Similar within-utterance loci of dysfluency in acquired neurogenic and persistent developmental stuttering.

Although the underlying neural mechanisms remain unknown for both persistent developmental stuttering (PSD) and acquired neurogenic stuttering (ANS), few studies have examined similarities/differences between these two disorders. We evaluated in both PDS (n = 35) and ANS (n = 5) phonetic, word class, word length, and word position variables that are widely believed to influence at which loci within utterances PDS speakers' stuttering is most likely to occur. For both groups, (a) word weights based on the combination of variables were greater for stuttered vs. fluent words, and (b) stuttered words were loaded more by individual variables. However, contrary to long-standing views regarding PDS, greater loading for stuttered words was not found for the position variable. Findings suggest similar loci of stuttering in adults with PDS and ANS, and, for both groups, the probability of stuttering on a given word was more influenced by motor production variables than language variables.

Dysgraphia in two forms of conduction aphasia.

Recent clinical observations, in the absence of experimental data, appear to suggest that written expression in conduction aphasics parallels their speech (Goodglass, 1992). The current study undertakes an analysis of word level writing in two conduction aphasics, and attempts to explore the posited 'parallel' relationship between speech production deficits and deficits in written expression. JL, a 66-year-old female with left posterior parietal lobe lesion and PP, a 65-year-old female with a left posterior temporo-parietal lobe lesion served as subjects of this study. Their response patterns on Boston Naming Test (BNT) and written naming task (John Hopkins Dysgraphia Battery) were utilized to verify the parallel hypothesis. Although both cases have exhibited phonological and semantic paraphasias on BNT, PP's overall performance was far superior to that of JL. JL produced numerous multiple responses to stimuli compared to PP's occasional multiple responses. PP's performance on the written naming task was far inferior to that of JL. JL's predominant error pattern in writing was the production of phonologically similar words to the target words. This paper argues that such seemingly contradictory, unpredicted patterns can be parsimoniously better explained, not by the parallel hypothesis but by current cognitive-neuropsychological models of writing.

Crossed apraxia of speech: a case report.

The present study reports on the first case of crossed apraxia of speech (CAS) in a 69-year-old right-handed female (SE). The possibility of occurrence of apraxia of speech (AOS) following right hemisphere lesion is discussed in the context of known occurrences of ideomotor apraxias and acquired neurogenic stuttering in several cases with right hemisphere lesion. A current hypothesis on AOS-the dual route speech encoding (DRSE) hypothesis-and predictions based on DRSE were utilized to explore the nature of CAS in SE. One prediction based on the DRSE hypothesis is that there should be no difference in the frequency of occurrence of apraxic errors on words and non-words. This prediction was tested using a repetition task. The experimental stimuli included a list of minimal pairs that signaled voice-voiceless contrasts in words and non-words. Minimal-pair stimuli were presented orally, one at a time. SE's responses were recorded using audio and videotapes. Results indicate that SE's responses were characterized by numerous voicing errors. Most importantly, production of real word minimal pairs was superior to that of non-word minimal pairs. Implications of these results for the DRSE hypothesis are discussed with regard to currently developing perspectives on AOS.

Acquired stuttering following right frontal and bilateral pontine lesion: a case study.

We report neurological information and experimental data regarding acquired neurogenic stuttering in a 57-year-old male following ischemic lesion to the orbital surface of the right frontal lobe and the pons. The experimental data consist of stuttering frequency measures under various conditions that are well known to enhance fluency in most individuals with developmental stuttering. Specifically, we report data for adaptation, unison reading, delayed auditory feedback (DAF), and frequency altered feedback (FAF). This work is the first published report of such a comprehensive examination of a variety of fluency-enhancing conditions in acquired stuttering. The patient read six 200-word texts under different conditions: Six solo readings (Text 1), five unison readings followed by five solo readings (Text 2), five readings with non-altered auditory feedback (Text 3), five readings with 50 ms delayed auditory feedback (Text 4), five readings with increased FAF (Text 5), and five readings with decreased FAF (Text 6). Results indicate that, unlike the typical situation for developmental stuttering, this individual with acquired neurogenic stuttering did not show increased fluency during an adaptation paradigm or under unison, DAF, and FAF conditions. We discuss possible implications of these findings and emphasize the need for further research on acquired neurogenic stuttering.