It used to be that if you wanted to locate an address, you bought a map. Or perhaps you belonged to a travel club that would draw the route to your destination in a paperback road atlas with a marker. Then along came computers and smartphones. Now you can really home in on the place you want to find—even to the point of seeing a picture of your destination.
Similarly, we’ve come a long way in mapping the geography of the brain. And we can be grateful for the work of neurosurgeons like Dr. Guy McKhann from the Center for Movement Disorders at Columbia University Medical Center/NewYork-Presbyterian Hospital. Dr. McKhann is a leader in the field of brain mapping—determining what areas in the brain perform which functions.
His considerable skill in this field proved useful in a research study of seizure patients recently published in the journal Epilepsy & Behavior. A seizure is a result of abnormal electrical activity in the brain. Most familiar are the seizures that involve abnormal, jerking muscle movements.
Dr. McKhann and his colleagues* studied an area of the brain called the temporal lobe. The temporal lobe, which is located in the lower front part of the brain near the temples and ears, often produces a very different type of seizure. Patients can experience abnormal smells, sounds or tastes that aren’t really present, or even a feeling of deja vu (feeling that a new experience is one you’ve had before).
Although many people with temporal lobe seizures improve with medicine alone, those who don’t may respond well to surgery. Removing parts of the temporal lobe can in fact end the seizures in some cases.
However, the temporal lobe performs many useful functions. Several are related to speech and language: it receives the signals (words and sounds) heard initially by the ear, lets us remember them, and allows us to call them up again and say them. So the surgeon is faced with the issue of how to remove the abnormal areas—the ones causing the seizure—without sacrificing the patient’s ability to speak.
That’s where Dr. McKhann’s research and skill in brain mapping come in. Using electrical stimulation, he was able to momentarily “disable” certain areas of patients’ temporal lobes while measuring the patient’s ability to use language. The researchers focused on two types of language skills: semantic (the ability to recall word meanings) and phonologic (the ability to recall the sounds present in a word).
Just as mapmakers might have to spend time exploring an area to learn the roads and landmarks, the authors collected extensive data and were able to map which parts of the temporal lobe appeared to be most important for these two language skills.
Other nearby areas in the temporal lobe appeared to be less important for speech. These areas, the researchers reasoned, could be more safely removed without the risk of affecting speech.
The mapping of less-charted territory in the brain done by Dr. McKhann and his colleagues will aid doctors in their quest for the best possible outcome: successful surgical treatment of temporal lobe seizures while preserving language skills.
Learn more about the Center for Movement Disorders here.
*Full list of authors: Marla J. Hamberger, Michele Miozzo, Catherine A. Schevon, Chris Morrison, Chad Carlson, Ashesh D. Mehta, Gad E. Klein, Guy M. McKhann II and Alicia C. Williams
Image credit: ©geralt/pixabay
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