Synaptic excitation in spinal motoneurons alternates with synaptic inhibition and is balanced by outward rectification during rhythmic motor network activity

TY - JOUR

T1 - Synaptic excitation in spinal motoneurons alternates with synaptic inhibition and is balanced by outward rectification during rhythmic motor network activity

AU - Guzulaitis, Robertas

AU - Hounsgaard, Jorn

PY - 2017

Y1 - 2017

N2 - Regular firing in spinal motoneurons of red-eared turtles (Trachemys scripta elegans, either sex) evoked by steady depolarization at rest is replaced by irregular firing during functional network activity. The transition caused by increased input conductance and synaptic fluctuations in membrane potential was suggested to originate from intense concurrent inhibition and excitation. We show that the conductance increase in motoneurons during functional network activity is mainly caused by intrinsic outward rectification near threshold for action potentials by activation of voltage and Ca2+ gated K channels. Intrinsic outward rectification facilitates spiking by focusing synaptic depolarization near threshold for action potentials. By direct recording of synaptic currents, we also show that motoneurons are activated by out-of-phase peaks in excitation and inhibition during network activity, whereas continuous low-level concurrent inhibition and excitation may contribute to irregular firing.

AB - Regular firing in spinal motoneurons of red-eared turtles (Trachemys scripta elegans, either sex) evoked by steady depolarization at rest is replaced by irregular firing during functional network activity. The transition caused by increased input conductance and synaptic fluctuations in membrane potential was suggested to originate from intense concurrent inhibition and excitation. We show that the conductance increase in motoneurons during functional network activity is mainly caused by intrinsic outward rectification near threshold for action potentials by activation of voltage and Ca2+ gated K channels. Intrinsic outward rectification facilitates spiking by focusing synaptic depolarization near threshold for action potentials. By direct recording of synaptic currents, we also show that motoneurons are activated by out-of-phase peaks in excitation and inhibition during network activity, whereas continuous low-level concurrent inhibition and excitation may contribute to irregular firing.

KW - Central pattern generator

KW - High-conductance states

KW - Motoneuron

KW - Outward rectification

KW - Reciprocal inhibition and excitation

U2 - 10.1523/jneurosci.0800-17.2017

DO - 10.1523/jneurosci.0800-17.2017

M3 - Journal article

C2 - 28842417

AN - SCOPUS:85029773011

SN - 0270-6474

VL - 37

SP - 9239

EP - 9248

JO - Journal of Neuroscience

JF - Journal of Neuroscience

IS - 38

ER -