The dorsal stream contribution to phonological retrieval in object naming

1 Moss Rehabilitation Research Institute, Einstein Healthcare Network, Elkins Park, PA 19027, USA.
Brain (Impact Factor: 9.2). 11/2012; 135(12). DOI: 10.1093/brain/aws300
Source: PubMed


Meaningful speech, as exemplified in object naming, calls on knowledge of the mappings between word meanings and phonological forms. Phonological errors in naming (e.g. GHOST named as 'goath') are commonly seen in persisting post-stroke aphasia and are thought to signal impairment in retrieval of phonological form information. We performed a voxel-based lesion-symptom mapping analysis of 1718 phonological naming errors collected from 106 individuals with diverse profiles of aphasia. Voxels in which lesion status correlated with phonological error rates localized to dorsal stream areas, in keeping with classical and contemporary brain-language models. Within the dorsal stream, the critical voxels were concentrated in premotor cortex, pre- and postcentral gyri and supramarginal gyrus with minimal extension into auditory-related posterior temporal and temporo-parietal cortices. This challenges the popular notion that error-free phonological retrieval requires guidance from sensory traces stored in posterior auditory regions and points instead to sensory-motor processes located further anterior in the dorsal stream. In a separate analysis, we compared the lesion maps for phonological and semantic errors and determined that there was no spatial overlap, demonstrating that the brain segregates phonological and semantic retrieval operations in word production.

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Available from: Junghoon Kim, Mar 16, 2014
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    • "Cytoarchitectonically, area Spt falls within area Tpt in the planum temporale/parietal operculum region which is not cellularly characteristic of nearby auditory cortex (Galaburda and Sanides, 1980), but rather shares features with Broca's area (Galaburda, 1982). Lesion-symptom and lesion-parameter mapping work has implicated the temporal– parietal junction in speech repetition (present study and reviewed above), as well as in phonological-level aspects of speech production (Dell et al., 2013; Schwartz et al., 2012). Both functional (Buchsbaum et al., 2001, 2005) and structural connectivity (Isenberg et al., 2012) studies have suggested a tight relation between Spt and the pars opercularis of Broca's area. "
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    ABSTRACT: For more than a century, speech repetition has been used as an assay for gauging the integrity of the auditory-motor pathway in aphasia, thought classically to involve a linkage between Wernicke's area and Broca's area via the arcuate fasciculus. During the last decade, evidence primarily from functional imaging in healthy individuals has refined this picture both computationally and anatomically, suggesting the existence of a cortical hub located at the parietal-temporal boundary (area Spt) that functions to integrate auditory and motor speech networks for both repetition and spontaneous speech production. While functional imaging research can pinpoint the regions activated in repetition/auditory-motor integration, lesion-based studies are needed to infer causal involvement. Previous lesion studies of repetition have yielded mixed results with respect to Spt's critical involvement in speech repetition. The present study used voxel-based lesion symptom mapping (VLSM) to investigate the neuroanatomy of repetition of both real words and non-words in a sample of 47 patients with focal left hemisphere brain damage. VLSMs identified a large voxel cluster spanning gray and white matter in the left temporal-parietal junction, including area Spt, where damage was significantly related to poor non-word repetition. Repetition of real words implicated a very similar dorsal network including area Spt. Cortical regions including Spt were implicated in repetition performance even when white matter damage was factored out. In addition, removing variance associated with speech perception abilities did not alter the overall lesion pattern for either task. Together with past functional imaging work, our results suggest that area Spt is integral in both word and non-word repetition, that its contribution is above and beyond that made by white matter pathways, and is not driven by perceptual processes alone. These findings are highly consistent with the claim that Spt is an area of sensory-motor translation in speech processing. Copyright © 2015. Published by Elsevier Ltd.
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    • "alysis was impossible . Patients in the apraxic group appear to have frontal and subcortical lesions more often , but our information is too limited to carry out statistical analyses . Voxel - based symptom - lesion mapping should be used by future studies to distinguish lesion sites in patients with different types of sound errors ( e . g . , see Schwartz et al . , 2012 , for a dis - tinction between phonological and semantic errors ) ."
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    • "Lesions superior to the Sylvian fissure, primarily in the supramarginal gyrus and extending anteriorly into inferior postcentral, precentral, and premotor cortex were associated with lower scores on the Speech Production factor (Fig. 6, blue–green). That is, speech production deficits were associated with damage to the dorsal language pathway, consistent with claims that this region is involved in sensorymotor transformations that support speech production (e.g., Buchsbaum et al., 2011; Hickok and Poeppel, 2007; Schwartz et al., 2012). Lesions in a parallel region, inferior to the Sylvian fissure, primarily in the posterior superior temporal gyrus and extending deep into planum temporale were associated with lower scores on the Speech Recognition factor (Fig. 6, red-yellow). "
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