Kyrana Tsapkini

The orthography-specific functions of the left fusiform gyrus: evidence of modality and category specificity.

We report on an investigation of the cognitive functions of an individual with a resection of the left fusiform gyrus. This individual and a group of control participants underwent testing to examine the question of whether or not there are neural substrates within the left fusiform gyrus that are dedicated to orthographic processing. We evaluated the modality specificity (written vs spoken language) and the category specificity (written language vs other visual categories) of this individuals impairments. The results clearly reveal deficits affecting lexical processes in both reading and spelling. Specifically, we find disruption of normal, rapid access to meaning from print in reading and of accurate retrieval of the spellings of words from their meaning in writing. These deficits stand in striking contrast with intact processing of spoken language and categories of visual stimuli such as line drawings of objects and faces. The modality and category specificity of the deficits provide clear evidence of neural substrates within the left-mid-fusiform gyrus that are specialized and necessary for normal orthographic processing.

Semantic and phonological processing in illiteracy.

Researchers of cognitive processing in illiteracy have proposed that the acquisition of literacy modifies the functional organization of the brain. They have suggested that, while illiterate individuals have access only to innate semantic processing skills, those who have learned the correspondence between graphemes and phonemes have several mechanisms available to them through which to process oral language. We conducted 2 experiments to verify that suggestion with respect to language processing, and to elucidate further the differences between literate and illiterate individuals in the cognitive strategies used to process oral language, as well as hemispheric specialization for these processes. Our findings suggest that semantic processing strategies are qualitatively the same in literates and illiterates, despite the fact that overall performance is augmented by increased education. In contrast, explicit processing of oral information based on phonological characteristics appears to be qualitatively different between literates and illiterates: effective strategies in the processing of phonological information depend upon having had a formal education, regardless of the level of education. We also confirmed the differential abilities needed for the processing of semantic and phonological information and related them to hemisphere-specific processing.

Adaptation and Validation of Standardized Aphasia Tests in Different Languages: Lessons from the Boston Diagnostic Aphasia Examination–Short Form in Greek

The aim of the current study was to adapt the Boston Diagnostic Aphasia Examination – Short Form (BDAE-SF) [1] to the Greek language and culture, determine the influence of demographic variables on performance and in particular the effects of age and education, develop normative data, and examine the discriminative validity of the test for acute stroke patients. A sample of 129 community healthy adults participated in the study (66 women), covering a broad range of ages and education levels so as to maximize representation of the Greek population and be able to examine the effects of age and education in language performance. Regression models showed that, overall, younger and more educated individuals presented higher performance on several subtests. Normative data for the Greek population are presented in percentile tables. Neurological patients performance was compared to that of the neurologically intact population using Wilcoxons rank sum test and for the most part was found to be significantly inferior, indicating good discriminant validity of the test. Qualitative errors of patients diagnosed with aphasia on the test are presented, and limitations and generalizable strengths of this adaptation are discussed.

Patterns of breakdown in spelling in primary progressive aphasia

INTRODUCTIONnThe objective of this study is to determine which cognitive processes underlying spelling are most affected in the three variants of primary progressive aphasia (PPA): Logopenic variant primary progressive aphasia (lvPPA), Semantic variant primary progressive aphasia (svPPA), and Nonfluent variant primary progressive aphasia (nfvPPA).nnnMETHODSn23 PPA patients were administered The Johns Hopkins Dysgraphia Battery to assess spelling. Subtests evaluate for effects of word frequency, concreteness, word length, grammatical word class, lexicality (words vs pseudowords), and regularity by controlling for the other variables. Significant effects of each variable were identified with chi square tests. Responses on all spelling to dictation tests were scored by error type. 16 of the 23 subjects also had a high resolution MRI brain scan to identify areas of atrophy.nnnRESULTSnWe identified 4 patterns of spelling that could be explained by damage to one or more cognitive processes underlying spelling. Nine patients (3 unclassifiable, 4 with lvPPA, 2 with svPPA) had dysgraphia explicable by impaired access to lexical representations, with reliance on sublexical phonology-to-orthography conversion (POC). Two patients (with nfvPPA) showed dysgraphia explicable by impaired access to lexical representations and complete disruption of sublexical POC. Seven patients (4 with lvPPA, 1 with svPPA, 2 unclassifiable) showed dysgraphia explicable by impaired access to lexical-semantic representations and/or lexical representations with partially spared sublexical POC mechanisms. Five patients (1xa0with nfvPPA, 2 with svPPA, 1 with lvPPA, and 1 unclassifiable) showed dysgraphia explicable by impairment of the graphemic buffer.nnnCONCLUSIONSnAny cognitive process underlying spelling can be affected in PPA. Predominance of phonologically plausible errors, more accurate spelling of regular words than irregular words, and more accurate spelling of pseudowords than words (indicating spared POC mechanisms) may indicate a low probability of progression to nfvPPA.

Lexical processing in illiteracy: Effect of literacy or education?

Difficulties in phonological processing in illiterates have been attributed to their limited phonological awareness, a consequence of their lack of literacy. We sought to explore the potential influence of education on auditory lexical processing above and beyond literacy per se. In order to achieve this goal, we compared a lexical decision making paradigm with a repetition paradigm using words and pseudo-words. We based this choice of tasks on previous research, which has shown that pseudo-word repetition is dependent on the phonological loop; such studies have thus demonstrated a literacy effect on repetition. Instead, lexical decision making is known to depend on the size of ones vocabulary, which is influenced by the level of education attained. Our sample comprised three groups: illiterate no education, literate/low education and literate/high education, individuals. The pattern of our findings confirmed that literacy has an effect on the capacity of the phonological loop, as our illiterate group alone had difficulty with repetition, as compared with both literate/educated groups. Also, our findings suggested an education effect on lexical decision making, as we found a gradation in the performance of the three groups. Therefore, we succeeded in dissecting the effect of literacy and education on auditory lexical processing through the application and comparison of two simple paradigms.

Spelling Intervention in Post-Stroke Aphasia and Primary Progressive Aphasia

Spelling–a core language skill–is commonly affected in neurological diseases such as stroke and Primary Progressive Aphasia (PPA). We present two case studies of the same spelling therapy (learning of phoneme-to-grapheme correspondences with help from key words) in two participants: one who had a stroke and one with PPA (logopenic variant). Our study highlights similarities and differences in the time course of each indivduals therapy. The study evaluates the effectiveness and generalization of treatment in each case, i.e. whether the treatment affected the trained items and/or untrained items, and whether or not the treatment gains were maintained after the end of therapy. Both participants were able to learn associations between phonemes and graphemes as well as between phonemes and words. Reliable generalization to untrained words was shown only for the participant with post-stroke aphasia, but we were not able to test generalization to untrained words in the individual with PPA. The same spelling therapy followed a different time course in each case. The participant with post-stroke aphasia showed a lasting effect of improved spelling, but we were unable to assess maintenance of improvement in the participant with PPA. We discuss these differences in light of the underlying nature of each disease.

Augmentation of spelling therapy with transcranial direct current stimulation in primary progressive aphasia: Preliminary results and challenges

Background: Primary progressive aphasia (PPA) is a neurodegenerative disease that primarily affects language functions and often begins in the fifth or sixth decade of life. The devastating effects on work and family life call for the investigation of treatment alternatives. In this article, we present new data indicating that neuromodulatory treatment, using transcranial direct current stimulation (tDCS) combined with a spelling intervention, shows some promise for maintaining or even improving language, at least temporarily, in PPA. Aims: The main aim of the present article is to determine whether tDCS plus spelling intervention is more effective than spelling intervention alone in treating written language in PPA. We also asked whether the effects of tDCS are sustained longer than the effects of spelling intervention alone. Methods & Procedures: We present data from six PPA participants who underwent anodal tDCS or sham plus spelling intervention in a within-subject crossover design. Each stimulation condition lasted 3 weeks or a total of 15 sessions with a 2-month interval in between. Participants were evaluated on treatment tasks as well as on other language and cognitive tasks at 2-week and 2-month follow-up intervals after each stimulation condition. Outcomes & Results: All participants showed improvement in spelling (with sham or tDCS). There was no difference in the treated items between the two conditions. There was, however, consistent and significant improvement for untrained items only in the tDCS plus spelling intervention condition. Furthermore, the improvement lasted longer in the tDCS plus spelling intervention condition compared to sham plus spelling intervention condition. Conclusions: Neuromodulation with tDCS offers promise as a means of augmenting language therapy to improve written language function at least temporarily in PPA. The consistent finding of generalisation of treatment benefits to untreated items and the superior sustainability of treatment effects with tDCS justifies further investigations. However, the small sample size still requires caution in interpretation. Present interventions need to be optimised, and particular challenges, such as ways to account for the variable effect of degeneration in each individual, are discussed.

'Does Broca's area exist?' Christofredo Jakob's 1906 response to Pierre Marie's holistic stance.

In 1906, Pierre Marie triggered a heated controversy and an exchange of articles with Jules Déjerine over the localization of language functions in the human brain. The debate spread internationally. One of the timeliest responses, that appeared in print 1 month after Maries paper, came from Christofredo Jakob, a Bavarian-born neuropathologist working in Buenos Aires. The present study comprises an English translation of Jakobs 1906 paper and a discussion of Jakobs ideas on the localizationist-holistic approach regarding the role of Brocas area. This issue is still at the core of scientific debate in the light of current neuropsychological and neuroimaging findings.

Effects of sentence context on lexical ambiguity resolution in patients with schizophrenia.

Previous research has suggested that a failure in processing contextual information may account for the heterogeneous clinical manifestations and cognitive impairments observed in schizophrenia. In the domain of language, context processing in schizophrenia has been investigated mostly with single-word semantic priming paradigms; however, natural language comprehension depends on more than semantic relations between words. The present study aimed to systematically assess sentence context effects in homonym meaning activation in patients with schizophrenia. Fourteen patients with schizophrenia and 14 normal controls matched to the patients on sex, age, education and parental education, were examined using a cross-modal priming paradigm. Primes were sentences biasing the first, second, or neither meaning of a sentence-final equibiased homonym; targets were related to either the first or the second meaning of the homonym and appeared after an interstimulus interval (ISI) of 0ms or 750ms. Patients with schizophrenia exhibited a trend towards facilitation of both target types following unbiased sentences at ISI=0ms, similar to controls. However, in contrast to the pattern of selective target facilitation exhibited by control subjects following first- or second meaning-biased sentences, no significant target facilitation was observed in patients in the same condition. At ISI=750ms, patients did no longer exhibit significant target facilitation in any sentence context condition. This pattern of results is compatible with the assumption of a combined impairment in lexical (automatic spreading of activation within the semantic network) and extralexical (working memory) processes in patients with schizophrenia.

A brief assessment of object semantics in primary progressive aphasia

Background: A cross-culturally valid nonverbal assessment of semantic knowledge is needed. Accurately identifying impairment of object semantics is important for diagnosis of several disorders, including distinguishing semantic variant primary progressive aphasia (svPPA), a neurodegenerative condition characterised by progressive impairment in word comprehension, from logopenic and nonfluent agrammatic variants, which are not associated with impaired object semantics. However, current assessments require culturally specific knowledge. Aims: We developed a cross-culturally valid short form of the Pyramids and Palm Trees Test to assess object semantic memory. We investigated its clinical utility in differentiating the semantic variant of primary progressive aphasia, from the logopenic and nonfluent agrammatic variants. Areas of atrophy associated with poor performance were identified. Methods & Procedures: Fourteen items that rely on knowledge of objects’ defining features were selected from the original 52-item version. The full and short forms were administered to healthy individuals in the US (N = 18), Argentina (N = 20), and Greece (N = 12) and performance was compared. Seventy-eight individuals with primary progressive aphasia in the US completed the short form. Behavioural performance of the svPPA group (N = 24) was compared to other variants. Atlas-based analysis identified regions where atrophy correlated with poor performance in 39 individuals with primary progressive aphasia who had high-resolution magnetic resonance imaging (MRI) scans. Outcomes & Results: Control performance was classified as normal on the short form significantly more often than on the full version. Across groups with primary progressive aphasia, the group with semantic variant performed significantly worse than the groups with logopenic or nonfluent agrammatic variants. Volume in left anterior and inferior temporal cortex correlated with performance. Conclusions: The short-form Pyramids and Palm Trees Test is a clinically relevant, cross-culturally valid assessment of nonverbal object semantics. It can be used to identify semantic impairments, with poor performance associated with atrophy of the temporal lobes.