Accuracy and Corrections¶
A science and medicine book is only useful if you can trust it. This page explains how the book is checked and lists mistakes that were found and fixed. Publishing corrections openly is standard practice for trustworthy references, and it helps readers know what changed.
How the book is checked¶
Every chapter went through five separate passes before and after release:
- Writing with sources. Each chapter was drafted from authoritative sources: U.S. health agencies (NIH, CDC, FDA), peer-reviewed research, and the open OpenStax textbook. Every statistic, date, and approval was logged with its source.
- Independent fact-check. A separate reviewer re-checked every claim, quiz answer, clinical case, and link against primary sources.
- Copy edit. The writing was made plain and readable for high school students. A script compared each file before and after editing to confirm that no number, link, or name changed by accident.
- Senior science edit. A final expert-style review checked each claim for precision, missing caveats, and oversimplifications that had become false. It also confirmed that every time-sensitive fact was current as of October 2026.
- Technical checks. Automated checks confirm that every chapter has its required parts, that every internal link and image works, that all 16 simulations run without errors, and that the site builds without warnings. All external links were tested, including ones on sites that block automated tools, which were opened in a real browser.
The author directed the project and is responsible for its content. See About This Book.
Still not perfect
No book is free of errors, and medical knowledge changes quickly. If you find a mistake, please report it on GitHub. Corrections are listed below once they are made.
Facts that change over time¶
These statements were current as of October 2026 and are likely to change. They are re-checked with each new version:
- FDA status of new Alzheimer's, ALS, Huntington's, Parkinson's, myasthenia gravis, and narcolepsy treatments (Chapters 3, 7, 10, and 13)
- National survey statistics on mental health, youth vaping, and overdose deaths (Chapter 15)
- Blood tests for Alzheimer's disease (Chapter 13)
- Stroke treatment guidelines (Chapters 14 and 16)
- NIH summer internship eligibility rules (Appendix B)
Corrections log¶
Version 1.1 (October 2026)¶
| Where | What was wrong | Correction |
|---|---|---|
| Chapter 1 | A table listed the motor cortex as where motor neurons that reach muscles have their cell bodies | Changed to the brainstem and spinal cord, which is where those neurons sit |
| Chapter 1 | Glia and neurons were described as exactly one to one | Changed to "about one to one or a little less," matching the cited cell-count review (von Bartheld et al., 2016) |
| Chapter 1 | A myth correction cited a source for a claim the source does not make | Rewritten to match what the source actually says |
| Chapter 1 | The longest axons were said to run from the spine to the toes | Corrected; some axons in that path are about a meter long, but sensory axons from the toes to the brainstem are longer |
| Chapter 2 | The withdrawal reflex skipped the interneuron in the spinal cord | Interneuron added |
| Chapter 2 | "Every spike is the same size" contradicted the chapter's own simulator | Clarified that spikes are the same size when they start from the same resting conditions |
| Chapter 3 | The synapse simulator implied every brain synapse fires its target with one release | Clarified that it models a strong synapse like the nerve-to-muscle junction, while most brain synapses need summation |
| Chapter 4 | A split-brain example contradicted itself | Corrected: the patient cannot read the word aloud but can still pick the matching picture |
| Chapter 4 | The share of people with a complete circle of Willis was overstated | Corrected to match imaging data (about 21% in a study of 525 adults) |
| Chapter 6 | Noise-induced hearing loss was described in a way that did not match NIDCD guidance | Rewritten using NIDCD's wording on temporary and permanent loss |
| Chapter 6 | Smell gene counts compared total genes in animals with working genes in humans | Corrected to compare working genes |
| Chapter 6 | The cause of phantom limb pain was presented as settled | Added a 2025 study that challenges the classic brain-remapping explanation |
| Chapter 7 | The motor "homunculus" was presented as a simple continuous map | Added the 2023 discovery of regions linked to action planning between body-part areas |
| Chapter 8 | Myelination was said to start one to two months before birth | Corrected; it begins much earlier in the spinal cord |
| Chapter 8 | Neural tube closure timing was confusing | Corrected to weeks after conception |
| Chapter 9 | The Patient H.M. case used the "fictional case" label | Labeled correctly as a real historical patient |
| Chapter 10 | The delta wave band was defined too narrowly | Corrected |
| Chapter 10 | "Sleep washes waste out of the brain" was presented as settled | Updated with a 2024 study that challenged it; described as a hypothesis |
| Chapter 11 | The amygdala "fast route" was presented as the settled explanation for being startled | Noted that it was mapped mainly in rats |
| Chapter 13 | The drug nusinersen was said to change how RNA is "edited" | Corrected to "spliced" |
| Chapter 14 | The concussion danger signs and seizure "call 911" list did not fully match CDC guidance | Matched to CDC wording |
| Chapter 14 | The FDA approval date for tenecteplase in stroke was given as March 3, 2025 | Corrected to February 28, 2025 (the FDA letter date); March 3 was the company announcement |
| Chapter 15 | The overdose case said the patient's pupils were still small after naloxone | Corrected; the small pupils were noted before naloxone was given |
| Chapter 15 | People with schizophrenia were said to be more likely to be harmed than to harm others | Matched to NIMH: they are more likely than people without the illness to be harmed by others |
| Chapter 16 | A simulated stroke patient showed brisk reflexes 50 minutes after onset | Corrected; brisk reflexes usually take days to appear |
| FAQ | The sharp first pain of an injury was linked to the wrong nerve fibers | Corrected to thin myelinated (A-delta) fibers |
| FAQ | fMRI was said to show which areas "use more oxygen" | Corrected; fMRI tracks blood oxygen levels that change when an area works harder |
| About page | The Brain Bee was said to have started in 1999 | Corrected to 1998, per the International Brain Bee |
Updated to the latest data (October 2026)¶
| Topic | Update |
|---|---|
| U.S. adults with a mental illness | 2025 National Survey on Drug Use and Health: 20.6% (54.6 million) |
| Teens with a major depressive episode | 2025 survey: 15.1% (3.7 million) |
| Youth vaping | 2025 National Youth Tobacco Survey figures |
| Overdose deaths | Final 2024 data plus provisional 2025 data from the CDC |
| Teens getting enough sleep | 2025 Youth Risk Behavior Survey |
| Alzheimer's disease | 2026 Alzheimer's Association estimate, newly cleared blood tests, 2024 diagnostic criteria, and the 2025 donanemab dosing change |
| New FDA decisions | Tavapadon for Parkinson's (2026), inebilizumab and expanded efgartigimod for myasthenia gravis (2025 and 2026), oveporexton for narcolepsy (2026), and xanomeline-trospium for schizophrenia (2024) |
Each change is documented in the chapter it affects, with a link to its source. The full history of the book's files is on GitHub.