Plateau potentials

Plateau potentials, caused by persistent inward currents (PICs), are a type of electrical behaviour seen by cells in the spinal cord. They are of particular importance to spinal motor systems. PICs are set up by the influence of descending monoaminergic reticulospinal pathways. Metabotropic neurotransmitters, via monoaminergic input such as 5-HT and norepinephrine, modulate the activity of dendritic L-type Calcium channels that allow a sustained, positive, inward current into the cell. This leads to a lasting depolarisation. In this state, the cell fires action potentials independent of synaptic input. The PICs can be turned off via the activation of high-frequency inhibitory input at which point the cell returns to a resting state. Plateau potentials are also seen in the cortical, and hippocampal pyramidal neurons. Using iontophoretic, or two-photon glutamate uncaging experiments, it has been discovered that these plateau potentials include activities of voltage dependent calcium channels and NMDA receptors.

References

Svirskis et al. (2001) Electrotonic structure of motoneurons in the spinal cord of the turtle: inferences for the mechanisms of bistability. J. Neurophysiol. 85:391-398 PMID 11152739

Suzuki T et al. (2008) A Plateau potential mediated by the activation of extrasynaptic NMDA receptors in rat hippocampal CA1 pyramidal neurons. EJ Neuroscience. 28:521-534

Major G et al. (2008) Spatiotemporally Graded NMDA Spike/Plateau Potentials in Basal Dendrites of Neocortical Pyramidal Neurons. J Neurophysiol. 99:2584-2601

Milojkovic BA (2005) A strict correlation between dendritic and somatic plateau depolarizations in the rat prefrontal cortex pyramidal neurons. J Neurosci. 13;25(15):3940-51.