Search PubMed⌕ Search

Biomedical subjects

P A Carpenter

Publications and source records attributed to P A Carpenter.

At least 19 recordsLinked to original sources
PubMed1997

A dose-intensive, cyclophosphamide-based regimen for the treatment of recurrent/progressive or advanced solid tumors of childhood: a report from the Australia and New Zealand Children's Cancer Study Group.

BACKGROUND: Children with solid tumors that progress or recur after conventional multimodality therapies have a very poor prognosis. In a pilot study, vincristine, etoposide, and dose-escalated cyclophosphamide (VETOPEC) was shown to be a promising salvage regimen. Continued accrual of patients and increased duration of follow-up has resulted in substantial experience with VETOPEC. METHODS: Between May 1991 and March 1994, 56 pediatric patients from 6 centers were enrolled in this study; 44 had recurrent or progressive tumors (Group A) and 12 had newly diagnosed, advanced tumors with a very poor prognosis (Group B). The VETOPEC regimen was comprised of vincristine, 0.05 mg/kg, on Days 1 and 14; etoposide, 2.5 mg/kg, on Days 1, 2, and 3; and fractionated, dose-escalated cyclophosphamide on Days 1, 2, and 3. The initial cyclophosphamide dose was 90 mg/kg (2.7 g/m2)/cycle with an escalation of 15 mg/kg/cycle in each subsequent cycle, to a maximum (over 6 cycles) of 165 mg/kg (5.0 g/m2)/cycle. Tumor response was evaluated every two to three cycles and included central review of imaging. RESULTS: The combined and partial response rates for Groups A and B were 66% (25 of 38 patients) and 91% (10 of 11 patients), respectively. In Group A, best evaluable responses and event free (EF) survivors were observed with: brain tumors (7 of 9 patients; 2 EF at 39 and 45 months [mos], respectively), Wilms' tumor (6 of 7 patients; 3 EF at 37-49 mos), and lymphoma (4 of 4 patients; 2 EF at 52 and 59 mos, respectively); in Group B best evaluable responses and EF were observed with: neuroblastoma (5 of 6 patients; 1 disease free at 57 mos) and rhabdomyosarcoma (4 of 4 patients; no survivors). Hematologic toxicity was limiting despite support with myeloid growth factors in 33 patients. Four deaths in Group A and one in Group B were directly associated with this toxicity. Specifically, no cases of drug-related myocardial toxicity or pneumonitis were observed. CONCLUSIONS: This chemotherapy regimen with its intense scheduling produced a high response rate and appreciable survival in patients with a variety of recurrent, progressive, or advanced solid tumors of childhood.

Adolescent↗
PubMed1997

Aphasic sentence comprehension as a resource deficit: a computational approach.

This article describes a new computational model of aphasic sentence comprehension. The model is based on the premise that all aphasics, however different, share a common deficit which determines a considerable amount of the individual variation observed in their sentence comprehension performance. This common deficit is construed as a pathological reduction in the activation resources of a working memory system that subserves sentence comprehension (Miyake, Carpenter, & Just, 1994). To test the theoretical feasibility of the resource reduction hypothesis, a new computer model of aphasic sentence comprehension was developed and tested. We describe the model as well as some initial simulation results, indicating that the model can account for some of the sentence complexity and severity effects that have been reported in the aphasia literature.

Aphasia↗
PubMed1996

Brain activation modulated by sentence comprehension.

The comprehension of visually presented sentences produces brain activation that increases with the linguistic complexity of the sentence. The volume of neural tissue activated (number of voxels) during sentence comprehension was measured with echo-planar functional magnetic resonance imaging. The modulation of the volume of activation by sentence complexity was observed in a network of four areas: the classical left-hemisphere language areas (the left laterosuperior temporal cortex, or Wernicke's area, and the left inferior frontal gyrus, or Broca's area) and their homologous right-hemisphere areas, although the right areas had much smaller volumes of activation than did the left areas. These findings generally indicate that the amount of neural activity that a given cognitive process engenders is dependent on the computational demand that the task imposes.

Adolescent↗
PubMed1996

The capacity theory of comprehension: new frontiers of evidence and arguments.

A capacity theory of comprehension (M.A. Just & P.A. Carpenter, 1992) has provided an integrated account of several central aspects of sentence comprehension, such as the processing of syntactic ambiguity, complex embeddings, syntactic (non) modularity, and individual differences, in terms of the working-memory capacity for language. Some of the evidence supporting the theory is questioned by G.S. Waters and D. Caplan (1996a). This article identifies some of Waters and Caplan's errors about the empirical support in Just and Carpenter (1992), evaluates Waters and Caplan's alternative hypothesis, and presents the results of a new neuroimaging study that supports capacity theory and not Waters and Caplan's separate resources hypothesis.

Arousal↗
PubMed1996

Late diagnosis and correction of purine nucleoside phosphorylase deficiency with allogeneic bone marrow transplantation.

A 5-year-old boy with spastic quadriplegia, T cell immunodeficiency, hypouricemia and immune cytopenias from age 8 months, was found to have purine nucleoside phosphorylase (PNP) deficiency, and developed chronic lung disease. Successful matched sibling BMT for PNP deficiency has not previously been reported. BMT using marrow from an HLA-identical sibling donor was performed after conditioning with busulfan (16 mg/kg), cyclophosphamide (200 mg/kg), melphalan (90 mg/m2) and anti-thymocyte globulin (36 mg/kg). T lymphocyte numbers, PNP activity and uric acid levels rapidly improved and he remains well 12 months after transplant.

Bone Marrow Transplantation↗
PubMed1996

Allogeneic bone marrow transplantation for children with acute lymphoblastic leukemia conditioned with busulfan, cyclophosphamide and melphalan.

Children with acute lymphoblastic leukemia (ALL) undergoing allogeneic bone marrow transplantation (BMT) using total body irradiation (TBI)-containing conditioning regimens are at risk of substantial late sequelae affecting growth and endocrine functions. This has lead to the use of non-TBI or chemotherapy conditioning regimens for ALL patients in many centers. However, it is unknown whether chemotherapy conditioning results in improved antileukemic efficacy or reduced transplant-related toxicity. We report our experience using a chemotherapy conditioning regimen (busulfan (Bu), cyclophosphamide (CY) and melphalan (Mel)) in 26 consecutively enrolled children with ALL (group I). At a median follow-up of 58 months, event-free survival (EFS) for Bu/CY/Mel-treated patients was 27% (+/- 8.7), while the leukemic relapse rate was 49% (+/- 13). Regimen-related toxicity was severe in these patients: overall treatment-related mortality was 42%, while 50% of patients had interstitial pneumonitis and 35% of patients had severe hemorrhagic cystitis. A historical control group of 25 consecutively enrolled patients, mostly treated with TBI-containing regimens (group II), had an EFS of 36% (+/- 9.6%) and a leukaemic relapse rate of 45% (+/- 11) at a median follow-up of 117 months. We conclude that the Bu/CY/Mel conditioning regimen leads to severe transplant-related toxicity and did not significantly improve leukemic relapse rates.

Adolescent↗
PubMed1993

The intensity dimension of thought: pupillometric indices of sentence processing.

This article explores the intensity of processing during sentence comprehension by measuring pupillary response during reading. Two experiments contrast the processing of simpler versus more complex sentences. The two more complex sentence types, object-relative center-embedded sentences and filler-gap sentences, not only take longer to process than their simpler counterparts, but they also produce a larger change in pupil diameter. We propose that the pupillary response is an indicator of how intensely the processing system is operating. The more complex sentences evoke some intense processing at the point in the sentence where a syntactic complexity is first encountered. The gaze durations at these points are elevated, indicating the immediate response to the demand of the syntactic processing. The pupil then starts to dilate, reaching a maximal diameter approximately 1.3 s later. The results from these various performance measures are integrated within a resource-limited computational model of comprehension. The paper develops a model of comprehension that includes an intensity dimension of thought, drawing a correspondence between the computational model's consumption of resources and the human pupillary response.

Adult↗
PubMed1992

Working memory constraints on the processing of syntactic ambiguity.

We propose a model that explains how the working-memory capacity of a comprehender can constrain syntactic parsing and thereby affect the processing of syntactic ambiguities. The model's predictions are examined in four experiments that measure the reading times for two constructions that contain a temporary syntactic ambiguity. An example of the syntactic ambiguity is The soldiers warned about the dangers . . . ; the verb warned may either be the main verb, in which case soldiers is the agent; or the verb warned may introduce a relative clause, in which case soldiers is the patient of warned rather than the agent, as in The soldiers warned about the dangers conducted the midnight raid. The model proposes that both alternative interpretations of warned are initially activated. However, the duration for which both interpretations are maintained depends, in part, on the reader's working-memory capacity, which can be assessed by the Reading Span task (Daneman & Carpenter, 1980). The word-by-word reading times indicate that all subjects do additional processing after encountering an ambiguity, suggesting that they generate both representations. Furthermore, readers with larger working-memory capacities maintain both representations for some period of time (several words), whereas readers with smaller working-memory capacities revert to maintaining only the more likely representation.

Adult↗
PubMed1992

A capacity theory of comprehension: individual differences in working memory.

A theory of the way working memory capacity constrains comprehension is proposed. The theory proposes that both processing and storage are mediated by activation and that the total amount of activation available in working memory varies among individuals. Individual differences in working memory capacity for language can account for qualitative and quantitative differences among college-age adults in several aspects of language comprehension. One aspect is syntactic modularity: The larger capacity of some individuals permits interaction among syntactic and pragmatic information, so that their syntactic processes are not informationally encapsulated. Another aspect is syntactic ambiguity: The larger capacity of some individuals permits them to maintain multiple interpretations. The theory is instantiated as a production system model in which the amount of activation available to the model affects how it adapts to the transient computational and storage demands that occur in comprehension.

Concept Formation↗
PubMed1990

Frames of reference for allocating attention to space: evidence from the neglect syndrome.

With respect to what frames of reference, or spatial coordinate systems, is attention allocated to locations in space? We posed this question about the spatial attention system that has been damaged in neglect patients, distinguishing among three possible types of spatial reference frame: viewer-centered, according to which locations are coded with respect to the viewer, environment-centered, according to which locations or coded with respect to the environment, and object-centered, according to which locations are coded with respect to an object. The three candidate frames of reference were decoupled from one another by rotating either the viewer or the stimulus object. Visual search performance suggested that the neglected hemifield was defined with respect to both viewer-centered and environment-centered frames of reference, but not with respect to an object-centered frame of reference. The role of objects in the allocation of attention to space, and the relation between our findings and the "two cortical visual systems" hypothesis, are discussed.

Aged↗
PubMed1990

What one intelligence test measures: a theoretical account of the processing in the Raven Progressive Matrices Test.

The cognitive processes in a widely used, nonverbal test of analytic intelligence, the Raven Progressive Matrices Test (Raven, 1962), are analyzed in terms of which processes distinguish between higher scoring and lower scoring subjects and which processes are common to all subjects and all items on the test. The analysis is based on detailed performance characteristics, such as verbal protocols, eye-fixation patterns, and errors. The theory is expressed as a pair of computer simulation models that perform like the median or best college students in the sample. The processing characteristic common to all subjects is an incremental, reiterative strategy for encoding and inducing the regularities in each problem. The processes that distinguish among individuals are primarily the ability to induce abstract relations and the ability to dynamically manage a large set of problem-solving goals in working memory.

Adult↗
PubMed1982

Paradigms and processes in reading comprehension.

This article compares several methods of presenting text, including a new paradigm that produces reading-time data with many of the characteristics of naturally occurring eye-fixation data. In the new paradigm, called the moving window condition, a reader presses a button to see each successive work in a text, and the previous work is removed when a new work appears. The words appear in the same position that they would in normal test, and word-length information is available in peripheral vision. The results are qualitatively and quantitatively compared to the results obtained by monitoring the eye fixations of subjects reading normal text. The word-level effects are generally similar. Readers pause longer on longer words, on less frequent words, on words that introduce a new topic, and at ends of sentences. The results suggest that readers initiate thr processing of each word as soon as they encounter it rather than buffer words and delay processing. Also considered are two other reading-time paradigms, one in which words are cumulatively displayed on the screen and one in which each successive word is presented at the same location on the screen. Finally, we consider how the tendency to immediately process text might interact with other techniques for text presentation, such as the rapid serial visual presentation (RSVP) condition, and we generate predictions about the nature and limits of the method.

Eye Movements↗
PubMed1977

A comparison of aphasic and normal adults in a sentence-verification task.

This study showed that in certain sentence-processing tasks, aphasics fail to perform correctly because they fail to execute particular mental operations. A straightforward information-processing model describes the mental processes that are used in deciding whether a sentence is true or false of an accompanying picture. The aphasics' performance, interpreted in light of the model, indicates what step in their processing is not operating properly in this task.

Aphasia↗
PubMed1975

The semantics of locative information in pictures and mental images.

Three experiments examined how people compare sentences about spatial location to pictures and images. Previous investigations have found that people are faster at judging relative location when the description contains the word above or right than when it contains the word below or left. Expt I showed that this asymmetry persisted when the words were replaced by arrows, indicating that the effect is not specific to particular lexical items. Expt. II showed the asymmetry persisted even when the response latency did not iclude the time to encode the description, indicating that the asymmetry does not lie in the description-encoding stage. Finally, Expt. III investigated how people compare sentences to information from a previously memorized picture. In this situation, the usual asymmetry was not present. The three studies suggest that the asymmetry arises from the way descriptions influence the encoding of perceptual events. The results also show that the information encoded in a mental representation of a picture is ordered such that certain features can be access-d more quickly than others. However, the same features are equally quickly accessed in a picture that is physically present.

Form Perception↗