Despite language disabilities in autism, music abilities are frequently preserved. Paradoxically, brain regions associated with these functions typically overlap, enabling investigation of neural organization supporting speech and song in autism. Neural systems sensitive to speech and song were compared in low-functioning autistic and age-matched control children using passive auditory stimulation during functional magnetic resonance and diffusion tensor imaging. Activation in left inferior frontal gyrus was reduced in autistic children relative to controls during speech stimulation, but was greater than controls during song stimulation. Functional connectivity for song relative to speech was also increased between left inferior frontal gyrus and superior temporal gyrus in autism, and large-scale connectivity showed increased frontal–posterior connections. Although fractional anisotropy of the left arcuate fasciculus was decreased in autistic children relative to controls, structural terminations of the arcuate fasciculus in inferior frontal gyrus were indistinguishable between autistic and control groups. Fractional anisotropy correlated with activity in left inferior frontal gyrus for both speech and song conditions. Together, these findings indicate that in autism, functional systems that process speech and song were more effectively engaged for song than for speech and projections of structural pathways associated with these functions were not distinguishable from controls.
Minimally verbal children with autism commonly demonstrate language dysfunction, including immature syntax acquisition. We hypothesised that transcranial direct current stimulation (tDCS) should facilitate language acquisition in a cohort (n = 10) of children with immature syntax. We modified the English version of the Bilingual Aphasia Test (BAT) to test only basic canonical subject-verb-object sentences. We tested syntactic accuracy after teaching then testing all vocabulary from the subsequent syntax test to ensure validity of syntactic scoring. We used scaffolding sentences for syntax training. All procedures were performed both before and after tDCS. Results demonstrated a large effect size of the difference between pre-/post-tDCS groups (p < 0.0005, d = 2.78), indicating syntax acquisition. Combining a modified BAT with tDCS constitutes effective modalities for assessment and treatment of immature syntax in children with autism. Future studies should explore the BAT for patients with an inability to use or understand language, in particular bilingual children with autism.
The supplementary motor area (SMA) is believed to be highly involved in the planning and execution of both simple and complex motor tasks. This study aimed to examine the role of the SMA in planning the movements required to complete reaction time, balance, and pegboard tasks using anodal transcranial direct current stimulation (tDCS), which passes a weak electrical current between two electrodes, in order to modulate neuronal activity. Twenty healthy adults were counterbalanced to receive either tDCS (experimental condition) or no tDCS (control condition) for 3 days. During administration of tDCS, participants performed a balance task significantly faster than controls. After tDCS, subjects significantly improved their simple and choice reaction time. These results demonstrate that the SMA is highly involved in planning and executing fine and gross motor skill tasks and that tDCS is an effective modality for increasing SMA-related performance on these tasks. The findings may be generalizable and therefore indicate implications for future interventions using tDCS as a therapeutic tool.
Functional MR imaging activation within the STG in response to passive speech stimulation helped differentiate autistic from control subjects, demonstrating the potential utility of functional MR imaging as an objective indicator of language impairment in autism. Future studies may lead to an early and objective indicator for autism with these methods.
Transcranial direct current stimulation (tDCS) has been investigated as a novel therapy for addressing motor, cognitive, and language deficits. While anodal tDCS to the primary motor cortex results in improved motor behaviors, few studies have examined if tDCS to other areas involved in motor output produces similar benefits. Although Broca's area is associated with speech production and grammar acquisition, it also contributes to motor planning and output in non-speech tasks. This study involved applying anodal tDCS to Broca's area and observing effects on non-verbal motor output. Twenty young adults completed two testing sessions separated by one week. Participants received either 30 minutes of 1.0 mA of anodal tDCS to Broca's area or sham stimulation. During stimulation (or sham), participants completed two tasks: (1) a limits of stability dynamic balance task and (2) a simple (SRT)/choice reaction time(CRT) tasks. Subjects who received tDCS to first performed significantly better on SRT and dynamic balance accuracy and showed a trend for dynamic balance speed when tested one week later compared to those who received sham stimulation first. These findings indicate that Broca's area is involved in the production of non-verbal motor behaviors and may have implications novel combined speech and movement therapy interventions.
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