... In this study we show that in bitufted interneurones from layer 2/3 of the somatosensory cortex, the height and width of APs recorded at the soma are sensitive to changes in the resting membrane potential, suggesting subthreshold activity of voltage-gated conductances. Attributes of K+ currents examined in nucleated patches revealed a fast subthreshold-inactivating K+ conductance (Kf ) and a slow suprathreshold-inactivating K+ conductance (Ks ). Simulations of these K+ conductances, incorporated into a Hodgkin–Huxley-type model, suggested that during a single AP or during low frequency trains of APs, subthreshold inactivation of Kf was the primary modulator of AP shape, whereas during trains of APs the shape was governed to a larger degree by Ks resulting in the generation of smaller and broader APs. ... Compartmental simulation of the back-propagating AP suggested a mechanism for the modulation of the back-propagating AP height and width by subthreshold activation of Kf . We speculate that this signal may modulate retrograde GABA release and consequently depression of synaptic efﬁcacy of excitatory input from neighbouring pyramidal neurones.
Model Type: Channel/Receptor
Cell Type(s): Neocortex bitufted interneuron
Currents: I K
Simulation Environment: NEURON
Implementer(s): Korngreen, Alon [alon.korngreen at gmail.com]
Korngreen A, Kaiser KM, Zilberter Y. (2005). Subthreshold inactivation of voltage-gated K+ channels modulates action potentials in neocortical bitufted interneurones from rats. The Journal of physiology. 562 [PubMed]