A computational model of action selection in the basal ganglia. II. Analysis and simulation of behaviour

Abstract

In a companion paper a new functional architecture was proposed for the basal ganglia based on the premise that these brain structures play a central role in behavioural action selection. The current paper quantitatively describes the properties of the model using analysis and simulation. The decomposition of the basal ganglia into selection and control pathways is supported in several ways. First, several elegant features are exposed--capacity scaling, enhanced selectivity and synergistic dopamine modulation--which might be expected to exist in a well designed action selection mechanism. The discovery of these features also lends support to the computational premise of selection that underpins our model. Second, good matches between model globus pallidus external segment output and globus pallidus internal segment and substantia nigra reticulata area output, and neurophysiological data, have been found which are indicative of common architectural features in the model and biological basal ganglia. Third, the behaviour of the model as a signal selection mechanism has parallels with some kinds of action selection observed in animals under various levels of dopaminergic modulation.

Where neuroscience and dynamic system theory meet autonomous robotics: A contracting basal ganglia model for action selection

“…Similarly to the simulations made by Gurney et al (2001b), we used a 6-channel model. The parameters of the model were hand-tuned in order to obtain a selective system and respecting the local contraction constraints defined below, their values are summarized in table B.1.…”

“…The CBG shares a number of similarities with the previously proposed GPR model (Gurney et al, 2001b), as its selection ability relies on two off-center on-surround subcircuits. However, it includes neglected connections from the GPe to the Striatum, which provide additional selectivity.…”

“…We first reproduced the selection test of Gurney et al (2001b) with our model and with the GPR model version presented in (Prescott et al, 2006). In this test, a specific sequence of five different salience vectors (represented by the dashed lines in fig.…”

“…The effects of the variation of this tonic DA level on the selection abilities of the BG has been examined in details for the GPR (Gurney et al, 2001b), and compared with symptoms of Parkinson's disease.…”

“…Among these, the model proposed by Gurney, Prescott and Redgrave (2001a;2001b) (henceforth the GPR model) has been successfully tested as an action selection mechanism for autonomous agents (Montes-Gonzalez et al, 2000;Girard et al, 2003Girard et al, , 2005aPrescott et al, 2006). In particular, it was shown to be able to solve a minimal survival task, and, compared with a simpler winner-takes-all mechanism, displayed dithering avoidance and energy-saving capabilities.…”