Reviewed by: Liberty Hamilton, PhD
Written by: Ashley Lawrence
Several areas of the brain must function together in order to process speech and language. During the process of hearing, vibrations are converted into frequency (pitch) and timing cues that are processed by different levels of your auditory system and transformed into phonemes, syllables, and words to interpret the meaning of what is actually being said. The brain is also able recognize when sentences and phrases start and stop and has the ability to filter out and ignore irrelevant background sounds.
But how does the brain accomplish this, what changes occur during development that aid in this process, and can this information help improve outcomes for children who undergo surgery that may affect areas of the brain that play a vital role in processing speech and language? These are the questions being asked by Liberty Hamilton, PhD, an assistant professor in both the Moody College of Communication Department of Speech, Language, and Hearing Sciences and the Dell Medical School Department of Neurology at The University of Texas at Austin.
“Broadly, my research focuses on how the brain processes speech and language when we listen, talk, and read,” explains Dr. Hamilton. “More specifically, my research involves two main lines of work. First, is my patient-centered work in which I am working with epilepsy patients at Dell Children’s Medical Center to understand how the brain changes during childhood and adolescence to help us parse sounds into meaningful language. Second, is my community-based research in which I am working with adults in the Austin community to understand how different sounds are turned into meaningful speech.”
Led by Dr. Hamilton, the Hamilton Lab, which is a part of the NeuroComms Labs within the Moody College of Communication and jointly affiliated with the Dell Medical School, aims to determine how natural sounds, including speech, are represented by the human brain as well as how those representations change during development. To accomplish this, Dr. Hamilton is studying how the human brain processes speech sounds by using intracranial electrocorticography (ECoG) recordings from patients with intractable epilepsy (a severe form of epilepsy that is not easily managed with medicines) who are undergoing surgery to treat their epilepsy.
“I completed a post-doctoral fellowship at the University of California, San Francisco with Dr. Edward Chang, a neurosurgeon and researcher, who also looks at speech and language in epilepsy patients,” shares Dr. Hamilton. “When I arrived at UT here in Austin, I really wanted to continue the patient-centered work that I’d done with Dr. Chang. I was lucky enough to meet Dr. Dave Clarke at Dell Children’s Medical Center. Dr. Clarke was also interested in bringing this type of research to Dell Children’s. Over the last several years, we’ve been building up the program.”
UT Health Austin board-certified pediatric epileptologist Dave Clarke, MD, serves as the Chief of the Comprehensive Pediatric Epilepsy Center within UT Health Austin Pediatric Neurosciences at Dell Children’s, a clinical partnership between UT Health Austin and Dell Children’s Medical Center. He specializes in the medical, dietary, and surgical management of pharmacoresistant epilepsy in children from birth through adulthood. He is also a professor in both the Dell Medical School Department of Neurology and the Dell Medical School Department of Pediatrics.
“I’m also excited that I get to work with people like Dr. Elizabeth Tyler-Kabara, who has experience with motor imagery-based brain-computer interfaces,” reveals Dr. Hamilton.
UT Health Austin board-certified pediatric neurosurgeon Elizabeth Tyler-Kabara, MD, PhD, serves as both the Chief of Pediatric Neurosurgery and the Co-Chief of Pediatric Neuroscience in the Pediatric Neurosurgery Clinic within UT Health Austin Pediatric Neurosciences at Dell Children’s. She specializes in functional neurosurgery and minimally invasive skull base surgery and pioneered the use of expanded endonasal surgery of the skull base in extremely young children, providing them with a minimally invasive alternative for the treatment of a variety of conditions. She is also an associate professor in the Dell Medical School Department of Neurosurgery.
“This work is a team effort in every sense,” shares Dr. Hamilton. “Other important members of the team include late pediatric neurosurgeon Dr. Tim George, epileptologists Dr. Aaron Cardon and Dr. Karen Skjei, neuropsychologist Dr. Nancy Nussbaum, and the Comprehensive Pediatric Epilepsy Center’s Program Manager Teresa Ontiveros and RN Coordinator Cassidy Wink. Our Texas Children’s collaborators include pediatric neurosurgeon Dr. Howard Weiner and pediatric epileptologist Dr. Anne Anderson.”
Dr. Hamilton recently received funding from the National Institutes of Health (NIH) and the National Institute on Deafness and Other Communication Disorders (NIDCD) to research how the organization of the brain’s speech areas changes throughout development in participants ages 4 to 18. When patients with intractable epilepsy are admitted for surgical treatment of their seizures, they are asked if they would like to participate in research tasks, which include listening to sounds or watching short movie clips, reading sentences aloud, and listening to speech in the presence of background noise.
“By recording brain signals from intracranial electrodes in the temporal lobe, frontal lobe, and insular cortex while patients perform these tasks, we can see millisecond-level changes in how sounds are processed in the brain,” explains Dr. Hamilton. “For patients who are being monitored for seizures for days at a time, these tasks can be carried out from their hospital bed, and for many patients, can be a fun way to pass the time during an in-patient stay.”
Patients who are undergoing surgery for epilepsy and are interested in contributing to speech and language research by becoming involved in this study can visit here for more information.
“I truly am so grateful for all the clinicians, patients, and families who choose to participate in this research,” says Dr. Hamilton. “While there are non-invasive methods, such as studies involving MRI and EEG, the level of detail that comes from intracranial recordings is unprecedented and being able to understand that comprehensive map of sound, particularly those sounds that make up speech and language, across the entire brain can improve outcomes for people who have to have brain surgery as well as targeted treatments and therapies. Our participants are helping to advance knowledge as well as inform future care, and the work we’re doing wouldn’t be possible without their generosity.”
If you are a patient or clinician interested in learning more about the research conducted at the Hamilton Lab, visit here.
If you are interested in scheduling an appointment with the Comprehensive Pediatric Epilepsy Center, call 1-512-628-1855 or visit here.