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K Patterson

Publications and source records attributed to K Patterson.

At least 55 records · Page 3Linked to original sources
PubMed1999

Is a picture worth a thousand words? Evidence from concept definitions by patients with semantic dementia.

Nine patients with semantic dementia (the temporal lobe variant of frontotemporal dementia) were asked to define concrete concepts either from presentation of a picture of the object or from its spoken name. As expected, the patients with the most severe semantic impairment produced the least detailed definitions, and the quality of the definitions overall was significantly related to concept familiarity. Further analyses of the definitions were designed to assess two key theoretical aspects of semantic organization. (i) Do objects and their corresponding names activate conceptual information in two neuroanatomically separable (modality-specific) semantic systems? If so, then-apart from any expected commonality in performance attributable to factors such as concept familiarity-one would not predict striking item-specific similarities in a patient's picture- and word-elicited definitions. (ii) Do sensory/perceptual features and more associative/functional attributes of conceptual knowledge form two neuroanatomically separable subsystems? If so, then one would predict significant dissociations in the prominence of these two types of information in the patients' definitions. The results lead us to favor a model of the semantic system that is divided by attribute type but not by modality.

Aged↗
PubMed1999

Myotonic dystrophy and progressive cognitive decline: a common condition or two separate problems?

We report the case of NG, a 43-year old woman with myotonic dystrophy (MYD) who has shown a slow decline in both motor and cognitive abilities since her referral to us at age 32. MYD is an autosomal dominant disorder characterised by weakening and wasting of the muscles together with impaired muscle relaxation. Cognitive abilities are usually little affected in the adult onset form, although there is a high risk of cognitive impairment in those with childhood onset. Cognitive decline is also typically associated with maternal inheritance. NG, who was diagnosed with MYD at the age of 18, inherited it from her father. We report the decline in NG's cognitive abilities over 11 years of longitudinal assessment, and consider whether she is an atypical MYD patient or whether the MYD and cognitive decline are attributable to two separate pathological processes.

Adolescent↗
PubMed1999

Selective disorders of reading?

Over the past few decades, refined cognitive architectures with highly specific components have been proposed to explain apparently selective disorders of reading, resulting from brain disease or injury, in previously literate adults. Recent analysis of the more general linguistic and cognitive abilities supported by neural systems damaged in the various forms of alexia favours a rather different view of reading and the kinds of models sufficient to account for its acquisition, skilled performance and disruption.

Adult↗
PubMed1999

Episodic memory: new insights from the study of semantic dementia.

The study of patients with semantic dementia, the temporal variant of frontotemporal dementia, has provided new insights into the interaction between episodic and semantic memory, and the different roles played by various structures in the temporal lobe. Recent findings indicate that the syndrome of semantic dementia can inform us about the organisation of long-term memory and the relationship between semantic memory and other cognitive systems.

Dementia↗
PubMed1999

Evidence for impaired sentence comprehension in early Alzheimer's disease.

We investigated sentence comprehension in 46 patients with probable minimal (very mild), mild, or moderate dementia of the Alzheimer type (DAT), comparing their performance on the Test for the Reception of Grammar (TROG), with that of 20 age- and education-matched controls. Performance on the TROG was generally related to dementia severity, independent of lexicosemantic and working memory (digit span) impairments, but related to at least 1 measure of attention. Some patients in the minimal group showed sentence comprehension deficits while others in the moderate group did not, indicating that DAT may impair sentence comprehension at the very earliest stages of disease, but that its effects are heterogeneous. Patients were most impaired on sentences with 2 propositions and noncanonical word order, suggesting difficulties with both interpretative and postinterpretative stages of sentence processing. Further investigation is needed into the relationship between attentional processes, interpretative and postinterpretative stages of syntactic processing in DAT.

Age Factors↗
PubMed1999

The differentiation of semantic dementia and frontal lobe dementia (temporal and frontal variants of frontotemporal dementia) from early Alzheimer's disease: a comparative neuropsychological study.

The authors compared age-matched groups of patients with the frontal and temporal lobe variants of frontotemporal dementia (FTD; dementia of frontal type [DFT] and semantic dementia), early Alzheimer's disease (AD), and normal controls (n = 9 per group) on a comprehensive neuropsychological battery. A distinct profile emerged for each group: Those with AD showed a severe deficit in episodic memory with more subtle, but significant, impairments in semantic memory and visuospatial skills; patients with semantic dementia showed the previously documented picture of isolated, but profound, semantic memory breakdown with anomia and surface dyslexia but were indistinguishable from the AD group on a test of story recall; and the DFT group were the least impaired and showed mild deficits in episodic memory and verbal fluency but normal semantic memory. The frontal and temporal presentations of FTD are clearly separable from each other and from early AD.

Age Factors↗
PubMed1999

Relearning and subsequent forgetting of semantic category exemplars in a case of semantic dementia.

Over 15 months of longitudinal assessment, a patient with semantic dementia, D.M., improved on tests of naming and category fluency for a specific set of items (Experiment 1). The authors attribute this to his home drill with the names of these concepts plus pictures and descriptions of them. In Experiment 2, D.M. produced significantly more exemplars on category fluency for semantic categories that he had been practicing at home than for nonpracticed categories, an effect that cannot be attributed to an inherent difference between the 2 sets because the fluency performance of control participants revealed no significant difference between the 2 sets. In Experiment 3, D.M. rehearsed some of his previously nonpracticed categories daily for a period of 2 weeks: His fluency scores on the experimental categories improved substantially, but they declined once he ceased the daily drill. The results are discussed with respect to current views of long-term memory, particularly new word learning and forgetting, and to current techniques for facilitating word finding in aphasia.

Aphasia↗
PubMed1999

Disrupted temporal lobe connections in semantic dementia.

Semantic dementia refers to the variant of frontotemporal dementia in which there is progressive semantic deterioration and anomia in the face of relative preservation of other language and cognitive functions. Structural imaging and SPECT studies of such patients have suggested that the site of damage, and by inference the region critical to semantic processing, is the anterolateral temporal lobe, especially on the left. Recent functional imaging studies of normal participants have revealed a network of areas involved in semantic tasks. The present study used PET to examine the consequences of focal damage to the anterolateral temporal cortex for the operation of this semantic network. We measured PET activation associated with a semantic decision task relative to a visual decision task in four patients with semantic dementia compared with six age-matched normal controls. Normals activated a network of regions consistent with previous studies. The patients activated some areas consistently with the normals, including some regions of significant atrophy, but showed substantially reduced activity particularly in the left posterior inferior temporal gyrus (iTG) (Brodmann area 37/19). Voxel-based morphometry, used to identify the regions of structural deficit, revealed significant anterolateral temporal atrophy (especially on the left), but no significant structural damage to the posterior inferior temporal lobe. Other evidence suggests that the left posterior iTG is critically involved in lexical-phonological retrieval: the lack of activation here is consistent with the observation that these patients are all anomic. We conclude that changes in activity in regions distant from the patients' structural damage support the argument that their prominent anomia is due to disrupted temporal lobe connections.

Anomia↗
PubMed1999

Dyspraxia in a patient with corticobasal degeneration: the role of visual and tactile inputs to action.

OBJECTIVES: To investigate the roles of visual and tactile information in a dyspraxic patient with corticobasal degeneration (CBD) who showed dramatic facilitation in miming the use of a tool or object when he was given a tool to manipulate; and to study the nature of the praxic and neuropsychological deficits in CBD. METHODS: The subject had clinically diagnosed CBD, and exhibited alien limb behaviour and striking ideomotor dyspraxia. General neuropsychological evaluation focused on constructional and visuospatial abilities, calculation, verbal fluency, episodic and semantic memory, plus spelling and writing because impairments in this domain were presenting complaints. Four experiments assessed the roles of visual and tactile information in the facilitation of motor performance by tools. Experiment 1 evaluated the patient's performance of six limb transitive actions under six conditions: (1) after he described the relevant tool from memory, (2) after he was shown a line drawing of the tool, (3) after he was shown a real exemplar of the tool, (4) after he watched the experimenter perform the action, (5) while he was holding the tool, and (6) immediately after he had performed the action with the tool but with the tool removed from his grasp. Experiment 2 evaluated the use of the same six tools when the patient had tactile but no visual information (while he was blindfolded). Experiments 3 and 4 assessed performance of actions appropriate to the same six tools when the patient had either neutral or inappropriate tactile feedback-that is, while he was holding a non-tool object or a different tool. RESULTS: Miming of tool use was not facilitated by visual input; moreover, lack of visual information in the blindfolded condition did not reduce performance. The principal positive finding was a dramatic facilitation of the patient's ability to demonstrate object use when he was holding either the appropriate tool or a neutral object. Tools inappropriate to the requested action produced involuntary performance of the stimulus relevant action. CONCLUSIONS: Tactile stimulation was paramount in the facilitation of motor performance in tool use by this patient with CBD. This outcome suggests that tactile information should be included in models which hypothesise modality specific inputs to the action production system. Significant impairments in spelling and letter production that have not previously been reported in CBD have also been documented.

Apraxias↗
PubMed1999

Identification of the t(15;17) in AML FAB types other than M3: evaluation of the role of molecular screening for the PML/RARalpha rearrangement in newly diagnosed AML. The Medical Research Council (MRC) Adult Leukaemia Working Party.

Acute promyelocytic leukaemia (APL) is characterized by the t(15;17) leading to the formation of PML-RARalpha and RARalpha-PML fusion genes; this rearrangement has been considered both diagnostic for, and restricted to, this subtype of acute myeloid leukaemia (AML FAB M3). We describe two cases of AML with the t(15;17) associated with a PML/RARalpha rearrangement which lacked typical APL morphology, classified as FAB M1 and M2 respectively. In both cases morphological review revealed small populations of cells which exhibited some features associated with APL. In the case classified as M1, PML immunofluorescence studies revealed the classic microparticulate nuclear staining pattern as observed in typical cases of APL with the t(15;17). Similarly, blasts from this case were found to be sensitive to ATRA in vitro as determined by NBT reduction test and by normalization of the PML nuclear body staining pattern. To determine the frequency of PML/RARalpha rearrangements in FAB subtypes other than M3, 530 patients from the MRC AML trials were screened using nested RT-PCR. Only one individual, initially classified as M5 with a normal karyotype, was found to have a PML/RARalpha rearrangement. The diagnosis was revised to M3 variant on subsequent morphological review. In conclusion, this study demonstrates that, in rare cases, the t(15;17) is not restricted to patients with M3 morphology as defined by current FAB criteria. Therefore, although we consider cytogenetic analysis of newly diagnosed cases of AML to be mandatory, our data suggests that routine molecular screening for PML/RARalpha rearrangements is not justified and should be reserved for those cases displaying features which may be suspicious of APL even if such cells comprise only a minority of the total population.

Adolescent↗
PubMed1998

Malignant tumors of the kidney, brain, and soft tissues in children and young adults with the tuberous sclerosis complex.

BACKGROUND: The tuberous sclerosis complex (TSC) is an autosomal dominant disorder characterized by seizures, mental retardation, and benign tumors of the brain, heart, skin, and kidney. Malignant tumors also can occur in patients with tuberous sclerosis, particularly in the kidney, although they occur less frequently than benign tumors. The types of malignancy that occur in TSC have not been characterized fully. METHODS: Clinical and pathologic features of 8 malignant tumors from 6 TSC patients ranging in age from 22 months to 21 years are reviewed. Six tumors were renal, one was from the inguinal region, and one was from the brain. The tumors were analyzed for loss of heterozygosity (LOH) in the chromosomal regions of the TSC1, TSC2, and VHL genes. RESULTS: Three patients (ages 7, 8, and 20 years) had renal cell carcinomas (RCCs). Two of these patients had multifocal RCCs. All three patients with RCC also had prominent multifocal dysplasia of renal cyst epithelium. Two patients (ages 20 and 21 years) had malignant angiomyolipomas (1 renal and 1 inguinal). One patient (age 22 months) had a Grade 4 giant cell astrocytoma (glioblastoma multiforme). LOH in the region of the TSC2 gene was found, either in the malignant tumor or in benign tumors, in all five patients whose DNA could be analyzed. CONCLUSIONS: Children with TSC, as well as adults with the disease, are at risk for developing malignant tumors. Two types of renal malignancy occur in TSC: RCC, which appears to arise from dysplastic renal cyst epithelial cells, and malignant angiomyolipoma. Tumors cytologically similar to malignant angiomyolipomas also may occur at extrarenal sites. LOH analyses suggest that the majority of patients with TSC who develop malignant tumors have germline TSC2, rather than TSC1, gene mutations.

Adult↗
PubMed1998

Single word production in nonfluent progressive aphasia.

We present an experiment investigation of the spoken single word production of two patients with nonfluent progressive aphasia. In Experiment 1, a task effect (reading > repetition > naming) suggested that phonological information available from task stimuli facilitated the patients' speech production; a length effect reflected the increased difficulty of phonological processing required for long words compared with that required for shorter words. Experiment 2 compared repetition, reading, copying, and writing to dictation tasks and demonstrated that a correspondence between input and output modality also facilitated performance. Experiment 3 showed that the patients' access to appropriate phonology in reading was positively related to the degree of correlation between orthographic and phonological forms. These results are discussed with reference to an account of pathologically weakened connections between nodes in an interactive spreading activation model of speech production of the type described by Dell (1986).

Aged↗
PubMed1998

Substrate use during and following moderate- and low-intensity exercise: implications for weight control.

Substrate utilization during and after low- and moderate-intensity exercise of similar caloric expenditure was compared. Ten active males [age: 26.9 (4.8) years; height: 181.1 (4.8) cm; Mass: 75.7 (8.8) kg; maximum O2 consumption (VO2max): 51.2 (4.8) ml x kg(-1) x min(-1)] cycled at 33% and 66% VO2max on separate days for 90 and 45 min, respectively. After exercise, subjects rested in a recumbent position for 6 h. Two h post-exercise, subjects ate a standard meal of 66% carbohydrate (CHO), 11% protein, and 23% fat. Near-continuous indirect calorimetry and measurement of urinary nitrogen excretion were used to determine substrate utilization. Total caloric expenditure was similar for the two trials; however, significantly (P < 0.05) more fat [42.4 (3.6) g versus 24.0 (12.2) g] and less CHO [142.5 (28.5) g versus 188.8 (45.2) g] was utilized as a substrate during the low-intensity compared to the moderate-intensity trial. Protein utilization was similar for the two trials. The difference in substrate use can be attributed to the exercise period because over twice as much fat was utilized during low-intensity [30.0 (11.0) g] compared to moderate-intensity exercise [13.6 (6.6) g]. Significantly more (P < 0.05) CHO was utilized during the moderate-intensity [106.0 (27.8) g] compared to the low-intensity exercise [68.7 (20.0) g]. Substrate use during the recovery period was not significantly different. We conclude that low-intensity, long-duration exercise results in a greater total fat oxidation than does moderate intensity exercise of similar caloric expenditure. Dietary-induced thermogenesis was not different for the two trials.

Adult↗
PubMed1998

Word reading in Alzheimer's disease: cross-sectional and longitudinal analyses of response time and accuracy data.

Using a list of high- and low-frequency regular and exception words, we measured the reading performance of three groups of subjects: patients with mild dementia of the Alzheimer's type (DAT) at presentation (Stage 1) and 2-3 years later (Stage 2); moderately severe DAT patients; and control subjects. In the longitudinally studied patients, there was a dramatic increase in response times (RTs) from Stage 1 to Stage 2, but little change in either error rate or pattern. By contrast, a comparison of the Stage 2 with the Moderate patients revealed similar RTs but a significant increase in error rate for the Moderate group, particularly on low-frequency exception words. These two results for word naming were almost exactly mirrored by effects in picture naming. We conclude that correct word reading, especially for less common words with atypical spelling-sound correspondences, is compromised in DAT only when the disease produces a significant deterioration of semantic memory. These results are relevant to current theories about normal and impaired reading processes.

Aged↗
PubMed1998

Category specific semantic loss in dementia of Alzheimer's type. Functional-anatomical correlations from cross-sectional analyses.

In the context of focal brain injury, selective loss of semantic knowledge in the domain of either natural kinds or artefacts is usually considered to reflect the differential importance of temporal and frontoparietal regions to the representations of perceptual and functional attributes, respectively. It is harder to account far as a feature of a more diffuse process, and previous cross-sectional analyses of patients with dementia of Alzheimer's type (DAT) have differed over whether category effects occur. In our series of 58 patients with probable DAT, we demonstrated a significant group advantage for artefacts, and explored possible reasons for the inconsistency of this finding in other studies. A multiple single-case strategy revealed not only individuals with consistent advantages for artefacts but also individuals with consistent advantages for natural kinds. By ranking the individuals according to measures of naming performance and global intellectual ability, we showed that the strength of the group advantage for artefacts was dependent on the former but not the latter variable. The findings are discussed in the context of two competing theories of semantic breakdown in DAT. One differentiates between domains of knowledge in terms of the structure of semantic representations within a single distributed network; the other emphasizes the importance of different brain regions in the category distinction. We conclude that our findings are in keeping with the predictions of the latter hypothesis.

Aged↗
PubMed1998

The immunohistological diagnosis of E. coli O157:H7 colitis: possible association with colonic ischemia.

OBJECTIVE: E. coli O157:H7 may cause hemorrhagic colitis resembling ischemic colitis. Diagnosis is usually made by finding sorbitol-negative colonies on MacConkey agar that react with O157 and H7 antisera. Most ischemic colitis is idiopathic, but some may be caused by E. coli O157:H7, inasmuch as this organism can produce fibrin thrombi in colon vasculature. The objectives of this study were to determine whether E. coli O157:H7 infection can be diagnosed retrospectively from paraffin blocks of colon sections and whether an association exists between E. coli O157:H7 infection and colonic ischemia. METHODS: Paraffin-embedded sections of normal colon (n = 2) and various colitides [ischemic (n = 11), E. coli O157:H7 (n = 2), IBD (n = 8) and pseudomembranous (n = 3)] were used. Sections were deparaffinized, rehydrated, incubated with 3% peroxide in methanol, rinsed, and incubated with peroxidase-labeled antibody isolated from goats immunized with whole E. coli O157:H7. Sections were stained with peroxidase chromagen reagent and counterstained with hematoxylin. Coarse, granular, orange-brown staining was considered positive. To determine the localization of the chromagen deposits, three cases that stained positive, including one of the culture-proved E. coli O157:H7 colitis and two of colonic ischemia, were processed for electron microscopy. RESULTS: Both cases (100%) of E. coli O157:H7 colitis and three of 11 (27.3%) cases of ischemic colitis stained positive by light microscopy. In one culture-proved case, electron microscopy demonstrated staining of bacillary structures; in two cases of colonic ischemia, extensive deposits of chromagen material were present that were associated neither with inflammatory cells nor with bacterial forms. CONCLUSIONS: Immunoperoxidase staining of archival sections may be used to diagnose E. coli O157:H7 infection. An etiological role for this organism is possible in some cases of colonic ischemia.

Aged↗