Effects of Hemisphere-Specific stimulation on brain activity and reading in dyslexics

Abstract

Dyslexic readers, classified as L-types or P-types, received direct or indirect stimulation of the right (L-types) or left (P-types) hemisphere. Direct stimulation was produced by presenting words in the left (L-types) or right (P-types) visual field. Indirect stimulation took place through the presentation of visual-perceptual (L-types) or phonetic (P-types) demanding texts. Analyses of event-related potentials (ERP), elicited by centrally presented words, revealed the component reflecting P250 activity to be asymmetrically affected by experimental vs. control treatments. Treatment effects on scholastic achievement were shown in L-type dyslexics who had received direct stimulation of their right hemisphere and in P-type dyslexics whose left hemisphere had been indirectly stimulated. Training-induced electrical changes in brain asymmetry correlated with changes in measures of reading accuracy and speed. The set of findings replicated most of the results of a previous study (Bakker, Moerland, & Goekoop-Hoefkens, 1981).

Inhibitory Deficits in Reading Disability Depend on Subtype: Guessers but not Spellers

“…A child was classified as having the guessing type of dyslexia when RS < 115 and RE < .40 (more than 60% of errors made were substantive errors), and as having the spelling type of dyslexia when RS > 135 and RE> .60 (more than 60% of errors made were time-consuming errors). The classification criteria were similar to those used by Van Strien (1999) and Patel and Licht (in press) and were adapted from Bakker and Vinke (1985) and Van Strien, Bakker, Bouma, and Koops (1990). Using this classification system, we were able to classify about 60% of our dyslexics as either spellers or guessers (N = 45).…”

Neural plasticity following auditory training in children with learning problems

“…Relationships between evoked potentials, auditory processing and speech perception have been shown for children with language impairment (Tonnquist-Uhlen, 1996), dyslexia (Bakker and Vinke, 1985;McPherson and Ackerman, 1999), dysphasia (Holopainen et al, 1997), spelling disabilities (Byring and Jarvilehto, 1985), auditory processing disorders (Jirsa and Clontz, 1990) and learning problems (Kraus et al, 1996;Cunningham et al, 2000;King et al, 2002;Wible et al, 2002).…”

Inhibitory Control During Sentence Reading in Dyslexic Children

“…A child was classified as having the guessing type of dyslexia when: RS < 120 and RE > 0.60 (more than 60% of errors made were substantive errors). The classification criteria were adapted from Bakker and Vinke (1985) and Van Strien, Bakker, Bouma, and Koops (1990) and have been applied in many studies (e.g., Jonkman, Licht, Bakker, & Van den Broek-Sandmann, 1992;Patel & Licht, 2000;Van Strien, 1999). Using this classification system, we were able to classify about 26% of our dyslexics as guessers (N ¼ 16).…”