People with autism spectrum disorder (ASD) have difficulty moving in response to what they see, reports a new study from the University of Texas Southwestern in Dallas. The study focuses on the cerebellum, a part of the brain that converts sensory input into signals for movement. The researchers found that the brains of people with ASD become overwhelmed when converting sensory stimuli into motion. The study strengthens theories suggesting that the cerebellum is a key player in autism.
The participants, 20 people with ASD and 23 controls, performed a sensory task while the researchers scanned their brains. The task resembled an old video game: participants controlled a line on a screen by squeezing a sensor with their thumb and forefinger. The goal was to keep their line matched with another line on the screen. The researchers could change the sensitivity levels in game, meaning that a small amount of pressure on the sensor could have huge or negligible results, depending on the setting. The participants had to adjust the pressure on their sensor as the researchers continued to alter the game’s sensitivity levels.
People with ASD performed at a similar level to the people in the control group when the game’s sensitivity was at a moderate level. However, the ASD participants struggled to maintain the position of their line when the game’s sensitivity was very high or very low. This suggests that people with ASD may overcompensate for sensory extremes.
Based on the brain scans, the researchers identified which areas of the brain were most active in the ASD participants when the game’s sensitivity was at high or low levels. While playing with a low sensitivity, the ASD group had relatively weak responses in the parts of the brain that lead in and out of the cerebellum. This could indicate that it was difficult for them to track the line on the screen. While playing at a high sensitivity, the ASD group demonstrated hyper-excitability in other brain regions. This suggests that the ASD participants were more sensitive to changes in visual feedback.
The results suggest that people with ASD may operate best in moderate sensory environments.
This research was presented at the 2014 Society for Neuroscience annual meeting in Washington, D. C.
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