Anne L. Richards

Instructional treatment associated with changes in brain activation in children with dyslexia

Objective: To assess the effects of reading instruction on fMRI brain activation in children with dyslexia. Background: fMRI differences between dyslexic and control subjects have most often involved phonologic processing tasks. However, a growing body of research documents the role of morphologic awareness in reading and reading disability. Methods: The authors developed tasks to probe brain activation during phoneme mapping (assigning sounds to letters) and morpheme mapping (understanding the relationship of suffixed words to their roots). Ten children with dyslexia and 11 normal readers performed these tasks during fMRI scanning. Children with dyslexia then completed 28 hours of comprehensive reading instruction. Scans were repeated on both dyslexic and control subjects using the same tasks. Results: Before treatment, children with dyslexia showed less activation than controls in left middle and inferior frontal gyri, right superior frontal gyrus, left middle and inferior temporal gyri, and bilateral superior parietal regions for phoneme mapping. Activation was significantly reduced for children with dyslexia on the initial morpheme mapping scan in left middle frontal gyrus, right superior parietal, and fusiform/occipital region. Treatment was associated with improved reading scores and increased brain activation during both tasks, such that quantity and pattern of activation for children with dyslexia after treatment closely resembled that of controls. The elimination of group differences at follow-up was due to both increased activation for the children with dyslexia and decreased activation for controls, presumably reflecting practice effects. Conclusion: These results suggest that behavioral gains from comprehensive reading instruction are associated with changes in brain function during performance of language tasks. Furthermore, these brain changes are specific to different language processes and closely resemble patterns of neural processing characteristic of normal readers.

Anatomical Signatures of Dyslexia in Children: Unique Information from Manual and Voxel Based Morphometry Brain Measures

Thirteen male control and thirteen male dyslexic children (age, 121-152 months) were studied to determine if voxel based morphometry (VBM) could identify anatomical differences in the right cerebellar anterior lobe, and right and left pars triangularis that were identified with manual measures of the same children. VBM demonstrated significant gray and white matter differences in these three brain regions. In contrast to the manual results, these differences were not significant after controlling for brain volume, suggesting the manual measures captured additional important variance that distinguished the groups. Post-hoc VBM comparisons demonstrated white matter volume differences in a left temporal-parietal region that are consistent in location with results from diffusion tensor imaging studies of dyslexia. The VBM analyses also identified, gray matter volume differences in the left and right lingual gyrus, left inferior parietal lobule and cerebellum, areas that had not been examined with manual methods. We conclude that manual and automated methods provide valuable and complementary approaches to the search for functionally significant neurobiological characteristics of dyslexia.

fMRI auditory language differences between dyslexic and able reading children

During fMRI, dyslexic and control boys completed auditory language tasks (judging whether pairs of real and/or pseudo words rhymed or were real words) in 30 s ‘on’ conditions alternating with a 30 s ‘off’ condition (judging whether tone pairs were same). During phonological judgment, dyslexics had more activity than controls in right than left inferior temporal gyrus and in left precentral gyrus. During lexical judgment, dyslexics were less active than controls in bilateral middle frontal gyrus and more active than controls in left orbital frontal cortex. Individual dyslexics were reliably less active than controls in left insula and left inferior temporal gyrus. Dyslexic and control children differ in brain activation during auditory language processing skills that do not require reading.

The illusion of presence in immersive virtual reality during an fMRI brain scan.

The essence of immersive virtual reality (VR) is the illusion it gives users that they are inside the computer-generated virtual environment. This unusually strong illusion is theorized to contribute to the successful pain reduction observed in burn patients who go into VR during woundcare (www.vrpain.com) and to successful VR exposure therapy for phobias and post-traumatic stress disorder (PTSD). The present study demonstrated for the first time that subjects could experience a strong illusion of presence during an fMRI despite the constraints of the fMRI magnet bore (i.e., immobilized head and loud ambient noise).

Converging Evidence for Triple Word Form Theory in Children With Dyslexia

This article has 3 parts. The 1st part provides an overview of the family genetics, brain imaging, and treatment research in the University of Washington Multidisciplinary Learning Disabilities Center (UWLDC) over the past decade that points to a probable genetic basis for the unusual difficulty that individuals with dyslexia encounter in learning to read and spell. Phenotyping studies have found evidence that phonological, orthographic, and morphological word forms and their parts may contribute uniquely to this difficulty. At the same time, reviews of treatment studies in the UWLDC (which focused on children in Grades 4 to 6) and other research centers provide evidence for the plasticity of the brain in individuals with dyslexia. The 2nd part reports 4 sets of results that extend previously published findings based on group analyses to those based on analyses of individual brains and that support triple word form awareness and mapping theory: (a) distinct brain signatures for the phonological, morphological, and orthographic word forms; (b) crossover effects between phonological and morphological treatments and functional magentic resonance imaging (fMRI) tasks in response to instruction, suggestive of cross-word form computational and mapping processes; (c) crossover effects between behavioral measures of phonology or morphology and changes in fMRI activation following treatment; and (d) change in the relationship between structural MRI and functional magnetic resonance spectroscopy (fMRS) lactate activation in right and left inferior frontal gyri following treatment emphasizing the phonological, morphological, and orthographic word forms. In the 3rd part we discuss the next steps in this programmatic research to move beyond word form alone.

Elevated brain lactate responses to neural activation in panic disorder: a dynamic 1H-MRS study.

Converging evidence suggests that patients with panic disorder have a metabolic disturbance that may influence the regulation of arousal systems and confer vulnerability to ‘spontaneous’ panic attacks. The consistent finding of elevated brain lactate responses to various metabolic challenges in panic disorder appears to support this model, although the mechanism of this effect is not understood. Several mechanisms have been proposed to account for elevated brain lactate responses in panic disorder, including (1) brain hypoxia due to excessive cerebral vasoconstriction, and (2) a metabolic disturbance affecting lactate metabolism. Recent studies have shown that neural activation (for example, sensory stimulation) causes local lactate accumulation in the presence of increased oxygen availability. The current study used proton magnetic resonance spectroscopic measures of visual cortex lactate changes during visual stimulation in 15 untreated patients with panic disorder and 15 matched volunteers to critically test these two proposed mechanisms of elevated brain lactate responses in panic disorder. Visual cortex lactate/N-acetylaspartate increased during visual stimulation in both groups. The increase was significantly greater in the panic patients than in the comparison group. There were no group differences in end-tidal pCO2. The finding that visual stimulation leads to significantly greater visual cortex lactate responses in panic patients is not predicted by the hypoxia model. These results suggest that a metabolic disturbance affecting the production or clearance of lactate is the cause of the elevated brain lactate responses consistently observed in panic disorder and provide further support for metabolic models of vulnerability to this illness.

Midlife memory improvement predicts preservation of hippocampal volume in old age

This study examines whether midlife change in episodic memory predicts hippocampal volume in old age. From the Seattle Longitudinal Study we retrospectively identified 84 healthy, cognitively normal individuals, age 52 to 87, whose episodic memory had reliably declined (n = 33), improved (n = 28) or remained stable (n = 23) over a 14-year period in midlife (age 43-63). Midlife memory improvement was associated with 13% larger hippocampal volume (p < 0.01) in old age (age 66-87), compared with old age individuals whose midlife episodic memory had either declined or remained stable during midlife. Midlife memory change did not predict total hippocampal volume for those currently in late middle age (age 52-65). The pattern of findings was not modified by gender, apolipoprotein ε4 status, education or current memory performance. Change in midlife memory scores over 14 years, but not any single assessment, predicted hippocampal volumes in old age, emphasizing the importance of longitudinal data in examining brain-cognition relationships. These findings suggest that improvement in memory in midlife is associated with sparing of hippocampal volume in later life.