scholarly journals Basal Ganglia Control of Reflexive Saccades: A Computational Model Integrating Physiology Anatomy and Behaviour

2017 ◽  
Author(s):  
Alex J. Cope ◽  
Jonathan M. Chambers ◽  
Tony J. Prescott ◽  
Kevin N. Gurney
Keyword(s):  
Basal Ganglia ◽  
Computational Model ◽  
Degrees Of Freedom ◽  
Model Comparison ◽  
Functional Anatomy ◽  
Computational Modelling ◽  
Action Selection ◽  
Oculomotor System ◽  
Model Dynamics ◽  
Reflexive Saccades

AbstractIt is hypothesised that the basal ganglia play a key role in solving the problem of action selection. Here we investigate this hypothesis through computational modelling of the primate saccadic oculomotor system. This system is an excellent target for computational modelling because it is supported by a reasonably well understood functional anatomy, has limited degrees of freedom, and there is a wealth of behavioural and electrophysiological data for model comparison. Here, we describe a computational model of the reflexive saccadic oculomotor system incorporating the basal ganglia, key structures in motor control and competition between possible actions. To restrict the likelihood of overfitting the model it is structured and parameterised by the known anatomy and neurophysiology along with data from a single experimental behavioural paradigm, then validated by testing against several additional behavioural experimental data without modification of the parameters. With this model we reproduce a range of fundamental reflexive saccadic results both qualitatively and quantitatively, comprising: the distribution of saccadic latencies; the effect of eccentricity, luminance and fixation-target interactions on saccadic latencies; and the effect of competing targets on saccadic endpoint. By investigating the model dynamics we are able to provide mechanistic explanations for the sources of these behaviours. Further, because of its accesibility, the oculomotor system has also been used to study general principle of sensorimotor control. We interpret the ability of the basal ganglia to successfully control saccade selection in our model as further evidence for the action selection hypothesis.

scholarly journals Is there a brainstem substrate for action selection?

2007 ◽  
Vol 362 (1485) ◽  
pp. 1627-1639 ◽  
Author(s):  
M.D Humphries ◽  
K Gurney ◽  
T.J Prescott
Keyword(s):  
Basal Ganglia ◽  
Hierarchical Control ◽  
Computational Modelling ◽  
Small World ◽  
Action Selection ◽  
Action Representation ◽  
Selection System ◽  
Neural Substrate ◽  
Main Component ◽  
Behavioural Repertoire

The search for the neural substrate of vertebrate action selection has focused on structures in the forebrain and midbrain, and particularly on the group of sub-cortical nuclei known as the basal ganglia. Yet, the behavioural repertoire of decerebrate and neonatal animals suggests the existence of a relatively self-contained neural substrate for action selection in the brainstem. We propose that the medial reticular formation (mRF) is the substrate's main component and review evidence showing that the mRF's inputs, outputs and intrinsic organization are consistent with the requirements of an action-selection system. The internal architecture of the mRF is composed of interconnected neuron clusters. We present an anatomical model which suggests that the mRF's intrinsic circuitry constitutes a small-world network and extend this result to show that it may have evolved to reduce axonal wiring. Potential configurations of action representation within the internal circuitry of the mRF are then assessed by computational modelling. We present new results demonstrating that each cluster's output is most likely to represent activation of a component action; thus, coactivation of a set of these clusters would lead to the coordinated behavioural response observed in the animal. Finally, we consider the potential integration of the basal ganglia and mRF substrates for selection and suggest that they may collectively form a layered/hierarchical control system.

scholarly journals Roles for globus pallidus externa revealed in a computational model of action selection in the basal ganglia

2019 ◽  
Vol 109 ◽  
pp. 113-136 ◽  
Author(s):  
Shreyas M. Suryanarayana ◽  
Jeanette Hellgren Kotaleski ◽  
Sten Grillner ◽  
Kevin N. Gurney
Keyword(s):  
Basal Ganglia ◽  
Computational Model ◽  
Globus Pallidus ◽  
Action Selection

scholarly journals Integration of Navigation and Action Selection Functionalities in a Computational Model of Cortico-Basal-Ganglia–Thalamo-Cortical Loops

2005 ◽  
Vol 13 (2) ◽  
pp. 115-130 ◽  
Author(s):  
Benoît Girard ◽  
David Filliat ◽  
Jean-Arcady Meyer ◽  
Alain Berthoz ◽  
Agnès Guillot
Keyword(s):  
Basal Ganglia ◽  
Computational Model ◽  
Action Selection

scholarly journals Differential dopamine receptor-dependent sensitivity improves action selection in the basal ganglia

2020 ◽  
Author(s):  
Olivier Codol ◽  
Paul L Gribble ◽  
Kevin N Gurney
Keyword(s):  
Basal Ganglia ◽  
Computational Model ◽  
A Priori ◽  
Action Selection ◽  
Dopaminergic Receptors ◽  
Anatomy And Physiology ◽  
The Core ◽  
Sensitivity Ratio ◽  
New Feature ◽  
High Level

The problem of selecting one action from a set of different possible actions, simply referred to as the problem of action selection, is a ubiquitous challenge in the animal world. For vertebrates, the basal ganglia (BG) are widely thought to implement the core computation to solve this problem, as the anatomy and physiology of the BG are well-suited to this end. However, the BG still displays physiological features whose role in achieving efficient action selection remains unclear. In particular, it is known that the two types of dopaminergic receptors (D1 and D2) present in the BG give rise to mechanistically different responses. The overall effect will be a difference in sensitivity to dopamine which may have ramifications for action selection. However, which receptor type leads to a stronger response is, a priori, unclear, due to the complexity of the intracellular mechanisms involved. In this study, we use the action selection hypothesis to {\em predict} which of D1 or D2 has the greater sensitivity. Thus, we ask - what sensitivity ratio would result in enhanced action selection functionality in the basal ganglia? To do this, we incorporated differential D1 and D2 sensitivity in an existing, high level computational model of the macro-architecture of the basal ganglia, via a simple weighting variable. We then quantitatively assessed the model's capacity to perform action selection as we parametrically manipulated the new feature. We show that differential (rather than equal) D1 and D2 sensitivity to dopaminergic input improves action selection, and specifically, that greater D1 sensitivity (compared to that for D2) leads to these improvements.

scholarly journals DNA-Guided Assembly for Fibril Proteins

Mathematics ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 404
Author(s):  
Alexandru Amărioarei ◽  
Frankie Spencer ◽  
Gefry Barad ◽  
Ana-Maria Gheorghe ◽  
Corina Iţcuş ◽  
...  
Keyword(s):  
Computational Model ◽  
Structural Properties ◽  
Self Assembly ◽  
Structural Characteristics ◽  
Computational Modelling ◽  
Shape Reconstruction ◽  
Raw Material ◽  
Dna Assembly ◽  
Mesh Structure ◽  
Elementary Fibril

Current advances in computational modelling and simulation have led to the inclusion of computer scientists as partners in the process of engineering of new nanomaterials and nanodevices. This trend is now, more than ever, visible in the field of deoxyribonucleic acid (DNA)-based nanotechnology, as DNA’s intrinsic principle of self-assembly has been proven to be highly algorithmic and programmable. As a raw material, DNA is a rather unremarkable fabric. However, as a way to achieve patterns, dynamic behavior, or nano-shape reconstruction, DNA has been proven to be one of the most functional nanomaterials. It would thus be of great potential to pair up DNA’s highly functional assembly characteristics with the mechanic properties of other well-known bio-nanomaterials, such as graphene, cellulos, or fibroin. In the current study, we perform projections regarding the structural properties of a fibril mesh (or filter) for which assembly would be guided by the controlled aggregation of DNA scaffold subunits. The formation of such a 2D fibril mesh structure is ensured by the mechanistic assembly properties borrowed from the DNA assembly apparatus. For generating inexpensive pre-experimental assessments regarding the efficiency of various assembly strategies, we introduced in this study a computational model for the simulation of fibril mesh assembly dynamical systems. Our approach was based on providing solutions towards two main circumstances. First, we created a functional computational model that is restrictive enough to be able to numerically simulate the controlled aggregation of up to 1000s of elementary fibril elements yet rich enough to provide actionable insides on the structural characteristics for the generated assembly. Second, we used the provided numerical model in order to generate projections regarding effective ways of manipulating one of the the key structural properties of such generated filters, namely the average size of the openings (gaps) within these meshes, also known as the filter’s aperture. This work is a continuation of Amarioarei et al., 2018, where a preliminary version of this research was discussed.

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