The Brain Explained.

MU Health Sciences
11 min readOct 28, 2020

By Stephen Filmanowicz

Marquette’s unique summer brain course is an enlightening 3D journey through brain form and function — and a window into the college’s invaluable gross anatomy traditions.

It’s day one of Marquette’s summer brain dissection course, lunch time.

After a meal of lasagna and salad, Jessica Alva is no longer hungry, but a different sort of intellectual craving remains. The truth is she’s been gripped by a deep-seated curiosity for a while now. It’s what prompted her to sign up for this course back in April, the same week she learned of it — and what got her in her car yesterday for the 430-mile drive from her home in Cleveland to Milwaukee. And this yearning has only continued growing this morning as Dr. William Cullinan, course founder, professor, and dean of the College of Health Sciences, has taken the 90 course participants on an illuminating slideshow tour of the brain features — including arteries, cranial nerves and major fiber pathways — they’ll soon inspect in the lab, scalpels in hand.

At the lunch table, course participants talk about what brought them here. Several are young doctoral students in clinical psychology, like Alva, seeking to signal their seriousness about brain study and improve their chances of landing prized internships in neuropsychology. And serious they are. Through her program at Case Western Reserve University, Alva works with patients whose struggles with language, memory or other forms of cognition suggest impairments in certain regions of their brain, perhaps damage from a stroke or Alzheimer’s disease. It’s vital, absorbing work — and personal too, since Alva’s father has struggled with earlyonset Alzheimer’s disease since being diagnosed when she was 16 and he was 59.

Still, the organ at the center of her attention remains somewhat obscure to her. She has never seen or inspected a human brain. The closest she’s come is a sheep brain dissected for an undergraduate biology course. Her curiosity had grown to the point that her husband, mother and other family members had all heard her lament that her brain anatomy experiences would probably end there. But that all changed in April when she learned of this course from a colleague, a postdoctoral fellow in neuropsychology who said the course has a strong following in his profession.

“Human dissection is really a dream of mine,” she tells her tablemates. Spending the better part of three summer days in a windowless room with brain specimens and cadavers might be a tough sell for some people, she acknowledges. “But not me. I can hardly wait.”

Arriving from nearly every state — and sometimes even crossing international borders to reach campus — educators, psychologists, physical therapists and a range of medical professionals know they are in for something special when they arrive in Cramer Hall on the third Thursday in July for Neuroanatomical Dissection: Human Brain and the Spinal Cord.

“To our knowledge, it is the only place in the world where you can come and dissect a human brain,” says Cullinan. Even more importantly, it is a three-day immersion in a revealing yet vanishing method of anatomical discovery known as blunt dissection.

In blunt dissection, the scientist wields the scalpel with the care of a sculptor before a block of clay. What’s revealed as she or he painstakingly removes brain tissue, starting with the outer coverings, surface arteries and cortical gray matter, are the brain’s deeper structures in all of their precisely interconnected complexity.

Regarded as a gold standard at top medical schools as recently as the 1980s, blunt dissection gave way in the space of a decade or so to the much simpler practice of viewing two-dimensional sliced cross sections of the brain. By contrast, Cullinan says, “This is a very different technique, where we incrementally take the brain apart from the outside in, with a view toward the threedimensional relationships of the fiber pathways to the cell-rich so-called gray matter.” It is in revealing these white-matter pathways and their role in transporting myriad brain signals exactly where they need to go that the technique shines. “The beauty of the blunt technique is that you can expose that.”

A course of this type requires a course leader who is intimately familiar with blunt dissection, a constraint that goes a long way in explaining the technique’s disappearance from medical schools and the few other settings where brain dissection is offered.

“There is a shortage of people classically trained as anatomists and you can understand why,” explains Cullinan. “Nerves and muscles are not being discovered anymore. It’s all been done, with rare exception, and new discoveries are taking place at the cellular and molecular levels.”

In his student days, as his research interests shifted to the microscopic scale along with those of his fellow neuroscientists — toward neurons, synapses and genes — Cullinan had been advised not to overlook the lessons of gross anatomy, which reveal the brain and body structures visible to the human eye. While earning his doctorate at the University of Virginia, he volunteered to serve as lab assistant for the blunt dissection courses taught by Dr. Lennart Heimer, a renowned Swedish-American neuroscientist whose neuroanatomy textbook and videotaped demonstrations were then standard fare at many medical schools. At Heimer’s side, Cullinan got his classical training.

Beyond the question of expertise, there are practical considerations to address in offering blunt dissection on this scale. To stand up to scalpel pressure, soft brain specimens must be specially preserved. Treated with enough (but not too much) fixative, the tissue reaches the delicate consistency of steamed cauliflower.

“We store them in a formaldehyde solution for six months before these dissections begin,” says Cullinan. “And we rinse them like crazy before the course so there are no vapors coming from them.”

And there’s no denying the need for a large number of generous donors providing brain specimens. When he joined Marquette’s biomedical sciences faculty in the mid-1990s, Cullinan had these favorable conditions essentially waiting for him here, though just out of view. By then, Marquette physical therapy professor Dr. Donald Neumann, an anatomical expert in his own right (see story on page 24), had established a popular four-day summer extremities dissection course that continues to this day.

“Hey Don, what becomes of brains in the cadavers used in your course?” Cullinan asked one day. They were cremated along with the rest of the remains, he was told. “I thought it was a tragic wasted opportunity,” he recalls. “So I asked, ‘Would you mind if I used them in a brain dissection course?’ ”

Fast forward nearly two decades, and the brain course, now in its 18th year, is off to a typically fast start. After lunch, students reconvene in the lecture hall where a general game plan for the afternoon’s dissection is provided by none other than Heimer, in video form. Thanks to master tapes retrieved from the vault and converted to DVD, Heimer’s instructions live on: his Swedishinflected expertise matched with pixelated subtitles and other Atari-era production values that never fail to amuse students. Concluding his first demonstration, Heimer turns to the camera and shares timeless advice to those about to pick up their scalpels. “Don’t be too bold,” he chirps melodiously, “but don’t be too shy either.”

Within a few minutes, the course participants are not only in scrubs, aprons and gloves, but are also evenly distributed among 15 dissection tables. Alva is joined by psychologists from Milwaukee and New York City, as well as Dr. Sujay Galen, an assistant clinical professor of physical therapy at Wayne State University in Detroit. Assigned to teach neuroanatomy this year, Galen says, “I figured I could either sit by myself and read a textbook day after day, or I could come here and work in 3D with real brain specimens.”

Not surprisingly, Alva is first to the table for the opening move: removing the dura mater or “tough mother,” the outer covering that resembles a thick, durable cabbage leaf. She confidently peels it back, applying just enough pressure to extricate it from deep crevices without damaging the cortex below. A few minutes later, she and Galen are taking turns at another brain sample — a hemisphere formed by cutting the brain vertically along its midline into left and right halves. They are doing their best to emulate what Cullinan demonstrates from his station, projected on video screens around the room.

Using the handle end of the scalpel to flake off small pieces of gray matter, they strive for the prescribed balance — neither too shy, nor too bold — but aren’t sure they’ve found it. The parts of the brain aren’t color-coded as they are in textbooks, notes Alva. Have they scraped too much or too little to see the first pathways — horizontal associative fibers that relay signals within the cortex? How deep will they find the dramatic up-and-down pathways of the corona radiata? Or closer to the brain’s base and posterior, the flurry of fibers that send signals to and from the brain’s vision center?

Fortunately, a welcome sight arrives in the form of a dissection coach who happens to be a neuroscientist with at least 80 publications to his credit, Dr. Robert Thompson of the University of Michigan. Back in year one, realizing he needed more neuroscience firepower for the course, Cullinan enlisted two colleagues with whom he’d just served as postdoctoral research fellows at the University of Michigan, Thompson and Dr. James Herman, now of the University of Cincinnati. They’ve come every year since, often bringing families, enjoying evening barbecues and generally making a summertime tradition of the course.

Holding the hemisphere in his hands, pointing out surface landmarks and dispensing phrases such as “we’re looking for striations of white matter posterior to the horn of the ventricle,” Thompson soon has confidence growing among the tablemates and white matter pathways emerging in their specimen, striated like string cheese. It helps that he offers advice with enthusiasm and a cheeriness in his eyes that isn’t surprising from a genetic specialist whose work email address is mutant@ his university’s domain. Working another table in the room, Herman brings roughly equivalent levels of authority and affability to the task.

Although Thompson’s research aims for molecularlevel breakthroughs involving the roles of genes in stress response, he explains his commitment to this brain course like this: In understanding the microscopic-level interactions of the brain, there’s no getting around their rootedness within the brain’s intricately connected architecture.

“I figured out pretty early that if you’re going to be in real estate, it’s hard to ignore ‘location, location, location.’ The same principle applies when you’re working with the brain,” he says.

“And really, as an educator, it’s simply wonderful to come back year after year and to teach professionals who may not have had an opportunity to study the brain this way. They have real life experiences, real life stories relating to what they’ve seen in clinical practice. They’re passionate. It’s not that you can’t find students who are like this in other settings, but when an entire group is like this, it’s wonderful.”

Exotic as they may seem, Marquette’s summer brain and extremities dissection courses reflect a commitment to gross anatomy that permeates and helps to define the College of Health Sciences.

The college offers the most popular undergraduate major on campus, biomedical sciences, which typically enrolls between 150 and 175 freshmen per year. During their sophomore year, these students all take an anatomy lecture course taught by Cullinan. Then about two-thirds continue into a comprehensive three-part dissection course. (The remaining third includes students aspiring to join physical therapy or physician assistant programs that offer their own dissection experiences.) And the middle part of that course is blunt dissection of the human brain, the same training that draws summer brain course participants from across the country.

This nearly unprecedented level of undergraduate “gross lab” exposure has surprised some peers in the health sciences through the years. “I think people wondered, ‘How?’ ” says Cullinan. “ ‘How are you getting all these cadavers for undergraduates?’ ” The answer has a lot to do with the kind of resourcefulness that helped launch the brain course 18 years ago. The dissections that the college leads for Marquette’s 400-plus dental students concentrate on the head, neck, and upper thorax. Neumann’s course only involves the extremities. Put together what’s untouched in both settings, including brains, and you have the basis for full-scale dissection course for undergraduates.

It’s an outstanding foundation for a biomedical sciences curriculum whose focus grows progressively more microscopic over four years, say faculty members. And it’s even been an engine of the college’s enrollment growth. Many undergraduates who have completed the dissection course become lab assistants the following year.

“We get a lot of high school students interested in touring the gross anatomy lab,” explains Cullinan. “They hear our undergraduate teaching assistants speaking with such authority about the human body, and want to come here and become those teaching assistants. It’s remarkable.”

Realizing the invaluable debt that the college and its students owe those who donate their bodies for anatomical study, college faculty members are committed to honoring the gift. Although the mood in the gross lab can be lighter than expected for the uninitiated, it is never so at the expense of cadavers. Personal photography is strictly prohibited. And students carefully keep any tissue removed from each donor in individual receptacles to be cremated with the rest of the body and returned to families as ashes.

“For these donors, their time here is a temporary stopover between death and cremation,” he says to the summer course participants, “We always try to remember that in the way we treat specimens in the lab.” Given the range of anatomy experience participants bring to the summer brain course, often rather light among the core audience of psychologists, Cullinan aims for a moderate level of detail and difficulty.

“We have to pitch it down the middle, so we don’t bore people or blow people away.” Nevertheless, a widely shared perception among participants is that the course’s knowledge spigot is open pretty wide from the start. “Someone next to me said she studied for a week and all of that material was covered in the first 10 minutes of the first lecture,” reports Galen.

“I realize I have so much more to know,” relates Alva. “But sometimes those wake-up calls are a good thing.”

Karina Powell, a doctoral student in the Illinois Institute of Technology’s joint program in clinical and rehabilitation psychology, registered for the course after multiple colleagues described it as “awesome.” She has found its scope awesome as well. At a casual reception following the first afternoon’s dissection, she and a few coursemates had an opportunity to engage in a long conversation with Thompson and Herman. “When did you feel that you really had this stuff down?” she pressed Thompson at one point.

“His answer was fantastic,” she relates. “He said, ‘I educated myself here, taught it from clinical perspective there and did research somewhere else, and somewhere along the way it all solidified.’ ”

Although still feeling humbled by what’s been revealed to them in the last 54 hours, by Saturday’s final dissection, Powell and fellow participants seem noticeably more proficient as they clear away tissue and point out once-obscure landmarks such as the pons, cerebellar peduncle and dentate nucleus. In other words, they resemble the teaching assistants who make such strong impressions on prospective students touring the lab.

How has the course compared to her expectations, Powell is asked.

“Oh my goodness, it has way exceeded them,” she says. “This has been one of the most enjoyable educational experiences I’ve had in my entire life, hands down. I’m pretty sure I have to do this again next year.”



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