Feilong Ma

Feilong Ma

@feilong.bsky.social

Studying brain functional organization and individual differences with computational approaches Assistant Prof. @sc.edu Previously ‪RAP/Postdoc/PhD @dartmouthpbs.bsky.social‬

182 followers186 following17 posts

Feilong Ma reposted

Feilong Ma reposted

Feilong Ma reposted

New preprint as my first post! "Monosynaptic connections link functionally similar regions in human cortex." We use electrical stimulation + fMRI in epilepsy patients to map whole-brain monosynaptic connectivity at 42 cortical sites. doi.org/10.64898/202... 1/n

Feilong Ma reposted

Check out our latest collab with Manish Saggar, @richardfbetzel.bsky.social, et al. (lead: Chunyin Siu)! We use TDA to show that 2nd-order (edge) brain interactions more distinctly segregate task connections than other kinds of network patterns. Paper/code/data: www.biorxiv.org/content/10.6...

biorxiv.orgGlobal topology of brain-wide co-fluctuations links task states, personality, and behavioral symptom dimensionsFunctional connectivity in network neuroscience is traditionally characterized using time-averaged correlations between brain regions. While these summaries capture stable large-scale organization, they do not fully reflect the temporal structure of moment-to-moment interactions. Here, we investigate how the order of interaction used to represent brain dynamics shapes the organization recovered from neural data. We compare three interaction representations of fMRI dynamics: regional activation (node time series), pairwise co-fluctuations (edge time series), and higher-order triplet interactions (triangle time series); within a common topological framework using Mapper from topological data analysis (TDA). Across task and resting-state data, Mapper representations derived from pairwise co-fluctuations more distinctly segregate task conditions than activation-based or higher-order representations. This organization reflects structured coordination patterns beyond activation polarity and is driven by high-amplitude interaction events. Beyond task states, modularity quality computed across all Mapper representations is highest for edge time series and selectively associated with stable individual differences: higher modularity relates to higher conscientiousness and lower internalizing and externalizing symptom dimensions. Together, these findings suggest that behaviorally relevant information is reflected in the topology of moment-to-moment brain interactions. Topological analysis of interaction-level dynamics therefore provides a complementary and interpretable framework for linking large-scale neural coordination to cognition, personality, and mental health. ### Competing Interest Statement The authors have declared no competing interest. National Institute of Mental Health, https://ror.org/04xeg9z08, MH127608 Stanford Maternal and Child Health Research Institute, https://ror.org/00yt0ea73, Faculty Scholar Award

Feilong Ma reposted

We're hiring! FT research assistant @ UT Dallas Join our team to work on a longitudinal neuroimaging study of midlife brain aging. Strong opportunity for those interested in brain networks, aging, and Alzheimer’s disease risk. App. deadline now May 15. Details: jobs.utdallas.edu/postings/31680

Feilong Ma reposted

So excited about Eghbal's (@eghbal-hosseini.bsky.social) and Jack King's work, which is building on Eghbal's earlier work on linguistic prediction as trajectory straightening!

Eghbal Hosseini@eghbal-hosseini.bsky.social

How is uncertainty in LLMs output reflected in internal representations? In our new work (to appear at ICML 2026), we show that the shape of internal token trajectories provides a direct geometric link to behavioral uncertainty (output entropy). 🧵(1/n)

Feilong Ma reposted

The final typeset version of this paper is online now! Check out the new analysis approach that Narjes developed to track changes in event structure at multiple timescales, allowing us to see how event dynamics in a film clip change with repeated viewing

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I love the work, not only because it speed up FIC models a lot, but also how it saves poor students from grad student descent 🤣🤣

Thomas Yeo@bttyeo.bsky.social

While the world burns, we cook up a new preprint! doi.org/10.1101/2025... Biophysical modeling is a key tool to derive mechanistic insights into the brain. These models are governed by biologically meaningful parameters (unlike artificial neural networks), but the dirty secret ... 1/N

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

The creation of onavg has greatly benefited from open science. We used 1,031 high-quality brains openly available from OpenNeuro, and we deeply appreciate the participants and researchers who generously shared their data. We also thank DataLad, StudyForrest, and Center for Open Neuroscience.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

In densely sampled regions, there are more vertices in each searchlight and more searchlight centers in the region, leading to prolonged computations. By uniformly sampling the cortex, onavg reduces the computational time of various commonly used algorithms.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

These benefits, in theory, generalizes to any analyses that rely on sampling density, uniformity, or spatial patterns. In Extended Data Figs 7–9, we showcased how onavg benefits resting-state functional connectivity, localizer contrast maps, and modeling individual differences.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

We optimized the location of cortical vertices by penalizing a pair of vertices if they were too close on the anatomical surface. After the optimization, we obtained the onavg template, where vertices are evenly distributed on the anatomical surface.

Our cortical surface template, onavg (short for OpenNeuro Average), is published in Nature Methods. Onavg evenly samples different parts of the cerebral cortex, leading to improved performance of various analysis and reduced computational time. www.nature.com/articles/s41...

nature.comA cortical surface template for human neuroscience - Nature MethodsOnavg is a surface template of the human cortex. In contrast to existing templates, the cortical surface is uniformly sampled, which has advantages in numerous applications.

Traditional templates choose their vertices based on the inflated spherical surface. Vertices are mostly uniform on the spherical surface. However, on the actual anatomical surface, vertices are often sparsely distributed on gyri and densely distributed on sulci.

Excited to shared this amazing work by the amazing Erica and colleagues! Based on data from >1000 ABCD children, we found that fine-grained connectome is more reliable but less heritable than coarse-grained, and it performs better in predicting less heritable cognitive traits.

jneurosci.orgDissociation of Reliability, Heritability, and Predictivity in Coarse- and Fine-Scale Functional Connectomes during DevelopmentThe functional connectome supports information transmission through the brain at various spatial scales, from exchange between broad cortical regions to finer-scale, vertex-wise connections that under...

Feilong Ma reposted

🚨My lab is searching for 1-2 full-time research coordinator(s) and a full-time research tech to contribute to our studies on 🧠 human brain networks🧠 Deadline: Feb. 28 for full consideration Start date: as early as this summer Additional info: pics below and 👇 Pls share/RT! 🙏

Feilong Ma reposted

In this preprint, Jin Ke (@jinke.bsky.social) identified a situation-general representation of arousal encoded in patterns of dynamic FC. Collab w/ Hayoung Song, Zihan Bai, and @monicarosenb.bsky.social See below of a teaser, and more details in the preprint! (1/X)

Jin Ke@jinke.bsky.social

Excited to share this new preprint in collaboration with Hayoung Song, Zihan Bai, @monicarosenb.bsky.social and @ycleong.bsky.social: Dynamic functional connectivity encodes generalizable representations of emotional arousal but not valence (1/10) www.biorxiv.org/content/10.1...

Feilong Ma reposted

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