Plateau potentials in models of striatal projection neurons were studied. Plateau potentials are supralinear dendritic voltage elevations which have: i) high somatic voltage amplitude and ii) are threshold, or all-or-none, events (like somatic action potentials). While the high somatic amplitude can sometimes be captured in models of striatal projection neurons, their all-or-none property is not usually not. In this study, we found that including glutamate spillover consistently and robustly provides all-or-none plateaus in addition to a high somatic amplitude. This result arises due to the prolonged duration of extrasynaptic glutamate. When glutamate spillover is not included, the all-or-none behavior is very sensitive to parameters in the model for the Mg2+ block of the NMDA receptors, which is the mechanism for generating plateaus. These results suggest a potentially significant role of glutamate spillover in plateau potential generation. See the related article for more details.
Experimental motivation: In experiments, plateau potentials are all-or-none (threshold) phenomena. Additionally, in striatal projection neurons (SPNs), the somatic amplitude can reach up to 20 mV when measured in the soma. In morphologically and biophysically detailed, multicompartmental SPN models it is not easy to reproduce these features of the plateau potentials. References: Oikonomou KD, Singh MB, Sterjanaj EV and Antic SD (2014) Spiny neurons of amygdala, striatum, and cortex use dendritic plateau potentials to detect network UP states. Front. Cell. Neurosci. 8:292. doi: 10.3389/fncel.2014.00292
Model Type: Neuron or other electrically excitable cell
Region(s) or Organism(s): Striatum
Cell Type(s): Neostriatum medium spiny direct pathway GABA cell; Striatal projection neuron
Currents: I Calcium; I K; I Na,t; Kir, inactivating
Genes:
Model Concept(s): Active Dendrites
Simulation Environment: NEURON
Implementer(s): Lindroos, Robert [robert.lindroos at ki.se]; Kozlov, Alexander [akozlov at nada.kth.se]; Trpevski, Daniel
References:
Trpevski D, Khodadadi Z, Carannante I, Hellgren Kotaleski J. (2023). Glutamate spillover drives robust all-or-none dendritic plateau potentials-an in silico investigation using models of striatal projection neurons. Frontiers in cellular neuroscience. 17 [PubMed]