Connor, S., Williams P. T., Armstrong, B., Petit, T. L., Ivanco, T. L., Weeks, A. C. (2006). Long-term potentiation is associated with changes in synaptic ultrastructure in the rat neocortex. Synapse, 59(6), 378-382. http://dx.doi.org/10.1002/syn.20248
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Abstract
Long-term
potentiation (LTP) in the sensorimotor cortex of freely moving rats has
been associated with changes in dendritic morphology and dendritic
spine density. The current research examined changes in synaptic number
and ultrastructure associated with LTP in this cortical region. LTP was
induced over a 1 h period and the animals were sacrificed 2 h after the
initial stimulation of the LTP group. Synapses within the terminal area
of the apical dendrites from layer III pyramidal neurons were
quantified
by determining the total number of synapses per neuron, the number of
excitatory and inhibitory contacts, number of synapses with different
curvature subtypes, number of perforated synapses, and synaptic length.
Several changes in synaptic morphology of excitatory synapses were
revealed but no overall increase in the number of synapses per neuron
was evident. Specifically, the induction of LTP was associated with an
increased number of excitatory perforated and concave shaped synapses.
Increased numbers of perforated concave synapses were also found to be
significantly correlated with the degree of potentiation in the LTP
animals. These and previous results suggest similar synaptic changes in
both the cortex and hippocampus during the early phases of LTP
maintenance and distinct synaptic changes during later phases of LTP
maintenance.
keywords: morphology; electron microscopy; dendritic spines; high-frequency stimulation
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