Biology subjects

Sangchooli, A.

Publications and source records attributed to Sangchooli, A..

3 recordsLinked to original sources

bioRxiv2025

Geometric constraints on the architecture of mammalian cortical connectomes

The intricate network of axonal fibres that forms the mammalian cortical connectome has a complex topology, being organized in a way that is neither completely regular nor random, as well as a characteristic topography, in which specific anatomical locations are imbued with distinctive connectivity profiles. The mechanisms that give rise to such properties remain a mystery. Here, we formulate a simple analytic model derived from neural field theory that prioritizes physical constraints on connectome architecture by assuming that connectivity is preferentially concentrated between pairs of cortical locations that facilitate the excitation of resonant geometric modes of the cortex. We show that the model outperforms existing approaches in reproducing multiple topological and topographical properties of cortical connectomes mapped at spatial scales spanning orders of magnitude in humans, chimpanzees, macaques, marmosets, and mice, as mapped with either non-invasive diffusion magnetic resonance imaging or invasive viral tract-tracing. Our findings thus point to a fundamental role of geometry in shaping the multiscale architecture of cortical connectomes that has been conserved across 90 million years of evolution.

neuroscience↗

bioRxiv2025

Weakening of subcortical and strengthening of cortical visual pathways across early adolescence

BackgroundMounting evidence suggests that amygdalar nuclei receive visual information via both a well-characterized cortical pathway through the inferior temporal cortex and a subcortical route through the superior colliculus and pulvinar. This subcortical pathway may facilitate rapid responses to salient visual stimuli and could explain phenomena such as blindsight. However, controversies remain about the organization of the subcortical pathway, its role in visual processing, and how the cortical and subcortical pathways mature across development. MethodsTo address these questions we used longitudinal diffusion magnetic resonance imaging (dMRI) data from 4361 participants in the Adolescent Brain Cognitive Development (ABCD) study, reconstructing every major segment of the cortical and subcortical amygdala pathways. We tested the existence of the subcortical pathway against null tractography models, characterized cortical and subcortical pathways development across early adolescence, and investigated their association with visual processing speed. ResultsWe provide evidence for the existence of bilateral pulvinar-amygdala pathways against a null model (all p < 0.001, corrected). While cortical tracts involving the primary and extrastriate visual cortex and the inferior-temporal cortex strengthened with chronological age and over pubertal development, we demonstrate that subcortical pulvinar-amygdala connectivity decreased over pubertal development. Greater connectivity strength of the right pulvinar-amygdala tract was associated with faster responses on a visual task for both emotional face and place stimuli, a relationship also seen for cortical tracts. ConclusionThis study provides evidence for the existence of pulvinar to amygdala tracts in the largest sample of adolescent participants studied to date. Greater connectivity in both cortical and subcortical tracts were associated with faster reaction time on a visual task, but further work will be needed to investigate the specificity of this association in terms of both task and tract. In line with the hypothesized importance of the subcortical pathway in early development, we show that the developmental trajectories of cortical and subcortical pathways diverge and highlight the influence of pubertal development, with cortical pathways generally strengthening and subcortical pathways weakening across early adolescence.

neuroscience↗

bioRxiv2025

An Evaluation of the Efficacy of Single-Echo and Multi-Echo fMRI Denoising Strategies

Resting-state functional magnetic resonance imaging (rsfMRI) is commonly used to study brain-wide patterns of inter-regional functional coupling (FC). However, the resulting signals are vulnerable to multiple sources of noise, such as those related to non-neuronal physiological fluctuations and head motion, which can alter FC estimates and influence their associations with behavioral outcomes. The best strategy for acquiring and processing rsfMRI data to mitigate noise remains an open question. In this study of 358 healthy individuals, we compared the denoising efficacy of 60 multi-echo (ME) and 30 single-echo (SE) rsfMRI preprocessing pipelines across six distinct measures of data quality. We also evaluated how each pipeline influences the effect sizes of FC-based predictive models of personality and cognitive measures estimated via cross-validated kernel ridge regression. We found that ME pipelines generally showed superior denoising efficacy to SE pipelines, but that no single pipeline was associated with both superior denoising efficacy and behavioural prediction. Using a heuristic scheme to rank pipelines across benchmark evaluations, we found that an ME acquisition combined with Automatic Removal of Motion Artifacts Independent Component Analysis (ICA-AROMA) and Regressor Interpolation at Progressive Time Delays (RIPTiDe) offered a reasonable compromise between denoising efficacy and brain-behavior predictions for both ME and SE data. In general, ME pipelines ranked more highly than SE pipelines. These findings support the use of ME acquisitions in future work but suggest that no single denoising pipeline should be considered optimal for all purposes.

neuroscience↗