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Impaired day-to-day communication in nonaphasic frontotemporal dementia patients with a disorder of social comportment and executive functioning is due in part to a striking deficit in discourse organization associated with right frontotemporal disease. Difficulty with discourse in progressive aphasia is due largely to the language impairments of these patients.

This paper investigates the perceptual aspect of quantitative sociolinguistic variation in order to derive properties of a sociolinguistic monitor integrated into linguistic processing in real time. A series of experiments measured listeners' sensitivity to frequencies in the form of variable percentages of the non-standard apical form of the variable (ING). Subjects heard ten trial readings of broadcast news from the same speaker, and rated them on a seven-point Likert scale of professional suitability. Responses conformed closely to a logarithmic function in which the effect of each deviation from the norm was proportional to the percent increase in deviations. The logarithmic pattern of responses was replicated in group and individual experiments in Philadelphia, Pennsylvania, and in group experiments in Columbia, South Carolina and Durham, New Hampshire. South Carolina subjects were less critical of the /in/ variant in news broadcasting but showed the identical logarithmic function in reacting to Northern and Southern speakers. Inferences are drawn on the window of temporal resolution of the sociolinguistic monitor, its sensitivity and the pattern of attenuation over time.

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We investigated the cognitive and neural bases of impaired speech fluency, a central feature of primary progressive aphasia. Speech fluency was assessed in 35 patients with frontotemporal lobar degeneration (FTLD) who presented with progressive non-fluent aphasia (PNFA, n=11), semantic dementia (SemD, n=12), or a social and executive disorder without aphasia (SOC/EXEC, n=12). Fluency was quantified as the number of words per minute in an extended, semi-structured speech sample. This was related to language characteristics of the speech sample and to neuropsychological measures. PNFA patients were significantly less fluent than controls and other FTLD patients. Fluency correlated with grammatical expression but not with speech errors or executive difficulty. SemD and SOC/EXEC patients were also less fluent than controls. In SemD, fluency was associated with semantically limited content. In SOC/EXEC, fluency was associated with executive limitations. Voxel-based morphometry analyses of high-resolution MRI related fluency to gray matter volume in left inferior frontal, insula, and superior temporal regions for the entire cohort of FTLD patients. This region overlapped partially distinct atrophic areas in each FTLD subgroup. It thus appears to play a crucial role in speech fluency, which can be interrupted in different ways in different FTLD subgroups.