I have been focused on neuroanatomy for 14 years now. The diencephalon chapter gives students headaches every year—and honestly, it gives me headaches too. Last year, I finally made up my mind to completely remake the entire diencephalon module. This article documents that process and some of my thoughts.
The diencephalon is located between the brainstem and the cerebral cortex. It contains four main structures: the thalamus, hypothalamus, epithalamus, and subthalamus. Sounds simple, but teaching it is anything but simple.
The Four Pillars of the Diencephalon
The diencephalon serves as a critical relay station between the brainstem and cortex, housing structures essential for sensory processing, endocrine function, autonomic regulation, and motor coordination.
Problems with the Old Teaching Materials
The set of slides I started using in 2009 was inherited from my advisor. He created them in 1996. You can imagine the image quality.
Students never complained directly, but I could tell from the exam scores. The accuracy rate for diencephalon-related questions consistently hovered between 58% and 64%, while other chapters were all above 75%. I have an Excel spreadsheet recording the accuracy rate for each question from 2011 to 2023—the data for the diencephalon section has always been poor.
There was also a problem with content organization. The old teaching plan was organized by anatomical location: first the position of the thalamus, then the position of the hypothalamus, then the position of the epithalamus. After students memorized all the positions, they had to start all over again when they got to the functions. Two systems fighting in their heads.
In 2019, a student came to see me after class. She said she had memorized all 13 thalamic nuclei names but still didn't understand why the lateral geniculate body was related to vision. I couldn't give her a satisfactory explanation at the time. I remembered this incident for a long time.
— The moment that sparked changeRemaking the Teaching Materials
Last summer, I spent two months rewriting the entire module.
Structural Adjustment
The new version is no longer organized by location. I changed it to be organized by functional systems: sensory relay, motor regulation, endocrine control, and autonomic nervous system integration. Related anatomical structures are introduced within each system.
The thalamus is no longer a standalone chapter but is distributed across the sensory relay and motor regulation sections. The hypothalamus was also split up—temperature regulation goes in the autonomic nervous system integration section, hormone control goes in the endocrine section.
This approach has one complication: some structures get mentioned two or even three times. For example, the paraventricular nucleus of the hypothalamus needs to be covered both in the osmotic pressure regulation section and in the oxytocin secretion section. My approach is to cover it in detail the first time it appears, and only make cross-references in subsequent appearances.
The Image Problem
Images were the most time-consuming part.
I contacted the school's medical illustrator, and she quoted $1,800 for 15 original illustrations. The department's teaching budget approved $1,200, and I paid the remaining $600 out of pocket. Whether it was worth it remains to be seen, but at least the images are clear now.
I obtained anonymized cases from the hospital radiology department and received IRB approval for educational use. This process took three months—longer than I expected. Some images I particularly wanted couldn't be used in the end because the quality loss from anonymization was too significant.
Some images I used directly from open-source textbooks, properly attributed under the CC BY-SA license. Radiopaedia has some excellent hypothalamic lesion images. I emailed to ask for permission, and they replied with approval within three days.
Newly Added Content
This time I added some clinical cases. Not the typical textbook cases, but real cases I've accumulated over the years (all de-identified, of course).
32-Year-Old Female — Hypothalamic Germ Cell Tumor
There's one case of a 32-year-old female that I've used for six years and still can't bear to remove: she presented with polydipsia and polyuria, and was ultimately diagnosed with a hypothalamic germ cell tumor that had invaded the suprachiasmatic nucleus and infundibular region. This case ties together the anatomical relationships of osmotic pressure sensing, antidiuretic hormone secretion, and the visual pathway. Students have reported that this case was very helpful.
13-Year-Old Male — Pineal Region Tumor
There's also a case of a 13-year-old boy with a pineal region tumor, used to teach Parinaud syndrome and the epithalamus. I saved his eye movement video from that time, and showing it in class is more effective than any diagram.
Some Still Unresolved Problems
I'm still not satisfied with the subthalamus section. The content on the subthalamic nucleus is too sparse—having it as a standalone section makes it look thin, but merging it into motor regulation makes it easy for students to overlook. Currently, I've placed it at the end of the motor regulation chapter as an "other related structures" supplement. Not ideal.
Another problem is the correspondence between English and Chinese terminology. Our school uses bilingual teaching, but the neuroanatomy naming system itself has historical legacy confusion. For example, "subthalamus"—some translate it as 底丘脑, others as 丘脑底部. I've marked both translations in the handouts and use 底丘脑 consistently in class. Every year, there are still students who write the wrong term on exams because of this.
Class hours are also a constraint. The entire neuroanatomy course is only 48 hours, and the diencephalon can be allocated at most 6 hours. Some content I can only compress or skip. I cut two-thirds of the content on the thalamic reticular nucleus, and the medial geniculate body basically gets just a single mention. If class hours can be increased in the future, these areas will need to be filled back in.
Current Results
The new teaching materials have been in use since the Fall 2023 semester.
In the student evaluations, several comments mentioned that the diencephalon chapter became clearer, and some said the clinical cases were very interesting. The negative feedback mainly said that some structures were covered too dispersedly, making them hard to find when reviewing.
I'm thinking about a solution to this problem—I might create a quick reference table indexed by anatomical structure to put at the end.
Next Steps: Await Fall 2024 semester data for comparison. Consider creating an anatomical structure index for student review convenience.