Reduced auditory steady state responses in autism spectrum disorder

Area of Science:

• Neuroscience
• Auditory Neuroscience
• Developmental Neuroscience

Background:

• Auditory steady state responses (ASSRs) are neural signals elicited by modulated auditory stimuli.
• Previous research indicates reduced ASSRs at 40 Hz in individuals with autism spectrum disorder (ASD) and their relatives.
• This study investigates these findings further in adolescent ASD participants.

Purpose of the Study:

• To replicate and extend previous findings on reduced 40 Hz ASSRs in ASD.
• To investigate the neural basis of ASSR reductions in ASD using Magnetoencephalography (MEG).
• To determine if the observed reductions are specific to ASSR oscillatory power and inter-trial coherence.

Main Methods:

• 18 adolescent ASD participants and 18 typically developing controls underwent MEG.
• A 1.5-second auditory clicktrain stimulus was used to elicit 40 Hz ASSRs.
• Analysis focused on oscillatory power and inter-trial coherence in bilateral primary auditory cortex (A1).

Main Results:

• ASSRs were localized to bilateral primary auditory regions (A1).
• The ASD group showed reduced 40 Hz oscillatory power in both left and right A1 from 0.5 to 1.5s post-stimulus.
• Reduced 40 Hz inter-trial coherence was observed in the ASD group in right A1 (0.64-0.82s) and left A1 (1.04-1.22s).

Conclusions:

• The findings support a specific reduction in ASSR oscillatory power and inter-trial coherence in ASD.
• This reduction is not a generalized gamma-band deficit.
• The results suggest a potential developmental reduction in non-linear neural processing in ASD.