Biology subjects

McNabb, C.

Publications and source records attributed to McNabb, C..

4 recordsLinked to original sources

bioRxiv2026

Human brain cortical oxygen consumption is positively related to soma surface area density.

Evidence from in-silico, ex vivo and invasive animal studies suggested the function of neural tissue to be inextricably linked to its structural and microstructural organization. However, this link has never been assessed non-invasively in humans. Here, we established a simple quantitative framework linking cerebral oxygen metabolism to gray matter microstructural features in healthy humans using advanced non-invasive MRI methods. The cerebral metabolic rate of oxygen consumption (CMRO2) was quantified with calibrated fMRI, whereas microstructural properties were estimated from diffusion MRI data fitted to the Soma and Neurite Density Imaging (SANDI) model, yielding soma radius (R soma) and soma volume fraction (fsoma) metrics, from which we derived maps of soma surface area density (SAD) and soma numerical density (ND) under the assumption of a spherical soma. CMRO2 was positively associated with SAD (r = 0.29, p < 0.01), fsoma (r = 0.28, p < 0.05) and ND (r = 0.25, p < 0.05), and negatively associated with Rsoma (r = -0.23, p < 0.05) across cortical brain regions. These relationships are consistent with predictions from experimental and theoretical studies, providing the first quantitative evidence that cerebral metabolic demand is coupled to microstructure in humans. The positive association of energy consumption with SAD is consistent with the notion that both the number of synapses (energy-demanding structures), and the energy required to maintain a membrane potential, scale with soma surface area. Our findings establish a non-invasive MRI framework for investigating the microstructural determinants of brain energy metabolism in health and potentially in disease.

neuroscience↗

bioRxiv2026

From Brain Microstructure to Dynamics: Linking Grey and White Matter Architecture to Propagation Delays

Understanding the relationship between neural dynamics and underlying brain structure, and in particular the impact of the latter on conduction delays, remains a core question in neuroscience. In humans, we primarily access these phenomena at the macroscale through neurophysiological measures of propagation. At this scale, signal propagation is reflected in measurable delays arising from both white matter (WM) axonal conduction and grey matter (GM) synaptic and integrative processes. While specific WM features have been explicitly linked to single-axon conduction delays, no clear models link GM microstructural properties to large-scale propagation. To this aim, we combined advanced MRI microstructural modelling with resting-state MEG to link brain structure to signal propagation in a sample of 94 healthy controls. WM metrics included axonal diameter, myelination (g-ratio, myelin water fraction), and tract length, while GM was characterised using the SANDI model and cortical thickness. Propagation delays were quantified using the neuronal avalanches framework. Our findings indicated significant associations between all of WM and GM metrics and the propagation delays. When attempting to use our W/GM metrics we were able to predict up to ~26% of the observed delay using linear regression modelling. We also found associations between frequency-specific propagation dynamics and tract length. Finally, using a canonical correlation analysis we demonstrated multivariate coupling between our W/GM metrics and the MEG frequency-specific propagation delays. Our findings provide evidence for the link between tissue structure and large-scale neural dynamics, supporting the development of biologically grounded models of signal propagation.

neuroscience↗

bioRxiv2026

Feasibility of PIANO-Cog for older adults: A randomised controlled pilot trial exploring changes in cognition and brain microstructure.

BackgroundExecutive functions are a key target of cognitive interventions for older adults due to their central role in daily functioning and maintaining a good quality of life. Piano training has been proposed as an ecologically valid method of improving cognition and brain structure in older adults. The primary aims of this study were to (i) evaluate the feasibility and acceptability of Piano Instruction for Adult Novices as an Online Cognitive Intervention (PIANO-Cog), a novel bespoke 8-week self-guided piano training programme for adults over 50 years of age, and (ii) assess the feasibility of conducting a fully-powered randomised controlled trial (RCT), including recruitment, retention, and adherence. Secondary aims explored effects of PIANO-Cog on executive functions and brain microstructure using advanced diffusion-weighted imaging (DWI). MethodThirty-three healthy music novices aged 51-80 years (M = 63.73, SD = 7.94) participated in a two-arm unblinded feasibility RCT. Participants were assigned by stratified allocation for age and sex to either (i) 8 weeks of PIANO-Cog, requiring 30 minutes of practice, 5 days per week, or (ii) a passive control group. Cognitive assessment and MRI scanning were conducted before and after the intervention using a strong-gradient (300mT/m) 3T Connectom scanner to acquire multi-shell DWI data with b-values ranging from 200 to 6,000 s/mm{superscript 2}. Grey and white matter microstructure were modelled with Soma And Neurite Density Imaging (SANDI) and Neurite Orientation Density and Dispersion Imaging (NODDI). ResultsAccording to predefined criteria, feasibility was established for recruitment (91.6%), retention (75%) and adherence (>100%) rates. Preliminary observations suggest that piano training compared with control was associated with improvements in verbal fluency and multiple changes in brain microstructure including increases in apparent soma size and radius and reductions in extracellular signal in frontal and temporal cortical regions, larger apparent neurite density in right inferior frontal gyrus and changes in neurite dispersion in left middle temporal and right precentral gyri. DiscussionThe results demonstrate that short-term remote piano training is a feasible cognitive intervention for healthy adults over 50. Preliminary evidence suggest that PIANO-Cog was associated cognitive improvements and changes in brain microstructure in executive, auditory and motor regions.

neuroscience↗

bioRxiv2025

LONGITUDINAL CHANGES IN WHITE MATTERMICROSTRUCTURAL STATUS FOLLOWING QUANTIFIEDHEAD-BALL IMPACTS IN SOCCER: A PRELIMINARY,PROSPECTIVE STUDY.

Repetitive, sub-concussive head impacts have been associated with increased chronic traumatic encephalopathy (CTE) incidence. CTE diagnosis traditionally relies on post-mortem examination, which limits precise correlation between cause- and-effect. This prospective study embraced innovative diffusion magnetic resonance imaging, which enables in vivo quantification of acute, sub-acute and chronic changes in brain tissue microstructure. This approach was used to evaluate changes in white matter microstructural status at intervals up to 180 days following a specified soccer heading protocol. This study was approved by the university ethics panel. Twelve males (21 - 23 years) were recruited to the study and gave signed, informed consent. Six Intervention participants were university-level soccer players, with 6 Control participants drawn from university-level non-contact sports. Multi-shell diffusion-weighted MRI data were acquired on a 3T Siemens Connectom (300mT/m) scanner using the HARDI protocols. Baseline measures of fractional anisotropy, mean diffusivity and mean kurtosis were acquired at day 0. The Intervention cohort then performed 10 soccer headers in a laboratory, with acceleration-time data captured using an instrumented mouthguard and post-processed to report common metrics. The Intervention group was then re-scanned at day 1 (n = 6), day 90 (n = 5) and day 180 (n = 4). The Control group was re-scanned at day 1 (n = 6) and day 180 (n = 3). Many brain tracts were identified as having significant (p < 0.05) changes in white matter microstructural changes at day 90, which correlated strongly with the magnitude of head impact. A smaller number of tracts had changes at day 1 and day 180. These results indicate that, within this pilot population, the magnitude of repeated soccer headers appears to correlate with the magnitude of white matter microstructural change. Additional investigation is required to determine whether the effect of such an intervention influences long-term brain health risk.

bioengineering↗