Deficits in auditory processing contribute to impairments in vocal affect recognition in autism spectrum disorders: A MEG study

Abstract

Objective: The primary aim of this study was to examine whether there is an association between magnetoencephalography-based (MEG) indices of basic cortical auditory processing and vocal affect recognition (VAR) ability in individuals with autism spectrum disorder (ASD).

Method: MEG data were collected from 25 children/adolescents with ASD and 12 control participants using a paired-tone paradigm to measure quality of auditory physiology, sensory gating, and rapid auditory processing. Group differences were examined in auditory processing and vocal affect recognition ability. The relationship between differences in auditory processing and vocal affect recognition deficits was examined in the ASD group.

Results: Replicating prior studies, participants with ASD showed longer M1n latencies and impaired rapid processing compared with control participants. These variables were significantly related to VAR, with the linear combination of auditory processing variables accounting for approximately 30% of the variability after controlling for age and language skills in participants with ASD.

Conclusions: VAR deficits in ASD are typically interpreted as part of a core, higher order dysfunction of the "social brain"; however, these results suggest they also may reflect basic deficits in auditory processing that compromise the extraction of socially relevant cues from the auditory environment. As such, they also suggest that therapeutic targeting of sensory dysfunction in ASD may have additional positive implications for other functional deficits.

Conflict of interest statement

Conflict of Interest: The authors declare that they have no conflict of interest.

(c) 2015 APA, all rights reserved).

Figures

Figure 1

Quantification of rapid processing and gating variables from cross correlations (CC) of source waveforms in single tone and two tones conditions. Boxes show tone type and stimulus onset. (a) The rapid auditory processing condition is quantified by taking the cross correlation between the source waveforms at 300-600ms in the two different tones condition (i.e., response to the second tone) versus the single tone condition (i.e., no second tone so no auditory response at 300-600ms). For intact rapid processing (top timecourse) there is low agreement between these two waveforms because one demonstrates an auditory response to a tone and one does not, resulting in a low CC coefficient. In contrast, when rapid processing is impaired (i.e., no or weak response to the second tone) there is higher agreement between the two waveforms (bottom timecourse), resulting in a high CC coefficient. (b) The 300-600ms response in the two same tones condition looks similar to the response in the single condition, even though a second tone is presented (top timecourse), resulting in high waveform agreement and a high CC coefficient. When a high CCSingle vs Same is achieved for a participant who is able to process both tones (i.e., intact rapid processing, or low CCSingle vs Different), sensory gating is intact. Therefore, sensory gating was quantified by subtracting CCSingle vs Different (the CC coefficient for rapid processing; bottom timecourse) from CCSingle vs Same (top timecourse). High CCSingle vs Same – Low CCSingle vs Different = Higher difference value = better sensory gating. Use of this difference score prevents mistaking impaired rapid processing (i.e., inability to process rapidly presented tones) for intact gating.

Figure 1

Quantification of rapid processing and gating variables from cross correlations (CC) of source waveforms in single tone and two tones conditions. Boxes show tone type and stimulus onset. (a) The rapid auditory processing condition is quantified by taking the cross correlation between the source waveforms at 300-600ms in the two different tones condition (i.e., response to the second tone) versus the single tone condition (i.e., no second tone so no auditory response at 300-600ms). For intact rapid processing (top timecourse) there is low agreement between these two waveforms because one demonstrates an auditory response to a tone and one does not, resulting in a low CC coefficient. In contrast, when rapid processing is impaired (i.e., no or weak response to the second tone) there is higher agreement between the two waveforms (bottom timecourse), resulting in a high CC coefficient. (b) The 300-600ms response in the two same tones condition looks similar to the response in the single condition, even though a second tone is presented (top timecourse), resulting in high waveform agreement and a high CC coefficient. When a high CCSingle vs Same is achieved for a participant who is able to process both tones (i.e., intact rapid processing, or low CCSingle vs Different), sensory gating is intact. Therefore, sensory gating was quantified by subtracting CCSingle vs Different (the CC coefficient for rapid processing; bottom timecourse) from CCSingle vs Same (top timecourse). High CCSingle vs Same – Low CCSingle vs Different = Higher difference value = better sensory gating. Use of this difference score prevents mistaking impaired rapid processing (i.e., inability to process rapidly presented tones) for intact gating.

Figure 2

Examples of source waveforms from one control participant and two participants with ASD. Data are shown for conditions when there is a single tone, two tones that are the same, and two tones that are different. Boxes indicate tone types and onset. For the control participant there is a clear response to the tone, with the response complete by 250 milliseconds. In the different condition, there is a strong response to the second tone indicative of good rapid auditory processing. The response in the same condition looks almost identical to the response in the single condition, even though a second tone is presented. In the context of this participant's intact rapid processing this indicates good sensory gating. The activity profile of the first ASD participant is similar to that of the control. The second ASD participant shows some impairment in rapid processing. Cross correlation values for these participants across conditions are presented below.

Figure 3

Relationships between Vocal Affect Recognition and Cortical Auditory Processing Adjusting for All Other Independent Variables. For each plot the vertical axis represents the residual values after regressing vocal affect recognition on all independent variables other than the variable identified in the horizontal axis. The horizontal axis represents the residual values after regressing the specified independent variable on all other independent variables.