Auditory sensory processing in autism: a magnetoencephalographic study
Received 3 September 2002; received in revised form 26 February 2003; accepted 4 March 2003.
Abstract
Background
Patients with autism show clinical features suggestive of abnormal processing of auditory and other sensory information. We hypothesized that low-functioning autistic subjects present abnormalities in discriminating simple auditory stimuli at sensory system preconscious stages of cortical processing.
Methods
To verify our hypothesis, we used magnetoencephalographic measurements of mismatch field (MMF), which reflects the detection of a change in the physical characteristics of a repetitive sound. Fourteen patients (aged 8–32 years) who met DSM-IV diagnostic criteria for autistic disorder participated in an auditory oddball experiment. Ten healthy participants matched for age and gender acted as control subjects.
Results
Significant differences in cerebral responses between patients and control subjects were recorded. Whereas control subjects showed a clearly identifiable MMF, with distinct generators in the M100 brain wave with regard to latency, position, and strength, no identifiable MMF was present in the autistic group.
Conclusions
Our findings suggest that low-functioning autistic subjects present a dysfunction at preconscious stages of cortical auditory discrimination, playing a role in the abnormal processing of auditory sensory afferences. The attention independence of the MMF allows for exclusion of an effect related to impaired attention or task-related responses.
Address reprint requests to Dr. Franca Tecchio, Instituto di Sciente e Tecnologie della Cognitione-Cousiglio Nationale delle Ricerche, Unità Magnetoencephalography, Ospedale Fatebenefratelli, Isola Tiberina, 00186 Roma, Italy.
ABSTRACT