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
2009 ◽  
Vol 9 ◽  
pp. 1321-1344 ◽  
Author(s):  
César Quiroz ◽  
Rafael Luján ◽  
Motokazu Uchigashima ◽  
Ana Patrícia Simoes ◽  
Talia N. Lerner ◽  
...  

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.


2011 ◽  
Vol 23 (2) ◽  
pp. 477-516 ◽  
Author(s):  
K. N. Magdoom ◽  
D. Subramanian ◽  
V. S. Chakravarthy ◽  
B. Ravindran ◽  
Shun-ichi Amari ◽  
...  

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.


2019 ◽  
Vol 5 (8) ◽  
pp. eaaw9297 ◽  
Author(s):  
Hidetoshi Amita ◽  
Okihide Hikosaka

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.


2009 ◽  
Vol 28 (5) ◽  
pp. 602-618 ◽  
Author(s):  
G. Gangadhar ◽  
D. Joseph ◽  
A.V. Srinivasan ◽  
D. Subramanian ◽  
R.G. Shivakeshavan ◽  
...  

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Lei Xiao ◽  
Devin P. Merullo ◽  
Therese M. I. Koch ◽  
Mou Cao ◽  
Marissa Co ◽  
...  

AbstractDisruption of the transcription factor FoxP2, which is enriched in the basal ganglia, impairs vocal development in humans and songbirds. The basal ganglia are important for the selection and sequencing of motor actions, but the circuit mechanisms governing accurate sequencing of learned vocalizations are unknown. Here, we show that expression of FoxP2 in the basal ganglia is vital for the fluent initiation and termination of birdsong, as well as the maintenance of song syllable sequencing in adulthood. Knockdown of FoxP2 imbalances dopamine receptor expression across striatal direct-like and indirect-like pathways, suggesting a role of dopaminergic signaling in regulating vocal motor sequencing. Confirming this prediction, we show that phasic dopamine activation, and not inhibition, during singing drives repetition of song syllables, thus also impairing fluent initiation and termination of birdsong. These findings demonstrate discrete circuit origins for the dysfluent repetition of vocal elements in songbirds, with implications for speech disorders.


2018 ◽  
Vol 10 (3) ◽  
Author(s):  
Nobuyuki Ishii ◽  
Hitoshi Mochizuki ◽  
Miyuki Miyamoto ◽  
Yuka Ebihara ◽  
Kazutaka Shiomi ◽  
...  

Chorea is thought to be caused by deactivation of the indirect pathway in the basal ganglia circuit. However, few imaging studies have evaluated the basal ganglia circuit in actual patients with chorea. We investigated the lesions and mechanisms underlying chorea using brain magnetic resonance imaging (MRI) and 18F-fluorodeoxyglucose positron emission tomography (FDG-PET). This retrospective case series included three patients with chorea caused by different diseases: hyperglycemic chorea, Huntington’s disease, and subarachnoid hemorrhage. All the patients showed dysfunction in the striatum detected by both MRI and FDG-PET. These neuroimaging findings confirm the theory that chorea is related to an impairment of the indirect pathway of basal ganglia circuit.


2012 ◽  
Vol 23 (5-6) ◽  
Author(s):  
Claudio Da Cunha ◽  
Alexander Gomez-A ◽  
Charles D. Blaha

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