Posterior cortical atrophy (PCA) and logopenic variant primary progressive aphasia (LvPPA) are considered early-onset dementias most commonly caused by Alzheimer pathology. PCA is characterized by a progressive decline in higher order visual processing functions, whereas LvPPA is a form of primary progressive aphasia. The clinical presentation of both syndromes is typically earlier in life relative to the more typical “amnestic” form of Alzheimer disease. Prominent language deficits have been well described in PCA. Here, we describe the case of a 56-year-old man presenting with overlapping anatomic, clinical, and cognitive features of PCA and LvPPA and review the existing literature relating to the clinical features shared by these conditions, exploring the etiology, and implications for clinical practice in cases with a PCA-LvPPA overlap syndrome. In PCA, atrophy occurs in temporoparietal-occipital regions, whereas in LvPPA atrophy occurs at the temporoparietal junctions, with left-sided predominance. A defective phonological loop (a short-term storage system which holds speech sounds in memory for 1 to 2 s) seems to underlie the logopenic syndrome in both conditions. Other parietal lobe deficits, in proximity to both language and visual processing areas, such as dyscalculia and ideomotor apraxia are also commonly found in both conditions. We suspect that cases with an overlap PCA-LvPPA syndrome are relatively underreported which may relate to the fact that these cases occur on a spectrum depending on the stage of disease progression and do not easily fit into strict diagnostic categories according to existing criteria of PCA and LvPPA, respectively.
Visual mathematic notation provides a succinct and unambiguous description of the structure of mathematical formulae in a manner that is difficult to replicate through the linear channels of synthesized speech and Braille. It is proposed that the use of auditory cues can enhance accessibility to mathematical material and reduce common ambiguities encountered through spoken mathematics. However, the use of additional complex hierarchies of non-speech sounds to represent the structure and scope of equations may be cognitively demanding to process. This can detract from the users' understanding of the mathematical content. In this paper, a new system is presented, which uses a mixture of non-speech auditory cues, modified speech (spearcons) and binaural spatialization to disambiguate the structure of mathematical formulae. A design study, involving an online survey with 56 users, was undertaken to evaluate an existing set of auditory cues and to brainstorm alternative ideas and solutions from users before implementing modified designs and conducting a separate controlled evaluation. It is proposed that by involving a wide number of users in the creative design process, intuitive auditory cues will be implemented with the potential to enhance spoken mathematics for visually impaired users.
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