A behavioural and neurobiological investigation of basic reading processes

There are competing theories in the literature regarding the extent to which the translation of print to speech involves single or multiple routes. Regardless of the number of routes in a model, all models of reading must account for both sight vocabulary (SV) processing, which specializes in mapping whole-word representations, and phonetic decoding (PD) processing, which specializes in mapping sub-word representations. The purpose of the present work was to examine two hypotheses regarding the relationship between SV and PD: independence versus redundancy. Both behavioural and functional Magnetic Resonance Imaging (fMRI) experiments were conducted and the results supported the hypothesis that SV and PD are behaviourally and neurobiologically independent processes. Furthermore, in the interest of advancing all models of basic word recognition, the neurobiological representations of some of the sub-systems within SV and PD routes were explored and the contribution that particular brain regions make to the completion of naming particular stimuli was evaluated. Finally, basic and applied areas of research were integrated to demonstrate how diagnostic stimuli developed from basic reading research can inform us about impaired reading performance following traumatic brain injury

To Go or Not to Go: Exploring brain activation during response inhibition reading tasks

Objective: Response inhibition is an understudied component of reading that aids in the selection of appropriate responses amidst complicated tasks. Our objective was to explore the contribution of brain regions associated with response inhibition processing in reading tasks that vary in difficulty of response inhibition. Method: Participants (N = 15) completed two go/no-go reading tasks while in a functional magnetic resonance imaging (fMRI) scanner, with the instructions to “name aloud the letter strings that spell a real word.” For the minimal response inhibition condition, the foils, which are stimuli that should not be repsonded to, were nonwords with unfamiliar spelling and sound (e.g., “bink”). For the maximal response inhibition condition, the foils were pseudohomophones with unfamiliar spelling but familiar sound (e.g., “pynt”). The following brain regions associated with decision-making processes were analyzed: the anterior cingulate cortex (ACC), the dorsomedial prefrontal cortex (DMPFC), the inferior frontal gyrus (IFG), the middle temporal gyrus (MTG), the middle occipital gyrus (MOG), and the posterior insula (PI). Results: Significant differences in activation within the nonword task were found for the DMPFC and the PI (the ACC approached significance). Significant differences in activation within the pseudohomophone task were found for the ACC, the MTG, and the PI. The IFG was found to be greatly activated for all words that had familiar phonemes (sounds). The MOG was found to be activated across all tasks. Conclusion: We provide evidence for differential response inhibition processing in the decision-making network during reading tasks. This work is a necessary step in better understanding response inhibition ability for individuals with and without reading impairments

Computer-based cognitive intervention for aphasia: Behavioural and neurobiological outcomes

Aphasia, an acquired impairment of language that commonly occurs after stroke, can have significant consequences on all aspects of functioning of affected individuals. Some have proposed that the language deficits observed in aphasia are due to underlying limitations in cognitive processes that support language1-3. This ‘cognitive’ theory of aphasia is gaining increased attention in the research literature4, and is the impetus for the study of treatments for aphasia that target these underlying cognitive processes5-8. Indeed, studies of cognitive interventions in healthy populations have reported positive outcomes in behavioural (i.e. language and overall cognitive functioning9, 10) as well as neurobiological (i.e., brain function and/or structure11-13) domains, offering promise for the application of these types of interventions to aphasia. Recently, computer-based ‘brain training’ programs have become increasingly prevalent. BrainFitness (BF) is one such commercially available program; it has been used to show improvement in auditory processing speed, attention and working memory in typically aging adults14, 15. This program has the potential to be a useful intervention for individuals with aphasia, but questions regarding the clinical utility of the program and neural correlates of training-related behavioural changes remain. The purpose of this study was to investigate the effect of BF training in people with aphasia using behavioural and neurobiological outcome measures

A neuroanatomical examination of embodied cognition: semantic generation to action-related stimuli

The theory of embodied cognition postulates that the brain represents semantic knowledge as a function of the interaction between the body and the environment. The goal of our research was to provide a neuroanatomical examination of embodied cognition using action-related pictures and words. We used functional magnetic resonance imaging (fMRI) to examine whether there were shared and/or unique regions of activation between an ecologically valid semantic generation task and a motor task in the parietal-frontocentral network (PFN), as a function of stimulus format (pictures versus words) for two stimulus types (hand and foot). Unlike other methods for neuroimaging analyses involving subtractive logic or conjoint analyses, this method first isolates shared and unique regions of activation within-participants before generating an averaged map. The results demonstrated shared activation between the semantic generation and motor tasks, which was organized somatotopically in the PFN, as well as unique activation for the semantic generation tasks in proximity to the hand or foot motor cortex. We also found unique and shared regions of activation in the PFN as a function of stimulus format (pictures versus words). These results further elucidate embodied cognition in that they show that brain regions activated during actual motor movements were also activated when an individual verbally generates action-related semantic information. Disembodied cognition theories and limitations are also discussed

Imaging imageability: Behavioral effects and neural correlates of its interaction with affect and context

The construct of imageability refers to the extent to which a word evokes a tangible sensation. Previous research (Westbury, Shaoul, Hollis, Smithson, Briesemeister, Hofmann, & Jacobs, 2013) suggests that the behavioral effects attributed to a word’s imageability can be largely or wholly explained by two objective constructs, contextual density and estimated affect. Here, we extend these previous findings in two ways. First, we show that closely matched stimuli on the three measures of contextual density, estimated affect, and human-judged imageability show a three-way interaction in explaining variance in LD RTs, but that imagebility accounts for no additional variance after contextual density and estimated affect are entered first. Secondly, we demonstrate that the loci and functional connectivity (via graphical models) of the brain regions implicated in processing the three variables during that task are largely over-lapping and similar. These two lines of evidence support the conclusion that the effect usually attributed to human-judged imageability is largely or entirely due to the effects of other correlated measures that are directly computable

Is the Letter ‘t’ in the Word ‘gourmet’? Disruption in Task-Evoked Connectivity Networks in Adults with Impaired Literacy Skills

Much work has been done to characterize domain-specific brain networks associated with reading, but very little work has been done with respect to spelling. Our aim was to characterize domain-specific spelling networks (SpNs) and domain-general resting state networks (RSNs) in adults with and without literacy impairments. Skilled and impaired adults were recruited from the University of Alberta. Participants completed three conditions of an in-scanner spelling task called a letter probe task (LPT). We found highly connected SpNs for both groups of individuals, albeit comparatively more connections for skilled (50) vs. impaired (43) readers. Notably, the SpNs did not correlate with spelling behaviour for either group. We also found relationships between SpNs and RSNs for both groups of individuals, this time with comparatively fewer connections for skilled (36) vs. impaired (53) readers. Finally, the RSNs did predict spelling performance in a limited manner for the skilled readers. These results advance our understanding of brain networks associated with spelling and add to the growing body of literature that describes the important and intricate connections between domain-specific networks and domain-general networks (i.e., resting states) in individuals with and without developmental disorders

Adult Learner Perspectives on Skill- and Life-Based Outcomes Following Literacy Remediation

Using the situated expectancy value theory (SEVT), we explored self-perceived attainment perspectives of adults with low literacy on skill-based (i.e., reading, writing, listening, speaking) and life-based (i.e., management of day-to-day challenges, use of skills in daily living, confidence) improvements following a literacy-focused remediation program. Participants (N = 103; Canadian, urban adults) completed a remediation program for low literacy via one-on-one tutoring over a period of 1 year. Four to six months into the program, participants completed a survey that asked about their perspectives regarding improvements in skill- and life-based areas of functioning. A series of Chi-Square tests provided evidence for self-perceived improvements in skill-based functioning in reading, writing, listening and speaking. Perceived improvements were not noted in areas not targeted by the remediation, namely, math and computer literacy. Further, there was a significant, positive correlation between self-perceived improvement and (1) self-perceived ability to deal with daily challenges, (2) self-reported use of literacy skills in day-to-day activities, and (3) overall confidence. Together, these findings underscore the importance of including activity- and participation-based outcome measures when evaluating adult literacy remediation. In addition, this work demonstrates an application of SEVT to explore changes over time in continuing adult education

The Impact of Dyslexia Awareness Month on Search Volume Using GoogleTrends

Dyslexia is one of the most common learning disabilities, but is also severely underdiagnosed. Early intervention is demonstrated to produce a better prognosis, but lack of awareness can impede pursuing and accessing treatment. Dyslexia Awareness Month has been implemented in both Canada and the United States during the month of October as a way of increasing the public’s knowledge of this learning disability. The objective of this study was to ascertain the effectiveness of these campaigns between the years of 2016 – 2019 in both countries. We employed ‘Google Trends’, which is a statistical tool that can be used to compare volumes of specific Google searches, to evaluate the relative number of searches for the term ‘dyslexia’ before, during, and after the awareness month campaigns each year. Our results show a significant increase in dyslexia-related search inquiries during October in both countries, but the timeline of these differences varies

Transcranial direct current stimulation (tDCS) selectively modulates semantic information during reading

© 2018 Elsevier Inc. The left angular gyrus has long been implicated in semantic processing. Here we tested whether or not transcranial direct current stimulation (tDCS) over the left angular gyrus modulated reading performance. Adult readers (N = 77) (1) read aloud words that varied in degree of imageability, a semantic word property known to activate the angular gyrus, and (2) completed an N-back task (control task). Individuals were randomly assigned to either the anodal, cathodal or sham stimulation conditions. We found that anodal (p = 0.001) and cathodal (p \u3c 0.001) stimulation impacted how imageability facilitates reading times such that readers who showed the largest imageability effects pre-stimulation showed the greatest reduction in these effects post-stimulation. No effects of stimulation were found in the sham group (p \u3e 0.05) or for the control task (i.e., N-back; p \u3e 0.05). These findings indicate that reading pathways can be modulated via brain stimulation (tDCS) to shift individuals’ sensitivity to word-level characteristics, namely imageability