Spring 1995 Volume 4, Number 1
Brain cells "talk" to each other by releasing chemical messengers at special
connections (called synapses) between them. But what turns a message
into a memory is one of the great riddles of brain research. Scientists know
that synapses are stronger during and just after periods of high frequency
signalling, and it is thought that such short term enhancement contributes to
short term memory. At Harvard Medical School, Wade Regehr and his colleagues
are looking deeper into this process - in particular, the role of calcium ions.
Calcium is the molecule that actually triggers the cell to release its chemical
messengers, but Regehr's work, and the work of others, is showing that calcium
is also involved in controlling synaptic strength. By measuring calcium at the
site of release in the sending neuron, they have found that calcium persists
for tens of seconds after triggering the messengers and that these elevations
in calcium can enhance subsequent responses between neurons. The next step for
the researchers is to learn how synaptic calcium dynamics help to define the
time, course and magnitude of short term enhancement.
(Drawings by Dr. Regehr; prepared for OTB by Leigh Coriale Design & Illustration)