MEG detection of delayed auditory evoked responses in autism spectrum disorders: towards an imaging biomarker for autism

Abstract

Motivated by auditory and speech deficits in autism spectrum disorders (ASD), the frequency dependence of superior temporal gyrus (STG) 50 msec (M50) and 100 msec (M100) neuromagnetic auditory evoked field responses in children with ASD and typically developing controls were evaluated. Whole-cortex magnetoencephalography (MEG) was obtained from 17 typically developing children and 25 children with ASD. Subjects were presented tones with frequencies of 200, 300, 500, and 1,000 Hz, and left and right STG M50 and M100 STG activity was examined. No M50 latency or amplitude Group differences were observed. In the right hemisphere, a Group × Frequency ANOVA on M100 latency produced a main effect for Group (P 5 0.01), with an average M100 latency delay of 11 msec in children with ASD. In addition, only in the control group was the expected association of earlier M100 latencies in older than younger children observed. Group latency differences remained significant when hierarchical regression analyses partialed out M100 variance associated with age, IQ, and language ability (all P-values < 0.05). Examining the right-hemisphere 500 Hz condition (where the largest latency differences were observed), a sensitivity of 75%, a specificity of 81%, and a positive predictive value (PPV) of 86% was obtained at a threshold of 116 msec. The M100 latency delay indicates disruption of encoding simple sensory information. Given similar findings in language impaired and nonlanguage impaired ASD subjects, a right-hemisphere M100 latency delay appears to be an electrophysiological endophenotype for autism.

Increased Hyperacusis with Risperidone in an Autistic Child

“…The SH-V interpeak latency of the auditory brainstem response was longer in ASD patients than in control patients (6). Event-related potentials and magnetoencephalography studies also showed delayed responses to auditory stimuli in ASD (6,7,8). Although these electrophysiological studies showed auditory processing differences between autistic and control patients, the cause of auditory hypersensitivity remains unknown.…”

Auditory Processing Disorder (APD): Progress in Diagnostics So Far. A Mini-Review on Imaging Techniques

“…These neuroimaging techniques provide a way to assess cortical networks during perception of a stimulus, such as sound in a background of noise, [24] and the results give a more fine-tuned localization when used in combination. Because their excellent temporal resolution, they are used for connectivity analysis in auditory processing [25,26] . Compared with EEG, MEG produces less distortion.…”

“…Four reasons that have been suggested as to why this neuroimaging technique is useful include the following: it can provide evidence of the mechanisms of cortical neural activity that occur in central APD (CAPD) and what kind of compensation occurs; it enables visualization of the link between patient performance and neural structures in clinical testing; if neural pathologies are identified, there can be new, better management of the condition based on the indicated neural abnormalities; and it can be used to determine how much restoration of normal neural activity in CAPD occurs via interventional management of CAPD patients [25] . MEG in combination with ABR can track neural activity at the start of a neural signal from the structures just below the midbrain up to the higher auditory cortex [26] . MEG and EEG can assess selective attention because it has been shown that attention causes a significant change in the M100 and N100 potentials, respectively, in normal listeners when attending to a particular signal when two signals are presented at the same time [17] .…”

“…Another study that compared typically developing children with children with autism spectrum disorders using MEG showed M100 latency when they were presented with pure tones of different frequencies [26] . A whole-cortex 275-channel MEG system (VSM MedTech Inc.; Coquitlam, BC) was used [26] .…”

“…A whole-cortex 275-channel MEG system (VSM MedTech Inc.; Coquitlam, BC) was used [26] . Raw data were corrected for eye-blinking by applying the pattern search function in the BESA 5.2 program (MEGIS Software GmbH; Gräfelfing, Germany) [26] . A delayed response was indicative of an abnormality in auditory processing pathways.…”