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Control of the temporal fidelity of synaptic transmission by a presynaptic high voltage‐activated transient K + current
Author(s) -
D'Incamps B. Lamotte,
Hess D.,
El Manira A.
Publication year - 2004
Publication title -
european journal of neuroscience
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.346
H-Index - 206
eISSN - 1460-9568
pISSN - 0953-816X
DOI - 10.1111/j.0953-816x.2004.03446.x
Subject(s) - neuroscience , neurotransmission , excitatory postsynaptic potential , chemistry , post tetanic potentiation , postsynaptic potential , postsynaptic current , long term potentiation , biophysics , electrophysiology , biology , inhibitory postsynaptic potential , biochemistry , receptor
The type of K + channels controlling the waveform of the presynaptic spike and synaptic transmission were examined in the lamprey spinal cord. Reticulospinal neuron somata displayed a transient K + current with a high voltage‐activation and inactivation. This current was selectively blocked by catechol at 100 µ m . Reticulospinal axons also displayed a high voltage‐activated fast K + current sensitive to catechol. The function of this presynaptic high voltage‐activated fast K + current in controlling synaptic transmission was investigated by using paired intracellular recordings from reticulospinal axons and their targets. Blockade of this current by catechol (100 µ m ) prolonged the presynaptic spike elicited by a single stimulus leading to a potentiation of the postsynaptic EPSP. Calcium imaging of reticulospinal axons showed an increase in presynaptic calcium transients after blockade of the presynaptic K + current by catechol. During high frequency firing, catechol revealed an activity‐dependent decrease in the spike duration, which resulted in a depression of synaptic transmission. These results suggest that the presynaptic high voltage‐activated transient K + current acts to optimize the temporal fidelity of synaptic transmission by minimizing activity‐dependent changes in the presynaptic spike waveform and calcium dynamics.