Begum Ali, J. | Search bioRxiv

bioRxiv2025

Crossmodal attention develops in the first year of life: Cortical signatures of tactile to visual exogenous spatial cuing at 8 but not 5 months of age

Adults are able to orient their attention between different (often fleeting) sensory cues that present to different senses ("crossmodal attention"), but we cannot assume that this is the case in early life. Here we report the findings of a study in which we probed the presence of tactile to visual crossmodal links in spatial attention using event related potentials (ERP) gathered from the scalp electroencephalograms (EEG) of 5-(n = 19) and 8-month-old (n = 19) infants. Whilst recording EEG, we presented 5- and 8month-old participants with vibrotactile stimuli on one of their hands, followed by visual stimuli on the same (Congruent) or the opposite (Incongruent) hand, or no touch at all (No probe). During the presentation of these stimuli the infants eyes were oriented centrally. We subtracted No probe trials from Congruent and Incongruent trials to yield visual evoked potentials (VEPs) free from the influence of prior somatosensory processing. Comparably to prior findings in adults, 8-month-olds first negative component of the VEP was enhanced in the hemisphere ipsilateral to the probe when the visual probe was spatially congruent with the tactile cue. No crossmodal effect was observed in the 5-month-olds, indicating developments in the crossmodal coordination of attention in the first year of life.

neuroscience↗

bioRxiv2025

Epigenome-wide analysis reveals novel DNA methylation signatures significantly associated with the infant pupillary light reflex, a candidate intermediate phenotype for autism.

Autism is a highly heterogeneous neurodevelopmental condition, currently diagnosed based on behavioural characteristics. Candidate early intermediate phenotypes, such as the Pupillary Light Reflex (PLR), a reflexive constriction of the pupil in response to increased optical luminance, may provide insights into etiological factors and potential biomarkers, such as DNA methylation (DNAm), involved in the emergence of autism. We conducted epigenome-wide DNAm association analyses of 9-, 14-, 24-month PLR onset latency and constriction amplitude in a sample of 51 infants enriched for autism family history, using buccal DNA collected at 9-months. Our epigenome-wide analysis (EWAS) identified four stringently significant differentially methylated probes (p < 2.4 x 10-7) associated with cross-section PLR latency measurements at 14- and 24-months, and with 14-to 24-month PLR latency developmental change. Differentially methylated probes associated with PLR amplitude were identified, but at a less stringent discovery threshold (p < 5 x 10-5). Our region analyses identified several significant differentially methylated regions associated with both PLR latency and amplitude Downstream exploratory pathway analysis identified enrichment for multiple developmental biological processes, as well as several susceptibility genes to autism and related neurodevelopmental conditions including NR4A2, HNRNPU and NAV2. Our findings provide novel insight into the role of DNAm in PLR development and illuminate biological mechanisms underpinning altered PLR in infancy in emerging autism.

neuroscience↗