Magnetoencephalographic Imaging of Auditory and Somatosensory Cortical Responses in Children with Autism and Sensory Processing Dysfunction

Abstract

This study compared magnetoencephalographic (MEG) imaging-derived indices of auditory and somatosensory cortical processing in children aged 8-12 years with autism spectrum disorder (ASD; N = 18), those with sensory processing dysfunction (SPD; N = 13) who do not meet ASD criteria, and typically developing control (TDC; N = 19) participants. The magnitude of responses to both auditory and tactile stimulation was comparable across all three groups; however, the M200 latency response from the left auditory cortex was significantly delayed in the ASD group relative to both the TDC and SPD groups, whereas the somatosensory response of the ASD group was only delayed relative to TDC participants. The SPD group did not significantly differ from either group in terms of somatosensory latency, suggesting that participants with SPD may have an intermediate phenotype between ASD and TDC with regard to somatosensory processing. For the ASD group, correlation analyses indicated that the left M200 latency delay was significantly associated with performance on the WISC-IV Verbal Comprehension Index as well as the DSTP Acoustic-Linguistic index. Further, these cortical auditory response delays were not associated with somatosensory cortical response delays or cognitive processing speed in the ASD group, suggesting that auditory delays in ASD are domain specific rather than associated with generalized processing delays. The specificity of these auditory delays to the ASD group, in addition to their correlation with verbal abilities, suggests that auditory sensory dysfunction may be implicated in communication symptoms in ASD, motivating further research aimed at understanding the impact of sensory dysfunction on the developing brain.

Keywords: auditory evoked fields; autism spectrum disorders (ASD); communication; processing speed; sensory processing disorder; somatosensory evoked fields.

Figure 1

Single participant examples of auditory evoked field source localizations and corresponding waveforms with flux topography for each peak. The waveform amplitude is normalized within subject on the y axis, which represents the z-score of the source waveform amplitude based on the pre-stimulus baseline (originally measured in fT). The timescale on the horizontal axis is in milliseconds. For (A), the chronology of changing flux topography identifies peaks for the M50, M100, and M200 that roughly correspond to their expected latencies in a TDC participant. For (B), the SPD participant demonstrates delays in the right M200 and left M100 and M200 responses. For (C), the ASD participant demonstrates a weak right M50 response and delays for all other responses. This profile of responses for these three participants parallels findings from group level analyses, with the SPD group demonstrating an intermediate phenotype between the auditory evoked responses for the ASD and TDC groups.

Figure 2

Examples of somatosensory evoked fields source localizations and corresponding waveforms with flux topography. The waveform amplitude is normalized within subject on the y axis, which represents the z-score of the source waveform amplitude based on the pre-stimulus baseline (originally measured in fT). The timescale on the horizontal axis is in milliseconds. For (A), the flux topography identifies the Somatosensory (SS) peak that roughly corresponds to the expected latency in TDC participants. For (B), the SPD participant demonstrates a delayed SS latency that does not meet a stringent significance threshold relative to the TDC or ASD cohort. For (C), the ASD participant demonstrates a delayed SS response that is characteristic for the group as a whole.

Figure 3

Somatosensory and auditory response latencies across groups. The left auditory M200 response is significantly delayed in the ASD group relative to both the SPD and TDC groups, whereas the ASD somatosensory response is significantly delayed relative to only the TDC group.

Figure 4

Scatterplots of DSTP Acoustic Linguistic Index, WISC-IV Verbal Comprehension Index, and the left auditory M200 latencies in each group. These associations were statistically significant in the ASD group, who showed a significant delay in the M200 response; however, the inclusion of all groups in the scatterplot highlights the intermediate profile of the SPD group relative to the ASD and TDC participants.