Saturday, May 22, 2010
Franklin Hall B Level 4 (Philadelphia Marriott Downtown)
11:00 AM
Auditory Evoked Fields Abnormalities in Children with Sensory Processing Differences Using Magnetocephalographic Imaging (MEG-I)
Susanna Hill, Anne Findlay, Susanne Honma, Anne Bernard, Leighton Hinkley, Srikantan Nagarajan, Elysa Marco, MD
Background: Atypical sensory processing in the auditory domain are ubiquitous in children with and without autism. These sensory difficulties likely contribute to communication and social deficits. We have recently found that children with sensory processing differences show atypical connectivity during rest in brain areas specialized for higher order integration. We used magnetoencephalographic imaging (MEG-I), a functional imaging tool with millisecond temporal resolution and millimeter spatial localization, to measure auditory evoked fields (AEFs) in children with sensory processing difficulties and matched controls. Examination of AEFs may contribute to understanding how latency and amplitude differences in sound awareness and can serve as a diagnostic tool and measure of intervention response in affected children.
Objectives: We hypothesized that children with sensory processing differences (SP) would have atypical sensory responses to simple auditory stimuli manifesting in differences in latency, amplitude, or both relative to matched healthy controls (HC).
Methods: Brain responses to a monaurally presented -45dB auditory tone were recorded for the SP group (n=10, mean age=10.6 years) and the HC group (n=10, mean age=10.0 years) using a 275-channel whole-head MEG at a sampling rate of 1200Hz. Epochs of 900ms (400ms pre-stimulus) were collected in each subject. For evoked field analysis, MEG sensor data was bandpass filtered (2-40Hz) and averaged in each subject. This study examined latency and amplitude (root mean squared; RMS) of the M50, M100, and M200 peaks. Comparisons between groups were made using unpaired two-tailed t-tests. Receiver Operator Characteristic (ROC) curves were plotted using the RMS values to evaluate the applicability of this measure for predicting sensory behavior.
Results: Robust auditory evoked field peaks were identified in the HC and the SP groups. The SP group showed significantly reduced M100 amplitude in the left hemisphere and reduced M200 amplitude bilaterally (p<0.05). The ROC analysis showed that the M200 left hemisphere RMS values were the best predictor of sensory behavior (area under the curve (AUC)=0.89), followed by the M200 right hemisphere (AUC=0.86), and then the M100 left hemisphere (AUC=0.8).
Conclusions: Our results suggest that children with sensory processing difficulties have measurable and reduced auditory-evoked responses in the left hemisphere at M100 and in both hemispheres at M200 following simple auditory stimuli. Furthermore, these data were obtained via a non-invasive technique not requiring patient participation and may serve as good diagnostic predictors of atypical sensory processing.
Susanna Hill, Anne Findlay, Susanne Honma, Anne Bernard, Leighton Hinkley, Srikantan Nagarajan, Elysa Marco, MD
Background: Atypical sensory processing in the auditory domain are ubiquitous in children with and without autism. These sensory difficulties likely contribute to communication and social deficits. We have recently found that children with sensory processing differences show atypical connectivity during rest in brain areas specialized for higher order integration. We used magnetoencephalographic imaging (MEG-I), a functional imaging tool with millisecond temporal resolution and millimeter spatial localization, to measure auditory evoked fields (AEFs) in children with sensory processing difficulties and matched controls. Examination of AEFs may contribute to understanding how latency and amplitude differences in sound awareness and can serve as a diagnostic tool and measure of intervention response in affected children.
Objectives: We hypothesized that children with sensory processing differences (SP) would have atypical sensory responses to simple auditory stimuli manifesting in differences in latency, amplitude, or both relative to matched healthy controls (HC).
Methods: Brain responses to a monaurally presented -45dB auditory tone were recorded for the SP group (n=10, mean age=10.6 years) and the HC group (n=10, mean age=10.0 years) using a 275-channel whole-head MEG at a sampling rate of 1200Hz. Epochs of 900ms (400ms pre-stimulus) were collected in each subject. For evoked field analysis, MEG sensor data was bandpass filtered (2-40Hz) and averaged in each subject. This study examined latency and amplitude (root mean squared; RMS) of the M50, M100, and M200 peaks. Comparisons between groups were made using unpaired two-tailed t-tests. Receiver Operator Characteristic (ROC) curves were plotted using the RMS values to evaluate the applicability of this measure for predicting sensory behavior.
Results: Robust auditory evoked field peaks were identified in the HC and the SP groups. The SP group showed significantly reduced M100 amplitude in the left hemisphere and reduced M200 amplitude bilaterally (p<0.05). The ROC analysis showed that the M200 left hemisphere RMS values were the best predictor of sensory behavior (area under the curve (AUC)=0.89), followed by the M200 right hemisphere (AUC=0.86), and then the M100 left hemisphere (AUC=0.8).
Conclusions: Our results suggest that children with sensory processing difficulties have measurable and reduced auditory-evoked responses in the left hemisphere at M100 and in both hemispheres at M200 following simple auditory stimuli. Furthermore, these data were obtained via a non-invasive technique not requiring patient participation and may serve as good diagnostic predictors of atypical sensory processing.