David P. Corina - US grants

The ability to comprehend and produce language stands as a defining characteristic of human cognition. It is this ability which enables the transfer of knowledge and culture within human society. A proper characterization of the human capacity for language is required for the development of interventions which may be used to remediate those individuals who have failed to achieve, or who have lost competence in, a full range of language behaviors (e.g. effective interpersonal communication, reading, writing, etc.). Cognitive psychologists have made great strides in understanding the functional and neural mechanisms underlying the use of spoken language. These studies have led to a wide range of effective educational and clinical programs for enhancing language behaviors. However, equivalent knowledge in the domain of signed languages is lacking. The long-term objective of this research is to develop a comprehensive neurocognitive model of sign language processing derived from behavioral and functional brain-imaging studies. Such a model would have practical educational value; it would guide the development of effective strategies and programs targeted toward improving specific language behaviors in deaf individuals who come from a variety of language backgrounds. It would also benefit basic science, providing insight into how sensory deprivation and early language experience impacts the development of neural systems. Finally, this model would benefit cognitive scientists interested in models of the functional neural specialization underlying human language. The development of a neurocognitive model of sign- language processing will require knowledge from several fronts, as sign language processing lies at the intersection of visual, linguistic, and motor processing domains. Construction of this model will require an understanding of not only the very general functional neural changes that may co-occur in response to early auditory deprivation, but also the modifications and specialization which may be specific to processing a visual-manual language. The current application proposes a hierarchy of studies ranging from the visual- sensory domain to the linguistic.cognitive domain likely to underlie sign language processing. These processing levels have been motivated by recent findings in cognitive neurosciences which argue for neuro-functional differences in the processing of visual movement and form.

DESCRIPTION (provided by applicant): The ability to comprehend and produce language stands as a defining characteristic of human cognition. It is this ability that enables the transfer of knowledge and culture within human society. A proper characterization of the human capacity for language is required for the development of interventions which may be used to remediate those individuals who have failed to achieve, or who have lost competence in, a full range of language behaviors (e.g., effective interpersonal communication, reading, writing, etc.). Cognitive psychologists have made great strides in understanding the functional and neural mechanisms underlying the use of spoken language. These findings have led to a wide range of effective educational and clinical programs for improving language behaviors. However, equivalent knowledge in the domain of signed languages is lacking. The long-term objective of this research is to develop a comprehensive neurocognitive model of sign language processing derived from behavioral and functional brain-imaging studies. Such a model would have practical educational value; it would guide the development of effective strategies and programs targeted toward improving specific language behaviors in deaf individuals who come from a variety of language backgrounds. It would also benefit basic science, providing specification as to how a non-speech based human communication system interfaces with sensory, motor and perceptual cognitive systems, and additionally explaining how sensory deprivation and early language experience impacts the development of neural systems. Finally, this model would benefit cognitive scientists interested in models of the functional neural specialization underlying human language by providing explicit understanding of how language may arise from the codification of manual-gesture based human actions. The development of a neurocognitive model of sign language processing will require knowledge from several fronts, as sign language processing lies at the intersection of linguistic, motor and visual processing domains. We seek to identify the representations and processes that underlie sign language recognition and perception, and understand how these are similar to or differ from representation and processes that are used in the service of spoken language, human action/motor processing and visual object/action processing. The current application builds upon findings from our previous grant and continues to ask basic questions concerning the influence of form-based "phonological" properties on the lexical recognition and production of American Sign Language. In addition, our previous findings force us to further consider the neural and functional relationships between sign processing and human action processing and the neural relationships between language and manual-gestural abilities. Finally, we examine how visual perceptual and attentional factors may mediate sign language recognition. We propose tests that are amenable to testing with native and non-native deaf signers and signing and sign-naive hearing subjects, allowing us to determine the degree to which the specific effects observed reflect linguistic experiences, auditory deprivation, or reflect more general, language independent, perceptual processes.

Models of language processing have primarily focused on word and sentence-level processing. When issues of social context have been considered, they have traditionally been argued to occur after sentence meaning has been computed. However, recent research suggests that larger contextual factors, such as world-knowledge and speaker-knowledge, are integrated during sentence interpretation by the same cognitive processes that support lexical-semantic integration. What remains relatively unknown and unexplored is how sociolinguistic variation is perceived during on-line speech processing. This study uses multiple methodologies to investigate language attitude and its relationship to language processing. The present study measures changes in brain activity using electrophysiological scalp recordings (i.e. event-related potentials) to assess the real-time integration of sentences that differ along well-defined sociolinguistic variables. In addition, the researchers make use of a novel behavioral technique -- the implicit attitude test -- to characterize the implicit attitudes and social meanings associated with specific sociolinguistic variables. Finally, direct field recording of participants is used to measure the degree of sociolinguistic variation evident in our participants' speech. Multiple linear regression models will be fitted to the data to elucidate the relationship between individual patterns of production and language attitude with electrophysiological measures of language perception. In this work they seek to understand the cognitive processes that support the perception of sociolinguistic variation during on-line language processing and the degree to which implicit sociolinguistic knowledge and native patterns of variation contribute to the processing of this variation. In our increasingly multicultural and multilingual world, an understanding of how we perceive language, dialects, and linguistic variation and the relationship these features have to language attitude, plays an increasingly important role in shaping social behavior and policy.

In human communication, in addition to the words we utter, how we choose to say something often carries social significance and meaning. For example, a speaker may report to his boss: "Last weekend I went hunting and fishing" while the same speaker talking amongst peers might say: "Las' weeken' I went huntin' an' fishin'." In informal conversational registers, speakers will more often delete word final t/d and drop their g's from progressive verbs than in more formal speech. Importantly, the manner in which an utterance is spoken and the frequency of sociolinguistic variables can influence how the speaker is perceived (e.g., educated vs. uneducated; aloof vs. friendly). Linguists have identified the systematic social, stylistic, and linguistic constraints that modulate the production of sociolinguistic variation. These include linguistic factors, such as lexical class and phonological environment, as well as external factors, such as gender, race, and socioeconomic status. Although there is a relative wealth of data on variation in language production, studies on variation perception have been much more limited. As speech perception is a fundamental aspect of human communication, the study of how individuals perceive, process, and represent linguistic variation is of inherent scientific interest. The study of variation perception can provide valuable evidence of how language intersects with attitude in shaping social stereotypes, prejudice, and behavior. The way we perceive variation and the social attitudes it engenders affects every one of us, from the recent child immigrant to the aspiring politician. As such, the study of variation perception and language attitude has important implications for education, law, and public policy.

? DESCRIPTION (provided by applicant): Congenital deafness leads to significant language delays in children acquiring spoken language. Cascading effects of impoverished linguistic knowledge impact a wide range of psychological and cognitive behaviors including self-regulation, working memory, and reading. Cochlear implants (CIs) are a popular treatment option for deaf children. These devices deliver electrical stimulation to the auditory nerve, bypassing malfunctioning peripheral auditory mechanisms. Deaf children who receive cochlear implants early in life and engage in intensive oral/aural therapy often make great strides in spoken language acquisition. However, despite clinicians' best efforts, even under optimal conditions, there is a great deal of variability in language outcomes. The interplay of factors contributing to this lack of success is poorly understood. One mounting concern is that under conditions of deafness, the auditory system may be subject to maladaptive cross-modal plasticity (CMP). In cross-modal plasticity the processing demands of an intact sensory system, such as vision, may recruit nascent auditory cortex making it less available for speech processing. Animal models of deafness have shown evidence of functionally significant cross-modal plasticity with enhancements in visual processing tied to auditory cortical activation. Studies of deaf signing adults have also reported evidence of cross-modal plasticity including visual responsiveness within primary auditory cortex. The specialization of left-hemisphere auditory regions for visual sign language processing attests to the malleability of temporal lobe cortical networks. However, there are significant gaps in our knowledge. The conditions that precipitate CMP and the developmental time course of CMP are not known. There is an urgent need for studies that simultaneously assess auditory and visual processing in deaf children with cochlear implants during the formative stages of language development. Nor is it known how communication modality (signed or speech) impacts cross-modal plasticity. We use electrophysiology to obtain auditory and visual evoked potentials and assess functional integrity and development of the auditory cortex and the presence of cross modal changes in prelingually deaf children who have received cochlear implant. Using innovative behavioral testing and standardized measures of language function we will assess the impact of spoken and signed language experience in the expression of cross-modal plasticity. The proposed studies will advance our understanding of the determinants of CMP and its relation to language use. The findings will have a significant impact on clinical practices for deaf children.

DESCRIPTION (provided by applicant): The overall aim of this project is to map the. The neural basis of gesture processing has received a great deal of attention in the last several years, particularly in connection with the mirror neuron theory of action understanding. This theory states that gestures are understood via motor simulation in the observer. Sign language provides a unique perspective on this issue given its extremely rich gestural system, its easy accessibility (as opposed to speech gestures which are largely obscured from view), and the opportunity to compare linguistic and non-linguistic forms of gestural processing. Sign language bridges the gap between the visuo-manual studies in animal models where mirror neurons were discovered and human language, where there is a tremendous concentration of research on the mirror system. There is substantial clinical importance as well, as the mirror system has been implicated in a range of acquired and developmental disorders ranging from apraxia and aphasia to autism. If therapies are being developed based on a motor simulation model of understanding, it is critical to have information regarding the validity of these claims. Sign language provides an ideal testing ground. In terms of theory, a dorsal-ventral model of gestural processing guides our investigations. Thus, the proposed project builds on a decades-long program of investigation into the neural basis of sign language and has four specific aims. Aim 1: Map of basic language functions in deaf signers using large-scale lesion-deficit mapping. Aim 2: Map the relation between perception and production of meaningless gestures using lesion and fMRI approaches. Aim 3: Map the relation between recognition and production of meaningful action and object-related gestures using lesion and fMRI approaches. Aim 4: Map the relation between recognition and production of pantomime vs. signed gestures using lesion and fMRI approaches.

? DESCRIPTION (provided by applicant): Congenital deafness leads to significant language delays in children acquiring spoken language. Cascading effects of impoverished linguistic knowledge impact a wide range of psychological and cognitive behaviors including self-regulation, working memory, and reading. Cochlear implants (CIs) are a popular treatment option for deaf children. These devices deliver electrical stimulation to the auditory nerve, bypassing malfunctioning peripheral auditory mechanisms. Deaf children who receive cochlear implants early in life and engage in intensive oral/aural therapy often make great strides in spoken language acquisition. However, despite clinicians' best efforts, even under optimal conditions, there is a great deal of variability in language outcomes. The interplay of factors contributing to this lack of success is poorly understood. One mounting concern is that under conditions of deafness, the auditory system may be subject to maladaptive cross-modal plasticity (CMP). In cross-modal plasticity the processing demands of an intact sensory system, such as vision, may recruit nascent auditory cortex making it less available for speech processing. Animal models of deafness have shown evidence of functionally significant cross-modal plasticity with enhancements in visual processing tied to auditory cortical activation. Studies of deaf signing adults have also reported evidence of cross-modal plasticity including visual responsiveness within primary auditory cortex. The specialization of left-hemisphere auditory regions for visual sign language processing attests to the malleability of temporal lobe cortical networks. However, there are significant gaps in our knowledge. The conditions that precipitate CMP and the developmental time course of CMP are not known. There is an urgent need for studies that simultaneously assess auditory and visual processing in deaf children with cochlear implants during the formative stages of language development. Nor is it known how communication modality (signed or speech) impacts cross-modal plasticity. We use electrophysiology to obtain auditory and visual evoked potentials and assess functional integrity and development of the auditory cortex and the presence of cross modal changes in prelingually deaf children who have received cochlear implant. Using innovative behavioral testing and standardized measures of language function we will assess the impact of spoken and signed language experience in the expression of cross-modal plasticity. The proposed studies will advance our understanding of the determinants of CMP and its relation to language use. The findings will have a significant impact on clinical practices for deaf children.

? DESCRIPTION (provided by applicant): Congenital deafness leads to significant language delays in children acquiring spoken language. Cascading effects of impoverished linguistic knowledge impact a wide range of psychological and cognitive behaviors including self-regulation, working memory, and reading. Cochlear implants (CIs) are a popular treatment option for deaf children. These devices deliver electrical stimulation to the auditory nerve, bypassing malfunctioning peripheral auditory mechanisms. Deaf children who receive cochlear implants early in life and engage in intensive oral/aural therapy often make great strides in spoken language acquisition. However, despite clinicians' best efforts, even under optimal conditions, there is a great deal of variability in language outcomes. The interplay of factors contributing to this lack of success is poorly understood. One mounting concern is that under conditions of deafness, the auditory system may be subject to maladaptive cross-modal plasticity (CMP). In cross-modal plasticity the processing demands of an intact sensory system, such as vision, may recruit nascent auditory cortex making it less available for speech processing. Animal models of deafness have shown evidence of functionally significant cross-modal plasticity with enhancements in visual processing tied to auditory cortical activation. Studies of deaf signing adults have also reported evidence of cross-modal plasticity including visual responsiveness within primary auditory cortex. The specialization of left-hemisphere auditory regions for visual sign language processing attests to the malleability of temporal lobe cortical networks. However, there are significant gaps in our knowledge. The conditions that precipitate CMP and the developmental time course of CMP are not known. There is an urgent need for studies that simultaneously assess auditory and visual processing in deaf children with cochlear implants during the formative stages of language development. Nor is it known how communication modality (signed or speech) impacts cross-modal plasticity. We use electrophysiology to obtain auditory and visual evoked potentials and assess functional integrity and development of the auditory cortex and the presence of cross modal changes in prelingually deaf children who have received cochlear implant. Using innovative behavioral testing and standardized measures of language function we will assess the impact of spoken and signed language experience in the expression of cross-modal plasticity. The proposed studies will advance our understanding of the determinants of CMP and its relation to language use. The findings will have a significant impact on clinical practices for deaf children.