Search

Introduction : Notwithstanding the high number of experimental studies examining limb and oral apraxia from a clinical, cognitive (Tessari et al., 2004) and neuroimaging point of view, the neural mechanisms underlying this impairment are still little clarified. Motor programming abilities have been recently investigated with f-MRI techniques (Martin et al., 2016) but lesions-to-symptoms mapping is still a fundamental method to underpin the anatomical basis of complex behaviors (Goldenberg et al., 2015). The aim of the present study is to investigate the anatomical basis of ideomotor, ideational, and oral apraxia in a cohort of left-hemisphere brain-damaged patients using the subtraction and voxel-based lesion-symptom mapping (VLSM) localization procedures. Methods : Ideomotor (arm and hand movements vs. finger movements), ideational and oral apraxia were studied through an anatomo-clinical correlative procedure in a sample of 48 left-hemisphere brain-damaged patients. Subtraction and VLSM procedures were used to localize the anatomical bases of these impairments. Results : Lesions of the left supramarginal gyrus and of the left angular gyrus were associated with ideomotor apraxia of the upper limb and hand; lesions of the left supramarginal gyrus and of the left middle frontal gyrus were associated with ideomotor apraxia of finger movement. Ideational apraxia was associated with lesions of the left supramarginal gyrus, left middle frontal gyrus and left inferior frontal gyrus (pars opercularis) suggesting a partial common neural substrate with ideomotor apraxia. A network of left perisylvian areas did emerge as anatomical correlate of oral apraxia, including the left insular cortex, and the left frontal and central opercula, the left inferior frontal gyrus (pars opercularis). Discussion : Our results confirm the existence of relatively independent anatomical specializations in the left hemisphere (Basso et al., 1985; Mengotti et al., 2015), with regards to the hiera

Phonological and articulatory programming impairments may co-occur in aphasic patients and previous research does not offer a clear-cut picture of their anatomical counterparts. Hickok and Poeppel (2007) put forward a seminal model of speech processes. The ventral stream (mostly bilateral) would be involved in speech recognition and phonological-lexical processing, whereas the dorsal stream (largely lateralized to the left hemisphere) would map phonological representations onto articulatory motor patterns. In this study we analyzed repetition errors for single words and spontaneous speech ratings on the Italian version of the Aachen Aphasia Test. Through a VLSM procedure we aimed at discriminating the neuroanatomical substrates of the phonological and articulatory impairment (and of their normal functional processing). We also estimated functional connectivity networks related to articulation and phonology using seed-to-voxel connectivity analysis with resting state fMRI data. Results indicate that repetition deficit of single words is associated with lesions in a network of left perisylvian areas including the central operculum, the Heschl's gyrus, the angular gyrus, and the supramarginal gyrus (posterior part). Articulatory impairment is associated with lesions in a number of areas in the left dorsal stream, such as the insula (anterior portion), the pars opercularis of the inferior frontal gyrus, the central operculum and the precentral gyrus. On the contrary, phonological impairment is underpinned by lesions of the Heschl's gyrus, and of the posterior portion of the superior temporal and supramarginal gyri. Anatomo-clinical correlative results partly support Hickok and Poeppel's functional model of phonological and articulatory processing.

Introduction: Phonological impairment and articulatory programming impairment may co-occur in aphasic patients and previous research does not offer a clear-cut picture of their anatomical counterparts. Methods: In this study we aimed at disentangling the neuroanatomical foundation of the phonological and articulatory component in a large cohort of aphasic patients. We analyzed speech sampling at the Aachen Aphasia Test (AAT) and we employed voxel-based lesion-symptom mapping (VLSM) to correlate the behavioral performance with the underlying neuroanatomical basis. Results: Predominant phonological impairment is associated with lesions localized in the areas assigned to the phonological network (dorsal superior temporal gyrus, mid-to-posterior superior temporal gyrus). Predominant articulatory impairment is underpinned by damage at the posterior inferior frontal gyrus, premotor cortex and anterior insula. Discussion: In general, our results are in line with Hickok and Poeppel’s (2004; 2008) model of phonological processing and also support a peculiar role played by the anterior insula in articulatory planning (Dronkers & Ogar, 2004). References: Hickok, G. et al. Nature (2007) 8:393-402; Hickok, G., et al. Cognition (2004) 92: 67-99; Dronkers, N. et al. Brain(2004)127:1461-1462.

The neural bases of spelling impairments are still uncertain, as only a paucity of single-case studies have been published so far on this topic. In this study we report the results of an investigation involving 35 left focal brain-damaged patients suffering from acquired surface, and phonological, dysgraphia. Patients were tested with four writing tasks, namely spelling of regular words, irregular words, loan words and nonwords. We used the subtraction technique and voxel-based lesion-symptom mapping (VLSM) procedure to highlight the anatomical correlates of functional damage along the lexical and sublexical routes of spelling. We found that surface dysgraphia is predominantly associated with left temporo-occipital lesions, along with lesions occurring in the left angular gyrus and the left supramarginal gyrus. Phonological dysgraphia follows from lesions in the left insular cortex, and a number of white matter tracts, such as the left external capsule, and the left superior longitudinal fasciculus. Results from VLSM analyses investigating spelling along the lexical/sublexical routes were consistent with those obtained using the subtraction condition. In brief, the results of this investigation indicate that different types of acquired dysgraphia result from damage to different cortical areas and subcortical pathways. Furthermore, data are consistent with dual-route models of spelling, and with a crucial role of subcortical white-matter pathways in spelling along the sublexical route.

In this study we investigated the neural correlates of acquired reading disorders through an anatomo-correlative procedure of the lesions of 59 focal brain damaged patients suffering from acquired surface, phonological, deep, undifferentiated dyslexia and pure alexia. Two reading tasks, one of words and nonwords and one of words with unpredictable stress position, were used for this study. We found that surface dyslexia was predominantly associated with left temporal lesions, while in phonological dyslexia the lesions overlapped in the left insula and the left inferior frontal gyrus (pars opercularis) and that pure alexia was associated with lesions in the left fusiform gyrus. A number of areas and white matter tracts, which seemed to involve processing along both the lexical and the sublexical routes, were identified for undifferentiated dyslexia. Two cases of deep dyslexia with relatively dissimilar anatomical correlates were studied, one compatible with Coltheart’s right-hemisphere hypothesis (1980) whereas the other could be interpreted in the context of Morton and Patterson’s, 1980, multiply-damaged left-hemisphere hypothesis. In brief, the results of this study are only partially consistent with the current state of the art, and propose new and stimulating challenges; indeed, based on these results we suggest that different types of acquired dyslexia may ensue after different cortical damage, but white matter disconnection may play a crucial role in some cases

Most compound words are constituted of a head constituent (e.g., light in moonlight) and a modifier constituent (e.g., moon in moonlight); the information transmitted by these head-modifier roles is fundamental for defining the grammatical and semantic properties of the compound and for identifying a correct combination of the constituents at the conceptual level. The objective of this study is to assess how lexical processing in aphasia is influenced by the head-modifier structure of nominal compounds. A picture-naming task of 35 compounds with head-initial (pescespada, swordfish, literally fishsword) and head-final (autostrada, highway, literally carroad) forms was administered to 45 Italian aphasic patients, and their accuracy in retrieving constituents was analysed with a mixed-effects logistic regression. The interaction between headedness and constituent position was significant: The modifier emerged as being more difficult to retrieve than the head, but only for head-final compounds. The results are consistent with previous data from priming experiments on healthy subjects and provide convincing evidence that compound headedness is represented at central processing levels.

Broca’s aphasia entails difficulty in understanding syntactically complex sentences, e.g., passive (P), object-cleft (OC), object-relative (OR) sentences as compared to their counterparts, i.e., active (A), subject-cleft (SC), and subject-relative (SR) sentences. One of the theories proposed to account for this deficit, the Trace-Deletion Hypothesis (TDH, Grodzinski, 2000), assumes an underlying difficulty in computing syntactic dependencies and the concomitant use of a “guessing strategy” that randomly assigns the role of Agent to the participants in the sentence. Seven patients with Broca’s aphasia were tested on the sentence comprehension test (SCT) of the Italian version of the Northwestern Assessment of Verbs and Sentences (NAVS, Cho-Reyes & Thompson, 2012). Syntactically complex sentences were significantly more impaired than their counterparts (P>A: p = .046; OC>SC: p < .001; OR>SR: p = .0015) at a group level. However, the analysis of single profiles reveals significant dissociation in accuracy patterns among P versus OC and OR sentences in two participants (PMA and LB), suggesting different underlying computational processes. In both participants, accuracy on P sentences in one case (PMA: 0%) and on OC and OR sentences in the other case (LB: 10%) is in contrast with the TDH-based predictions of “at chance” performance on sentences entailing syntactic movement.

Background: The syntactic impairment which frequently emerges in aphasia is mostly due to damage to the ability to map thematic information to the corresponding verb argument structure (VAS). In agrammatic patients this disorder is usually associated with initiation difficulties. Aims: The present study describes a new technique for the rehabilitation of VAS deficits in the matrix clause. Methods & Procedure: The treatment is organized in six levels, and is based on a set of sentence lists of increasing VAS complexity. The efficacy of the treatment was tested on a sample of five chronic (more than one year post-onset) agrammatic patients and three chronic severe non-classifiable aphasic patients suffering from predominant impairment in mapping thematic information to the appropriate VAS. Two sentence list sets were employed: one for the evaluation and treatment phases and the other for the evaluation phase only. Improvement in performance on the first list indicates efficacy of the training program on the treated material, while improvement on the second list indicates generalization to untreated material. The treatment efficacy and generalization to other communicative conditions was also tested with a picture-naming task of nouns and verbs, a picture description task and a spontaneous speech sample (mean sentence length). The patients’ syntactic abilities were tested at the beginning and at the end of the treatment, and again after a six-to-twelve month follow-up. Outcomes & Results: Patients improved significantly on both lists (i.e., there was significant training effect as well as generalization effect to the untreated material) and on the verb-naming task, the picture description task, and on mean sentence length in spontaneous speech. The treatment effect was seen to be stable at the six-to-twelve month follow-up. Conclusions: The VAS training described in the present study is an efficacious technique for the treatment of severe syntactic impairments of the m

In this study we investigated twelve cases of "mixed dysgraphia", a spelling impairment where regular words are spelt better than either ambiguous words or regular nonwords. Two explanations of mixed dysgraphia were formerly offered by Luzzatti et al. (1998): (i) a double functional lesion of the Orthographic Output Lexicon (or damage to its access) and of the Acoustic-to-Phonological Conversion; (ii) some kind of interaction/summation between lexical and sublexical spelling routes when processing regular words. We first analysed whether a double functional lesion was sufficient to explain the mixed dysgraphia, checking acoustic-to-phonological conversion by means of the Repetition of words and nonwords: the answer was positive in 5 cases and uncertain in 3. We tested the remaining 4 cases to see if there was an interaction between lexical and sublexical processing of regular words, quantifying for each patient, on a probabilistic basis, the separate contribution of the residual lexical and sublexical resources. We investigated whether the processing along these routes was simultaneous but independent ("independent cooperation") or if instead there was “interaction”, i.e. the simultaneous activity led to an added increase of efficiency over and above the mere combination of separate success probabilities. For one case the processing along the two routes was independent, in the other 3 cases an interaction resulted. Following the same approach, we found that for the 5 cases with a double functional lesion, the observed success on regular word spelling was higher than that expected on a probabilistic basis, but the interpretation of this finding was different

Aphasic patients occasionally manifest a dissociated naming ability between objects and actions: this phenomenon has been interpreted as evidence of a separate organization for nouns and verbs in the mental lexicon. Nevertheless Bird et al. [Bird, H., Howard, D., Franklin, S. (2000). Why is a verb like an inanimate object? Grammatical category and semantic category deficits. Brain and Language, 72, 246-309], suggested that the damage underlying noun-verb dissociation affects the corresponding semantic concepts and not the lexical representation of words; moreover, they claimed that many dissociations reported in literature are caused merely by a strong imageability effect. In fact, most authors used a picture-naming task to assess patients' naming ability, and due to the fact that this test involves the use of pictures to represent actions and objects, nouns were frequently more imageable than verbs [Luzzatti, C., & Chierchia, G. (2002). On the nature of selective deficit involving nouns and verbs. Rivista di Linguistica, 14, 43-71]. In order to overcome this drawback, we devised a new task - nouns and verbs retrieval in a sentence context (NVR-SC) - in which nouns and verbs have the same imageability rate. Patients' performance on this task is compared with that obtained by the same patients on a standard picture-naming task. Of the 16 aphasic patients with a selective verb deficit, as revealed by the picture-naming task, two continued to show dissociation in the NVR-SC task, while 14 did not. The data indicate that at least some patients have an imageability-independent lexical deficit for verbs. The functional locus/i of the damage is also considered, with particular reference to the lemma/lexeme dichotomy suggested by Levelt et al. [Levelt, W.J.M., Roelofs, A., & Meyer, A.S. (1999). A theory of lexical access in speech production. Behavioral and BrainSciences, 22, 1-75]

Background: This study aimed (i) to verify whether the classical word-naming models developed for English-speaking participants also account for the performance of patients who speak a shallow-orthography language such as Italian, and (ii) to study the effects of word frequency, concreteness, and grammatical class on word naming. Methods & Procedures: A total of 90 Italian aphasic patients participated in two reading tasks. The first task contained four sets of items: (i) concrete nouns (natural objects and artefacts), (ii) abstract nouns, (iii) function words, (iv) morphologically simple legal nonwords. The second task (trisyllabic words with unpredictable stress position) was designed to test reading ability along the lexical route (the position of the major word stress is the only opaque variable in the Italian reading system). The patients' performances on the two tasks were analysed for strong dissociations, and to test the effect of grammatical class, concreteness, word frequency, and item length. The effect of age of acquisition was tested in a subsequent analysis. Outcomes & Results: Reading scores were pathological for all patients. The present sample reflected the entire spectrum of reading impairments: phonological (49), surface (4), undifferentiated (32), and letter-by-letter (5) dyslexia, which is in line with data reported for English-speaking aphasic patients. Only one of the phonological dyslexic patients made semantic errors (a reading impairment compatible with the diagnosis of deep dyslexia). The vast majority of Broca's aphasic patients suffered from phonological dyslexia (76%), while fluent aphasic patients were distributed more evenly across dyslexia types; all four surface dyslexic patients belonged to the fluent aphasia group. Overall, grammatical class (concrete nouns vs function words) had a significant effect on 14 patients (15.6%), concreteness (concrete vs abstract nouns) on 15 (16.7%), and word frequency on 5 (5.6%). Grammatical class a