VIP Summary #10: Deletion and duplication of 16p11.2 are associated with opposing effects on visual evoked potential amplitude

LeBlanc and Nelson - Deletion and duplication of 16p11.2 are associated with opposing effects on visual evoked potential amplitude (2016)

This article examines the effects 16p11.2 deletions and duplications have on brain development and functioning, specifically how these genetic changes can impact cortical processing. Cortical processing is the brain’s translation of sensory stimuli received by the eye into usable information, such as the production of a memorable image from something you saw.

 

In many neurodevelopmental disorders, the interpretation of sensory information can be reduced. This means it can be an indicator of some problem with cortical processing  which can lead to intellectual and behavioral difficulties. A previous study on cortical processing in individuals with the 16p11.2 copy number variant (CNV) reported that auditory (hearing) responses were delayed in deletion carriers but not in duplication carriers. Keeping this in mind, LeBlanc and Nelson were interested in understanding if the differences in the copy number would also impact how these individuals process visual information. 

To test how visual information is interpreted by individuals with 16p11.2 CNVs (copy number variants), Leblanc and Nelson used pattern-reversal visual evoked potentials (VEPs).

 

This is a noninvasive method of tracking the neuronal response of visual pathways from the eye to the optic nerve and finally to brain, where this information is processed.  VEPs are produced in the form of a wavelength recorded through imaging technology; this visualization helps determine the response an individual has to various stimuli.

For this study, 19 deletion carriers, 9 duplication carriers, and 13 control individuals (children that do not have the CNV) between the ages of 3 and 14 were examined using electroencephalogram (EEG) to record VEPs. When averaged, the deletion carriers had VEP recordings that had higher amplitudes (peak in blue on the graph) and the duplication carriers had lower amplitudes (peak in green on the graph). These measurements were in comparison to the recorded values for the control individuals (peak in black on the graph). The differences in the amplitude recordings were dependent on the over-presence (duplication) or absence (deletion) of the 16p11.2 region. However, there was no significant difference in how quickly individuals with the CNV versus control subjects processed the visual images, which indicates that visual information arrives in the brain correctly for all subjects. More research will need to be done to determine how deletions and duplications impact visual processing, but LeBlanc and Nelson concluded that the use of VEPs is an effective method of measuring the variation between the two types of 16p11.2 CNVs.

 

 

All of the 16p11.2 CNV participants for this study were enrolled through Simons VIP. The Simons VIP team appreciates the active participation by our members and will continue to provide families with updates on how their involvement helps the research community better understand these genetic changes.