scholarly journals Modeling Basal Ganglia for Understanding Parkinsonian Reaching Movements

2011 ◽  
Vol 23 (2) ◽  
pp. 477-516 ◽  
Author(s):  
K. N. Magdoom ◽  
D. Subramanian ◽  
V. S. Chakravarthy ◽  
B. Ravindran ◽  
Shun-ichi Amari ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Motor Cortex ◽  
Reaching Movements ◽  
Substantia Nigra Pars Compacta ◽  
Temporal Difference ◽  
Indirect Pathway ◽  
Dynamical Disease ◽  
Exploratory Movements ◽  
Dopamine Signal

We present a computational model that highlights the role of basal ganglia (BG) in generating simple reaching movements. The model is cast within the reinforcement learning (RL) framework with correspondence between RL components and neuroanatomy as follows: dopamine signal of substantia nigra pars compacta as the temporal difference error, striatum as the substrate for the critic, and the motor cortex as the actor. A key feature of this neurobiological interpretation is our hypothesis that the indirect pathway is the explorer. Chaotic activity, originating from the indirect pathway part of the model, drives the wandering, exploratory movements of the arm. Thus, the direct pathway subserves exploitation, while the indirect pathway subserves exploration. The motor cortex becomes more and more independent of the corrective influence of BG as training progresses. Reaching trajectories show diminishing variability with training. Reaching movements associated with Parkinson's disease (PD) are simulated by reducing dopamine and degrading the complexity of indirect pathway dynamics by switching it from chaotic to periodic behavior. Under the simulated PD conditions, the arm exhibits PD motor symptoms like tremor, bradykinesia and undershooting. The model echoes the notion that PD is a dynamical disease.

Modeling the role of basal ganglia in saccade generation: Is the indirect pathway the explorer?

2011 ◽  
Vol 24 (8) ◽  
pp. 801-813 ◽  
Author(s):  
R. Krishnan ◽  
S. Ratnadurai ◽  
D. Subramanian ◽  
V.S. Chakravarthy ◽  
M. Rengaswamy
Keyword(s):  
Basal Ganglia ◽  
Indirect Pathway ◽  
Saccade Generation

scholarly journals Key Modulatory Role of Presynaptic Adenosine A2AReceptors in Cortical Neurotransmission to the Striatal Direct Pathway

2009 ◽  
Vol 9 ◽  
pp. 1321-1344 ◽  
Author(s):  
César Quiroz ◽  
Rafael Luján ◽  
Motokazu Uchigashima ◽  
Ana Patrícia Simoes ◽  
Talia N. Lerner ◽  
...  
Keyword(s):  
Basal Ganglia ◽  
Neuropsychiatric Disorders ◽  
Receptor Function ◽  
Striatal Neurons ◽  
Indirect Pathway ◽  
Direct Pathway ◽  
Selective Modulation ◽  
Efferent Pathways

Basal ganglia processing results from a balanced activation of direct and indirect striatal efferent pathways, which are controlled by dopamine D1and D2receptors, respectively. Adenosine A2Areceptors are considered novel antiparkinsonian targets, based on their selective postsynaptic localization in the indirect pathway, where they modulate D2receptor function. The present study provides evidence for the existence of an additional, functionally significant, segregation of A2Areceptors at the presynaptic level. Using integrated anatomical, electrophysiological, and biochemical approaches, we demonstrate that presynaptic A2Areceptors are preferentially localized in cortical glutamatergic terminals that contact striatal neurons of the direct pathway, where they exert a selective modulation of corticostriatal neurotransmission. Presynaptic striatal A2Areceptors could provide a new target for the treatment of neuropsychiatric disorders.

scholarly journals A Dual Role Hypothesis of the Cortico-Basal-Ganglia Pathways: Opponency and Temporal Difference through Dopamine and Adenosine

2018 ◽  
Author(s):  
Kenji Morita ◽  
Yasuo Kawaguchi
Keyword(s):  
Basal Ganglia ◽  
Activity Patterns ◽  
D2 Receptor ◽  
Medium Spiny Neuron ◽  
Temporal Difference ◽  
Receptor Signaling ◽  
Indirect Pathway ◽  
Wide Range ◽  
Cortical Inputs

The hypothesis that the basal-ganglia direct and indirect pathways represent goodness (or benefit) and badness (or cost) of options, respectively, explains a wide range of phenomena. However, this hypothesis, named the Opponent Actor Learning (OpAL), still has limitations. Structurally, the OpAL model does not incorporate differentiation of the two types of cortical inputs to the basal-ganglia pathways received from intratelencephalic (IT) and pyramidal-tract (PT) neurons. Functionally, the OpAL model does not describe the temporal-difference (TD)-type reward-prediction-error (RPE), nor explains how RPE is calculated in the circuitry connecting to the DA neurons. In fact, there is a different hypothesis on the basal-ganglia pathways and DA, named the Cortico-Striatal-Temporal-Difference (CS-TD) model. The CS-TD model differentiates the IT and PT inputs, describes the TD-type RPE, and explains how TD-RPE is calculated. However, a critical difficulty in this model lies in its assumption that DA induces the same direction of plasticity in both direct and indirect pathways, which apparently contradicts the experimentally observed opposite effects of DA on these pathways. Here, we propose a new hypothesis that integrates the OpAL and CS-TD models. Specifically, we propose that the IT-basal-ganglia pathways represent goodness/badness of current options while the PT-indirect pathway represents the overall value of the previously chosen option, and both of these have influence on the DA neurons, through the basal-ganglia output, so that a variant of TD-RPE is calculated. A key assumption is that opposite directions of plasticity are induced upon phasic activation of DA neurons in the IT-indirect pathway and PT-indirect pathway because of different profiles of IT and PT inputs. Specifically, at PT→indirect-pathway-medium-spiny-neuron (iMSN) synapses, sustained glutamatergic inputs generate rich adenosine, which allosterically prevents DA-D2 receptor signaling and instead favors adenosine-A2A receptor signaling. Then, phasic DA-induced phasic adenosine, which reflects TD-RPE, causes long-term synaptic potentiation. In contrast, at IT→iMSN synapses where adenosine is scarce, phasic DA causes long-term synaptic depression via D2 receptor signaling. This new Opponency & Temporal-Difference (OTD) model provides unique predictions, part of which is potentially in line with recently reported activity patterns of neurons in the globus pallidus externus on the indirect pathway.

THE ROLE OF THE BASAL GANGLIA IN EXPLORATION IN A NEURAL MODEL BASED ON REINFORCEMENT LEARNING

2006 ◽  
Vol 16 (02) ◽  
pp. 111-124 ◽  
Author(s):  
D. SRIDHARAN ◽  
P. S. PRASHANTH ◽  
V. S. CHAKRAVARTHY
Keyword(s):  
Reinforcement Learning ◽  
Basal Ganglia ◽  
State Space ◽  
Chaotic Systems ◽  
Neural Model ◽  
Learning System ◽  
Substantia Nigra Pars Compacta ◽  
Water Pool ◽  
Oscillatory Dynamics

We present a computational model of basal ganglia as a key player in exploratory behavior. The model describes exploration of a virtual rat in a simulated water pool experiment. The virtual rat is trained using a reward-based or reinforcement learning paradigm which requires units with stochastic behavior for exploration of the system's state space. We model the Subthalamic Nucleus-Globus Pallidus externa (STN-GPe) segment of the basal ganglia as a pair of neuronal layers with oscillatory dynamics, exhibiting a variety of dynamic regimes such as chaos, traveling waves and clustering. Invoking the property of chaotic systems to explore state-space, we suggest that the complex exploratory dynamics of STN-GPe system in conjunction with dopamine-based reward signaling from the Substantia Nigra pars compacta (SNc) present the two key ingredients of a reinforcement learning system.

scholarly journals Role of Individual Basal Ganglia Nuclei in Force Amplitude Generation

2007 ◽  
Vol 98 (2) ◽  
pp. 821-834 ◽  
Author(s):  
Matthew B. Spraker ◽  
Hong Yu ◽  
Daniel M. Corcos ◽  
David E. Vaillancourt
Keyword(s):  
Basal Ganglia ◽  
Motor Cortex ◽  
Globus Pallidus ◽  
Neural Circuit ◽  
Activation Volume ◽  
Force Amplitude ◽  
Percent Signal Change ◽  
Signal Change ◽  
Increased Activity

The basal ganglia-thalamo-cortical loop is an important neural circuit that regulates motor control. A key parameter that the nervous system regulates is the level of force to exert against an object during tasks such as grasping. Previous studies indicate that the basal ganglia do not exhibit increased activity with increasing amplitude of force, although these conclusions are based mainly on the putamen. The present study used functional magnetic resonance imaging to investigate which regions in the basal ganglia, thalamus, and motor cortex display increased activity when producing pinch-grip contractions of increasing force amplitude. We found that the internal portion of the globus pallidus (GPi) and subthalamic nucleus (STN) had a positive increase in percent signal change with increasing force, whereas the external portion of the globus pallidus, anterior putamen, posterior putamen, and caudate did not. In the thalamus we found that the ventral thalamic regions increase in percent signal change and activation volume with increasing force amplitude. The contralateral and ipsilateral primary motor/somatosensory (M1/S1) cortices had a positive increase in percent signal change and activation volume with increasing force amplitude, and the contralateral M1/S1 had a greater increase in percent signal change and activation volume than the ipsilateral side. We also found that deactivation did not change across force in the motor cortex and basal ganglia, but that the ipsilateral M1/S1 had greater deactivation than the contralateral M1/S1. Our findings provide direct evidence that GPi and STN regulate the amplitude of force output. These findings emphasize the heterogeneous role of individual nuclei of the basal ganglia in regulating specific parameters of motor output.

scholarly journals The Dopaminergic Control of Movement-Evolutionary Considerations

2021 ◽  
Vol 22 (20) ◽  
pp. 11284
Author(s):  
Juan Pérez-Fernández ◽  
Marta Barandela ◽  
Cecilia Jiménez-López
Keyword(s):  
Basal Ganglia ◽  
Dopaminergic Neurons ◽  
Dopaminergic System ◽  
Great Part ◽  
Substantia Nigra Pars Compacta ◽  
Motor Deficits ◽  
Motor Responses ◽  
Early Vertebrates ◽  
Characteristic Motor

Dopamine is likely the most studied modulatory neurotransmitter, in great part due to characteristic motor deficits in Parkinson’s disease that arise after the degeneration of the dopaminergic neurons in the substantia nigra pars compacta (SNc). The SNc, together with the ventral tegmental area (VTA), play a key role modulating motor responses through the basal ganglia. In contrast to the large amount of existing literature addressing the mammalian dopaminergic system, comparatively little is known in other vertebrate groups. However, in the last several years, numerous studies have been carried out in basal vertebrates, allowing a better understanding of the evolution of the dopaminergic system, especially the SNc/VTA. We provide an overview of existing research in basal vertebrates, mainly focusing on lampreys, belonging to the oldest group of extant vertebrates. The lamprey dopaminergic system and its role in modulating motor responses have been characterized in significant detail, both anatomically and functionally, providing the basis for understanding the evolution of the SNc/VTA in vertebrates. When considered alongside results from other early vertebrates, data in lampreys show that the key role of the SNc/VTA dopaminergic neurons modulating motor responses through the basal ganglia was already well developed early in vertebrate evolution.

scholarly journals Indirect pathway from caudate tail mediates rejection of bad objects in periphery

2019 ◽  
Vol 5 (8) ◽  
pp. eaaw9297 ◽  
Author(s):  
Hidetoshi Amita ◽  
Okihide Hikosaka
Keyword(s):  
Basal Ganglia ◽  
Choice Task ◽  
Inhibitory Influence ◽  
Indirect Pathway ◽  
Crucial Component ◽  
Rejection Mechanism ◽  
Everyday Task ◽  
Goal Directed Behavior ◽  
Globus Pallidus Externus

The essential everyday task of making appropriate choices is a process controlled mainly by the basal ganglia. To this end, subjects need not only to find “good” objects in their environment but also to reject “bad” objects. To reveal this rejection mechanism, we created a sequential saccade choice task for monkeys and studied the role of the indirect pathway from the CDt (tail of the caudate nucleus) mediated by cvGPe (caudal-ventral globus pallidus externus). Neurons in cvGPe were typically inhibited by the appearance of bad objects; however, this inhibition was reduced on trials when the monkeys made undesired saccades to the bad objects. Moreover, disrupting the inhibitory influence of CDt on cvGPe by local injection of bicuculline (GABAA receptor antagonist) impaired the monkeys’ ability to suppress saccades to bad objects. Thus, the indirect pathway mediates the rejection of bad choices, a crucial component of goal-directed behavior.

scholarly journals Cortico-subthalamic projections send brief stop signals to halt visually-guided locomotion

2020 ◽  
Author(s):  
Elie M. Adam ◽  
Taylor Johns ◽  
Mriganka Sur
Keyword(s):  
Basal Ganglia ◽  
Motor Cortex ◽  
Subthalamic Nucleus ◽  
Behavioral Strategy ◽  
Visually Guided ◽  
Short Route ◽  
Mesencephalic Locomotor Region ◽  
Neuronal Control ◽  
Control Signals

SummaryGoal-directed locomotion necessitates control signals that propagate from higher-order areas to regulate spinal mechanisms. The cortico-subthalamic hyperdirect pathway offers a short route for cortical information to reach locomotor centers in the brainstem. We developed a task where head-fixed mice run to a visual landmark, then stop and wait to collect reward, and examined the role of secondary motor cortex (M2) projections to the subthalamic nucleus (STN) in controlling locomotion. Our modeled behavioral strategy indicates a switching point in behavior, suggesting a critical neuronal control signal at stop locations. Optogenetic activation of M2 axons in STN leads the animal to stop prematurely. By imaging M2 neurons projecting to STN, we find neurons that are active at the onset of stops, when executed at the landmark but not spontaneously elsewhere. Our results suggest that the M2-STN pathway can be recruited during visually-guided locomotion to rapidly and precisely control the mesencephalic locomotor region through the basal ganglia.

Paper 22: Experimental Studies on the Role of the Basal Ganglia in the Control of Movement

1968 ◽  
Vol 183 (10) ◽  
pp. 126-134
Author(s):  
E. M. Sedgwick
Keyword(s):  
Basal Ganglia ◽  
Motor Cortex ◽  
Caudate Nucleus ◽  
Reticular Formation ◽  
Sensory Input ◽  
Inferior Olive ◽  
Experimental Studies ◽  
Sensory Inputs ◽  
Influence Activity

When the basal ganglia are damaged by disease processes in man, various disorders of movement occur. In order to control movement the basal ganglia must have a sensory input and in the absence of direct connections to motoneurones or motor cortex they must act through intermediate structures. The experiments, on cats, demonstrate: (1) which sensory inputs reach the caudate nucleus and how they influence activity of the neurones there; (2) the effect of the output from the caudate nucleus and globus pallidus on the neurones of the inferior olive and reticular formation. The results are discussed with respect to the control of movement.

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