Properties of Neurons in External Globus Pallidus Can Support Optimal Action Selection
PLoS Comput Biol. 2016-07-07; 12(7): e1005004
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1. PLoS Comput Biol. 2016 Jul 7;12(7):e1005004. doi: 10.1371/journal.pcbi.1005004.
eCollection 2016 Jul.
Properties of Neurons in External Globus Pallidus Can Support Optimal Action
Bogacz R(1)(2), Martin Moraud E(1)(2), Abdi A(3)(4), Magill PJ(1), Baufreton
(1)Medical Research Council Brain Network Dynamics Unit, Department of
Pharmacology, University of Oxford, Oxford, United Kingdom.
(2)Nuffield Department of Clinical Neurosciences, University of Oxford, Oxford,
(3)Univ. Bordeaux, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux,
(4)CNRS, Institut des Maladies Neurodégénératives, UMR 5293, Bordeaux, France.
The external globus pallidus (GPe) is a key nucleus within basal ganglia circuits
that are thought to be involved in action selection. A class of computational
models assumes that, during action selection, the basal ganglia compute for all
actions available in a given context the probabilities that they should be
selected. These models suggest that a network of GPe and subthalamic nucleus
(STN) neurons computes the normalization term in Bayes’ equation. In order to
perform such computation, the GPe needs to send feedback to the STN equal to a
particular function of the activity of STN neurons. However, the complex form of
this function makes it unlikely that individual GPe neurons, or even a single GPe
cell type, could compute it. Here, we demonstrate how this function could be
computed within a network containing two types of GABAergic GPe projection
neuron, so-called ‘prototypic’ and ‘arkypallidal’ neurons, that have different
response properties in vivo and distinct connections. We compare our model
predictions with the experimentally-reported connectivity and input-output
functions (f-I curves) of the two populations of GPe neurons. We show that,
together, these dichotomous cell types fulfil the requirements necessary to
compute the function needed for optimal action selection. We conclude that, by
virtue of their distinct response properties and connectivities, a network of
arkypallidal and prototypic GPe neurons comprises a neural substrate capable of
supporting the computation of the posterior probabilities of actions.
PMID: 27389780 [Indexed for MEDLINE]