Linear vs non-linear integration in CA1 oblique dendrites (Gómez González et al. 2011)

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The hippocampus in well known for its role in learning and memory processes. The CA1 region is the output of the hippocampal formation and pyramidal neurons in this region are the elementary units responsible for the processing and transfer of information to the cortex. Using this detailed single neuron model, it is investigated the conditions under which individual CA1 pyramidal neurons process incoming information in a complex (non-linear) as opposed to a passive (linear) manner. This detailed compartmental model of a CA1 pyramidal neuron is based on one described previously (Poirazi, 2003). The model was adapted to five different reconstructed morphologies for this study, and slightly modified to fit the experimental data of (Losonczy, 2006), and to incorporate evidence in pyramidal neurons for the non-saturation of NMDA receptor-mediated conductances by single glutamate pulses. We first replicate the main findings of (Losonczy, 2006), including the very brief window for nonlinear integration using single-pulse stimuli. We then show that double-pulse stimuli increase a CA1 pyramidal neuron’s tolerance for input asynchrony by at last an order of magnitude. Therefore, it is shown using this model, that the time window for nonlinear integration is extended by more than an order of magnitude when inputs are short bursts as opposed to single spikes.
1 . Gómez González JF, Mel BW, Poirazi P (2011) Distinguishing Linear vs. Non-Linear Integration in CA1 Radial Oblique Dendrites: It's about Time. Front Comput Neurosci 5:44 [PubMed]
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Model Information (Click on a link to find other models with that property)
Model Type: Neuron or other electrically excitable cell;
Brain Region(s)/Organism:
Cell Type(s): Hippocampus CA1 pyramidal GLU cell;
Channel(s): I Na,p; I CAN; I Sodium; I Calcium; I Potassium; I_AHP;
Gap Junctions:
Receptor(s): NMDA;
Simulation Environment: NEURON;
Model Concept(s): Active Dendrites; Detailed Neuronal Models; Synaptic Integration;
Search NeuronDB for information about:  Hippocampus CA1 pyramidal GLU cell; NMDA; I Na,p; I CAN; I Sodium; I Calcium; I Potassium; I_AHP;
// The NMDA conductance at each synapse in the cell is estimated as
// a percent of the AMPA conductance. The ratio of NMDA/AMPA conductances
// for different cell regions are given by the following values.
// modified by Yiota Poirazi, July 2001,
// modified by Jose Gomez April 2006,


// Using the Peti_Augustine, 2000 and Andrasfaltvy_Magee, 2001 and Otmakhova & Lisman, 2000 
//and Takumi et al, 1999 and Catrel at al 2000 paper for a linear increase in GLU and GABA 
//currents along trunk and basal dendrites


SOMA_NMDA_AMPA_RATIO=3               //~0.6 peak current
BASAL_NMDA_AMPA_MAX_RATIO=5          // about the same peak current
APICAL_TRUNK_NMDA_AMPA_MAX_RATIO=5   //at 250 is equivalent to the same peak current -> ~2 peak current! at SLM
APICAL_NON_TRUNK_NMDA_AMPA_MAX_RATIO= 1.2*0.33 //0.8 // April 8, 2008 0.25 // ~2 peak current in side branches of SLM and ~1 of SC

//Attila Losonczy, and Jeffrey C. Magee, Neuron 50,291-307 (April 2006). They say that AMPA/NMDA ratio is 4.7+/-1 (n=4)