MGH Martinos Center for Biomedical Imaging 2016 | Page 29

new insights into the brain

Using the cutting-edge PET-MR facilities in the MGH Martinos Center, investigators have revealed how
the interactions between key neural
networks change during working
memory—the short-term memory
buffer that allows us to call on stored
information when performing particular tasks. Published in Science
Advances in June 2016, the findings could pave the way for studies
of how disruptions in dopamine
signaling contribute to working
memory deficits characteristic of
schizophrenia and other psychiatric disorders, and thus could aid in
treating the disorders.
“Our principal finding is that dopamine signaling within the cortex predicts the extent to which the
frontoparietal control network—
which directly mediates working
memory performance—becomes
disconnected from the default network—which is active when the
brain is awake but directed towards
internal tasks, such as thinking
about past or future events,” said
Joshua Roffman, an affiliated faculty
member in the Center and lead author of the Science Advances study.
“The disengagement of these two
networks is what allows us to shift
our focus away from internal events
and towards the performance of
many types of cognitive tasks.”

Image by Joshua Roffman

Understanding Working Memory

new insights into the brain

On Dopamine Receptors And
Risk And Reward
The study of dopamine receptors
and their function in the brain could
tell us a great deal about risk-taking
and other behaviors associated with
the reward pathway. However, an
ability to measure dynamics of receptor adaptations in vivo—that is,
in the living brain—has proved elusive.
In a paper published in April 2016
in the Nature journal Neuropsychopharmacology, the Martinos
Center’s Christin Sander and col-

leagues proposed a new technique
for in vivo measurements of receptor desensitization and internalization using simultaneous PET and
functional fMRI. As reported in the
paper, the technique could offer the
first means of assessing receptor adaptations in the living brain, thus
opening the door to new insights
about how neuroreceptors adapt to
alter brain function.