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Karalyn Patterson

Publications and source records attributed to Karalyn Patterson.

17 recordsLinked to original sources
PubMed2003

Language function and dysfunction in corticobasal degeneration.

OBJECTIVE: S: The authors assessed language functioning in corticobasal degeneration (CBD), an area that has received little systematic study. Aphasia has been reported occasionally, and the authors hypothesized that appropriate assessments would reveal at least mild language impairment, particularly affecting phonologic (sound-based) processing, even in cases without frank aphasia. METHODS: A series of 10 unselected patients with CBD (one with pathologic confirmation) were administered neuropsychological tests assessing the following aspects of cognitive functioning: verbal fluency, naming, reading, oral spelling, auditory-verbal short-term memory, phoneme blending and segmentation, visuospatial skills, and semantic memory. RESULTS: Phonologic and spelling impairments were prevalent, even in nonaphasic patients. The prevalence of visuospatial, constructional, and frontal impairments, demonstrated in previous research, was also replicated. A minority of patients had deficits in semantic memory, naming, and reading, but the impairments were usually mild. CONCLUSIONS: The authors found phonologic impairment to be a typical feature of CBD. There is substantial overlap between progressive nonfluent aphasia and CBD, and the linguistic impairment can be thought of as a continuum, with mild phonologic impairment at one end and severe aphasia at the other.

Aged↗
PubMed2003

Progressive non-fluent aphasia is associated with hypometabolism centred on the left anterior insula.

Progressive non-fluent aphasia (PNFA) is a syndrome in which patients lose the ability to communicate fluently in the context of relative preservation of single word comprehension and non-linguistic cognitive abilities. Neuroimaging in case studies with PNFA has failed to identify a consistent neural substrate for the language disorder. In this study of a group of patients (n=10) whose presenting complaint was progressive dysfluency, resting cerebral metabolism was measured using [18F]fluorodeoxyglucose-PET and analysed with the technique of statistical parametric mapping (SPM). Regional atrophy was assessed with voxel-based morphometry (VBM). Seven patients had a 'pure' PNFA syndrome, while the remaining three had additional features of a more pervasive dementia. Compared with controls, the patients showed hypometabolism in several regions that, most notably, included the left anterior insula/frontal opercular region. The VBM analysis revealed only one small area of atrophy in the left peri-Sylvian region. Analysis of the pure PNFA cases (n=7) relative to controls yielded qualitatively similar results to those of the whole group, suggesting that these cases were also at risk of a more generalized dementia, a finding borne out in subsequent follow-up of two cases to date. The PNFA group was then compared with a group with Alzheimer's disease (n=10) whose clinical profile did not include non-fluent aphasic features. In this analysis, the only persisting hypometabolic region was that centred over the left anterior insula. VBM did not identify any regional differences in atrophy between PNFA and Alzheimer's disease. In the light of current theories of fluent language production, the findings offer anatomical evidence that the breakdown in fluency is due to a motor articulatory planning deficit (speech apraxia) combined with a variable degree of agrammatism.

Aged↗
PubMed2003

Homogeneity and heterogeneity in mild cognitive impairment and Alzheimer's disease: a cross-sectional and longitudinal study of 55 cases.

This study investigated cross-sectional and longitudinal neuropsychological data from 55 patients: 38 with Alzheimer's disease and 18 with mild cognitive impairment (MCI). The analyses were designed to investigate two issues: the relationship of MCI to Alzheimer's disease, and that of atypical to typical Alzheimer's disease. When longitudinal data were averaged across individual patients, a consistent staging of neuropsychological deficits emerged: the selective amnesia characteristic of the MCI phase was joined next by semantic and other linguistic impairments plus emerging difficulties with demanding visuospatial tasks. A two-stage statistical procedure was used to extract underlying factors that corresponded to the severity-governed decline in neuropsychological test scores and then to the consistent deviations away from this typical longitudinal profile; i.e. identifying patterns of atypical Alzheimer's disease. The severity-based factor accounted for nearly 60% of the variance in this MCI-Alzheimer's disease longitudinal and cross-sectional database. This suggests that there is a fairly high degree of homogeneity within this group of patients, and that most of their longitudinal progression can be predicted by dementia severity alone. There were also two main patterns of atypical variation corresponding to patients with exaggerated semantic or visuospatial deficits. Although such cases may mimic more focal lobar degenerative conditions, patients with atypical Alzheimer's disease have pronounced episodic memory impairments, suggesting amnesia as a critical diagnostic feature.

Alzheimer Disease↗
PubMed2003

Actions speak louder than functions: the importance of manipulability and action in tool representation.

PET was used to investigate the neural correlates of action knowledge in object representations, particularly the left lateralized network of activations previously implicated in the processing of tools and their associated actions: ventral premotor cortex (VPMCx), posterior middle temporal gyrus (PMTG), and intraparietal sulcus (IPS). Judgments were made about the actions and functions associated with manipulable man-made objects (e.g., hammer); this enabled us to measure activations in response to both explicit and implicit retrieval of knowledge about actions associated with manipulable tools. Function judgments were also made about nonmanipulable artifacts (e.g., traffic light) providing a direct comparison for manipulable objects. Although neither the left VPMCx nor the left PMTG were selective for tool stimuli (nonmanipulable objects also activated these areas relative to a visual control condition), both regions responded more strongly to manipulable objects, suggesting a role for these cortical areas in the processing of knowledge associated with tools. Furthermore, these activations were insensitive to retrieval task, suggesting that visually presented tools automatically recruit both left VPMCx and left PMTG in response to action features that are inherent in tool representations. In contrast, the IPS showed clear selectivity for explicit retrieval of action information about manipulable objects. No regions of cortex were more activated by function relative to action judgments about artifacts. These results are consistent with the brain's preferential responsiveness to how we interact with objects, rather than what they are used for.

Adult↗
PubMed2003

Involvement of the medial temporal lobe in priming for new associations.

This study was addressed to the question of whether the medial temporal lobe (MTL) plays a critical role in implicit memory for new associations. Priming for new associations was examined in two different tasks in 18 patients with focal lesions all involving the MTL. In Experiment 1, following a study phase for pairs of unrelated words, subjects performed a perceptual identification task on old, recombined, and new pairs of words presented at brief exposure durations. In contrast to control subjects, and despite a normal level of item priming, the patients failed to show superior identification of the old pairs relative to the recombined pairs, the measure of associative priming. In Experiment 2, subjects engaged in speeded naming of the print color for previously studied words presented in the original color or in a different old color, and for unstudied words. Again, in contrast to control subjects and despite a normal level of item facilitation on color naming reaction time (RT), the patients failed to show priming for recently experienced new associations between words and colors. Explicit recognition memory by the patients was abnormal in both experiments. This study records an absence of priming for new associations, in two different tasks in which the nature of the stimuli was considerably different, in a large group of patients with lesions in the MTL. Although some previous research has reported significant associative priming in other tasks for patients with MTL lesions, the present results suggest that this region is critical for forming new associations of the types assessed here.

Adolescent↗
PubMed2003

Surface dyslexia in a Japanese patient with semantic dementia: evidence for similarity-based orthography-to-phonology translation.

We studied the reading performance of a Japanese-speaking patient, TI, with bilateral but asymmetrical (left more than right) temporal-lobe atrophy, severe anomia, and poor word comprehension. Most Japanese kanji characters correspond to several different legitimate pronunciations in different contexts, with varying degrees of correspondence consistency. TI made many errors in reading aloud words that violate statistically typical character-sound correspondences, especially for less common words, but had relatively preserved ability to read aloud strings in which the assignment of the typical pronunciation for each component character yields the correct pronunciation for the whole word. The degree of consistency of character-sound correspondences affected his performance on both words and nonwords in a graded manner. One interpretation is that TI's surface dyslexic reading reflects intact direct computation of phonology from orthography, but without the additional constraint from word meaning that is, in this framework, considered critical for correct pronunciation of lower-frequency words with atypical character-sound correspondences. Another interpretation is that TI's performance reflects partially damaged lexical knowledge of whole-word orthography and phonology, coupled with spared sublexcal knowledge of character-sound correspondence rules. Whichever of these interpretations is preferred, this study offers the most detailed information yet available on the characteristics of surface dyslexia in Japanese.

Dementia↗
PubMed2003

What does the object decision task measure? Reflections on the basis of evidence from semantic dementia.

The authors investigated the impact of semantic knowledge on visual object analysis by assessing the performance of patients with semantic dementia on a different-views object matching test and on 2 object decision tests differing, for example, in whether the nonreal items were nonsense objects or chimeras of 2 real objects. On average, the patients scored normally on both the object matching and the object decision test including nonsense objects but were impaired on the object decision test including chimeras; this latter was also the only visual object test that correlated significantly with degree of semantic impairment. These findings demonstrate that object decision is not a single task or ability and that it is not necessarily independent of conceptual knowledge.

Aged↗
PubMed2002

Rules or connections in past-tense inflections: what does the evidence rule out?

Pinker and colleagues propose two mechanisms - a rule system and a lexical memory - to form past tenses and other inflections. They predict that children's acquisition of the regular inflection is sudden; that the regular inflection applies uniformly regardless of phonological, semantic or other factors; and that the rule system is separably vulnerable to disruption. A connectionist account makes the opposite predictions. Pinker has taken existing evidence as support for his theory, but the review of the evidence presented here contradicts this assessment. Instead, it supports all three connectionist predictions: gradual acquisition of the past tense inflection; graded sensitivity to phonological and semantic content; and a single, integrated mechanism for regular and irregular forms, dependent jointly on phonology and semantics.

Journal Article↗
PubMed2002

Regional brain activations differ for semantic features but not categories.

Is human semantic knowledge neurally organised according to either category (e.g. living non-living) or attribute type (e.g. perceptual non-perceptual information)? Normal subjects were scanned using PET during a novel semantic production task, in which they generated either perceptual or non-perceptual information in response to names of living or non-living concepts. Analyses of blood flow in the temporal lobes revealed no significant differences associated with responses to living non-living concepts. Comparisons between retrieval of perceptual non-perceptual information, however, revealed significantly greater blood flow in left posterior inferior temporal cortex and right fusiform cortex associated with perceptual information and in left middle temporal cortex with non-perceptual information. These findings support a primarily attribute-based neural organisation of semantic knowledge.

Adult↗
PubMed2002

Apraxia, mechanical problem solving and semantic knowledge: contributions to object usage in corticobasal degeneration.

To investigate the nature of the apraxia in corticobasal degeneration (CBD) five patients with CBD and five matched controls were compared on tests of: i) meaningless and symbolic gesture production, ii) a battery of semantic tasks based on 20 everyday items (involving naming and picture-picture matching according to semantic attributes, matching gestures-to-objects, object usage from name and with the real object) and iii) a novel tool test of mechanical problem solving. All five patients showed severe impairment in the production of meaningless and symbolic gestures from command, and by imitation, and were also impaired when using real objects. Deficits were not, however, restricted to action production: four were unable to match gestures to objects and all five showed impairment in the selection and usage of novel tools in the mechanical problem solving task. Surprising was the finding of an additional semantic knowledge breakdown in three cases, two of whom were markedly anomic. The apraxia in CBD is, therefore, multifactorial. There is profound breakdown in the organisation and co-ordination of motor programming. In addition, patients show central deficits in action knowledge and mechanical problem solving, which has been linked to parietal lobe pathology. General semantic memory may also be affected in CBD in some cases and this may then contribute to impaired object usage. This combination of more than one deficit relevant for object use may explain why CBD patients are far more disabled by their dyspraxia in everyday life than any other patient group.

Aged↗
PubMed2002

Is knowledge of famous people disproportionately impaired in patients with early and questionable Alzheimer's disease?

Twenty-two patients with early dementia of Alzheimer's type (DAT) and 31 controls were administered tests of person-specific semantics (Experiment 1). DAT patients were impaired on all test components. In Experiment 2, 31 DAT patients, 28 questionable DAT (QDAT) patients, and 42 controls were administered the Graded Naming Test (GNT) and the newly designed Graded Faces Test (GFT), matched for difficulty with the GNT. DAT patients were impaired throughout but showed an advantage for naming objects over faces. The QDAT patients were impaired on the GFT only. Of the 7 QDAT patients who evolved to DAT within 1-2 years, 6 showed initial impairment on the GFT, whereas 17 of the nonconverters scored normally on the GFT. Results suggest greater and earlier vulnerability of person knowledge than general semantic knowledge in DAT.

Aged↗
PubMed2002

Multiple inputs to episodic memory: words tell another story.

Seven patients with semantic dementia were asked to recall and recognize 10-word lists of object-name vocabulary preselected as either still "known" (correct picture naming and word-picture matching) or now "unknown" (incorrect picture naming and word-picture matching) to each individual patient. The patients showed a significant advantage for known words in immediate free recall after several learning trials and also in delayed recall and recognition. The majority of errors of commission for known words were semantic, whereas phonological errors, especially blends of target words, were produced in the unknown condition. These findings support claims that (a) multiple inputs from semantic and perceptual systems support episodic memory and (b) success in verbal and nonverbal episodic memory tasks is differentially dependent on semantic and perceptual information.

Aged↗
PubMed2002

Theories of word naming interact with spelling-sound consistency.

In a previous study (E. Strain, K. Patterson, & M. S. Seidenberg, 1995), the authors concluded that word naming is characterized by an interaction between spelling-sound typicality and word imageability, thus implicating a role for word meaning in the naming process. J. Monaghan and A. W. Ellis (2002) reject E. Strain et al.'s conclusion, arguing that it is age of acquisition (AoA) and not imageability that interacts with spelling-sound typicality. In this article, the authors question their alternative interpretation (a) by raising a number of conceptual and methodological issues germane to this debate and (b) by presenting new data that confirm a significant interaction between spelling-sound typicality and imageability in word-naming latencies, an interaction that is reliable when word AoA is controlled in a regression analysis.

Adult↗
PubMed2002

The influence of personal familiarity and context on object use in semantic dementia.

Several laboratory experiments assessing the ability of patients with semantic dementia to use familiar objects have revealed deficits corresponding directly to the patients' remaining conceptual knowledge for the same items. The same patients, however, were reported to demonstrate normal use of some objects relevant to their everyday lives. The study reported here was designed to explore this apparent discrepancy by examining the influence of personal familiarity with object exemplars, and of the contexts in which they are typically used. Two patients with severe semantic impairment were given single objects that they were still using at home on a regular basis and asked to demonstrate the use of each. Performance on these items was compared with use of perceptually similar and perceptually different exemplars of the same objects. All three sets were tested in the patients' own homes and also in the laboratory. Both patients were significantly more successful at using their own objects than the perceptually different exemplars, while an advantage for 'own' relative to similar exemplars characterized one of the two patients. Familiar home context had no impact on performance. The results suggest that repeated experience with personally familiar objects helps to maintain appropriate responses to them in the face of severely degraded conceptual knowledge.

Activities of Daily Living↗
PubMed2002

When objects lose their meaning: what happens to their use?

The 8 patients involved in this study were impaired on tests assessing knowledge of objects and on the demonstration of their use. The patients' success in object use was significantly correlated with their knowledge about the objects, providing further evidence that conceptual knowledge plays a key role in object use. Having a recipient present improved performance in the moderately impaired patients, suggesting that a certain level of conceptual knowledge must remain for the additional information to be beneficial. Although overall accuracy in using the target objects was not related to our measures of affordance, the specific aspects of use afforded by the objects' structures were relatively impervious to semantic impairment, suggesting a role for affordance information when object-specific knowledge is disrupted. The patients' familiarity with the objects was an important predictor of performance. Finally, despite good performance on tests of mechanical problem solving, the patients showed very little evidence of employing these skills in their interactions with real objects.

Aged↗