TROPICAL SYNAPSES
Reflections on topics including clinical neurology, recent publications in neuroscience,
philosophy of biology, "neuro-doubt" about modern media hype of new neuro-scientific procedures and methods, local oceanography, tropical horticulture, the Hawai'i health scene, and whatever else dat's da kine...
Lala
A new online neuroanatomy resource: the ANCHOR Brainstem Atlas
Synopsis: A new open-access platform at anchor.humanbrain.in provides a readily available online histological and neurochemical mapping of the human brainstem at three stages: 25 fetal gestational weeks (GW), 9 years old, and 54 years old.
The brainstem remains one of the most challenging regions for both surgical intervention and pathological correlation. CT imaging is generally poor, and MRI imaging often lacks cues to decide upon functional zones. The new atlas allows histochemical and MRI images to be evaluated side by side.
According to the preprint at biorxiv, this online atlas was constructed from three whole-brain specimens representing distinct developmental stages:
| Fetus at 25 gestational weeks (critical window for brainstem nuclei maturation) |
|---|
| Child at 9 years (most development completed, still some myelinating) |
| 54 years (adult, representative of mature, aging brainstem) |
More than 800 serial sections were processed using both the usual Nissl staining for cytoarchitectonic demarcation as well as 7 different immunochemical (IHC) markers enabling neurochemical characterization of specific cell populations, including catecholaminergic groups (dopaminergic, noradrenergic, and adrenergic nuclei). I inspected the catachlamine staining of the substantia nigra compacta and found it clear and well labeled. In fact, I found the anatomic labeling applied to the sections to be quite impressively thorough. Over 200 structures are stated to be manually annotated across all three specimens. Even the within-brain cranial nerve pathways seem clearly delineated and annotated. Highly recommended, though it needs a better index.
ABSTRACT
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ANCHOR : Atlas of Neurochemical Characterization of the Human Brainstem with 3D Reconstruction
Authors: Mihail Bota, Soundharya Venkatesh, Shevani Arun Arunesh, Nagajothi Ganesan, Supriti Mulay, Karan Ramana Gopi, Sruti Rekha Muni, Shrimathi Mani, Sam C. Chrisline, A.S.T. Aditya Bharg, Kanna G Vinoth, Rajeswaran Rangaswami, S. Lata, E. Harish Kumar, S. Suresh, Mousumi Sen, Ranjit Immanuel James, Abi Manesh, George M. Varghese, K.V. Vinoth, Keerthi Ram, Richa Verma, Paul R. Manger, Mohanasankar Sivaprakasam
doi: https://doi.org/10.64898/2026.06.03.727794
Abstract
The human brainstem is a complex division of the brain comprised of more than 200 nuclei and fiber tracts. The brainstem is essential for the functioning of the entire body. We introduce here the most detailed human brainstem Atlas across the human lifespan: fetus, child, adult. ANCHOR, the Atlas of Neurochemical Characterization of the Human Brainstem, is an online platform that includes more than 800 serial histological sections, stained for Nissl and seven immunochemical (IHC) markers, from the human brainstem of three ages: 25 fetal gestational weeks (GW), 9 years old, and 54 years old. This makes ANCHOR the most comprehensive human brainstem Atlas to date. In these three brainstems, we identified and manually annotated over 200 structures. We further characterized these structures with the seven IHC markers. We specifically describe the catecholaminergic groups in the human brainstem across all three age groups. In addition, we identified the protoplasmic commissural dendrites of the hypoglossal nucleus and we describe the pretectal nuclei in the Nissl-stained fetal 25 GW brainstem. ANCHOR includes an online viewer that integrates multimodal data, from magnetic resonance imaging and block face imaging to Nissl- and IHC-stained serial sections and 3D reconstruction of the entire brainstem. For the 9-year-old specimen, the online viewer allows simultaneous navigation of annotated sections with corresponding IHC, for viewing the specific region-wise cellular features accessible at https://anchor.humanbrain.in/.
New study published on NPH this month.
Periods of excessive amounts of cerebrospinal fluid pressure in and around the brain, despite a normal average pressure of the fluid, have been felt to be a cause of NPH. A clinical concern regarding reasons for referral to a neurologist or neurosurgeon is that normal pressure hydrocephalus is commonly an incidental diagnosis made or mentioned as a differential by a radiologist when interpreting the relative quantity of CSF volume on a CT or MRI scan made for symptoms different than those of NPH itself.
The past published practice standard of the American Academy of Neurology on surgical shunt placement as treatment of normal hydrocephalus has been to refer patients for neurosurgical intervention with shunting if the patient or family desire. What counseling is best regarding the risks and benefits of such surgery has not been clear. This new trial is quite important, since it suggests that such patients can be told there might be a small improvement in gait from the surgery, but that cognition and incontinence issues are unlikely to improve from shunting surgery. In addition, there is a substantial risk of complicating subdural hematoma (internal bleeding around the brain) according to this new study.
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A Randomized Trial of Shunting for Idiopathic Normal-Pressure Hydrocephalus
Authors: Mark G. Luciano, M.D., Ph.D. https://orcid.org/0000-0002-5664-2956, Michael A. Williams, M.D. https://orcid.org/0000-0002-7284-8014, Mark G. Hamilton, M.D., C.M. https://orcid.org/0000-0002-3380-8829, Heather L. Katzen, Ph.D. https://orcid.org/0009-0001-7297-9380, Nickolas A. Dasher, Ph.D. https://orcid.org/0000-0001-5858-5265, Abhay Moghekar, M.B., B.S. https://orcid.org/0000-0001-9464-1551, Jun Hua, Ph.D. https://orcid.org/0000-0001-5481-7380, +13 , for the PENS Trial Investigators and the Adult Hydrocephalus Clinical Research Network*Author Info & Affiliations
Published September 16, 2025
DOI: 10.1056/NEJMoa2503109
Copyright © 2025
Background
Idiopathic normal-pressure hydrocephalus is a neurologic disorder characterized by impaired gait, balance, cognition, and bladder control in older adults. The disorder is treated with shunt surgery, but the effectiveness of shunting is unclear.
Methods
We conducted a double-blind, randomized, placebo-controlled trial involving participants selected for shunt surgery on the basis of gait-velocity improvement with cerebrospinal fluid (CSF) drainage. Participants were randomly assigned to an open-shunt valve setting (opening pressure, 110 mm of water) or a placebo valve setting (opening pressure, >400 mm of water) of a noninvasively adjustable shunt. The primary outcome was the change in gait velocity 3 months after surgery. Secondary outcomes were the change at 3 months in the Tinetti scale total score (range, 0 to 28; lower scores indicate worse gait and balance), Montreal Cognitive Assessment (MoCA) score (range, 0 to 30; lower scores indicate worse cognition), and Overactive Bladder Questionnaire score (range, 0 to 100; higher scores indicate worse urinary incontinence).
Results
A total of 99 participants underwent randomization and received the assigned intervention. At 3 months, gait velocity had increased in the open-shunt group (mean [±SD] change, 0.23±0.23 m per second; assessed in 49 participants) and was unchanged in the placebo group (mean change, 0.03±0.23 m per second; assessed in 49 participants), resulting in a treatment difference of 0.21 m per second (95% confidence interval, 0.12 to 0.31; P<0.001). A significantly greater improvement in the open-shunt group than the placebo group was seen for the Tinetti scale score (mean change, 2.9 points vs. 0.5 points; P=0.003) but not the MoCA score (1.3 points vs. 0.3 points) or the Overactive Bladder Questionnaire score (−3.3 points vs. −1.5 points). The results regarding adverse events were mixed, with more participants in the placebo group reporting falls (46% vs. 24%), an equal percentage having cerebral bleeding (2% in both groups), and more participants in the open-shunt group having subdural bleeding (12% vs. 2%) and positional headaches (59% vs. 28%).
Conclusions
Among participants with idiopathic normal-pressure hydrocephalus who had a response to temporary CSF drainage, shunting resulted in significant improvements at 3 months in gait velocity and a measure of gait and balance but not in measures of cognition or incontinence. (Funded by the National Institute of Neurological Disorders and Stroke and the Trial Innovation Network; PENS ClinicalTrials.gov number, NCT05081128.)
Implanted electrodes can be used to transcribe "inner speech"
It has been long known that electronic amplification of "subvocalization" can cause words that a person says "under their breath" to be heard. The researchers in the study below have taken this further, showing that an implanted electrode grid can pick up words we merely think to ourselves via traces such thinking of speech can create by its activation of the portion of the motor cortex responsible for the muscles which express our ordinary speech. This technique takes pickup of subvocalization one step further, into the brain, if not actually into the language center itself. Note that the success rate was still a bit lower than needed for a truly effective communucations brain implant, since their 20% error rate clearly would benefit from further improvment. However, for those robbed of speech by bulbar weakness from conditions like ALS, this type of adaptive device can be a great boon.
The authors also explored "inner speech" as a kind of mind reading, and found a technique that patients, who normally were training to make the machine better read words, could also learn to hide their thoughts in large part. It is likely that people can learn to demodulate coactivation of the motor area during their thinking in words in a way analogous to children learning to count without using fingers, though there would usually be no need for such learning. The researchers also implemented a privacy code phrase, "chitty chitty bang bang," to temporarily stop the device from transcribing.
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ABSTRACT
TITLE - Inner speech in motor cortex and implications for speech neuroprostheses
AUTHORS - Kunz, Erin M.; Abramovich Krasa, Benyamin; Kamdar, Foram; Avansino, Donald T.; Hahn, Nick; Yoon, Seonghyun; Singh, Akansha; Nason-Tomaszewski, Samuel R.; Card, Nicholas S.; Jude, Justin J.; Jacques, Brandon G.; Bechefsky, Payton H.; Iacobacci, Carrina; Hochberg, Leigh R.; Rubin, Daniel B.; Williams, Ziv M.; Brandman, David M.; Stavisky, Sergey D.; AuYong, Nicholas; Pandarinath, Chethan; Druckmann, Shaul; Henderson, Jaimie M.; Willett, Francis R.
doi: 10.1016/j.cell.2025.06.015
Cell, https://doi.org/10.1016/j.cell.2025.06.015
Speech brain-computer interfaces (BCIs) show promise in restoring communication to people with paralysis but have also prompted discussions regarding their potential to decode private inner speech. Separately, inner speech may be a way to bypass the current approach of requiring speech BCI users to physically attempt speech, which is fatiguing and can slow communication. Using multi-unit recordings from four participants, we found that inner speech is robustly represented in the motor cortex and that imagined sentences can be decoded in real time. The representation of inner speech was highly correlated with attempted speech, though we also identified a neural ?motor-intent? dimension that differentiates the two. We investigated the possibility of decoding private inner speech and found that some aspects of free-form inner speech could be decoded during sequence recall and counting tasks. Finally, we demonstrate high-fidelity strategies that prevent speech BCIs from unintentionally decoding private inner speech.
Hīnano
The hala tree in Hawaii, species name Pandanus tectorius, is an evergreen tree with very long, narrow leaves and a pale, branching trunk that is surrounded at its base by a conical group of propping air roots.
We have two such trees by the street. The female hala produces clusters of fruit that look like giant candy corn and taste like mildly sweet candy wax. Our male hala tree produces hīnano (the male flowers) once or twice a year, including this week. Hīnano flowers are long white clusters with petals (actually bracts) that are about 30 to 50 cm in length and a creamy white. The modified leaves that make up the hīnano's bracts have some similarity to the long (150 cm) hala leaves, but are much softer and lack their strong fiber and thorny edges.
Polynesians have long used strips of hala tree leaves (lauhala) for weaving. I'm told that the old Hawaii's nobility prized the hīnano's sweet smelling flower petals for making soft, expensive floor mats.
A new color to be seen
AU - James Fong
AU - Hannah K. Doyle
AU - Congli Wang
AU - Alexandra E. Boehm
AU - Sofie R. Herbeck
AU - Vimal Prabhu Pandiyan
AU - Brian P. Schmidt
AU - Pavan Tiruveedhula
AU - John E. Vanston
AU - William S. Tuten
AU - Ramkumar Sabesan
AU - Austin Roorda
AU - Ren Ng
TI - Novel color via stimulation of individual photoreceptors at population scale
PT - Journal Article
DP - 2025
TA - Science Advances
PG - eadu1052
VI - 11
IP - 16
AID - 10.1126/sciadv.adu1052 [doi]
PMID - 40249825
4099 - https://www.science.org/doi/abs/10.1126/sciadv.adu1052
4100 - https://www.science.org/doi/full/10.1126/sciadv.adu1052
SO - Science Advances 2025-04-18 11(16): eadu1052
AB - We introduce a principle, Oz, for displaying color imagery: directly controlling the human eye’s
photoreceptor activity via cell-by-cell light delivery. Theoretically, novel colors are possible through
bypassing the constraints set by the cone spectral sensitivities and activating M cone cells exclusively.
In practice, we confirm a partial expansion of colorspace toward that theoretical ideal. Attempting to
activate M cones exclusively is shown to elicit a color beyond the natural human gamut, formally measured
with color matching by human subjects. They describe the color as blue-green of unprecedented saturation.
Further experiments show that subjects perceive Oz colors in image and video form. The prototype targets
laser microdoses to thousands of spectrally classified cones under fixational eye motion. These results
are proof-of-principle for programmable control over individual photoreceptors at population scale.
Image display by cell-by-cell retina stimulation, enabling colors impossible to see under natural viewing.
You are what you eat?
Well, maybe your microbiome is about 3% exactly what you ate, at least.
ABSTRACT
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TITLE: Unexplored microbial diversity from 2,500 food metagenomes and links with the human microbiome
AUTHORS: Niccolò Carlino, Aitor Blanco-Míguez, Michal Punčochář, Paul D. Cotter, Nicola Segata1, Edoardo Pasolli and many more...
DOI: doi: 10.1016/j.cell.2024.07.039
Published online in Cell, 2024/09/03
Highlights
With curated Food Metagenomic Data (FMD), we integrated and analyzed >2,500 food metagenomes.
Over 10,000 prokaryotic and eukaryotic MAGs uncover substantial food microbial diversity.
Food microbes account for up to an average of 3% of the adult gut microbiome.
Strain-level analysis highlights potential instances of food-to-gut microbe transmission.
Summary
Complex microbiomes are part of the food we eat and influence our own microbiome, but their diversity remains largely unexplored. Here, we generated the open access curatedFoodMetagenomicData (cFMD) resource by integrating 1,950 newly sequenced and 583 public food metagenomes. We produced 10,899 metagenome-assembled genomes spanning 1,036 prokaryotic and 108 eukaryotic species-level genome bins (SGBs), including 320 previously undescribed taxa. Food SGBs displayed significant microbial diversity within and between food categories. Extension to >20,000 human metagenomes revealed that food SGBs accounted on average for 3% of the adult gut microbiome. Strain-level analysis highlighted potential instances of food-to-gut transmission and intestinal colonization (e.g., Lacticaseibacillus paracasei) as well as SGBs with divergent genomic structures in food and humans (e.g., Streptococcus gallolyticus and Limosilactobabillus mucosae). The cFMD expands our knowledge on food microbiomes, their role in shaping the human microbiome, and supports future uses of metagenomics for food quality, safety, and authentication.
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It has been long known that electronic amplification of "subvocalization" can cause words that a person says "under their b... -
Where is the color of what we see? Is it part of the object we see? Is it in the light from that object? Is it in our eyes, our retinas? O... -
The Ship of Theseus is a classic thought experiment in Greek philosophy. As related by Plutarch the historian, Theseus' ship was kept as...