Visual motion processing deficits in infants with the fragile X premutation
Pamela K Gallego1, Jessica L Burris1, Susan M Rivera2
1Department of Psychology, University of California Davis, Davis, CA 95618, USA ; Center for Mind and Brain, University of California Davis, 202 Cousteau Place, Suite 250, Davis, CA 95618, USA.
Insights
Infants with fragile X premutation (FX) show visual processing deficits similar to those with full mutation FX syndrome. This suggests early-onset visual processing issues in FX premutation, highlighting the need for further study in this population.
Area of Science:
- Neuroscience
- Developmental Psychology
- Genetics
Background:
- Fragile X syndrome (FXS) stems from FMR1 gene CGG repeat expansion, causing FMRP absence and cognitive/behavioral issues.
- Previous research detailed cognitive and visual processing in infants with FXS.
- Emerging evidence shows cognitive and brain differences in FX premutation adults.
Purpose of the Study:
- To investigate if low-level visual processing deficits observed in FXS infants are also present in infants with the FX premutation.
- To determine if second-order motion processing deficits are specific to FXS or a broader fragile X-associated phenomenon.
Main Methods:
- A contrast detection task using second-order motion stimuli was employed.
- Infants with FXS, FX premutation, Down syndrome (DS), and typically developing (TD) infants participated.
- Participants were matched for chronological and mental age.
Main Results:
- Infants with FXS exhibited significantly higher motion contrast detection thresholds than TD controls.
- Infants with FX premutation also showed significantly higher thresholds than TD infants.
- FX premutation infants' thresholds were comparable to those with FXS and DS.
Conclusions:
- FX premutation infants display visual processing deficits similar to FXS and DS infants.
- These findings align with evidence of mild cognitive and perceptual deficits in older individuals with FX premutation.
- There is a critical need to study and characterize the processing capabilities of infants and toddlers with the FX premutation.
Background:
Fragile X syndrome (FXS) results from a trinucleotide repeat expansion (full mutation >200 cytosine-guanine-guanine (CGG) repeats) in the FMR1 gene, leading to a reduction or absence of the gene's protein product, fragile X mental retardation protein (FMRP), ultimately causing cognitive and behavioral impairments that are characteristic of the syndrome. In our previous work with infants and toddlers with FXS, we have been able to describe much about their cognitive and visual processing abilities. In light of recent work on the mild cognitive deficits and functional and structural brain differences that are present in adults with the fragile X (FX) premutation, in the present study we examined whether some of the low-level visual processing deficits we have observed in infants with FXS would also be present in infants with the FX premutation (55-200 CGG repeats).
Methods:
We chose a contrast detection task using second-order motion stimuli on which infants with FXS previously showed significantly increased detection thresholds (Vision Res 48:1471-1478, 2008). Critically, we also included a developmental delay comparison group of infants with Down syndrome (DS), who were matched to infants with FXS on both chronological and mental age, to speak to the question of whether this second-order motion processing deficit is a FX-specific phenomenon.
Results:
As reported previously, infants with the FX full mutation showed motion contrast detection threshold levels that were significantly higher than age-matched typically developing control infants. Strikingly, the motion detection contrast levels of FX premutation infants were also significantly higher than typically developing (TD) infants and not significantly different from the group of infants with FXS or with DS.
Conclusions:
These results, which are in keeping with a growing body of evidence on the mild cognitive and perceptual processing deficits and functional and structural brain differences that are present in adults and older children with the FX premutation, underscore the pressing need to study and describe the processing capabilities of infants and toddlers with the FX premutation.
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