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My name is Bob Zucker.
And I'm at the University
of California Berkeley.
You have selected a Henry Stewart
Talk on presynaptic plasticity.
Neurons rarely fire single
isolated action potentials.
They signal information with
trains of spikes that could be more
or less regular, irregular,
bursty, or sparse.
When these action potentials
invade nerve terminals,
they evoke transmitter release at
synapses, exciting or inhibiting
neighboring cells to communicate
and process information.
Synapses transmit signals of
this activity in complex ways.
The postsynaptic potentials they
generate are rarely constant.
They may wax or wane or both
compared to their amplitudes
to infrequent presynaptic
At vertebrates central
synapses, the slide
shows the effects of a natural
pattern of presynaptic spikes
on the top rows, evoking a mixture
of facilitated and depressed PSPs,
shown in the graph.
Responses are often complicated.
They can grow, then
decline, and then
sometimes even grow
again during a burst.
And afterwards, they can be larger
or smaller than isolated responses.
When changes in synaptic efficacy
occur in a timeframe of seconds
or, at most, a few
minutes, the changes
are classified as short-term
The underlying mechanisms
and physiological roles
are distinct from longer
lasting changes in transmission
lasting hours or days
and referred to as
These are discussed in a
separate Henry Stewart Talk,
while here I will consider only
short-term synaptic plasticity.