentence repetition, logical memory, delayed logical memory, immediate recall of the Rey-Osterrieth complex figure, immediate reproduction of a cube, visuospatial memory, and sequential memory. In visuospatial tasks all differences between the two groups were statistically significant. Five of the seven visuospatial tasks (all but telling time and recognition of superimposed figures) showed differences between age groups with a better performance found in the younger groups and four of the tasks (cube, house, Rey-Osterrith complex figure copying, and telling time) were significant between sexes with a better performance in men. In memory tasks, with the exception of the immediate memory of sentences, all tasks showed statistically significant differences between educational groups. Eight of the 13 memory tasks (digits forward and backward, delayed memory of words, immediate and delayed logical memory, Rey-Osterrieth immediate memory, cube immediate memory, and sequential memory) showed significant differences for age while 4 of the tasks (digits backward, memory curve, Rey-Osterrieth immediate memory, and cube immediate memory) were significant for sex. Results are analyzed with regard to current theories in cognitive psychology and anthropology. Emphasis is placed on the finding that cognitive skills usually examined by neuropsychological tests represent learned and highly trained abilities.

Illiteracy and brain damage. 3: A contribution to the study of speech and language disorders in illiterates with unilateral brain damage (initial testing)

This report bears on the behavior of 188 unilateral stroke subjects when administered an aphasia screening test comprising a short interview as well as naming, repetition, word-picture matching and sentence-picture matching tasks. All subjects were unilingual lusophone adult (40 yr of age or older) right-handers. Furthermore, they were either totally unschooled illiterates or they had received school education and thereafter retained writing skills and reading habits. Subjects were tested less than 2 months after a first unilateral stroke. In all tasks, global error scores were greater among left and right brain-damaged illiterate and literate subjects than among their controls. In repetition and matching, these differences were statistically significant for the left but not for the right-stroke groups, irrespective of the literacy factor. In naming, on the other hand, significant differences were found not only for the two left-stroke groups but also for the right-stroke illiterate group although not for the right-stroke literate one. Likewise, some degree of word-finding difficulty and of reduction in speech output as well as sizeable production of phonemic paraphasias were observed in the interviews of several right-stroke illiterates, clearly less in those of right-stroke literates. These findings lead us to suggest that cerebral representation of language is more ambilateral in illiterates than it is in school educated subjects although left cerebral "dominance" remains the rule in both.