Sequential neuromodulation of Hebbian plasticity in reward-based navigation (Brzosko et al 2017)

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" ...Here, we demonstrate that sequential neuromodulation of STDP by acetylcholine and dopamine offers an efficacious model of reward-based navigation. Specifically, our experimental data in mouse hippocampal slices show that acetylcholine biases STDP toward synaptic depression, whilst subsequent application of dopamine converts this depression into potentiation. Incorporating this bidirectional neuromodulation-enabled correlational synaptic learning rule into a computational model yields effective navigation toward changing reward locations, as in natural foraging behavior. ..."
1 . Brzosko Z, Zannone S, Schultz W, Clopath C, Paulsen O (2017) Sequential neuromodulation of Hebbian plasticity offers mechanism for effective reward-based navigation. Elife [PubMed]
Model Information (Click on a link to find other models with that property)
Model Type:
Brain Region(s)/Organism: Hippocampus;
Cell Type(s):
Gap Junctions:
Transmitter(s): Acetylcholine; Dopamine;
Simulation Environment: MATLAB;
Model Concept(s): Reinforcement Learning; Reward-modulated STDP;
Implementer(s): Zannone, Sara [s.zannone14 at];
Search NeuronDB for information about:  Acetylcholine; Dopamine;
function [ conv1_pre, conv1_post,tot_conv, trace, W] = weights_update_stdp(A_plus, A_minus, tau_plus, tau_minus, X, Y, conv1_pre, conv1_post, trace, tau_e)

[a,b] = size(conv1_pre);
% tot_conv = total change to apply to the synapse * learning rate
conv_pre_old = convolution_type2(conv1_pre, tau_plus,  A_plus, zeros(a, b)); %pre trace without spikes - used for coincident spikes
conv_post_old = convolution_type2(conv1_post, tau_minus,A_minus, zeros(a, b)); %post trace without spikes - used for coincident spikes

[conv_pre, conv1_pre] = convolution_type2 (conv1_pre, tau_plus,  A_plus, X); %trace given by pre-synaptic neuron, amplitude A+ and time constant tau+
[conv_post, conv1_post] = convolution_type2 (conv1_post, tau_minus,A_minus, Y); %trace given by post-synaptic neuron, amplitude A- and time constant tau-
W = (conv_pre.*Y + conv_post.*X).*(X+Y~=2)+((conv_pre_old.*Y + conv_post_old.*X)+(A_plus+A_minus)/2).*(X+Y==2); %total change in synapse due to stpd 

%%Eligibility Trace
[tot_conv, trace] = convolution_type2 (trace, tau_e,  1, W); %all weight changes filtered through the eligibility trace


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