Cortical sound processing in children with autism disorder: an MEG investigation

Abstract

Previous work investigating frequency encoding mechanisms in human auditory cortex has provided evidence that latency of the auditory evoked M100 is strongly proportional to frequency, with low frequency (100^200 Hz) tones associated with B30 ms longer latencies than mid-range frequency (1^2 kHz) tones. Motivated by pervasive speech and auditory perception de¢cits observed in autism spectrum disorder, we evaluated M100 frequency dependence in children with autism disorder and typically developing controls.Results indicate that for control children, the dynamic range of frequency modulation was similar to previous reports for healthy adults. Children with autism had a much reduced range of modulation in right hemisphere sites. Findings indicate that frequency encoding mechanisms may follow a di¡erential maturational path in autism spectrum disorder.

Electrophysiological signatures: Magnetoencephalographic studies of the neural correlates of language impairment in autism spectrum disorders

“…Mean (± SEM) latency values for the left hemisphere were: TD = 120.7±1.5ms, children with ASD = 130.2±9.4ms, p=0.3; right hemisphere values were: TD = 117.4±3.4ms, children with ASD = 136.8±4.4ms, p<0.01 ( Figure 2c). Although present findings show a developmental trajectory of M100 latency that is not significantly different than that of typical development, the finding reported in our previous study of longer M100 latencies in ASD (Gage et al, 2003b) was replicated. Furthermore, in these small sample studies, differences in the clinical and behavioral scores of the children with autism certainly exist, precluding direct comparison between studies but motivating further studies.…”

“…This latency shift is delayed in children with autism (and essentially not evident in the right hemisphere) (Gage et al 2003b). Recent pilot work extended previous M100 latency findings, examining M100 latencies from each hemisphere in children with typical development and in children with an ASD using whole-head 275-channel MEG.…”

Atypical Bilateral Brain Synchronization in the Early Stage of Human Voice Auditory Processing in Young Children with Autism

“…Reports have indicated that the ASD population exhibits elevated rates of brain stem or peripheral hearing dysfunction [13][14][15][16][17][18][19][20] and abnormalities in AEF components (i.e., cortical dysfunction) [1][2][3][4][5][6][7][8][9][10][21][22][23][24][25]. Intriguingly, research has indicated that individuals with ASD may present with peripheral auditory asymmetry [13], which may distort the cortical bilateral synchronization of AEF components in the central nervous system.…”

“…In the last decade, MEG has emerged as an important investigatory tool in neurodevelopmental studies because MEG has advantages over other neuroimaging techniques for young children, including safety, fewer constraints and less environmental noise. Using MEG, many recent studies have observed aberrant brain activities in children with ASD [1][2][3][4][5][6][7][8][9][10][21][22][23][24][25][26][27][28][29] by investigating brain connectivity [26,[28][29][30] or atypical brain responses to auditory stimuli [1][2][3][4][5][6][7][8][9][10][21][22][23][24][25].…”

“…In previous MEG studies, this component has been alternatively labeled M100 or N100m; we here call this component "N1m." The main sources of the P1m and N1m are the auditory cortex and association cortices, and abnormalities in AEF components have been reported in patients with ASD [1][2][3][4][5][6][7][8][9][10][21][22][23][24][25]. Although many prior studies have focused on the aberrant intensity or latency of AEF components in children with ASD, no investigations have focused on the bilateral synchronization of AEF components in children with ASD.…”