Dan Handwerker

Senior Director - Scientific Officer Primary Work Address: 4000 Jones Bridge Road, Chevy Chase, MD, 20815 Current HHMI Employees, click here to apply via your Workday account. The Howard Hughes Medical Institute (HHMI) advances the disco...

Great Job - Great Colleagues - Great Science👍
Help us pick the next generation of @hhmi.org Investigators, Freeman Hrabowski Scholars, Hanna Gray Fellows, Gilliam Fellows
Relocation to DC is required, perfect for academic PIs looking for their next chapter
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Nobel Prizes This Year Offer Three Cheers for Slow Science www.nytimes.com/2025/10/09/s...

Assuming one cleanly modeled a multimodal aftereffect (i.e. visual+audio) I'd expect additional responses in auditory and audiovis integration areas to the inducer stims. Based on this work, I'd hypothesize broader responses to aftereffects with some cortical feedback contributions.

Visual only

The standard dev of resting time series is correlated with CVR probably via voxelwise vessel diameters & baseline CBF (i.e. doi.org/10.1016/j.ne... ). This new method might be more precise, but I'm curious how much better this method matches baseline CBF vs simply the stdev of the resting state TS.

We are looking for our next colleague. Feel free to reach out to me if you have questions!

Cortical influences of afterimages may not be essential for day-to-day life, but it's just one example how a behavioral variable we rarely probe may be linked to some of this whole-brain activity. 5/5

As for what the whole brain does, our new preprint looks at afterimages and shows both variations in human influences and a lot of cortical influences bsky.app/profile/dani... 4/5

Localization is not everything but it's only part of the story. One of my core take homes from that work is that much of what we either localize or define as part of networks is limited by our data quality. If collecting 9X data gives diff results, more humility is needed about false negatives. 3/5

Task Dependence, Tissue Specificity, and Spatial Distribution of Widespread Activations in Large Single-Subject Functional MRI Datasets at 7T - PubMed It was recently shown that when large amounts of task-based blood oxygen level-dependent (BOLD) data are combined to increase contrast- and temporal signal-to-noise ratios, the majority of the brain s...

Javier's initial whole-brain activity fMRI paper & our followup definitely show whole brain activity to a visual stimulus, but the response is an order of magnitude larger in classically localized visual regions. pubmed.ncbi.nlm.nih.gov/25405938/ 2/5

Brain damage / lesion studies partially answer that some localized regions are essential for behavior and some have more subtle (if any real-time effects). 1/5

Know anyone who would be an excellent NIMH director? Application deadline is 10/6. hr.nih.gov/jobs/search/...

The human brain mechanisms of afterimages: From networks to cortical layers Afterimages are common visual illusions that have long attracted scientific interest, yet their neural mechanisms remain little understood. We used high-spatial-resolution fMRI to investigate human wh...

Contributed to nice work by @sharifkronemer.bsky.social That combines a novel behavioral paradigm with both whole-brain and layer fMRI to examine cortical processing of afterimages. www.biorxiv.org/content/10.1...

"The NIH pilot Science of Science Scholars Program provides an opportunity for experienced science of science researchers to analyze internal NIH administrative data." "...special volunteer for a one-year term (potentially renewable). Scholars may work remotely." dpcpsi.nih.gov/oepr/pilot-n...

Some subject variables such has age or clinical conditions can systemically may vary with dropout: head motion, heavy breathing, head size, metal in mouth...
Suggest calculating voxelwise & ROIwise TNSR (mean/ detrended stdev). If TSNR varies with the behavioral variable, that's a likely cause. 2/2

One possibility is signal dropout. OFC & accumbens are both in areas susceptible to dropout. If an area has significantly less signal or signif more noise, I'd expect all correlations to that area to drop. 1/2

trying this with GPT-5 and charting new frontiers in gaslighting

"In August 2025, BLS announced larger than usual monthly revisions to estimates of employment change in both May and June 2025; nearly half of these employment revisions were due to revisions in government employment (largely in local government education and state government education)."

The 4% of survey respondents who agree the Earth is flat, but don't disagree that the Earth makes a yearly orbit around the Sun are either messing with the poll or were really confused by the questions.

Rapid decoding of neural information representation from ultra-fast functional magnetic resonance imaging signals High spatio-temporal resolution is crucial for neuroimaging techniques to improve our understanding of human brain function. While the fMRI signal is slow and shows a spread in latencies over space, t...

Nice work by @yoichimiyawaki.bsky.social showing the fMRI hemodynamic response contains enough info to decode stimulus type within 2sec. Happy to have helped with this project.
www.biorxiv.org/content/10.1...

"Mind Fixers" by Anne Harrington. Expansive and critical history of biological psychiatry. Uneven at points and I have critiques of some claims, but still a good read.

Currently reading "Until Proven Safe: The history & future of Quarantine" by Nicola Twilley & Geoff Manaugh. Great history that leads to more questions than easy answers.

A series of talks on 7T (f)MRI from the SIEMENS UHF user meeting in Frankfurt are now online:
www.magnetomworld.siemens-healthineers.com/clinical-cor...

For the pubic in-person conference, what's the duration of the schedule each day? (i.e. 9AM-5PM?) Is there a registration cost?

We’re hiring! Pls share widely:

In conjunction w/ the @bowers-wbhi.bsky.social, my team is recruiting a full-time clinical research coordinator to assist with research efforts at UC Santa Barbara. 1-2 yrs experience in MRI data collection preferred.

Submit apps to: recruit.ap.ucsb.edu/JPF02974

Maybe @cwindfmri.bsky.social @tmsfmri.bsky.social can suggest some most current TMS safety literature.

Moving beyond processing- and analysis-related variation in resting-state functional brain imaging - Nature Human Behaviour Functional connectivity estimates vary significantly across different functional magnetic resonance imaging preprocessing pipelines. Due to these variations, using seemingly similar minimal preprocess...

The flatness to 1000 parcels does surprise me because it's slightly in conflict with doi.org/10.1038/s415... where I think their main effect is caused by instability of group anat alignment increasing with smaller ROIs. 3/3

For ROIs, depending on output measure, I suspect there's a balance between SNR from averaging, whether one is averaging distinct areas together, & when ROIs are so small that they don't reliably represent the same areas across the population. 2/3

Even though the data may support it, I think few people use flip angle <30, but I do use well lower than Ernst angle. A main take-away is that TNSR is flat across a wide range of SNRs, but it does drop with very low SNR and drop point will depend on other factors like voxel size & echo time. 1/3

Just to be clear, this paper really is great & important work. If what I'm saying is even a critique, it's pushing at potential ways to build on top of this work. 4/4