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1.  Support for Anterior Temporal Involvement in Semantic Error Production in Aphasia: New Evidence from VLSM 
Brain and language  2010;117(3):110-122.
Semantic errors in aphasia (e.g., naming a horse as “dog”) frequently arise from faulty mapping of concepts onto lexical items. A recent study by our group used voxel-based lesion-symptom mapping (VLSM) methods with 64 patients with chronic aphasia to identify voxels that carry an association with semantic errors. The strongest associations were found in the left anterior temporal lobe (L-ATL), in the mid- to anterior MTG region. The absence of findings in Wernicke’s area was surprising, as were indications that ATL voxels made an essential contribution to the post-semantic stage of lexical access. In this follow-up study, we sought to validate these results by re-defining semantic errors in a manner that was less theory dependent and more consistent with prior lesion studies. As this change also increased the robustness of the dependent variable, it made it possible to perform additional statistical analyses that further refined the interpretation. The results strengthen the evidence for a causal relationship between ATL damage and lexically-based semantic errors in naming and lend confidence to the conclusion that chronic lesions in Wernicke’s area are not causally implicated in semantic error production.
PMCID: PMC3037437  PMID: 20961612
aphasia; voxel-based lesion-symptom mapping; naming; semantic; errors
2.  Short form Philadelphia Naming Test: Rationale and Empirical Evaluation 
To create two matched short forms of the Philadelphia Naming Test (PNT) that yield similar results to the PNT for measuring anomia.
Study 1: We first used archived naming data from 94 aphasic individuals to identify which PNT items should be included in the short forms, and the two constructed sets of 30 items, PNT30-A and PNT30-B, were validated using archived data from a separate group of 56 aphasic individuals. Study 2: We then evaluated the reliability of the PNT, PNT30-A, and PNT30-B across independent test administrations with a new group of 25 aphasic individuals selected to represent the full range of naming impairment.
Study 1: PNT30-A and PNT30-B were found to be internally consistent; and accuracy scores on these subsets of items were highly correlated with the full PNT. Study 2: PNT accuracy was extremely reliable over the span of one week; and independent administrations of PNT30-A and PNT30-B produced similar results to the PNT and to each other.
The short forms can be used to reliably estimate PNT performance, and the results can be compared to the provided norms. The two matched tests allow for measurement of change in naming ability.
PMCID: PMC3397242  PMID: 22294412
Aphasia; Assessment; Speech production; Stroke
3.  A large, searchable, web-based database of aphasic performance on picture naming and other tests of cognitive function 
Cognitive neuropsychology  2011;27(6):495-504.
Many research questions in aphasia can only be answered through access to substantial numbers of patients and to their responses on individual test items. Since such data are often unavailable to individual researchers and institutions, we have developed and made available the Moss Aphasia Psycholinguistics Project Database: a large, searchable, web-based database of patient performance on psycholinguistic and neuropsychological tests. The database contains data from over 170 patients covering a wide range of aphasia subtypes and severity, some of whom were tested multiple times. The core of the archive consists of a detailed record of individual-trial performance on the Philadelphia (picture) Naming Test. The database also contains basic demographic information about the patients and patients' overall performance on neuropsychological assessments as well as tests of speech perception, semantics, short-term memory, and sentence comprehension. The database is available at
PMCID: PMC3162111  PMID: 21714742
aphasia; database; picture naming; language
4.  Anterior temporal involvement in semantic word retrieval: voxel-based lesion-symptom mapping evidence from aphasia 
Brain  2009;132(12):3411-3427.
Analysis of error types provides useful information about the stages and processes involved in normal and aphasic word production. In picture naming, semantic errors (horse for goat) generally result from something having gone awry in lexical access such that the right concept was mapped to the wrong word. This study used the new lesion analysis technique known as voxel-based lesion-symptom mapping to investigate the locus of lesions that give rise to semantic naming errors. Semantic errors were obtained from 64 individuals with post-stroke aphasia, who also underwent high-resolution structural brain scans. Whole brain voxel-based lesion-symptom mapping was carried out to determine where lesion status predicted semantic error rate. The strongest associations were found in the left anterior to mid middle temporal gyrus. This area also showed strong and significant effects in further analyses that statistically controlled for deficits in pre-lexical, conceptualization processes that might have contributed to semantic error production. This study is the first to demonstrate a specific and necessary role for the left anterior temporal lobe in mapping concepts to words in production. We hypothesize that this role consists in the conveyance of fine-grained semantic distinctions to the lexical system. Our results line up with evidence from semantic dementia, the convergence zone framework and meta-analyses of neuroimaging studies on word production. At the same time, they cast doubt on the classical linkage of semantic error production to lesions in and around Wernicke's area.
PMCID: PMC2792374  PMID: 19942676
aphasia; voxel-based lesion-symptom mapping; naming; semantic; errors

Results 1-4 (4)