1985 — 1994 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Cognitive-Linguistic Mechanisms in Writing Disorders @ Johns Hopkins University
The long-term objective of this project is to characterize the cognitive and linguistic mechanisms that underly the spelling (writing) process and the ways in which this process may be disrupted as a consequence of brain damage. The specific aims of the project are: 1) to evaluate the hypothesis that specific forms of spelling dysfunction (dysgraphia) result from damage to distinct components of the spelling process; and 2.) to characterize in detail the internal structure of the components assumed to comprise the spelling system, thereby providing a basis for a deeper understanding of the various forms of spelling disorders found in brain-damaged patients. These aims will be accomplished through a two-phase program of research. In the first phase, a large number of patients with focal brain damage will be tested with a spelling test battery, specially designed to distinguish among various types of spelling disorders. Patients' performance on the test battery will be used to a) evaluate models of the spelling process and b) define subgroups of patients with selective deficits to various components of the spelling process. In the second phase, patients with selective deficit to particular processing components (e.g., the component that stores knowledge of the orthographic structure of words) will be tested with sets of experimental tasks designed to probe in considerable detail the strucure of the various components involved in spelling. Information generated from the detailed analyses in this phase of the project will be used to a) revise the test battery to better discriminate among different types of spelling disorders and b) evaluate specific hypothesis about the internal structure of particular components of processing. A further major component of the proposed research involves the use of computational modelling techniques. This aspect of the proposed research will allow the formulation of a computationally-explicit model of the spelling process and the stimulation of spelling disorders by the "experimental lesioning" of the implemented model. Finally, the detailed characterization of spelling disorders in terms of damage to specific components of the cognitive/linguistic mechanisms that underly spelling will be used to explore correlations between locus of brain damage and type of functional disorder. The results of the proposed studies will contribute to a deeper understanding of the basis for spelling disorders in brain-damaged patients--an indispensable foundation for the diagnosis and remediation of dysgraphia.
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1 |
1986 — 1994 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Morphological Processing Deficits in Aphasia @ Johns Hopkins University
The proposed research addresses the nature of cognitive/linguistic deficits that involve impairments to morphological aspects of lexical processing, and examines the contribution of these deficits to sentence comprehension and sentence production impairments. The program of research involves testing of language impaired speakers of English and Italian. Because of the structural differences between these languages, the use of these two groups allow consideration of issues that could not be addressed with one group alone, and permits the assessment of cross-language generality of hypotheses concerning language processing. Subjects who have been screened for morphological disruptions will be tested on a series of single-word processing tasks in order to determine the variety of lexical deficit (e.g., whether the deficit is an input or output deficit and whether it effects performance in the visual or auditory modality), and to determine the variety of morphological deficity in terms of the types of lexical items affected (e.g., whether inflected words are selectively affected, or whether morphologically regular and irregular forms are similarly disrupted). These subjects will also be tested on a series of sentence processing tasks in order to evaluate the effect of morphological processing deficits in more complex language processing contexts. Information derived from these experiments will serve (a) to differentiate among varieties of morphological deficits, (b) to assess specific hypotheses about the cognitive/linguistic basis for particular deficits and further elaborate the structure of the linguistic and cognitive mechanisms that subserve morphological processing, (c) to determine the roles that various types of morphological deficit play in disorders of comprehension and production, and (d) to enable the exploration of correlations between types of lexical processing deficits and loci of brain lesions, with the aim of illuminating the relation between cognitive and neural mechanisms of language.
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0.957 |
1992 — 1993 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Mechanisms Underlying Disorders of Naming @ Johns Hopkins University |
0.957 |
1996 — 1999 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Cognitive Linguistic Mechanisms of Writing Disorders |
1 |
1996 — 1999 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Mechanisms of Neglect Dyslexia |
1 |
2000 — 2004 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Disorders of Lexical Access in Speech Production
The goal of the proposed research is to understand the nature of naming and word-finding difficulties in aphasia. The objective is to explain patterns of word production deficits in terms of damage to the cognitive/linguistic mechanisms that underlie normal word production, and then to use this knowledge toward the development of a theory of the functional organization of the brain. Two general questions will be addressed: 1) What are the causes of the grammatical class deficits? And, 2) what are the causes of the different error types in naming deficits? More specific questions include: 1) Are there different subtypes of grammatical class disorders? 2) What is the relationship between impairments in the production of nouns and the ability to produce noun phrase structure? 3) Are the causes of access failure for nouns and verbs the same as for failure to retrieve adjectives? What are the causes of failure to access function words and inflectional morphology? 4) Are different mixtures of error types the result of global lesions that affect equally all stages of the lexical access process or are they the result (at least in some cases) of different lesions to different stages of the process? 5) What relationship is there between the distribution of error types in naming and other tasks (such as reading, repetition, comprehension, etc.)? These and related questions will be addressed through a three-pronged program of research. The most important part involves the detailed investigation of the word and phrase processing performance of English and Italian monolingual aphasics and Spanish-Catalan bilingual aphasics. The two other components of the research involve the computational modeling of the patients' patterns of word production deficits and the experimental investigation of normal subjects' word and phrase production performance. This integrated approach to the study of lexical access deficits should provide important information about the organization and processing structure of the lexicon and about the functional causes of word production disorders in aphasia. These are necessary components of the larger goal of understanding the functional architecture of the brain and for developing intervention strategies for remedial training of aphasia.
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1 |
2006 — 2010 |
Caramazza, Alfonso |
R01Activity Code Description: To support a discrete, specified, circumscribed project to be performed by the named investigator(s) in an area representing his or her specific interest and competencies. |
Cortical Organization of Noun and Verb Processing
The long term goal of the proposed research is to increase our understanding of the neurobiology of language, particularly the neural mechanisms that underlie the representation and access of words. The more immediate objective of the research is to understand the cortical organization of noun and verb processing. We will achieve this through a two-pronged experimental approach using event-related functional magnetic resonance imaging (fMRI) and repeated transcranial magnetic stimulation (rTMS) in order to infer patterns of brain activation during processing of words of different grammatical categories. The first specific aim is to identify cortical regions that are differentially implicated in processing nouns and verbs. One set of experiments uses event-related fMRI to chart the areas of cortical activation differentially associated with noun and verb processing. Other experiments use rTMS to establish whether the areas of cortical activation play a central or a secondary role in this processing. The second specific aim is to distinguish those cortical regions that are primarily involved in processing the semantics of nouns and verbs from those that are implicated specifically in their grammatical processing. To this end, event-related fMRI experiments explore the effects of grammatical versus semantic factors on cortical activation patterns, and rTMS experiments determine whether the identified regions are essential for semantic and/or grammatical processing of words. The third specific aim is to determine the extent to which it is specifically grammatical category membership and not the different morphological processes undertaken with nouns and verbs that are represented in the regions of maximal cortical activation for nouns and verbs. The fMRI and rTMS experiments designed to achieve this goal involve comparison of performance on tasks that require regular morphological changes (jump/jumps) versus irregular (take/took) and/or no morphological changes. The fourth specific aim is to clarify the role that noun- and verb-specific processing areas play in the lexical retrieval tasks used to investigate the noun/verb distinction. This is addressed through the comparison of performance across the various task types used in the fMRI and rTMS experiments. The proposed research should increase our understanding of the cortical organization of noun and verb processing and provide the basis for explaining the causes of grammatical category deficits in various types of aphasia.
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