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In medical school Alex Golby had planned to be a neurologist. "I was really interested in how the brain makes the mind," she explains. But then she rotated through neurosurgery. The patient was a singer with a vascular lesion (a blood vessel malformation) in her language cortex. In the hopes of leaving it intact, the doctor was monitoring her language function during surgery, so the patient was awake. "I was a young, very impressionable medical student, and here was this lady practicing her singing from underneath the drapes—and we were staring at her brain," Golby recalls. Although it meant extra years of residency, that's when she decided that neurosurgery was for her.

Direct contact with the living human brain

Now Golby is doing the work she dreamed of: caring for patients and running the Surgical Brain Mapping Laboratory. Her clinical work focuses on patients with lesions in the eloquent cortex, which she defines as "brain that you can't take out without causing a big problem." It turns out that much of the brain can be operated on with very little consequence, but a few areas are definite exceptions. "If you take out part of the motor cortex, the patient will probably be paralyzed for life," says Golby. The language cortex is equally unforgiving. One of the underlying questions that drives her research, she says, "is why are these two regions so much less plastic in response to surgery?"

Looking into the eloquent brain

Golby's lab investigates various mapping techniques that provide information before and during neurosurgical procedures, a field that's seen vast innovation over the last 20 years. The CAT scan, the first breakthrough, produces cross-sectional images of the brain. The next, huge step was the MRI scan, "which shows the differentiation of tissue, so you can look inside the head and see the whole brain in three planes," she explains. "It's funny, because patients are always asking what I found in surgery, and 90 percent of the time the information is less useful than what I learned from the imaging, because it's so good."

It's now increasingly common for neurosurgeons to use image-guided surgery. An MRI scan of the surgical patient's brain appears on a computer screen; the image on the screen is then positioned to match the position of the patient on the operating table. "It works like GPS [global positioning systems]," says Golby. "I can point anywhere and see where that spot is on the MRI scan on the screen in three dimensions. It's useful because the head is round and the brain is very homogenous, so it's actually quite hard to know where you are."

CAT scans and MRIs yield structural data, while an fMRI produces functional data: information about what parts of the brain are active during a particular task. Golby's lab is now working on integrating these data onto a patient's structural data for use during surgery. Just because a region of the brain is participating in a task doesn't mean it's critical, which is why surgical decisions are usually based on the sum total of different types of data.

Golby also uses a technique called Intracranial Electrical Stimulation Testing, which uses electricity to map brain function while the patient is awake under local anesthesia. The surgeon manipulates a little probe that runs a very mild current between two electrodes, interrupting normal neural activity. When operating on a patient with a tumor in his language area, for example, Golby might have him talk while moving the probe. "When we're over his critical language areas, he would either stop talking, or start slurring his speech, or have trouble finding words," she explains.

Research that comes full circle

Golby refers to the other part of her research as "sort of the flip side: being more of a neuroscientist and trying to understand how the brain does functions like language." Since the mapping yields information from the living brain, her research is almost circular: the information is applied to improve patients' surgical outcomes, while the unique window of surgery yields new knowledge about how the brain works. "A lot of really smart people have worked on it for centuries, and what we don't know still far outweighs what we know," says the doctor. "The human brain is the ultimate mystery."

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IMAGING EXPLAINED

Images of the brain of a 29-year-old man who came to Dr. Golby with a malignant tumor in his left temporal lobe, a key language area.

A 3-D rendering of the surface of his brain, with his ear showing in the upper left corner and his nose cut off by the upper edge.

The yellow crosshairs show where the surgeon is.
The pale area is the scalp.
The tumor is the brighter spot near his ear.
The blue spots are from his functional MRI and show brain activity.
The colored spheres show places that were being stimulated or recorded from during surgery.
The red ones indicate areas where the patient had language difficulty.
the green ones indicate where he did not.

Some information is being added in real-time to structural data obtained earlier. The objective is to obtain the best possible picture of the precise boundaries of the tumor in relation to the surrounding brain, in order to assess which areas are untouchable and which are not.

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