Biology subjects

Layton, C.

Publications and source records attributed to Layton, C..

3 recordsLinked to original sources

bioRxiv2025

The School Cafeteria Problem: Disrupted Visuospatial Attention During Multisensory Speech-in-Noise Perception in Children with ADHD

BackgroundMany children with attention deficit hyperactivity disorder (ADHD) have difficulty distinguishing speech in crowded scenarios with competing conversations and noise. This can impact learning and community participation. Prior work has implicated audiovisual integration of lip movements with speech sounds as a potential underlying mechanism, but difficulty in accurately deploying spatial attention is an important, often overlooked, factor that may impact the accuracy of speech perception in noisy environments. ObjectiveEvaluate patterns of audiovisual integration and allocation of visuospatial attention during speech processing in a multiple-talker scenario among school-age children with ADHD and typically developing children (TD). MethodsWe recruited 7-12-year-old children with ADHD to participate in an integrated virtual reality and electrophysiologic (EEG) speech-in-noise perception paradigm. In virtual reality, children were asked to press a button whenever a centrally-located target character spoke a target monosyllabic word, while ignoring any words spoken by two flanking distractor characters. We manipulated 1) audiovisual (AV) content by intermixing trials containing either audio, visual, or multisensory AV representations of the three characters and 2) spatial attention demands by including trials with and without interference from the distracting speakers. We measured AV gain in target detection accuracy. Simultaneously, steady-state visual evoked potentials (SSVEP) were continuously recorded via a 128-channel electrode array as an index of visuospatial attention allocation to each speaker. To elicit SSVEP, the target and distractor speakers were tagged with different visual frequency oscillations (23hz and 15hz, respectively). EEG signal-to-noise ratio (SNR) in the corresponding first and second harmonics for those frequency bands was measured over the occipital scalp. ResultsChildren with ADHD showed reduced AV gain relative to TD controls. TD controls also demonstrated more robust SSVEP at 23Hz and 46Hz (target speaker) than at 15Hz (distractor speakers). Compared to TD children, children with ADHD had reduced selective activation in response to the target. As a result, children with ADHD showed more equivalent allocation of visuospatial attention between 23Hz target and 15Hz distractor frequencies. ConclusionsChildren with ADHD demonstrate a reduction in the typical perceptual benefit afforded by exposure to multisensory compared to unisensory speech stimuli, accompanied by substantial differences in the allocation of visuospatial attention to the relevant speaker. Thus, dysregulation of selective visuospatial attention may impair their ability to effectively perceive language in noisy settings.

neuroscience↗

bioRxiv2023

Population genomic analysis reveals genetic structure and thermal-tolerant genotypes in remnant Tasmanian giant kelp populations

Giant kelp, Macrocystis pyrifera, is a foundation species that forms dense forests of complex physical habitat and supports coastal biodiversity, productivity, and other essential ecosystem services. Tasmanian coasts have suffered a massive decline in giant kelp forests due to changes in regional oceanography and environmental conditions, but efforts are being made to restore these disappearing populations using identification and selective breeding for lineages that are more tolerant to warmer temperatures. Here, we used gametophytes that originated from remnant populations collected at three sites in northeastern and three sites in southeastern Tasmania to determine the genetic structure of the giant kelp population via genotyping-by-sequencing (GBS) and assembled a draft genome from a Tasmanian giant kelp sporophyte individual. Previous research identified seven strain lines that were tolerant to warm temperatures, and we used the GBS data to test whether genotypes were associated with warm tolerance. Kelps from the north were genetically distinct from the southern ones, with much lower gene flow between regions than within regions. These results revealed that giant kelp populations from Tasmania are more genetically structured than previously thought. Two loci were significantly associated with warm temperature tolerance. They are population-specific: the alternative allele from one of the loci was found only in the northern populations, while the other was found in the southern populations. This could suggest that thermal tolerance is adapting locally or drifting given large changes in population demography, but further research is needed to confirm this hypothesis. Our research sheds light on genetic patterns in this critical habitat-forming kelp and will help inform conservation management, including selective breeding.

genetics↗

bioRxiv2021

Missing the forest for the trees: A reappraisal of global seaweed carbon sequestration

Global seaweed carbon sequestration estimates are currently taken as the fraction of the net primary production (NPP) exported to the deep ocean. However, this perspective does not account for CO2 from the consumption of external subsidies. Here we clarify: i) the role of export relative to seaweed net ecosystem production (NEP) for a closed system and one more likely open to subsidies; ii) the importance of subsidies by compiling published estimates of NEP from seaweed-dominated ecosystems; and iii) discuss their impact on the global seaweed net carbon balance and other sequestration constraints as a mitigation service. Examples of seaweed NEP (n = 18) were sparse and variable. Nevertheless, the average NEP (-9.2mmol C m-2 day-1 SE {+/-} 11.6) suggested that seaweed ecosystems are a C source, becoming increasingly heterotrophic as their export is consumed. Critically, mitigation of greenhouse gas emissions was mixed relative to their replacement or baseline states, and where CO2 is supplied independently of organic metabolism and atmospheric exchange we caution a sole reliance on NEP or NPP. This will ensure a more accurate seaweed mitigation assessment, one that does exceed their capacity and is effective within a compliance and carbon trading scheme.

ecology↗