The influence of instruction modality on brain activation in teenagers with nonverbal learning disabilities: two case histories.

Teenagers with nonverbal learning disabilities (NLD) have difficulty with fine-motor coordination, which may relate to the novelty of the task or the lack of "self-talk" to mediate action. In this study, we required two teenagers with NLD and two control group teenagers to touch the thumb of each hand firmly and accurately to the fingertips of the same hand, in an order specified by verbal or tactile instruction. Brain activity patterns (measured using functional magnetic resonance imaging) suggest that unlike control participants, the NLD participants used internalized speech to facilitate the novel task only when instructions were verbal. NLD participants also showed activity in a more widely distributed network of neural structures. These findings provide preliminary evidence for remediation strategies that encourage internal speech.