The groups of regions
of the brain that synchronize their activity during memory-related tasks
get smaller and more numerous with age, demonstrated UCSB scientists. The number of connections is as
individual as the study participants. The research findings appear in
the journal PLOS Computational Biology.
Studies of brain activity typically draw their findings from
measurement averages across entire groups of subjects. But new research
out of UC Santa Barbara that highlights a novel method of characterizing
and comparing the brain dynamics in individuals may signal a shift in
‘As people grow older, their brains adopt new communications for memory-related tasks, demonstrated UCSB scientists.’
"We found that the way our brain organizes its communications
changes as we age," said co-author Kimberly Schlesinger, a Ph.D. student
at UCSB. "Even though we saw different patterns of brain activity in
older people, we didn't see any changes in memory performance. This
suggests that while older people have less synchronized communication
across their entire brains, they may be compensating for this by using
different strategies to successfully remember things."
The scientists used functional magnetic resonance imaging (fMRI) to
record healthy people's brain activity during memory tasks, attention
tasks and periods of rest. For each person, fMRI data was recast as a
network composed of brain regions and the connections among them. The
investigators then measured how closely different groups of connections
changed together over time.
They found that regardless of whether a person is using memory,
directing attention or resting, the number of synchronous groups of
connections within one brain is consistent for that person. However,
among multiple people, these numbers vary dramatically.
Specifically during memory, variations among people are closely
linked to age. Younger participants had only a few large synchronous
groups that link nearly the entire brain in coordinated activity, while
older participants showed progressively more and smaller groups of
connections, indicating loss of cohesive brain activity - even in the
absence of memory impairment.
"This method elegantly captures important differences between
individual brains, which are often complex and difficult to describe,"
said Elizabeth Davison, who initiated the work as an undergraduate at
UCSB, where Schlesinger served as her mentor. Davison is now a graduate
student at Princeton University. "The resulting tools show promise for
understanding how different brain characteristics are related to
behavior, health and disease."
The research originated from the Worster Summer Research Fellowship
in UCSB's Department of Physics. Other UCSB members of the project team
included physics professor Jean Carlson, neuroscientist Scott Grafton
and then-postdoctoral scholar Danielle Bassett, now an assistant
professor at the University of Pennsylvania.
Future work will investigate how to use individual brain signatures
to differentiate between brains that are healthily aging and those with