Summary: Early memory skills predict the strength of future neural connections, and the strength of early brain connections predict future memory acuity.
In early childhood, memory skills predict the strength of future brain connections, and conversely, the strength of early brain connections predict future memory acuity. New research published in Journal of Neuroscience highlights the complex, bidirectional relationship between brain function and ability during development.
It is difficult, if not impossible, to remember events from the first few years of life. A person’s first long-term memories appear around age four, when memory networks begin solidifying. Both early life experience and maturation of the hippocampus contribute to memory development, but the exact relationship between the two is unknown.
Geng et al. measured memory skills and resting brain activity in children aged four and six over the course of three years. The children learned facts and were quizzed on both the fact and how they learned it (a source memory) one week later.
Source memory and synchronized activity between the hippocampus and other memory regions — called functional connectivity — improved with age. Improvements in source memory over a year predicted functional connectivity in both younger and older children, but to a greater extent in younger children.
In addition, the level of functional connectivity at age six predicted the improvement in source memory at age eight. In other words, changes in ability predict changes in brain function, particularly for younger children, while function predicts ability solely in older children.
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Source: SfN Contact: Calli McMurray – SfN Image: The image is credited to Geng et al., JNeurosci 2020
How Behavior Shapes the Brain and the Brain Shapes Behavior: Insights From Memory Development
Source memory improves substantially during childhood. This improvement is thought to be closely related to hippocampal maturation. As previous studies have mainly used cross-sectional designs to assess relations between source memory and hippocampal function, it remains unknown whether changes in the brain precede improvements in memory or vice versa. To address this gap, the current study used an accelerated longitudinal design (n=200, 100 males) to follow 4- and 6-year-old human children for 3 years. We traced developmental changes in source memory and intrinsic hippocampal functional connectivity and assessed differences between the 4- and 6-year-old cohorts in the predictive relations between source memory changes and intrinsic hippocampal functional connectivity in the absence of a demanding task. Consistent with previous studies, there were age-related increases in source memory and intrinsic functional connectivity between the hippocampus and cortical regions known to be involved during memory encoding. Novel findings showed that changes in memory ability early in life predicted later connectivity between the hippocampus and cortical regions and that intrinsic hippocampal functional connectivity predicted later changes in source memory. These findings suggest that behavioral experience and brain development are interactive, bidirectional processes, such that experience shapes future changes in the brain and the brain shapes future changes in behavior. Results also suggest that both timing and location matter, as the observed effects depended on both children’s age and the specific brain regions of interest. Together these findings add critical insight into the interactive relations between cognitive processes and their underlying neurological bases during development.
Cross-sectional studies have shown that the ability to remember the contextual details of previous experiences (i.e., source memory) is related to hippocampal development in childhood. It is unknown whether hippocampal function changes precede improvements in memory or vice versa. By using an accelerated longitudinal design, we found that early source memory changes predicted later intrinsic hippocampal functional connectivity and that this connectivity predicted later source memory changes. These findings suggest that behavioral experience and brain development are interactive, bidirectional processes, such that experience shapes future changes in the brain and the brain shapes future behavioral changes. Moreover, these interactions varied as a function of children’s age and brain region, highlighting the importance of a developmental perspective when investigating brain-behavior interactions.