Amit Almor - US grants

Recent theoretical work on word-level (i.e., lexical) and sentence-level processes in the normal population suggests that these two processes are not independent of each other, as was previously thought, but rather that syntactic processes are strongly guided by knowledge about individual words and combinations of words, particularly verbs. The proposed research investigates the extent to which this hypothesis can account for language disorders in dementia of the Alzheimer Type (DAT). Specifically, we hypothesize that damage to lexical representation in DAT results in impaired processing of both nouns and verbs, and furthermore that this lexical damage has a direct effect on DAT patients' abilities to compute syntactic structure, thus affecting their sentence-level language comprehension and production abilities. This research assesses the effects of lexical organization on semantic, morphological, and sentence processing in three populations: young healthy adults, older healthy adults, and patients with DAT. A first set of studies involves a detailed investigation of semantic and morphological knowledge concerning nouns and verbs in these populations. A second set of studies addresses sentence-level processes that are hypothesized to be driven by lexical knowledge. Both sets of studies are guided the common theme, that the frequency and idiosyncrasy of the underlying lexical features predicts ease of processing in normal populations and patterns of impairment in DAT. Processing lexical items and morphological and syntactic structures is harder and more prone to damage if the underlying features are idiosyncratic and infrequent. Finally, computational "connectionist" models are developed in order to test the hypotheses concerning the common basis of semantic, morphological, and syntactic processes. These models allow us to test the claim that the widespread brain damage associated with DAT has non- random effects, with lower frequency words and structures that are characterized by idiosyncratic features suffering greater impairments that other words and structures. Together, the empirical and modeling results will provide a detailed account of lexical organization and the role of lexical organization in the impairments associated with aging and Alzheimer's disease.

[unreadable] DESCRIPTION (provided by applicant): This research aims to uncover the functional and neural processes that underlie reference comprehension, especially with respect to the relation between reference form and referent salience. Explaining how reference is processed is critical for understanding natural language use, which crucially depends on the matching between referential expressions and real world referents. The specific hypothesis tested in this research is that the choice and processing of referential form reflect general memory processes that are involved in the representation of multiple referents and that are prone to interference, especially when the referents are salient. According to this "interference view", the use of general referential forms such as pronouns can reduce this interference and is therefore preferred when referents could be easily identified. At the neural level this hypothesis predicts that repeated full reference to salient referents would increase brain activation both in areas that are involved in the semantic representation of referents (e.g., regions in the temporal lobe for many types of object referents) and in areas that are known to support the manipulation and integration of multiple representations such as the areas around the intra parietal sulcus (IPS). Self paced reading and matching functional MRI (fMRI) experiments will test the central predictions of this view. The first prediction that will be tested is that behavioral and neural interference is associated with repeated reference to a salient referent but not to a non salient referent. The second prediction that will be tested is that not only repeated names (e.g., 'Joe') but also repeated definite description referents (e.g., 'the man') lead to behavioral and neural interference when the referent is salient. The third and last prediction that will be tested is that non repeated category definite description references (e.g., 'the bird' as a reference to 'the robin') lead to reduced interference similar to pronouns. Because little is currently known about the brain basis of referential processing, any data about these issues would be valuable. The application of converging behavioral and fMRI methodologies to this new theoretical account is unique in discourse research and holds promise for bridging functional accounts of discourse processes with their possible brain basis. Therefore, tying referential processing to underlying brain mechanisms would represent a major leap forward in terms of the scientific understanding of these issues. Such understanding is important for the diagnosis and treatment of language disorders, especially ones that involve deficits in referential processing such as Alzheimer's disease. The better understanding of these processes may also lead to methods and strategies for improving life quality in patients suffering from language disorders and their families. PUBLIC HEALTH RELEVANCE Explaining how reference is processed is critical for understanding natural language use, which crucially depends on the matching between referential expressions and real world referents. Tying referential processing to underlying brain mechanisms would represent a major leap forward in terms of the scientific understanding of these issues. Such understanding is important for the diagnosis and treatment of language disorders, especially ones that involve deficits in referential processing such as Alzheimer's disease and may suggest methods and strategies for improving life quality in patients suffering from language disorders and their families. [unreadable] [unreadable] [unreadable] [unreadable]

The goal of this research is to understand how different referential forms are processed in the brain. Most instances of real-life language use involve discourses in which several sentences or utterances are coherently linked through the use of repeated references. Repeated references can be made with different forms. For example, a person mentioned early in discourse (the referent) can be later referred to by a proper name (e.g., Bill), a specific definite description (e.g., the waiter), a less specific definite description (e.g., the man), or a pronoun (e.g., he). The form of referential expressions has played a key role in theories of reference, but not much is known about the underlying brain mechanisms.

This research project will test the theoretical claim that the choice and processing of referential form reflect general memory processes that are involved in the representation of multiple referents and that these processes are prone to interference, especially when the referents are salient. According to this "interference view", high semantic overlap between the referential expression and the representation of the referent in memory results in more interference. General referential forms such as pronouns and general definite descriptions, which represent conditions of low semantic overlap, reduce this interference and these expressions are preferred when referents could be easily identified. At the neural level, the interference view predicts that semantic overlap between the representations of the referential expression and the referent can increase brain activation both in areas that are involved in the semantic representation of referents (e.g., regions in the temporal lobe for many types of object referents) and in areas that are known to support the manipulation and integration of multiple representations (e.g., areas around the intra parietal sulcus (IPS)). Self paced reading and matching functional MRI (fMRI) experiments will test the predictions of this view by examining the relation between brain activation and behavioral aspects of processing definite description references.

The application of converging behavioral and fMRI methodologies is unique in discourse research and holds promise for bridging functional accounts of discourse processes with their possible brain basis. Tying referential processing to underlying brain mechanisms would represent a major leap forward in terms of the scientific understanding of these issues. Moreover, explaining linguistic phenomena on the basis of non language brain mechanisms is a potentially transformative research in that it could disrupt the well accepted theoretical perspective that reference processing is driven by language "rules" or arbitrary conventions.

The cognitively based theories that influence current psycholinguistic research are based largely on non-neural data and theoretical constructs. The foundations of these theories are formal linguistic models of grammar as well as cognitive models of memory, attention, and learning. However, given that language processing must take place in a physical structure, it is critical to develop theories that are biologically plausible and compatible with other theories in the cognitive neurosciences. The 26th Annual CUNY Human Sentence Processing Conference, to be held in March 2013 at the University of South Carolina, will include a Special Session to address this question: Can the basic architecture of language developed in the 1950s and 1960s that was based primarily on linguistic evidence, or in the 1980s and 1990s based on statistical constraint-based models, survive in the era of brain imaging, brain stimulation, and sophisticated cognitive neuropsychology? If not, what new architectures for the language system are compatible with what has been learned from the entire range of relevant evidence--including linguistic, behavioral, and biological data?

The Special Session will bring together six prominent researchers to consider this fundamental issue. This particular group was chosen because a range of major cognitive neuroscience methodologies besides traditional neuropsychology is represented, and because the speakers take diverse theoretical perspectives on linguistic architectures and processing.

The Special Session will make contact with the widest possible spectrum of conference attendees, but particularly with younger scientists with interests in neurobiological approaches to cognition and language. The Special Session will also help to ensure that the resource-intensive research undertaken by neuroscientists studying language will have as broad an impact as possible and will begin to seriously inform fundamental theorizing in all areas of psycholinguistics.