Scientist Finds Distinct Way To Map Maturing Memories

A developmental cognitive neuroscientist at The University of Texas at Dallas' Center for Vital Longevity is exploring an unconventional opportunity to gather high-precision data about the brain in an effort to understand how the ability to retain information improves from childhood to adulthood.

Dr. Noa Ofen, professor of psychology in the School of Behavioral and Brain Sciences, is the recipient of a grant from the National Institute of Mental Health, a component of the National Institutes of Health, to continue her work examining the development of memory networks in children. The grant will bring approximately $2.4 million to UT Dallas.

Her project involves gathering data from intracranial electroencephalography (iEEG) via electrodes implanted in the brains of epilepsy patients undergoing brain mapping as part of clinical care procedures.

Her goal is to provide an unprecedented level of detail about the neural underpinnings of memory, an ability that is fundamental to everyday life.

"This work has the potential to open new dimensions in understanding brain development with more localized, temporally precise measures than ever before."

Dr. Noa Ofen, professor of psychology in the School of Behavioral and Brain Sciences

"Memory is critical for one's self-identity and for making everyday decisions, such as where you need to go next. Ultimately, it is a linchpin of most cognitive abilities," said Ofen, principal investigator in the Cognitive and Brain Development Lab. "We see, recognize and hold our attention to what's relevant so we can come back to it in our mind and use it to guide the way we see and act in the world."

A person's ability to remember and recall improves greatly throughout childhood, but the neurophysiological mechanisms behind this trajectory are not well understood.

"Memory retrieval relies on precisely timed dynamic interactions between brain regions," Ofen said. "Noninvasive techniques such as functional MRI and EEG cannot measure both the location and timing of memory-related brain activity at high resolution."

Ofen and her research team conceived the project during her time at Wayne State University, her home before joining the UT Dallas faculty in January.

"A colleague at Wayne State was doing brain mapping with focal epilepsy patients who were candidates for resection - removing a small portion of the brain as treatment," she said. "In this two-phase procedure, they implant electrodes to map where the patient's seizures originate in the brain and what crucial functions are controlled by nearby regions; this information is used in guiding clinical treatment decisions. While the electrodes are implanted for mapping purposes, patients can choose to participate in our research, which for them is not much more than playing a simple memory game."

With the electrodes in place, the patients play the memory game, and Ofen and her team collect iEEG recordings, which they believe will provide unique insights about the neural basis of memory in the developing brain.

"Functional MRI can show how brain regions communicate based on blood dynamics, not electrical activity, while EEG charts electrical activity with limited information about where it originates," she said. "Measurements from an iEEG will give us time precision that fMRI doesn't have and spatial specificity that EEG lacks.

"The opportunity is fantastic: It's spatial and temporal precision at levels that no other method provides."

Ofen plans to investigate memory retrieval via two complementary processes that occur in the brain: enactment of strategic control mediated by the prefrontal cortex, and representation of mnemonic content in the medial temporal lobe and visual cortices.

"Our hypothesis is that the improvement in memory ability between childhood and adulthood is largely supported by the development of what occurs in the prefrontal cortex, while what occurs in the medial temporal lobe and visual cortices is mostly stable across development," she said.

The study will test this hypothesis with iEEG data from 50 pediatric epilepsy patients as well as longitudinal fMRI data from 100 typically developing children, adolescents and young adults. The brain signatures of memory retrieval that will be identified in the prefrontal cortex, medial temporal lobe and visual cortices will then serve to test individual differences in scores on standardized memory tests.

Ofen said that determining what allows older children to do better on memory tasks could shed light on which neurophysiological aspects aren't maturing or developing optimally in children with inadequate memory development. The study also could impact research into other cognitive abilities.

"This work has the potential to open new dimensions in understanding brain development with more localized, temporally precise measures than ever before," she said. "This method provides a new host of opportunities to explore from this very rich signal."