Distinguished Postdoctoral Fellows Map Language in the Brain

Carnegie Mellon University’s Neuroscience Institute (NI) aims to attract diverse, world-class talent and create an unmatched collaborative community. Its Distinguished Postdoctoral Fellowship Program is one way it achieves this goal.

Supported by The Dietrich Foundation, this postdoctoral fellowship annually invites early career applicants to collaborate with university-wide faculty working on brain research. The NI’s two newest Distinguished Postdoctoral Fellows are Julien Dirani and Chiara Repetti-Ludlow.

Meet Julien Dirani

Before joining CMU, Dirani traveled around the world for opportunities to study the brain. “Wherever the opportunity took me, I went,” he said.

Dirani earned his bachelor’s in psychology with a minor in philosophy from the American University of Beirut, Lebanon. Wanting to learn more about the neural bases of human behavior, Dirani received his master’s degree in cognitive neuroscience from University College London, England. There, he learned about experimental techniques such as transcranial magnetic stimulation, a non-invasive tool clinically used to treat depression and other mental health conditions, but also used in research to study language and semantic processing in the brain.

Shortly after, Dirani worked as a research scientist at New York University (NYU) Abu Dhabi in Liina Pylkkänen’s lab studying how language processes unfold in the brain with the utilization of imaging techniques such as magnetoencephalography (MEG). Fascinated by the research, Dirani continued his work and earned his Ph.D. in cognition and perception from NYU New York.

He joined the NI’s Distinguished Postdoctoral Fellowship Program last fall under the mentorship of Brad Mahon, associate professor of psychology, and Leila Wehbe, associate professor of machine learning. Dirani primarily investigates the neural basis of language including how areas of the brain store, access and maintain semantics during specific tasks and across various sensory modalities.

“Compared to a huge amount of work in machine vision and its application to object recognition, relatively less research uses modern computational approaches to test how object-directed actions are coded in the brain,” said Mahon. “Julien's work promises to open up new directions in understanding how everyday abilities and activities are implemented in the brain.”

Dirani recognizes this postdoctoral program is unlike many others because it requires collaborative links among NI faculty, teaching fellows to approach modern problems in neuroscience through interdisciplinary teamwork.

“Brad works on brain imaging and neuropsychology, and Leila’s expertise is in computational methods applied to neuroscience questions; I get to learn and work at the intersection of these disciplines,” he said. “This program is great because I’m encouraged to bring an idea and the people together to accomplish it.”

From this collaboration and the scope of his project, Dirani is excited to also work with Jorge González-Martínez, Stuart Nile Rowe Professor and director of the Cortical Systems Laboratory at the University of Pittsburgh. His lab aims to develop safer and more efficient methods for treating patients with epilepsy and other abnormal movement disorders. As a collaborator, Dirani utilizes MEG to develop pre surgical language mapping tasks.

“Ultimately, the clinical, computational and neuropsychological training I will receive through this program will make me a better researcher,” said Dirani. “I’m happy to see these projects bridge many disciplines and am excited to learn from each of them.”

Meet Chiara Repetti-Ludlow

Looking to conjugate her love of Latin and language learning, Repetti-Ludlow received her bachelor’s degree from Brown University with a double major in classics and linguistics. There, she completed her thesis investigating how language evolved from Latin to the modern Romance languages.

Having studied a number of languages, Repetti-Ludlow wanted to address important questions related to speech processes. This motivated her to obtain her Ph.D. in linguistics from NYU New York where she analyzed the acoustic cues of understudied languages to determine how we recognize language-specific sounds. She also worked on projects utilizing transcranial direct current stimulation with the goal of helping aphasia patients regain motor speech abilities following stroke.  

“The aphasia project gave me a great introduction into the neuroscience field, which offers really interesting and useful tools with broader clinical applications,” said Repetti-Ludlow. “But there seems to be a gap in the literature where great phonetic and phonological theories lack a neuroscientific backing.”

To bridge this gap, Repetti-Ludlow joined the Distinguished Postdoctoral Fellowship Program last fall under the mentorship of Barbara Shinn-Cunningham, Glen de Vries Dean of the Mellon College of Science, and Christina Bjorndahl, assistant teaching professor in the Department of Philosophy.

Her project examines how multiple acoustic cues (i.e. pitch, duration, etc.) contribute to the perception of different speech sounds using electroencephalography (EEG).

“The theoretical motivations for Chiara’s research question are linguistic and psychological, while the methods are those of neuroscience,” said Bjorndahl. “Given the centrality of this question in linguistic research, I have no doubt this work will generate a lot of enthusiasm and interest.”

Repetti-Ludlow values the balance this program offers between developing independent skills and collaborating. “People at CMU are excited to do collaborations,” she said. “And at the same time, I have the opportunity to develop a project of my own, which is very rewarding.”

“Chiara shows an interdisciplinary disposition that is weaving together substantive and productive conversations that draw on our distinct fields of research,” said Bjorndahl. “Her research is a perfect example of what the NI postdoctoral fellowship is designed to do in terms of bringing faculty together from different disciplines.”