Spike-dependent intrinsic plasticity increases firing probability in rat striatal neurons in vivo.
The Journal of Physiology. 2003-08-01; 550(3): 947-959
DOI: 10.1113/jphysiol.2003.043125
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1. J Physiol. 2003 Aug 1;550(Pt 3):947-59. Epub 2003 Jul 4.
Spike-dependent intrinsic plasticity increases firing probability in rat striatal
neurons in vivo.
Mahon S(1), Casassus G, Mulle C, Charpier S.
Author information:
(1)Chaire de Neuropharmacologie, INSERM U114, Collège de France, 11 place
Marcelin Berthelot, 75230 Paris 05, France.
The collision of pre- and postsynaptic activity is known to provide a trigger for
controlling the gain of synaptic transmission between neurons. Here, using in
vivo intracellular recordings of rat striatal output neurons, we analyse the
effect of a single action potential, generated by ongoing synaptic activity, on
subsequent excitatory postsynaptic potentials (EPSPs) evoked by electrical
stimulation of the cerebral cortex. This pairing induced a short-term increase in
the probability that cortically evoked EPSPs caused striatal cells to fire. This
enhanced EPSP-spike coupling was associated with a decrease in the voltage firing
threshold with no apparent change in the synaptic strength itself. Antidromic
action potentials in striatal cells were also able to induce the facilitation
while subthreshold EPSPs were ineffective, indicating that the postsynaptic spike
was necessary and sufficient for the induction of the plasticity. A prior
spontaneous action potential also enhanced the probability with which directly
applied current pulses elicited firing, suggesting that the facilitation
originated from changes in the intrinsic electrical properties of the
postsynaptic cell. Using whole-cell recordings in cortico-striatal slices, we
found that the increase in membrane excitability as well as in EPSP-spike
coupling was abolished by low concentration of 4-aminopyridine. This suggests
that the intrinsic plasticity results from a time-dependent modulation of a
striatal voltage-dependent potassium current available close to the firing
threshold. Action potentials thus provide a postsynaptic signal, not only for
associative synaptic plasticity but also for activity-dependent intrinsic
plasticity, which directly controls the efficacy of coupling between pre- and
postsynaptic neurons.
DOI: 10.1113/jphysiol.2003.043125
PMCID: PMC2343063
PMID: 12844508 [Indexed for MEDLINE]