- Poster presentation
- Open Access
Cortico-striatal plasticity for action-outcome learning using spike timing dependent eligibility
- Kevin N Gurney1Email author,
- Mark D Humphries1 and
- Peter Redgrave1
https://doi.org/10.1186/1471-2202-10-S1-P135
© Gurney et al; licensee BioMed Central Ltd. 2009
- Published: 13 July 2009
Keywords
- Dopamine
- Action Selection
- Active Afferents
- Medium Spiny Neuron
- Dependent Form
Introduction
We recently proposed that short-latency, sensory-evoked dopamine release is critical for learning action-outcome causality [1]. If an action causes an unexpected outcome associated with a phasic visual event, there will be a phasic burst of dopamine in the striatum. Subsequent reinforcement of the striatal response to the cortical representation of the action then makes the selection of the action (and its outcome) more likely; i.e. there is "repetition biasing" of action selection. This, in turn, facilitates associative learning of the action-outcome pairing elsewhere in the brain. Here, we present a model of cortico-striatal plasticity in medium spiny neurons (MSNs) that could form the basis for a quantitative account of action-outcome learning in basal ganglia.
Methods
a. MSN spike count in response to causal, and other, actions over trials. The phasic DA dip occurs after assigning a noxious value to the outcome of the causal action. b. Synaptic conductances at key trials. Only the first 50 synapses contribute to the action representation.
Results
When phasic dopamine is elicited by the causal action, it induced a rapid increase in MSN response that would be the foundation for inducing repetition bias of action selection. Further, the MSN has become receptive to the action request through synaptic pattern matching (Fig 1b top panel). Subsequent trials induce more selective synaptic patterning (reduced response at trial 1200). Dopamine dips (caused by assigning a noxious value to the outcome) induce a reduction in response. We conclude that the recently discovered complex dopamine-receptor dependent forms of STDP [2] can lead to cortico-striatal plasticity that can support action-outcome learning.
Declarations
Acknowledgements
This work was part funded by EPSRC grant EP/C516303/1
Authors’ Affiliations
References
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Copyright
This article is published under license to BioMed Central Ltd.