MUSC neuropsychologist part of study finding new brain cells help with verbal learning

A neuropsychologist at the Medical University of South Carolina is a senior author with a team of researchers that has linked the importance of new brain cells, or neurons, with verbal memory and intellectual functioning. These cells help us learn and remember what we hear in conversation and everyday life, such as hearing the news.

The fact that they were able to show that adults were generating new neurons at all was newsworthy, said Jason Smith, Ph.D. “It's been controversial that adult human brains could actually produce stem cells, which can turn into various different kinds of cells. And for a long time that was thought not to be the case,” the assistant professor at MUSC said.

“But there is neurogenesis, new neurons created in the hippocampus, a particular section of the brain that's associated with memory and learning - and which is also involved very closely with temporal lobe epilepsy,” Smith said. “We've demonstrated that neurogenesis happens and that it is closely related to our thinking, learning and memory.”

They found that evidence by looking at brain tissue from people with mesial temporal lobe epilepsy, a condition that not only causes seizures but also leads to cognitive decline. The patients involved were scheduled to have surgery to treat their seizures. 

Neuropsychologists, including Smith, assessed the patients’ cognitive abilities before surgery. His colleagues at the University of Southern California, Michael Bonaguidi, Aswathy Ammothumkandy and Luis Corona, then studied the tissue collected during the surgery to look for neuronal changes. 

The researchers found that evidence of fewer new neurons was linked to a greater cognitive decline of verbal learning and memory. Conversely, newer, immature brain cells appear to support better learning and memory. That’s important, Smith said, because cognitive decline is a big problem - not only for people with epilepsy but also people with other neurodegenerative conditions. “Cognitive impairments very much affect quality of life. Patients ask, ‘Can I work? Can I drive?’ Every facet of life we can think of it is affected. The whole human.”

Smith said having this new understanding opens up possibilities for investigating potential therapies at the neuronal level, such as how exercise/behavioral neuromodulation and pharmacotherapy might promote neurogenesis and thereby further promote cognition. “It may ultimately help us treat the functional independence of people with epilepsy, and hopefully beyond.”

As a rehabilitation psychologist and neuropsychologist, he called that possibility exciting. “This study provides further evidence to push for more translational and reverse translational research, i.e., where clinical observations and basic sciences converge and inform one another to move medicine and the clinical neurosciences forward," Smith said.

“This study is incredibly valuable as it presents a model for studying the impact of neurotherapeutic interventions with humans, as part of the investigation aligns with the treatment needs of the patients who may require brain surgery to eliminate their seizure burden. Furthermore, this study elucidates the relationship of the progressive nature of intractable epilepsy and its effect on verbal learning and memory, visuospatial functioning and broader intellectual functioning.”

Smith made a key contribution to the study through his rehabilitation work with people suffering from epilepsy at Rancho Los Amigos National Rehabilitation Center in Los Angeles, where he lived before moving to the Charleston area. He saw the value of this clinical data and how it could be used in this unique line research. It paid off in the new study. 

Smith said his work on that science is a good fit for his new role with the MUSC Institute for Neuroscience Discover, or MIND. “This is a neurological discovery, and coming from the neurorehabilitation world, this is the kind of thing that I believe pushes the field forward directly to improve people's quality of life.”

This research was completed with Smith’s co-senior authors Bonaguidi and Charles Liu, both of the University of Southern California and its Neurorestoration Center, where Smith is also a research associate. Additional authors include Kristine Ravina, Victoria Wolseley, Jeremy Nelson, Nadiya Atai, Aidin Abedi, Lina D’Orazio, Alisha Cayce, Carol McClearly, George Nune, Laura Kalayjian, Darrin Lee, Brian Lee, Christianne Heck, Robert Chow, and Jonathan Russin from USC; Nora Jimenez from Los Angeles General Medical Center; Michelle Armacost from USC and Rancho Los Amigos National Rehabilitation Center; and Virginia Zuverza-Chavarria from Rancho Los Amigos National Rehabilitation Center.