A Novel Means to Examine Response to Spelling Treatment

According to a dual-route model of written language processing, spelling of irregular words provides an index of the status of lexical spelling procedures, whereas nonword spelling provides information about non-lexical processing that relies on phoneme-grapheme conversion. Because regular words can be spelled using either route, accuracy for such words may reflect the combined function of the two routes, and may be mathematically predicted on the basis of spelling accuracy for irregular words and nonwords. Pre- and post-treatment spelling performance of a group of eight individuals with acquired spelling impairment demonstrated the utility of comparing such predictions with actual performance

Lexical Retrieval Treatment for Primary Progressive Aphasia

Similar to aphasia due to stroke, lexical retrieval difficulties are pervasive in primary progressive aphasia (PPA).  In fact, increasing word retrieval difficulties typically herald the onset of PPA, regardless of the underlying etiology or PPA subtype.  For that reason, behavioral interventions to improve or sustain word retrieval abilities have considerable potential to enhance language performance in PPA.  We report here on positive responses to lexical retrieval treatment in two individuals with fluent progressive aphasia profiles.  The treatment approach extends work accomplished in stroke-related aphasia that promotes strategic engagement of residual language abilities to promote self-cueing to resolve lexical retrieval difficulties

Phonological processing in primary progressive aphasia

Primary progressive aphasia (PPA) is a debilitating condition wherein speech and language deteriorate as a result of neurodegenerative disease. Three variants of PPA are now recognized, each of which shows a unique constellation of speech-language deficits and pattern of underlying atrophy in the brain (Gorno-Tempini et al., 2011). The variants include a nonfluent/agrammatic type (nfvPPA), characterized by syntactic and motor speech deficits and fronto-insular atrophy in the left hemisphere. The semantic variant (svPPA) shows degradation of semantic knowledge in the context of anterior and inferior temporal lobe atrophy (left hemisphere greater than right). Finally, the more recently characterized logopenic variant (lvPPA) shows impairments in naming and repetition that are thought to be phonological in nature. This variant, associated with atrophy of temporoparietal regions in the left hemisphere, has also been referred to as the “phonological” variant of PPA due to observed deficits on tasks that require phonological storage (i.e., the “phonological loop”) and to the presence of phonological paraphasias in connected speech (Gorno-Tempini et al., 2008). Impaired phonological processing has been considered a unique feature of the logopenic variant of PPA, however, phonological skills have not been thoroughly characterized across the three variants. Recent models of the functional neuroanatomy of language propose two pathways by which speech is processed in the brain (Hickok & Poeppel, 2007). A dorsal pathway involving temporoparietal and posterior frontal structures is thought to be involved in mapping phonological representations onto articulatory representations. A ventral pathway located in the middle and inferior temporal lobes is considered crucial for mapping phonological representations onto lexical-semantic representations. Both the dorsal and ventral streams emanate from a common cortical region in posterior, superior temporal cortex/sulcus that appears critical to the mental representation of phonology. We investigated phonological processing in PPA, with the goal of identifying whether patterns of performance in the different variants support this functional-anatomical framework. Based on our knowledge of the locus of anatomical damage in the subtypes of PPA, we hypothesized that patients with damage to dorsal route structures (nonfluent and logopenic variants) would show greater impairment on phonological processing tasks, whereas patients with damage to ventral route structures (semantic variant) would show relative preservation of phonological abilities

Efficient visual object and word recognition relies on high spatial frequency coding in the left posterior fusiform gyrus: Evidence from a case-series of patients with ventral occipito-temporal cortex damage

Recent visual neuroscience investigations suggest that ventral occipito-temporal cortex is retinotopically organized, with high acuity foveal input projecting primarily to the posterior fusiform gyrus (pFG), making this region crucial for coding high spatial frequency information. Because high spatial frequencies are critical for fine-grained visual discrimination, we hypothesized that damage to the left pFG should have an adverse effect not only on efficient reading, as observed in pure alexia, but also on the processing of complex non-orthographic visual stimuli. Consistent with this hypothesis, we obtained evidence that a large case series (n = 20) of patients with lesions centered on left pFG: 1) Exhibited reduced sensitivity to high spatial frequencies; 2) demonstrated prolonged response latencies both in reading (pure alexia) and object naming; and 3) were especially sensitive to visual complexity and similarity when discriminating between novel visual patterns. These results suggest that the patients' dual reading and non-orthographic recognition impairments have a common underlying mechanism and reflect the loss of high spatial frequency visual information normally coded in the left pFG

Verbal Learning with the Right Hemisphere

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Neural Substrates of Improvement Following Treatment in a Case of Phonological Agraphia/Alexia

Damage to left perisylvian regions often results in phonological alexia/agraphia syndromes, which are characterized by disproportionate difficulty reading or spelling novel sequences of phonemes or graphemes (pseudowords) compared to real words. A relatively small literature has documented that a sequence of behavioral treatments directed toward phonological skills and phonology-orthography relations can improve reading and spelling performance on pseudowords, with additional functional benefits for written language skills overall (e.g. Beeson et al., 2010). However, the neural substrates supporting these improvements remain to be elucidated. Because phonological processing is a strongly left-lateralized skill in most literate adults, we hypothesized that neural support for improvement is likely to remain in the left hemisphere. To examine this hypothesis, we conducted pre and post treatment fMRI with an individual with acquired phonological alexia/agraphia due to left hemisphere stroke before and after administration of treatment sequence to improve phonological skills

A comparison of errorless and errorful therapies for dysgraphia after stroke.

Despite the increasing significance of written communication, there is limited research into spelling therapy for adults with acquired dysgraphia. Existing studies have typically measured spelling accuracy as an outcome, although speed may also be important for functional writing. As spelling is relatively slow, effortful and prone to errors in people with dysgraphia, minimising errors within therapy could be a factor in therapy success. This within-participant case-series study investigated whether errorless and errorful therapies would differ in their effects on spelling speed and accuracy for four participants with acquired dysgraphia. Matched sets of words were treated with errorless or errorful therapy or left untreated. Results were collated one week and five weeks after therapy. Both therapy approaches were successful in improving spelling accuracy. For three participants, equivalent gains were demonstrated following errorless and errorful therapy. One participant made significantly greater improvements in spelling accuracy following errorless therapy. The effects were maintained five weeks later. There was no significant difference in post-therapy spelling speed between the two therapy conditions. The results of this study suggest that both errorful and errorless therapies can be effective methods with which to treat spelling in adults with acquired dysgraphia

Processing deficits for familiar and novel faces in patients with left posterior fusiform lesions

Pure alexia (PA) arises fromdamage to the left posterior fusiformgyrus (pFG) and the striking reading disorder that defines this condition has meant that such patients are often cited as evidence for the specialisation of this regiontoprocessing of writtenwords.There is,however, an alternative view that suggests this region is devoted to processing of high acuity foveal input, which is particularly salient for complex visual stimuli like letter strings. Previous reports have highlighted disrupted processing of non-linguistic visual stimuli after damage to the left pFG, both for familiar and unfamiliar objects and also for novel faces. This study explored the nature of face processing deficits in patients with left pFG damage. Identification of famous faces was found to be compromised in both expressive and receptive tasks. Discrimination of novel faces was also impaired, particularly for those that varied in terms of second-order spacing information, and this deficit was most apparent for the patients with the more severe reading deficits. Interestingly, discrimination of faces that varied in terms of feature identity was considerably better in these patients and it was performance in this condition that was related to the size of the length effects shown in reading. This finding complements functional imaging studies showing left pFG activation for faces varying only in spacing and frontal activation for faces varying only on features. These results suggest that the sequential part-based processing strategy that promotes the length effect inthe reading of these patients also allows themto discriminate between faces on the basis of feature identity, but processing of second-order configural information is most compromised due to their left pFG lesion. This study supports a view in which the left pFG is specialised for processing of high acuity foveal visual information that supports processing of both words and faces.variou

Dissociating Object Directed and Non-Object Directed Action in the Human Mirror System; Implications for Theories of Motor Simulation

Mirror neurons are single cells found in macaque premotor and parietal cortices that are active during action execution and observation. In non-human primates, mirror neurons have only been found in relation to object-directed movements or communicative gestures, as non-object directed actions of the upper limb are not well characterized in non-human primates. Mirror neurons provide important evidence for motor simulation theories of cognition, sometimes referred to as the direct matching hypothesis, which propose that observed actions are mapped onto associated motor schemata in a direct and automatic manner. This study, for the first time, directly compares mirror responses, defined as the overlap between action execution and observation, during object directed and meaningless non-object directed actions. We present functional MRI data that demonstrate a clear dissociation between object directed and non-object directed actions within the human mirror system. A premotor and parietal network was preferentially active during object directed actions, whether observed or executed. Moreover, we report spatially correlated activity across multiple voxels for observation and execution of an object directed action. In contrast to predictions made by motor simulation theory, no similar activity was observed for non-object directed actions. These data demonstrate that object directed and meaningless non-object directed actions are subserved by different neuronal networks and that the human mirror response is significantly greater for object directed actions. These data have important implications for understanding the human mirror system and for simulation theories of motor cognition. Subsequent theories of motor simulation must account for these differences, possibly by acknowledging the role of experience in modulating the mirror response