Plastic neural changes and reading improvement caused by audiovisual training in reading-impaired children

Abstract

This study aimed at determining whether audiovisual training without linguistic material has a remediating effect on reading skills and central auditory processing in dyslexic children. It was found that this training resulted in plastic changes in the auditory cortex, indexed by enhanced electrophysiological mismatch negativity and faster reaction times to sound changes. Importantly, these changes were accompanied by improvement in reading skills. The results indicate that reading difficulties can be ameliorated by special training programs and, further, that the training effects can be observed in brain activity. Moreover, the fact that the present training effects were obtained by using a program including no linguistic material indicates that dyslexia is at least partly based on a general auditory perceptual deficit.

Figures

Figure 1

(Upper) Task examples of the computer game version 1 and 2 are presented. In version 1, the child had to choose which of the two visual patterns corresponds to the sound pattern that is played. In version 2, only one pattern is displayed on the screen, after which a sound pattern is played. The child has to press the space bar when the sound corresponding to the last element of the visual pattern is being played. (Lower) Examples of the patterns used in the game. An elevation of a visual element corresponds to a higher pitch sound, whereas sound intensity is visually coded with element thickness and sound duration with element length. (A) A simple good Gestalt formed by the upward scale. Although the pattern itself is simple, the lack of repetition complicates the perception of the structure. (B) Finding subgroups according to good Gestalts. Although there is no pause between the subgroups, the accents clearly mark their beginnings, which helps one to follow the pattern. (C) The subgroups clearly marked by the pause. The accents are perceived the easiest as the beginnings of the subgroups; the positions of the accents here thus require some structuring against good Gestalts. (D) Patterns having the same elements but different structures. Because the most probable expectation on the second group of elements is the repetition of the first, this task requires the change of expectations. Perceiving differences within the subgroups is also needed, for the beginnings and ends of the groups are similar.

Figure 2

Reading performance before and after the training period. (Left) The average number (with standard errors of the mean) of correctly read words. (Right) The average reading speed (seconds per word). No significant group differences were found before the training period, whereas after it, the training group read correctly significantly more words than the control group (24 children in each group) and was nearly significantly faster in reading.

Figure 3

Electrophysiological responses of dyslexic children in the training and control groups (11 children in each group) at the frontal scalp to tone-order reversals (the response elicited by the standard pair subtracted from that elicited by the deviant pair). The responses of the training group are presented with the thick line and those of the control group (with no audiovisual training) with the thin line. Responses before (Upper) and after (Lower) the audiovisual training are shown. No significant group differences were obtained for the responses measured before the training. In contrast, after the training, the earlier parts of the MMN response were enhanced in the training group as compared with those of the control group.