Reduced brain activation during imitation and observation of others in children with pervasive developmental disorder: a pilot study

BACKGROUND: Children with pervasive developmental disorder (PDD) are thought to have poor imitation abilities. Recently, this characteristic has been suggested to reflect impairments in mirror neuron systems (MNS). We used near-infrared spectroscopy (NIRS) to examine the brain activity of children with PDD during tasks involving imitation and observations of others. FINDINGS: The subjects were 6 male children with PDD (8–14 years old) and 6 age- and gender-matched normal subjects (9–13 years old). A video in which a woman was opening and closing a bottle cap was used as a stimulus. Hemoglobin concentration changes around the posterior part of the inferior frontal gyrus and the adjacent ventral premotor cortex were measured with a 24-channel NIRS machine during action observation and action imitation tasks. Regional oxygenated hemoglobin concentration changes were significantly smaller in the PDD group than in the control group. Moreover, these differences were clearer in the action observation task than in the action imitation task. CONCLUSIONS: Dysfunction in the MNS in children with PDD was suggested by the reduced activation in key MNS regions during tasks involving observations and imitations of others. These preliminary results suggest that further studies are needed to verify MNS dysfunction in children with PDD.