Functional
magnetic resonance imaging shows how activity within different regions
of the hippocampus correlates with memory formation
Extremely high-resolution
functional magnetic resonance imaging has allowed researchers to detect
changes in blood flow within the hippocampus during the process of
memory formation, according to an article in the January 24th issue
of Science. The study focused on differential blood flow within the
hippocampus as 10 healthy human volunteers learned to associate names
with faces.
The study identified two regions --- the cornu ammonis and the dentate
gyrus --- as highly active only during encoding of the face/name pairs.
This activity decreased as associations were learned. The subiculum
was active primarily during retrieval of the face/name associations.
Activity in the subiculum decreased as retrieval became more practiced.
Previous studies have demonstrated
the importance the hippocampus in forming memories. However, no
previous studies have directly examined how activity patterns within
specific regions change during learning.
"Our findings demonstrate that memory
formation is a dynamic process, with subdivisions within the hippocampus
making distinct but changing contributions as learning takes place,"
said lead author Michael M. Zeineh, Ph.D. "Brain activity increases
as information is introduced, then diminishes as the new information
becomes better learned.
"As knowledge about the brain's complex
circuitry grows, neuroscientists will be better able to understand
and address a host of debilitating neurological disorders, from
Alzheimer's disease to epilepsy to damage caused by head injuries,"
Zeineh said.
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