A two-route model of speech production. Evidence from aphasia.
ABSTRACT Quantitative investigations of speech production deficits are reported in three aphasic patients. Two had impaired paraphasic performance in repetition tasks but relatively well preserved spontaneous speech (conduction aphasia). The other patient had impaired paraphasic spontaneous speech but intact repetition (transcortical motor aphasia). In repetition tasks which required active semantic processing the conduction aphasics were facilitated and the transcortical motor aphasic impaired; in tasks which required passive repetition the opposite pattern of dissociation was observed. These findings are accounted for within a two-route model of the speech production process.
- SourceAvailable from: Scott K Holland[Show abstract] [Hide abstract]
ABSTRACT: The ability to comprehend narratives constitutes an important component of human development and experience. The neural correlates of auditory narrative comprehension in children were investigated in a large-scale functional magnetic resonance imaging (fMRI) study involving 313 subjects ages 5-18. Using group independent component analysis (ICA), bilateral task-related components were found comprising the primary auditory cortex, the mid-superior temporal gyrus, the hippocampus, the angular gyrus, and medial aspect of the parietal lobule (precuneus/posterior cingulate). In addition, a right-lateralized component was found involving the most posterior aspect of the superior temporal gyrus, and a left-lateralized component was found comprising the inferior frontal gyrus (including Broca's area), the inferior parietal lobule, and the medial temporal gyrus. Using a novel data-driven analysis technique, increased task-related activity related to age was found in the components comprising the mid-superior temporal gyrus (Wernicke's area) and the posterior aspect of the superior temporal gyrus, while decreased activity related to age was found in the component comprising the angular gyrus. The results are discussed in light of recent hypotheses involving the functional segregation of Wernicke's area and the specific role of the mid-superior temporal gyrus in speech comprehension.NeuroImage 02/2006; 29(1):254-66. DOI:10.1016/j.neuroimage.2005.07.020 · 6.13 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: Goldberg (1985) hypothesized that as language output changes from internally to externally guided production, activity shifts from supplementary motor area (SMA) to lateral premotor areas, including Broca's area. To test this hypothesis, 15 right-handed native English speakers performed three word generation tasks varying in the amount of internal guidance and a repetition task during functional magnetic resonance imaging (fMRI). Volumes of significant activity for each task versus a resting state were derived using voxel-by-voxel repeated-measures t tests (p <.001) across subjects. Changes in the size of activity volumes for left medial frontal regions (SMA and pre-SMA/BA 32) versus left lateral frontal regions (Broca's area, inferior frontal sulcus) were assessed as internal guidance of word generation decreased and external guidance increased. Comparing SMA to Broca's area, Goldberg's hypothesis was not verified. However, pre-SMA/BA 32 activity volumes decreased significantly and inferior frontal sulcus activity volumes increased significantly as word generation tasks moved from internally to externally guided.Journal of Cognitive Neuroscience 03/2001; 13(2):272-83. DOI:10.1162/089892901564225 · 4.69 Impact Factor
- [Show abstract] [Hide abstract]
ABSTRACT: We present a patient (PW) with non-fluent progressive aphasia, characterized by severe word finding difficulties and frequent phonemic paraphasias in spontaneous speech. It has been suggested that such patients have insufficient access to phonological information for output and cannot construct the appropriate sequence of selected phonemes for articulation. Consistent with such a proposal, we found that PW was impaired on a variety of verbal tasks that demand access to phonological representations (reading, repetition, confrontational naming and rhyme judgement); she also demonstrated poor performance on syntactic and grammatical processing tasks. However, examination of PW's repetition performance also revealed that she made semantic paraphasias and that her performance was influenced by imageability and lexical status. Her auditory-verbal short-term memory was also severely compromised. These features are consistent with 'deep dysphasia', a disorder reported in patients suffering from stroke or cerebrovascular accident, and rarely reported in the context of non-fluent progressive aphasia. PW's pattern of performance is evaluated in terms of current models of both non-fluent progressive aphasia and deep dysphasia.Neurocase 02/2001; 7(6):473-88. DOI:10.1093/neucas/7.6.473 · 1.38 Impact Factor