100-YEAR-OLD BRAIN MYSTERY: WHAT DOES THE TEMPORAL POLE DO?

Featuring: Marsel Mesulam, MD

A colorful, vital function of this human brain region revealed
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Every part of the brain surface (the cerebral cortex) has a specific job description. Some areas move the arms, others the legs, still others make it possible to see or speak.  

But one part of the brain surface, a region called the temporal pole because it is at the very tip of the temporal lobe, could not be linked to a specific function for at least the first 100 years of research on the cortex, according to a recent study published in Annals of Neurology.

Northwestern Medicine scientists have just discovered that this mysterious and seemingly silent surface is actually one of the most colorful regions of the brain. It has critical functions in word comprehension, face recognition and the regulation of behavior.

The scientists were able to identify this region’s previously unknown function through the investigation of 28 patients with a unique disease, known as TDP-C, that ultimately destroys the temporal pole. The cases reviewed post-mortem offer the most precise delineation of the brain areas that are first hit in a disease that progresses over 10 to 15 years.
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“Research on this disease helps us understand how the brain decodes the meaning of words, the feelings of others and the identity of faces,” said study corresponding author Marsel Mesulam, MD, chief of Behavioral Neurology in the Ken and Ruth Davee Department of Neurology and a Northwestern Medicine neurologist. “This knowledge will help to determine the nature of the disease and the nature of brain networks that are responsible for word comprehension, person identification and the monitoring of interpersonal conduct.”

Now Northwestern investigators are studying the relationship between the temporal pole and these complex functions, and the nature of the relationships between TDP-C and the temporal pole.

“Answering these questions is key for helping patients with this condition,” said Mesulam, also the Ruth Dunbar Davee Professor of Neuroscience and founder of the Mesulam Center for Cognitive Neurology and Alzheimer’s Disease. “The next steps in the research are to identify the unique properties of the areas targeted by TDP-C, determine how the disease progresses and find out if there are patient-specific risk factors.” 

The patients with TDP-C had been followed longitudinally at the Mesulam Center. The longitudinal data on brain function was linked to the tissue damage seen by examination with the microscope after autopsy.
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Other Northwestern authors include Emily Rogalski, PhD, the Ann Adelmann Perkins and John S. Perkins Professor of Alzheimer’s Disease Prevention in the Department of Psychiatry and Behavioral Sciences; Tamar Gefen, PhD, assistant professor of Psychiatry and Behavioral Sciences;  Margaret Flanagan, MD; Rudolph Castellani, MD, professor of Pathology; Pouya Jamshidi, MD; Elena Barbieri, PhD; Jaiashre Sridhar, MS; Allegra Kawles; Sandra Weintraub, PhD, professor of Psychiatry and Behavioral Sciences; and Changiz Geula, PhD, research professor in the Mesulam Center for Cognitive Neurology and Alzheimer’s Disease.
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​This article was originally published in the Feinberg School of Medicine News Center on July 13, 2023. 
Marsel Mesulam, MD, chief of Behavioral Neurology in the Ken and Ruth Davee Department of Neurology and a Northwestern Medicine neurologist.

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