Prominence of M50 auditory evoked response over M100 in childhood and autism

Abstract

This study investigated the 50 ms (M50) and 100 ms (M100) components of the auditory evoked field to explore their change during development. Using MEG, neuromagnetic fields elicited by a 1 kHz sinusoidal tone were recorded in adults and two groups of children and adolescents with typical development or autism spectrum disorder. M50 amplitude was larger in children than in adults, suggesting a developmental trajectory with M50 amplitude decreasing and M100 increasing with age. Child M50 and M100 latencies were prolonged relative to adults. Children with autism did not differ from control children with respect to these observations. The M50 in relation to the M100 is a robust index of early auditory system maturation suitable for future developmental investigations.

A review of behavioural and electrophysiological studies on auditory processing and speech perception in autism spectrum disorders

“…The M100 magnetic field is comparable to the N1 that was described earlier; the M50 is analogous to the Pa/P1 complex of the electroencephalographic evoked responses (Oram Cardy, Ferrari, Flagg, Roberts, & Roberts, 2004).…”

“…Thus, this evidences intact initial auditory cortical processing, but delayed pitch discrimination of pure tones. A study by Oram Cardy et al (2004) found that initial auditory cortical processing was intact, as no differences in M50 or M100 between children with ASD and typically developing children were found for sequences of pure tones. Both in typically developing children and in children with ASD the M50 dominated the auditory evoked field relative to M100.…”

“…Behavioural studies (Bonnel et al, 2003(Bonnel et al, , 2010Jones et al, 2009) as well as ERP and ERF studies (Č eponienè et al, 2003;Ferri et al, 2003;Gomot et al, 2002;Oram Cardy et al, 2004) have shown enhanced pitch processing and discrimination of pure tones. The electrophysiological findings, however, are not unequivocal as some ERP or ERF studies have also shown deficient pure tone pitch processing and discrimination in ASD (Jansson-Verkasalo et al, 2003, 2005Oram Cardy, Flagg, Roberts, Brian, et al, 2005;Tecchio et al, 2003).…”

Auditory evoked fields predict language ability and impairment in children

“…Sixteen participants (eight female, one lefthanded) had typical development, 14 met clinical diagnostic criteria for autism (two female), 10 for Asperger Syndrome (two female, one left-handed), and 5 for SLI (three female). Left hemisphere evoked fields for 18 of these children have been previously described in Oram Cardy et al (2004).…”

“…Passive tasks offer an opportunity to bypass this confound. Second, although numerous investigations of children have focused on the M100 auditory evoked field, the M50 is equally, if not more, robust in children and adolescents (Oram Cardy et al, 2004). Therefore, both the M50 and M100 are worthwhile to consider in MEG studies of pediatric populations.…”