How do Neurologists and Neurosurgeons study the brain?
There are many functional systems in our brain, and thus there are many methods used to understand how love works in the brain.
No single method can study everything we need to know about the brain in love, so we typically use multiple methods, each one telling us a different aspect of our brain function.
Nonmedical authors have published studies purely based on functional MRI. They proclaim that increased activity in brain regions involved in processing reward, motivation, and emotion when lovers view photographs of their partners are evidence for brain changes of love. I disagree. I have discussed in a previous blogs whether functional MRI is based on solid science or not. I believe that these fMRI studies are based on questionable science.
Here are some of the diverse methods Neurologists and Neurosurgeons normally use to study brain function and how each study method can tell us about one aspect of brain functions. This are the real world technologies used today by specialists in the field of brain science, neurologists and neurosurgeons.
Autopsies on humans and animals
This is a time-honored method that started millennia ago. Further examination of brain structures evolved as more precise technologies developed. We can now see minor cell details under the electron microscope. Various staining techniques help identify certain structures by staining them with certain-colored dyes. Comparing structures in health and disease, we can understand how diseases affect us.
Experiments on living animals
Animal studies have contributed a tremendous amount of knowledge about our biology, as well as the biology of love. To the surprise of many people, we share about 90 percent of our genetic code with some animals. Via the study of animal behaviors, we can record the chemicals associated with different behaviors. We can block or increase (stimulate) the effect of certain chemicals and see the behavioral effect on animals. We can insert tiny tubes to measure chemicals in the brain, and so on. A good part of our knowledge came from animal studies. I know that many of us feel squeamish about it, but it is a necessary evil.
Our behaviors are based on the effects of multiple brain chemicals, or neurotransmitters. We can give medication or pharmaceutical agents to enhance or block these neurotransmitters and see the effect on behaviors. A very significant amount of knowledge in humans was acquired by this method.
When a neurology student starts his neurology training, he is told “you will learn your neurology stroke by stroke”. That is to say, neurologists learn the brain structure and function by watching the real changes in real humans suffering from strokes. Each stroke will damage a certain location in the brain and the loss of function in the patient shows the function and purpose of this particular location of the brain. The field of neurology is mostly based on these clinical observations. Brain tumors also damage certain locations and cause similar change in human functions. The other side of the coin, stimulation of one location in the brains shows the function of this location. An example, a patient has a seizure focus in the left frontal area. When the seizure stimulates the brain, the right side of body will shake (have a focal seizure). This proves that this area has to do with movement. The same can be used to understand what areas of the brain do for emotions such as love and can be used to prove or disprove that certain locations have nothing to do with love, such as the ventral tegmental area.
These are electric studies of the brain. They include EEGs and MEGs, as defined below.
EEG (Electro-encephalo-gram): EEG measures electric changes between two points on the brain surface. The EEG is used to study the electricity of the brain.
MEG (Magneto-encephalo-graphy): Any electrical current in the brain will produce a magnetic field, and it’s this field that is measured by the magnet used in MEG.
Combining both EEG & MEG gives a better image of the electrical changes in the brain.
Brain mapping is the science of generating visual images of the brain structures. This is a partial list as the options keep expanding.
CAT Scan: (Computerized Axial Tomography or CT Scan): The CAT scan, used since 1972, uses X-rays and a computer program to generate 3-D images of the brain. Because X-rays don’t penetrate bone well, the thick human skull makes the base of the brain hard to see. MRI shows the brain better because it can’t see bone well.
Perfusion CT: This CT measures the blood flow in the brain. It is commonly used to look at the blood flow during acute strokes.
MRI: (Magnetic Resonance Imaging): This technique uses a magnetic field, radio waves, and an electric-field gradient to generate 3-D images of the brain. The MRI, discovered in 1977, is of tremendous value in studying the structure of the brain because we can see fairly detailed images of the brain’s superficial and deep structures. MRI is now the gold standard in seeing the brain’s internal structures.
Subtypes if MRIs
- Diffusion MRI: The diffusion-weighted MRI measures the motion of water molecules in tissues. It’s the earliest way to see acute brain injury, such as a stroke.
- FLAIR MRI (Fluid Attenuation Inversion Recovery): This technology allows better visualization of deep structures near the brain’s center.
- Susceptibility MRI or SWI (susceptibility weighted imaging): This image uses the local magnetic field by measuring the movement of magnetically charged particles. It is useful in detecting blood products, calcium, iron, etc. This is the modality used to generate fMRI images.
- MRS (Magnetic Resonance Spectroscopy): This variant of MRI that selects a small area of the brain, then measures the levels of metabolic products in this small area. MRS is used to estimate the metabolic activity in this small area of the brain, often times a section of dead tissue from a silent stroke or a tumor.
- fMRI (Functional MRI): Invented in 1990 at Bell Labs, this is a traditional MRI with overlapping colored susceptibility MRI images, presumably from changes in oxygenation at a specific location. It does not measure neuronal activity and it can’t measure very fast events in the brain. The fMRI has never given us answers about love, in my opinion. It tends to generate false positive results in over 70% of the images, per a study published by the National Academy of Science.
- DBS (Deep Brain Stimulation): This neurosurgical procedure, invented in 1987, is done awake or under anesthesia, by inserting tiny wires into specific location(s) deep in the brain. The other end of the wire is connected to a stimulator, such as a pacemaker, to interfere in cell activity electrically. This procedure has been of tremendous value in understanding the deep structures of the brain and is also of great therapeutic value in many brain disorders.
- DTI or DTMRI (Diffusion Tensor Imaging): This technology, started in 1993, captures images of the electric cables running across different areas of the brain. This test has been of tremendous value for neurosurgeons in planning surgery on the brain; it gives them an individualized picture of these cables so they don’t accidentally injure them during surgery, making neurosurgery much safer.
- DaT (Dopamine Transporter scan): Approved by the FDA in 2011, this is the best way that we have today to see dopamine in the brain. The DaT scan uses a radioactive substance that generates images of the dopamine transporter protein. This shows us the number of dopamine cells in the brain.
- MRA (Magnetic Resonance Angiogram): This is a non-invasive way to see the blood vessels inside the brain while awake. We can see the blood flow in the vessels as well. We can find a clogged artery with this noninvasive technology.
While there are many more technologies available to study the brain, you’ve seen enough to conclude that there is an expansive array of technologies to study brain structure and brain function. There is no single “magical method” to study all aspects of the brain or all the emotions and chemicals involved in love.
Fred Nour, M.D.