Neuroplasticity of language networks in aphasia: advances, updates, and future challenges

Researchers have sought to understand how language is processed in the brain, how brain damage affects language abilities, and what can be expected during the recovery period since the early 19th century. In this review, we first discuss mechanisms of damage and plasticity in the post-stroke brain, both in the acute and the chronic phase of recovery. We then review factors that are associated with recovery. First, we review organism intrinsic variables such as age, lesion volume and location and structural integrity that influence language recovery. Next, we review organism extrinsic factors such as treatment that influence language recovery. Here, we discuss recent advances in our understanding of language recovery and highlight recent work that emphasizes a network perspective of language recovery. Finally, we propose our interpretation of the principles of neuroplasticity, originally proposed by Kleim and Jones (1) in the context of extant literature in aphasia recovery and rehabilitation. Ultimately, we encourage researchers to propose sophisticated intervention studies that bring us closer to the goal of providing precision treatment for patients with aphasia and a better understanding of the neural mechanisms that underlie successful neuroplasticity.P50 DC012283 - NIDCD NIH HHSPublished versio

To Pair or Not To Pair: Sources of Social Variability with White-Faced Saki Monkeys (Pithecia Pithecia) As a Case Study

Intraspecific variability in social systems is gaining increased recognition in primatology. Many primate species display variability in pair-living social organizations through incorporating extra adults into the group. While numerous models exist to explain primate pair-living, our tools to assess how and why variation in this trait occurs are currently limited. Here I outline an approach which: (i) utilizes conceptual models to identify the selective forces driving pair-living; (ii) outlines novel possible causes for variability in social organization; and (iii) conducts a holistic species-level analysis of social behavior to determine the factors contributing to variation in pair-living. A case study on white-faced sakis (Pithecia pithecia) is used to exemplify this approach. This species lives in either male-female pairs or groups incorporating extra adult males and/or females. Various conceptual models of pair-living suggest that high same-sex aggression toward extra-group individuals is a key component of the white-faced saki social system. Variable pair-living in white-faced sakis likely represents alternative strategies to achieve competency in this competition, in which animals experience conflicting selection pressures between achieving successful group defense and maintaining sole reproductive access to mates. Additionally, independent decisions by individuals may generate social variation by preventing other animals from adopting a social organization that maximizes fitness. White-faced saki inter-individual relationships and demographic patterns also lend conciliatory support to this conclusion. By utilizing both model-level and species-level approaches, with a consideration for potential sources of variation, researchers can gain insight into the factors generating variation in pair-living social organizations

Reluctance of Adolescents with Cerebral Palsy to Participate in an Online Intervention on Self-management: Lessons Learned from a Randomized Control Trial

Purpose: Assess the effectiveness of an online intervention to encourage self-management in adolescents with cerebral palsy (CP). Specific Aims: (a) assess effectiveness of an online intervention to promote readiness for self-management in adolescents with CP, (b) describe health literacy and associations with readiness to assume self-management, and (c) evaluate adolescents’ exposure to the online intervention. Hypotheses: (a) intervention subjects would demonstrate improvement in self-management, and (b) subjects with higher health literacy would demonstrate higher self-management capabilities. Framework: Transtheoretical Model of Health Behavior Change Design: Randomized control trial, performed in a multidisciplinary CP clinic at a university based children’s hospital. Instruments used: (a) Transition Readiness Assessment Questionnaire (TRAQ) and (b) the Health Literacy Skills Instrument-SF (HLSI). Due to low engagement, the study terminated early. Intervention subjects were interviewed to assess their limited engagement. Results: Seventy-five percent of subjects demonstrated inadequate HL. Mean baseline TRAQ score (n=24) was 2.71 (SE = .24). Positive associations were found between TRAQ and age (.47, p = .00) and TRAQ and HL (.48, p = .00). Conclusion: Failure to engage with the intervention appeared to be related to: (a) low HL, (b) low TRAQ scores (indicating subjects in contemplation stage) (c) inconsistency between subjects’ preference for learning and delivery of information, and (d) low motivation for self directed learning. Online interventions should be easy to use and include learning preferences. Lessons learned will inform future development of interventions for this population

Neural connectivity in syntactic movement processing

Linguistic theory suggests non-canonical sentences subvert the dominant agent-verb-theme order in English via displacement of sentence constituents to argument (NP-movement) or non-argument positions (wh-movement). Both processes have been associated with the left inferior frontal gyrus and posterior superior temporal gyrus, but differences in neural activity and connectivity between movement types have not been investigated. In the current study, functional magnetic resonance imaging data were acquired from 21 adult participants during an auditory sentence-picture verification task using passive and active sentences contrasted to isolate NP-movement, and object- and subject-cleft sentences contrasted to isolate wh-movement. Then, functional magnetic resonance imaging data from regions common to both movement types were entered into a dynamic causal modeling analysis to examine effective connectivity for wh-movement and NP-movement. Results showed greater left inferior frontal gyrus activation for Wh > NP-movement, but no activation for NP > Wh-movement. Both types of movement elicited activity in the opercular part of the left inferior frontal gyrus, left posterior superior temporal gyrus, and left medial superior frontal gyrus. The dynamic causal modeling analyses indicated that neither movement type significantly modulated the connection from the left inferior frontal gyrus to the left posterior superior temporal gyrus, nor vice-versa, suggesting no connectivity differences between wh- and NP-movement. These findings support the idea that increased complexity of wh-structures, compared to sentences with NP-movement, requires greater engagement of cognitive resources via increased neural activity in the left inferior frontal gyrus, but both movement types engage similar neural networks.This work was supported by the NIH-NIDCD, Clinical Research Center Grant, P50DC012283 (PI: CT), and the Graduate Research Grant and School of Communication Graduate Ignition Grant from Northwestern University (awarded to EE). (P50DC012283 - NIH-NIDCD, Clinical Research Center Grant; Graduate Research Grant and School of Communication Graduate Ignition Grant from Northwestern University)Published versio

Real-time production of unaccusative vs. unergative sentences in normal and agrammatic speakers: an eyetracking study

This study examined real-time production of unergative and unaccusative verbs in sentences in 13 controls and 9 agrammatic speakers, using eyetracking. Speakers constructed a sentence, using written words. Results showed that both controls and aphasics showed increased gazes in producing the subject noun phrase in the unaccusative condition as compared to the unergative condition. However, aphasic speakers showed the difference before speech onset, while controls showed the difference during speech. The findings suggest that aphasic speakers are sensitive to the unaccusative-unergative distinction among intransitive verbs, but their time course of sentence planning may be different from that of normal speakers

Effects of Phonological Complexity Training on Pseudoword Reading in Acquired Phonological Dyslexia

Individuals with acquired phonological dyslexia experience difficulty associating written letters with corresponding sounds, especially with pseudowords. In training studies with children, when phonologically “more complex” consonant clusters were trained, improvement was noted on trained clusters and untrained “less complex” clusters, but not vice versa. To date, no treatment studies for acquired phonological dyslexia have systematically manipulated phonological complexity to improve reading ability. The present study applied principles of phonological complexity to letter-sound training in acquired phonological dyslexia. Our findings suggest phonological complexity can be used to improve generalization to untrained phonologically related words in this population

Effects of lexical processing deficits on agrammatic sentence comprehension: An eyetracking study

Individuals with Broca’s aphasia show lexical processing deficits, such as deficits in lexical access or lexical integration. Although studies have implicated lexical processing as areas of impairment in Broca’s aphasia, few studies have looked at the effects of these deficits on sentence comprehension. We conducted a series of eyetracking experiments to test whether Broca’s aphasic individuals are impaired in lexical access or lexical integration and whether such deficits affect sentence comprehension. Results showed that while lexical access and lexical integration are both impaired in Broca’s aphasia, only the deficit in lexical integration affects sentence comprehension

Production of Arguments and Adjuncts in Normal and Agrammatic speakers: An Eyetracking study

Agrammatic Broca’s aphasic speakers often are impaired in producing verbs and sentences with complex argument structure. In addition, deficits in production of adjunct phrases has been noted (Caplan, unpublished; Thompson et al.,1997). Based on models of normal sentence production, the former deficits have been attributed to problems at both the positional and functional level. However, these models do not address the latter. This study examined real-time production of adjuncts vs. arguments, by tracking eye movements in 13 young control and 9 agrammatic speakers. Controls showed greater difficulty for adjuncts than for arguments during production of the verb predicate structure. However, aphasic speakers showed differences prior to speech onset, suggesting an impairment in computing thematic-to-grammatical (functional) relationships between sentence constituents

Semantic Lexicon Acquisition for Learning Natural Language Interfaces

viii List of Tables xii List of Figures xiii Chapter 1 Introduction 1 Chapter 2 Background 6 2.1 Chill . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 2.2 The Work of Jeff Siskind . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 Chapter 3 Lexicon Learning and Wolfie 11 3.1 Problem Definition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11 3.2 Potential Approaches . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16 3.3 The Wolfie Algorithm and an Example . . . . . . . . . . . . . . . . . . . . . . . . . 18 3.4 Generating Candidate Lexicon Items . . . . . . . . . . . . . . . . . . . . . . . . . . . 22 3.5 Finding the Best Pair . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23 3.6 Constraining Remaining Candidates . . . . . . . . . . . . . . . . . . . . . . . . . . . 25 Chapter 4 Wolfie Experimental Results: Learning for Database-Query Parsing 30 4..