Biology subjects

O'Brien, A. M.

Publications and source records attributed to O'Brien, A. M..

7 recordsLinked to original sources

bioRxiv2026

Neurodiversity in the brain: More variable localization of face regions in autism

A fundamental principle in human neuroscience is that the brain is organized into distinct functional regions specialized for particular processes. These functional regions develop early and are shaped by sensory experiences. Strikingly, the precise location of these functional regions is relatively consistent across individuals, with specific regions found in stereotyped locations with respect to the macroanatomy (e.g., particular sulci and gyri). An important question is how flexible this functional neuroanatomy is, particularly in neurodevelopmental disorders like autism which are characterized by atypical brain development and behavior. Here, we investigated this question by focusing on the organization of the face-processing network -- a well-characterized system of regions that are reliably localized across neurotypical individuals, including, famously, the fusiform face area. Using precision fMRI, we identified subject-specific face-sensitive regions in the brains of autistic and neurotypical adults, and assessed their topographical alignment across individuals. Face regions in autism were globally and highly variably displaced - located farther from their expected locations in the brain relative to much more homogenous localization in neurotypical adults. Autistic individuals whose face regions were more displaced had greater sociocommunicative challenges. In contrast, the spatial organization of object-sensitive regions was not affected. These findings suggest that the spatial organization of the face network is atypical in autism, with behaviorally meaningful increased variability in the precise location of face-sensitive areas, and highlights the importance of individualized approaches in neuroimaging. Significance StatementThe human brain is organized into specialized functional regions positioned in remarkably consistent locations across individuals. It is unclear how altered neurodevelopment affects this organization. Using precision fMRI, we found that autism was characterized by globally and highly variably displaced face-sensitive functional brain regions. Atypical spatial organization of these regions was associated with greater sociocommunicative difficulties. In contrast, the spatial organization of object-sensitive regions did not differ in autism. These findings reveal that functional neuroanatomy in autism is altered in category-specific ways, with direct relevance to core sociocommunicative features of the condition. This work underscores the importance of individualized brain mapping in neuroimaging and may shed light on inconsistent findings in previous group-level neuroimaging studies.

neuroscience↗

bioRxiv2024

Precision fMRI reveals that the language network exhibits adult-like left-hemispheric lateralization by 4 years of age

In adults, left hemisphere (LH) damage often leads to aphasia, but many cases of early damage leave linguistic processing intact, with a functional language system developing in the right hemisphere. To explain this early apparent equipotentiality of the two hemispheres for language, some have proposed that the language system is more bilateral during early development and becomes increasingly left-lateralized with age. We examined language lateralization using fMRI in two large developmental cohorts (total n=273 children aged 4-16 years; n=107 adults). Strong, adult-like LH lateralization (in response magnitude and activation volume) was evident by age 4, although other features of the LH language network showed protracted development, including the magnitude of language response and the strength of functional connectivity. Thus, although the RH can take over language function in some cases of early brain damage, this plasticity occurs in spite of adult-level LH bias present by age 4 years.

neuroscience↗

bioRxiv2024

Synthesis, Structure and Anticancer Activity of a Dinuclear Organoplatinum(IV) Complex Stabilized by Adenine

The dinuclear organoplatinum(IV) compound {Pt(CH3)3}2(-I)2(-adenine) (abbreviated Pt2ad), obtained by treating cubic [Pt(CH3)3(3-I)]4 with two equivalents of adenine, was isolated and structurally characterized by single crystal X-ray diffraction. The National Cancer Institute Developmental Therapeutics Programs in vitro sulforhodamine B assays showed Pt2ad to be particularly cytotoxic against central nervous system cancer cell line SF-539, and human renal carcinoma cell line RXF-393. Furthermore, Pt2ad displayed some degree of cytotoxicity against non-small cell lung cancer (NCI-H522), colon cancer (HCC-2998, HCT-116, HT29, and SW-620), melanoma (LOX-IMVI, MALME-3M, M14, MDA-MB-435, SK-MEL-28, and UACC-62), ovarian cancer (OVCAR-5), renal carcinoma (A498), breast cancer (BT-549 and MDA-MB-468), and triple-negative breast cancer (MDA-MB-231).

cancer biology↗

bioRxiv2022

Accelerated High-throughput Plant Imaging and Phenotyping System

The complex web of interactions in biological communities is an area of study that requires large multifactorial experiments with sufficient statistical power. The use of automated tools can reduce the time and labor associated with experiment setup, data collection, and analysis in experiments aimed at untangling these webs. Here we demonstrate tools for high-throughput experimentation (HTE) in duckweeds, small aquatic plants that are amenable to autonomous experimental preparation and image-based phenotyping. We showcase the abilities of our HTE system in a study with 6,000 experimental units grown across 1,000 different nutrient environments. The use of our automated tools facilitated the collection and analysis of time-resolved growth data, which revealed finer dynamics of plant-microbe interactions across environmental gradients. Altogether, our HTE system can run experiments of up to 11,520 experimental units and can be adapted to studies with other small organisms.

ecology↗

bioRxiv2021

Strengthened mutualistic adaptation between teosinte and its rhizosphere biota in cold climates

O_LIWhile abiotic environments consistently shape local adaptation, the strength of local adaptation to biotic interactions may vary more. One theory, COCO (CO-evolutionary Outcomes across Conditionality), predicts it may be strongest where species experience greater stress, because stress increases fitness impacts of species interactions. For example, in plant interactions with rhizosphere biota, positive outcomes increase with stress from low soil fertility, drought and cold. C_LIO_LITo investigate the influence of abiotic stress gradients on adaptation between plants and rhizosphere biota, we used a greenhouse common garden experiment recombining teosinte, Zea mays ssp. mexicana (wild relative of maize), and rhizosphere biota, collected across a stress gradient (elevational variation in temperature, precipitation, and nutrients). C_LIO_LIWe found stronger local adaptation between teosinte and rhizosphere biota from colder, more stressful sites, as expected by COCO. However, biota from less stressful, warmer sites provided greater average benefits across teosinte populations. Links between plant traits and 20-element profiles of plant leaves explained fitness variation, persisted in the field, were influenced by both plants and biota, and largely reflected patterns of local adaptation. C_LIO_LIIn sum, we uncovered greater local adaptation to biotic interactions in colder sites, and that both plants and rhizosphere biota affect the expression of plant phenotypes. C_LI

evolutionary biology↗

bioRxiv2018

Mutualism outcome across plant populations, microbes, and environments in the duckweed Lemna minor

The picture emerging from the rapidly growing literature on host-associated micro-biota is that host traits and fitness often depend on complex and interactive effects of host genotype, microbial interactions, and abiotic environment. However, testing these main and interactive effects typically requires large, multi-factorial experiments and thus remains challenging in many systems. Furthermore, most studies of plant microbiomes focus on terrestrial hosts and microbes. Aquatic habitats may confer unique properties to plant micriobiomes. We grew different populations of duck-weed (Lemna minor), a floating aquatic plant of increasing popularity in freshwater phytoremediation, in three microbial treatments (adding no, \"home\", or \"away\" microbes) at two levels of zinc, a common water contaminant in urban areas. Thus, we simultaneously manipulated plant source population, microbial community, and the abiotic environment, and measured both plant and microbial performance as well as plant traits. Although we found little evidence of interactive effects, we found strong main effects of plant source, microbial treatment, and zinc on both duckweed and microbial growth, with significant variation among both duckweed and microbial communities. Despite strong growth alignment between duckweed and microbes, zinc consistently decreased plant growth, but increased microbial growth. Furthermore, as in recent studies of terrestrial plants, microbial interactions altered a duckweed phenotype (frond aggregation). Our results suggest that the duckweed source population, its associated microbiome, and the contaminant environment may all need to be considered in real-world phytoremediation efforts. Lastly, we propose that duckweed microbes offer a robust experimental system for study of host-microbiota interactions under a range of environmental stresses.

ecology↗

bioRxiv2018

Adaptive phenotypic divergence in teosinte differs across biotic contexts

Climate is a powerful force shaping adaptation within species, often creating dramatic phenotypic clines. Yet adaptation to climate does not occur in a vacuum: species interactions filter the fitness consequences of both climatic and phenotypic variation. In other words, the translation of genotype to phenotype may be altered by biotic context, influencing the variation upon which climatic selection can act. We investigate the role of such interactions in changing the phenotypes on which selection acts using ten populations of an annual grass species (teosinte: Zea mays ssp. mexicana) sourced from along an elevational gradient, along with rhizosphere biota sourced from three of those populations. We grow teosinte families in a half-sibling design in separate biota treatments to first test whether the divergence we see among traits in teosinte populations exceeds what we would expect from genetic drift and then whether the source of rhizosphere biota affects the expression of divergent traits. We also assay the influence of these three rhizosphere biotas on contemporary additive genetic variation in teosinte traits across populations. We find that expression of most measured traits in teosinte is altered by rhizosphere biota, as well as the degree of variance and covariance among traits involved in root mass and flowering time. As a number of these traits are also found to underlie adaptive divergence across habitats, our data suggest that biota influence the expression of traits underlying local adaptation. Together, our results suggest that changes in trait expression and covariance elicited by interactor communities in root mass and flowering time may have played a historical role in local adaption of teosinte to environments, and that they would play a contemporary role in responses to changing selection pressures.

evolutionary biology↗