Neural Mechanisms of Anaphoric Reference Revealed by fMRI

Pronouns are bound to their antecedents by matching syntactic and semantic information. The aim of this functional magnetic resonance imaging study was to localize syntactic and semantic information retrieval and integration during pronoun resolution. Especially we investigated their possible interaction with verbal working memory manipulated by distance between antecedent and pronoun. We disentangled biological and syntactic gender information using German sentences about persons (biological/syntactic gender) or things (syntactic gender) followed by congruent or incongruent pronouns. Increasing the distance between pronoun and antecedent resulted in a short and a long distance condition. Analysis revealed a language related network including inferior frontal regions bilaterally (integration), left anterior and posterior temporal regions (lexico-semantics and syntactic retrieval) and the anterior cingulate gyrus (conflict resolution) involved in pronoun resolution. Activities within the inferior frontal region were driven by Congruency (incongruent > congruent) and Distance (long > short). Temporal regions were sensitive to Distance and Congruency (but solely within long distant conditions). Furthermore, anterior temporal regions were sensitive to the antecedent type with an increased activity for person pronouns compared to thing pronouns. We suggest that activity modulations within these areas reflect the integration process of an appropriate antecedent which depends on the type of information that has to be retrieved (lexico-syntactic posterior temporal, lexico-semantics anterior temporal). It also depends on the overall syntactic and semantic complexity of long distant sentences. The results are interpreted in the context of the memory–unification-control model for sentence comprehension as proposed by Vosse and Kempen (2000), Hagoort (2005), and Snijders et al. (2009)

The Paradox of Reading Disabilities: Assessing Creative Potential in Children at-risk for Reading Disabilities

This study explores the profiles of children who are at-risk for reading disabilities on both traditional reading-based tasks and measures of creativity. Twenty-six (26) children referred to the Learning Disabilities Association of Niagara Region were administered a series of reading-based measures, as well as measures of creativity and creative thinking. It was hypothesized that children at-risk for reading disabilities may be predisposed to characteristics aligned with creative thinking. Results of the study indicated that children at-risk for learning disabilities demonstrated phonological awareness abilities that were statistically significantly discrepant from their creative thinking skills. The sample of children in this study often demonstrated significantly below average phonological processing skills and creativity skills that were within average limits. In several cases, participants had creativity skills that were well above average. Such findings hold important implications for policy and practice around supporting children with reading disabilities

Lateral inferotemporal cortex maintains conceptual-semantic representations in verbal working memory

Verbal working memory, that is, the temporary maintenance of linguistic information in an activated state, is typically assumed to rely on phonological representations. Recent evidence from behavioral, neuropsychological, and electrophysiological studies, however, suggests that conceptual-semantic representations may also be maintained in an activated state. We developed a new semantic working memory task that involves the maintenance of a novel conceptual combination. Functional magnetic resonance imaging data acquired during the maintenance of conceptual combinations, relative to an item recognition task without the possibility of conceptual combination, demonstrate increased activation in the posterior left middle and inferior temporal gyri (known to be involved in conceptual representations) and left inferior frontal gyrus (known to be involved in semantic control processes). We suggest that this temporo-frontal system supports maintenance of conceptual information in working memory, with the frontal regions controlling the sustained activation of heteromodal conceptual representations in the inferior temporal cortex

The commonality of neural networks for verbal and visual short-term memory.

peer reviewedAlthough many neuroimaging studies have considered verbal and visual short-term memory (STM) as relying on neurally segregated short-term buffer systems, the present study explored the existence of shared neural correlates supporting verbal and visual STM. We hypothesized that networks involved in attentional and executive processes, as well as networks involved in serial order processing, underlie STM for both verbal and visual list information, with neural specificity restricted to sensory areas involved in processing the specific items to be retained. Participants were presented sequences of nonwords or unfamiliar faces, and were instructed to maintain and recognize order or item information. For encoding and retrieval phases, null conjunction analysis revealed an identical fronto-parieto-cerebellar network comprising the left intraparietal sulcus, bilateral dorsolateral prefrontal cortex, and the bilateral cerebellum, irrespective of information type and modality. A network centered around the right intraparietal sulcus supported STM for order information, in both verbal and visual modalities. Modality-specific effects were observed in left superior temporal and mid-fusiform areas associated with phonological and orthographic processing during the verbal STM tasks, and in right hippocampal and fusiform face processing areas during the visual STM tasks, wherein these modality effects were most pronounced when storing item information. The present results suggest that STM emerges from the deployment of modality-independent attentional and serial ordering processes toward sensory networks underlying the processing and storage of modality-specific item information

The neural and cognitive bases of ambiguous and unambiguous conceptual combination

Conceptual representations can be altered to align with the current context given learning and task goals. One cognitive process, known as conceptual combination, allows for a unique perspective for exploring how complex conceptual processing occurs and how this processing influences the underlying representations of concepts. During novel nominal conceptual combination, two constituent nouns, a modifier noun (e.g., lemon) and a head noun (e.g., flamingo) are creatively combined to form a novel meaning (e.g., a lemon flamingo might be a yellow flamingo). Different strategies can be taken up by combiners - typically being either attributive (as above) or relational (e.g., a lemon flamingo is a flamingo that consumes lemons). Importantly, few studies have directly examined more ambiguous combinations, which are more complex to process, having an equal likelihood of being combined attributively or relationally between individuals. This dissertation addresses two main aims for understanding nominal conceptual combination through a series of four studies. First, it explores the pathways driving different kinds of conceptual combination. In Study 1, I examine how easily conceptual combinations can be formed and subsequently remembered. In Study 2, I explore how individual differences in cognition predict ease of combining. The second aim explores how conceptual combination differently impacts the representations of the constituent concepts. In Study 3, I address whether and how the cognitive representations of the head noun in a conceptual combination are altered because of being conceptually combined. Finally, Study 4 addresses both aims using neuroimaging to explore how different types of conceptual combinations are processed and how the neural representations of concepts are altered because of their combination. The findings show representational change due to conceptual combination in early visual processing regions of the brain and suggest that conceptual combination may rely on additional cognitive processes throughout the lifespan. There is also an emerging theme of the importance of cognitive control in the ease of combining. Finally, the findings show differences in the processing of different types of conceptual combinations, both between attributive and relational combinations and between unambiguous and ambiguous, advocating for the inclusion of ambiguous compounds in future studies of conceptual combination

The Role Of Working Memory And Linguistic Knowledge On Language Performance

The language system is highly flexible and draws on distinct but interconnected cognitive mechanisms, including verbal working memory and long-term linguistic knowledge. Verbal working memory is the ability to manipulate verbal information in mind. Long-term linguistic knowledge refers to our knowledge of the language (i.e., phonology, semantics, syntax), stored in long-term memory. The close interaction between verbal working memory and linguistic knowledge highlights a pressing need to investigate the construct of verbal working memory, its separability and its relationship with linguistic knowledge. To understand the way working memory influences and interacts with language abilities in children and adults, I ask the following questions: Are verbal working memory and language separable constructs? And, does verbal working memory operate within a dynamic network of cognitive systems including the language network? In Chapter 2, I examined whether working memory and linguistic abilities could be teased apart using the same language task, namely a modified Token Test. Indeed, factors related to working memory and linguistic abilities explained performance on our modified Token Test and were differentially related to other language measures. Despite evidence of separability, it must be acknowledged that verbal working memory and language processing are highly intertwined. Chapters 3 and 4 investigated this interrelationship in detail. Specifically, I used experimental tasks to delineate the involvement of phonological and semantic representations in the maintenance of verbal items (words, sentences) in working memory. In Chapter 3, I used a novel word recognition paradigm and found separable phonological and semantic effects on immediate memory, with semantic processing supporting long-term retention. These findings confirmed that both phonological and semantic information were readily activated and accessed when a word is encountered and processed. Chapter 4 further evaluated the interplay between different cognitive processes underlying verbal working memory in the context of sentence recall. Similarly, results supported the idea that multiple representations influence performance, but their contributions differ. Semantic processing was beneficial for both immediate and long-term memory whereas phonological processing had more immediate benefits. Finally, in the concluding chapter, I discuss the importance of these results for models of verbal short-term memory and highlight some potential implications for clinical practice

The nature of the interactions between verbal working memory and long-term memory knowledge: a behavioral and neuroimaging investigation

The research conducted in this PhD Thesis aimed to determine the nature of the interactions between verbal working memory (WM) and long-term memory (LTM) knowledge by investigating the cognitive and neural aspects of the potential overlap between the two systems. This question was addressed through three experimental studies employing behavioral paradigms and advanced neuroimaging techniques, including the investigation of the impact of syntactic knowledge on verbal WM performance (Study 1), an fMRI investigation of the neural substrates associated with long-term semantic knowledge and maintenance of semantic information in verbal WM (Study 2), and an fMRI investigation of the language learning-related changes in the cortices that support verbal WM (Study 3). Our findings demonstrate at least partial overlap between verbal WM and long-term linguistic knowledge, characterized by dynamic and flexible interactions. Overall, these results support hybrid, partially emergent language-based models of WM, while emphasizing that although verbal WM and LTM knowledge interact, verbal WM performance extends beyond the simple activation of linguistic knowledge. Verbal WM interacts dynamically with other cognitive processes, and LTM knowledge rather intervenes in a flexible manner in verbal WM. This thesis highlights the importance of adopting an integrative approach that encompasses all language representations, takes into account potential interactions between verbal WM and episodic memory processes, and reflects the flexible and adaptive nature of long-term linguistic knowledge activation in verbal WM