J Psychiatry Neurosci 2013; 38(6): 398-406
Eelke Visser, PhD; Marcel P. Zwiers, PhD; Cornelis C. Kan, MD, PhD; Liesbeth Hoekstra, MD; A. John van Opstal, PhD; Jan K. Buitelaar, MD, PhD
Visser, Zwiers, Buitelaar — Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Centre for Cognitive Neuroimaging, Nijmegen, the Netherlands; Visser, Zwiers, Hoekstra, Buitelaar — Radboud University Nijmegen Medical Centre, Department of Cognitive Neuroscience, Nijmegen, the Netherlands; Kan, Hoekstra — Radboud University Nijmegen Medical Centre, Department of Psychiatry, Nijmegen, the Netherlands; van Opstal — Radboud University Nijmegen, Department of Biophysics, Nijmegen and Donders Institute for Brain, Cognition and Behaviour, Centre for Neuroscience, Nijmegen, the Netherlands; Hoekstra, Buitelaar — Karakter, Child and Adolescent Psychiatry University Centre, Nijmegen, the Netherlands
Background: Autism spectrum disorders (ASDs) are associated with auditory hyper- or hyposensitivity; atypicalities in central auditory processes, such as speech-processing and selective auditory attention; and neural connectivity deficits. We sought to investigate whether the low-level integrative processes underlying sound localization and spatial discrimination are affected in ASDs.
Methods: We performed 3 behavioural experiments to probe different connecting neural pathways: 1) horizontal and vertical localization of auditory stimuli in a noisy background, 2) vertical localization of repetitive frequency sweeps and 3) discrimination of horizontally separated sound stimuli with a short onset difference (precedence effect).
Results: Ten adult participants with ASDs and 10 healthy control listeners participated in experiments 1 and 3; sample sizes for experiment 2 were 18 adults with ASDs and 19 controls. Horizontal localization was unaffected, but vertical localization performance was significantly worse in participants with ASDs. The temporal window for the precedence effect was shorter in participants with ASDs than in controls.
Limitations: The study was performed with adult participants and hence does not provide insight into the developmental aspects of auditory processing in individuals with ASDs.
Conclusion: Changes in low-level auditory processing could underlie degraded performance in vertical localization, which would be in agreement with recently reported changes in the neuroanatomy of the auditory brainstem in individuals with ASDs. The results are further discussed in the context of theories about abnormal brain connectivity in individuals with ASDs.
Submitted Sept. 5, 2012; Revised Jan. 14, Mar. 20, 2013; Accepted Mar. 20, 2013.
Competing interests: C. Kan is on the ADHD Advisory Board at Eli Lilly and has received royalties for 2 Dutch books on autism. J.K. Buitelaar declares an internal grant from the University Medical Centre, Radboud University. No other competing interests declared.
Contributors: E. Visser, M. Zwiers, A.J. van Opstal and J.K. Buitelaar designed the study. E. Visser, C.C. Kam and L. Hoekstra acquired the data, which E. Visser, M. Zwiers, A.J. van Opstal and J.K. Buitelaar analyzed. E. Visser, M. Zwiers and A.J. van Opstal wrote the article, which all authors reviewed and approved for publication.
Correspondence to: E. Visser, Radboud University Nijmegen, Donders Institute for Brain, Cognition and Behaviour, Kapittelweg 29, 6525EN, Nijmegen, the Netherlands; firstname.lastname@example.org