7. VHSS intervention in English

Subsequent research using FlashWord in English with American students has built on the successes in Dutch and Italian. Koen et al. used fMRI technology to localize brain activity before and after VHSS training in students who qualified with the characteristics of developmental dyslexia. This research was designed to test the hypothesis that subtyping students with the characteristics of dyslexia based on their reading behaviors as Bakker proposed, and administering VHSS intervention based on those subtypes (FlashWord-modified and in English), would improve fluency performance across dyslexia sub-types more effectively than other currently used reading fluency programs. Secondarily, the location and level of activation differences from pre-intervention and post-intervention scans were analyzed for evidence of developing automaticity in regions of interest [78].

FlashWord, Ver. 2.2, written by Franco Fabbro and Cristina Masutto (copyright, 1995–2004 by Editrice TecnoScuola) is a computer program that uses a gameformat to present words or phrases in the right or left visual hemi-field at increasingly rapid rates. According to their dyslexia sub-type, each student sees the words (or phrases) projected on either the right or left side of the computer screen, stimulating either the right or left visual field and the opposite brain hemisphere. Ocular fixation is confirmed by directing the child to watch a luminous dot oscillating up and down on the screen at an adjustable speed. A word is revealed only when the child clicks the mouse exactly when the dot is crossing the central target. This ensures visual attention to the stimulus. The child's task is to read the words as they are flashed on the screen in ever shortening durations. Reading rates of 250– 100 ms for single words are generally considered to reflect "emerging fluency" [75]. For this study, students repeated all of the lessons in their assigned program (34 for the LH program and 27 for the RH program) at their own speed, matching the Italian students in total time spent: 1440 minutes (or 24 hours) total.

This fMRI experiment used a mixed design, in that the events of interest (Word Pair analysis) are randomized with perceptual controls (Letter Match analysis) to provide robust event-related activation maps and estimates of hemodynamic response. The Letter Match task demands that the child decide whether two letter strings (e.g., szpy and sxpy), printed in all black letters and shown simultaneously one above the other, match exactly. The length of the letter strings is comparable to the length of the pseudo-words used in the phonological analysis task. As this is the control task, attention to all letter positions is necessary but the assignment of speech sounds to letters is not. For the phonological analysis task, the Word Pairs were two decodable non-words printed in black, also presented visually, one above

the other. Each word contained a letter, or group of letters, printed in pink. The child was instructed to press the button "Yes", if the pink letter(s) in the top word could stand for the same sound as the pink letter(s) in the bottom word, and to press a different button "No", if the pink letters represent different sounds.

Among other statistical procedures, the results of 1440 minutes of intervention measured in milliseconds and representing a change in speed of processing was used as a measure of achieved fluency in the Intervention group only. This sub-grouping was necessary because three individuals in the Intervention group did not achieve fluent processing with the FastWord program. This evidence of processing change was analyzed by means of a two-way mixed design ANOVA having two levels of reading fluency scores (pre- and post-intervention) as a within-subjects factor and two levels of fluency: those students (N = 6) who reached levels of emerging fluency, 100 ms or less, and those (N = 3) who did not, as a between-subjects factor. The between-subjects main effect of the fluency rate achieved during intervention was significant, F(1,8) = 5.38, p = .05, indicating significant differences between the students who achieved fluent processing and those who did not [78].

The fMRI results were remarkable for their corroboration of brain activations found during tasks requiring phoneme analysis. This analysis focused on three Regions of Interest (ROIs) within the core sub-systems supporting the processing of written language in normal readers: the left hemisphere (LH) superior temporal gyrus (STG) in the inferior parietal lobule within the temporoparietal system associated with word meaning; the posterior aspect of the inferior frontal gyrus (IFG) within the anterior system associated with sound/symbol associations; and the LH inferior occipito-temporal/fusiform area (VWFA) within the ventral system associated with quick recall of high frequency words first documented by Shaywitz et al. [73]. It was hypothesized that achieving fluency in reading will involve automaticity within each of these ROIs and that the brain activation maps of phonological processing of Word Pairs greater than perceptual control of Letter Match condition would show changes in activation patterns. Through comparisons of preintervention processing and post-intervention processing, there are clearly subjects who demonstrate much more focused activation bilaterally in the temporal regions around the STG and Postcentral Gyrus with very little activation in the visual word form area (VWFA) in the LH occipital lobe, and others who show an increase in left hemisphere activation around the IFG and VWFA [78].

Using a clustering threshold of five voxels, a sample of the activation locations were found post-intervention in the condition of Word Pairs over Letter Match in a fluent subject. Table 3 contains a partial list of left hemisphere only activation sites, noting the location, relative size, and maximum recorded t-score.

(3.16) makes sense in that area 40 is part of Wernicke's Gyrus where sound/symbol associations are refined and area 13 is a bridge between lateral and medial layers. The Postcentral activation could be evidence of compensatory systems being used

Structure x y z Cluster size Max t score

LH inferior frontal gyrus 48 24 12 523 1.52 LH superior temporal gyrus 60 28 12 352 3.10 LH Brodmann area 41 56 20 12 147 3.71 LH insula 36 16 12 119 1.97 LH Brodmann area 42 60 20 12 114 3.94 LH Brodmann area 13 40 16 12 73 1.93 LH precentral gyrus 56 8 12 67 1.66

LH superior temporal gyrus 40 40 16 233 2.56 LH angular gyrus 52 64 36 86 2.46 LH insula 42 16 16 68 2.21 LH postcentral gyrus 52 31 52 33 3.87 LH Brodmann area 13 44 16 16 29 3.08 LH inferior parietal lobule 52 36 28 26 2.74

LH sub-gyral 36 4 32 30 1.54 LH middle temporal gyrus 40 0 32 19 1.42 LH Brodmann area 20 44 8 32 7 1.80 LH Brodmann area 21 40 4 32 5 2.05 LH Brodmann area 35 24 16 32 5 2.01 LH fusiform (aal) 28 24 32 5 3.06

ROI-IFG

The Neurobiological Development of Reading Fluency DOI: http://dx.doi.org/10.5772/intechopen.82806

ROI-STG

ROI-VWFA

Table 3.

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Even more unexpected, was the finding that only 1440 minutes of intervention resulted in increases in the reading speed of connected text for many subjects. Since the training mostly involved single word reading and some phrases, it was not anticipated that the intervention would make any difference in the reading of longer passages of connected text. However, this was found to be false. Six of the nine students in the Intervention Group who achieved levels of automatic

The largest activation in the VWFA ROI is found in the smallest clusters detected. The Brodmann areas 21 (2.05) and 35 (2.01) appear to support automatic processing through their connection to Middle Temporal Gyrus, believed to access word meaning, and the perirhinal cortex, critical to memory. The left aspect of the Fusiform Gyrus shows the strongest activation (3.06) as would be expected if automatic retrieval of letter patterns was triggered [78]. So taken together, the activation locations identified in the subjects of this study, generally follow activation patterns found in the literature. Shaywitz et al. found that activation in the left

for phonological analysis in immature processing systems.

Post-intervention activation locations in a fluent subject.

occipito-temporal cortex increases with reading skill [79].

These data confirm some anticipated activation areas with sizeable groups of voxels contributing and some remarkable lack of activation within the ROIs studied. The largest activated cluster in the IFG ROI is the Inferior Frontal Gyrus (1.52), but activation in the STG (3.10), and Brodmann areas 41 (3.17) and 42 (3.94) is much stronger. This could indicate that most of the processing in this region involved sound/symbol associations with support in the primary and auditory association cortex. The weak activation in the IFG, which supports the encoding of phonological features, could mean that less effort was required to accomplish the phonological analysis task by this subject.

The largest activated cluster in the STG ROI is the STG (2.56), but again, other areas show stronger levels of stimulation. The Postcentral Gyrus activation (3.87) is odd in that this area is the primary somatosensory cortex receiving all sensory input, especially touch. However, except for the pressing of the response button, there was no variation in the motor demands of the scanner task that would explain activation in this area. The activation found in Brodmann areas 13 (3.08) and 40

