"... How does the brain know what firing patterns of what neurons are responsible for the reward if 1) the patterns are no longer there when the reward arrives and 2) all neurons and synapses are active during the waiting period to the reward? Here, we show how the conundrum is resolved by a model network of cortical spiking neurons with spike-timing-dependent plasticity (STDP) modulated by dopamine (DA). Although STDP is triggered by nearly coincident firing patterns on a millisecond timescale, slow kinetics of subsequent synaptic plasticity is sensitive to changes in the extracellular DA concentration during the critical period of a few seconds. ... This study emphasizes the importance of precise firing patterns in brain dynamics and suggests how a global diffusive reinforcement signal in the form of extracellular DA can selectively influence the right synapses at the right time." See paper for more and details.
Model Type: Realistic Network
Region(s) or Organism(s): Neocortex
Model Concept(s): Synaptic Plasticity; Long-term Synaptic Plasticity; Learning; STDP
Simulation Environment: MATLAB
Implementer(s): Izhikevich, Eugene [Eugene.Izhikevich at braincorporation.com]
References:
Izhikevich EM. (2007). Solving the distal reward problem through linkage of STDP and dopamine signaling. Cerebral cortex (New York, N.Y. : 1991). 17 [PubMed]