When two memory regions in the brain communicate, they influence how we remember what we’ve just experienced, and as these regions mature, the precise ways in which they interact improve our ability to form long-lasting memories.
In the Feb. 15 issue of Current Biology, a study entitled “Dissociable oscillatory theta signatures of memory formation” was published.
When it comes to memory formation, researchers have long held a theory that the MTL and PFC, two brain regions that play a key role in supporting memory formation, are responsible for the robust increase between childhood and adulthood in the amount of information that can be stored in the brain. ECoG data from children and adults undergoing neurosurgery and attempting to memorize pictures of scenes were examined to better understand the nature of these interactions. The researchers used these unique data to investigate how interactions between the MTL and PFC aid in the development of long-term memory.
For the MTL, we identified two distinct brain signals—oscillations in coordinated electrical brain activity, both at theta frequencies of 3 Hz and 7 Hz—that underlie memory formation. When we looked at the MTL-PFC interactions, we found that these fast and slow theta oscillations had unique effects on these interactions,” said Noa Ofen, Ph.D., an associate professor of psychology in the College of Liberal Arts and Sciences and faculty member in the Institute of Gerontology. ‘We were excited to find that these distinct signatures of interactions between memory regions dictated whether or not a memory was successfully formed,’ the team said of their discovery that both oscillations underlined MTL-PFC interactions but in complementary unique ways.”
Later, the team wondered if those MTL-PFC interaction signatures explained in any way why older people had better memories than younger people, and they discovered that MTL-PFC interactions immediately preceding the onset of the scene distinguished top-performing adolescents from lower-performing adolescents and children, thereby showing direct links to memory development.”
Another interesting finding from the study is that the frequency of fast and slow theta oscillations appears to change with age. This is a significant new finding that could have far-reaching implications for our understanding of brain development and the differences in recognition performance that arise with age.
Researchers paired their findings with diffusion-weighted MRI data from a subset of subjects to better understand the anatomical infrastructure that underlies memory-supporting interactions. This white matter tract, known as the cingulum, was found to be linked to the development of neurophysiological signatures of memory development.
Elizabeth Johnson, Ph.D., an assistant professor of medical social sciences and pediatrics at Northwestern University, said that “putting the pieces together, this research reveals that key memory regions interact via two increasingly dissociable mechanisms as memory improves with age.”
Study results suggest memory development is linked to an increased capacity for brain multitasking, as evidenced by findings that show the slow and fast theta networks coexist in a single brain tract. Insight into how memory develops is provided by this.
