We have a three-pound mass lying between our ears, firing away at the speed of light. As so many unanswered questions remain on the function of the brain, some scientists are turning to their patients for answers.

In the Neuroscience Interdisciplinary Graduate Program, one way researchers study the brain is by examining what goes wrong when a person suffers damage to a certain region of the brain. This is done with the help of the world-renowned Iowa Neurological Patient Registry — a collection of 525 active members with damage to a specific brain region.

By studying these unique patients, graduate students and faculty members have made many groundbreaking discoveries. Recently, they showed that the amygdala is the fear sensor in the human brain — a finding that could improve treatment of Post-Traumatic Stress Disorder (PTSD) and other anxiety conditions through psychotherapy and medications.

“This finding points us to a specific brain area that might underlie PTSD,” said Daniel Tranel, UI professor of neurology and psychology and director of the Neuroscience Program. “Psychotherapy and medications are the current treatment options for PTSD and could be refined and further developed with the aim of targeting the amygdala.”

One patient in the registry is Tara Fall, an Iowa native who suffered a stroke at age 27. The stroke damaged her right fusiform face area, resulting in prosopagnosia or face blindness — meaning she is unable to recognize other humans by their faces, despite having good eyesight.

While face blindness makes life more complicated, Tara has adapted. Even though she can’t recognize her friends and family members by their faces, she picks up on other clues to recognize them — like their voices, or the way they walk. By studying Tara, Iowa researchers learn about the amazing amount of compensation that’s possible after a brain injury, and about the resilience of the human spirit.

Fall shared her inspirational story with NBC Chief Medical Editor Nancy Snyderman on the Today show May 4. Justin Feinstein, a UI graduate student studying clinical neuropsychology, also was featured in the story. He conducted an experiment for Snyderman to illustrate the nature of Fall's deficit.

“I think the patient registry is just immensely important. Through the patients who volunteered themselves in the past I’m to the stage where I am now,” Fall said. “It makes me excited to think in another 30 or 40 years, with information I’m giving and all the other wonderful patients who are on the patient registry, where will we be?”

Like Fall, many patients choose to participate in the registry to advance scientific knowledge and impact the lives of others. Patients are recruited to join the registry during their medical appointments at UI Hospitals and Clinics. Most participants live in Iowa.

The registry drew Feinstein from California to Iowa to study clinical neuropsychology at the UI. His research with registry patients has attracted international interest and may impact the lives of people with neurological conditions like Alzheimer’s disease.

“All the patients are extremely excited to help out. It’s a great cause, because it gives them sort of a bright side to a very negative state of affairs,” Feinstein said. “You could imagine if you have a serious brain injury of some sort you would want to do something to contribute, something to give back, so maybe we could learn how to prevent this in the future.”

The Iowa Neurological Patient Registry was started in 1982 by Tranel and former UI neurology professors Antonio and Hanna Damasio.

Tranel has spent the last three decades studying patients in this one-of-a-kind registry, which is funded by the National Institutes of Health.

“I don’t think we’ve ever flown around the world to prove this, but to the best of our knowledge it’s probably the best patient registry of its kind in existence,” Tranel said. “It’s really provided a unique resource to study neurological problems and neurological diseases and to really give us some strategies to conduct research that hopefully will identify cures and preventions for neurological diseases.”

Feinstein, who works with Tranel, conducted memory and emotion research that offers good news for caregivers of individuals with Alzheimer’s disease.

Studying five registry members with a type of amnesia shared by early-stage Alzheimer’s patients, he concluded that while people with memory loss might forget a joke or a meaningful conversation, the happy feelings associated with the experience can stick around and boost their mood.

“Even though their memories aren’t there, their emotions are existing and they’re lasting well beyond the memory,” Feinstein said. “It does make a difference whether you visit people with Alzheimer’s disease.”

Currently, there is no cure for Alzheimer’s disease, which is expected to affect as many as 100 million people worldwide by 2050.

This health concern illustrates the importance of contributions from registry members who provide researchers a window into how the brain works.