Biology subjects

Noonan, M. P.

Publications and source records attributed to Noonan, M. P..

3 recordsLinked to original sources

bioRxiv2021

Home alone: A population neuroscience investigation of brain morphology substrates

As a social species, ready exchange with peers is a pivotal asset - our "social capital". Yet, single-person households have come to pervade metropolitan cities worldwide, with unknown consequences in the long run. Here, we systematically explore the morphological manifestations associated with singular living in [~]40,000 UK Biobank participants. The uncovered population-level signature spotlights the highly associative default mode network, in addition to findings such as in the amygdala central, cortical and corticoamygdaloid nuclei groups, as well as the hippocampal fimbria and dentate gyrus. Sex-stratified analyses revealed male-specific neural substrates, including somatomotor, saliency and visual systems, while female-specific neural substrates centred on the dorsomedial prefrontal cortex. In line with our demographic profiling results, the discovered neural imprint of living alone is potentially linked to alcohol and tobacco consumption, anxiety, sleep quality as well as daily TV watching. The secular trend for solitary living will require new answers from public-health decision makers.

neuroscience↗

bioRxiv2021

Dissociable mechanisms of reward learning co-mature during human adolescence as predicted by macaque lesion models

Reward-guided learning and decision-making is a fundamental adaptive ability and depends on a number of component processes. We investigate how such component processes mature during human adolescence. Our approach was guided by analyses of the effects of lateral orbitofrontal lesions in macaque monkeys, as this part of the brain shows clear developmental maturation in humans during adolescence. Using matched tasks and analyses in humans (n=388, 11-35yrs), we observe developmental changes in two key learning mechanisms as predicted from the monkey data. First, choice-reward credit assignment - the ability to link a specific outcome to a specific choice - is reduced in adolescents. Second, the effects of the global reward state - how good the environment is overall recently - exerts a distinctive pattern of influence on learning in humans compared to other primates and across adolescence this pattern becomes more pronounced. Both mechanisms were correlated across participants suggesting that associative learning of correct reward assignments and GRS based learning constitute two complementary mechanisms of reward-learning that co-mature during adolescence.

neuroscience↗

bioRxiv2021

Dissociable developmental trajectories of Orbitofrontal subregion grey matter volume.

Adolescence is a period of development which is characterised by distinct differences in decision-making strategies relative to adults. While it is broadly established that there are relative differences in the structural maturation of the prefrontal cortex (PFC) and subcortical reward nuclei, such as the amygdala and ventral striatum, heterogeneity within the PFC is often neglected. In particular very little is known about the fine-scale gray matter (GM) development of the Orbitofrontal Cortex (OFC), itself critical to a number of learning and decision-making mechanisms which show delayed development trajectories. Here we applied voxel-based morphometry to examine subregional differences in OFC grey matter in high-quality structural MRI scans of 125 subjects aged 11-35yrs from the Human Connectome Project. First, we examined fine-scale GM maturation in 5 anatomically dissociable OFC subregions and identified the best-fitting polynomial model. Next, we directly compared developmental trajectories across 3 functionally dissociable subregions, revealing a complex topological developmental profile from medial to lateral subregions. Collectively, the two complementary analyses suggest that while unequivocally the phylogenetically younger lateral OFCs showed the greatest shift in GM volume across adolescence, with maturation continuing well into young adulthood, the differences between the medial and central OFC subregions suggested a more complex pattern of maturation than a simple graded medial to lateral topological development. We argue that knowledge of these fine-scale anatomical differences in maturation could explain precise mechanistic differences in goal-directed behaviours.

neuroscience↗