Canceling actions involves a race between basal ganglia pathways
TL;DR: The results support race models of action cancellation, with stopping requiring Stop-cue information to be transmitted from STN to SNr before increased striatal input creates a point of no return.
Abstract: Salient cues can prompt the rapid interruption of planned actions. It has been proposed that fast, reactive behavioral inhibition involves specific basal ganglia pathways, and we tested this by comparing activity in multiple rat basal ganglia structures during performance of a stop-signal task. Subthalamic nucleus (STN) neurons exhibited low-latency responses to 'Stop' cues, irrespective of whether actions were canceled or not. By contrast, neurons downstream in the substantia nigra pars reticulata (SNr) only responded to Stop cues in trials with successful cancellation. Recordings and simulations together indicate that this sensorimotor gating arises from the relative timing of two distinct inputs to neurons in the SNr dorsolateral 'core' subregion: cue-related excitation from STN and movement-related inhibition from striatum. Our results support race models of action cancellation, with stopping requiring Stop-cue information to be transmitted from STN to SNr before increased striatal input creates a point of no return.
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TL;DR: It is proposed that the rIFC (along with one or more fronto-basal-ganglia networks) is best characterized as a brake, and this brake can be turned on in different modes and in different contexts.
1,568 citations
TL;DR: Although all reward, reinforcement, and decision variables are theoretical constructs, their neuronal signals constitute measurable physical implementations and as such confirm the validity of these concepts.
Abstract: Rewards are crucial objects that induce learning, approach behavior, choices, and emotions. Whereas emotions are difficult to investigate in animals, the learning function is mediated by neuronal reward prediction error signals which implement basic constructs of reinforcement learning theory. These signals are found in dopamine neurons, which emit a global reward signal to striatum and frontal cortex, and in specific neurons in striatum, amygdala, and frontal cortex projecting to select neuronal populations. The approach and choice functions involve subjective value, which is objectively assessed by behavioral choices eliciting internal, subjective reward preferences. Utility is the formal mathematical characterization of subjective value and a prime decision variable in economic choice theory. It is coded as utility prediction error by phasic dopamine responses. Utility can incorporate various influences, including risk, delay, effort, and social interaction. Appropriate for formal decision mechanisms, rewards are coded as object value, action value, difference value, and chosen value by specific neurons. Although all reward, reinforcement, and decision variables are theoretical constructs, their neuronal signals constitute measurable physical implementations and as such confirm the validity of these concepts. The neuronal reward signals provide guidance for behavior while constraining the free will to act.
803 citations
Cites background from "Canceling actions involves a race b..."
...The opposing functions of the direct and indirect striatal output pathways are modeled by a race between movement and countermanding signals that reflect the relative timing of the two signals as they race towards a threshold (511)....
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TL;DR: The results indicate that dopamine conveys a single, rapidly evolving decision variable, the available reward for investment of effort, which is employed for both learning and motivational functions.
Abstract: Dopamine cell firing can encode errors in reward prediction, providing a learning signal to guide future behavior. Yet dopamine is also a key modulator of motivation, invigorating current behavior. Existing theories propose that fast (phasic) dopamine fluctuations support learning, whereas much slower (tonic) dopamine changes are involved in motivation. We examined dopamine release in the nucleus accumbens across multiple time scales, using complementary microdialysis and voltammetric methods during adaptive decision-making. We found that minute-by-minute dopamine levels covaried with reward rate and motivational vigor. Second-by-second dopamine release encoded an estimate of temporally discounted future reward (a value function). Changing dopamine immediately altered willingness to work and reinforced preceding action choices by encoding temporal-difference reward prediction errors. Our results indicate that dopamine conveys a single, rapidly evolving decision variable, the available reward for investment of effort, which is employed for both learning and motivational functions.
653 citations
TL;DR: It is suggested that imbalance between goal-directed and habitual action and inhibition contributes to some manifestations of Parkinson's disease, Tourette syndrome and obsessive–compulsive disorder and is proposed that basal ganglia surgery improves these disorders by restoring a functional balance between facilitation and inhibition.
Abstract: Classically, the basal ganglia have been considered to have a role in producing habitual and goal-directed behaviours. In this article, we review recent evidence that expands this role, indicating that the basal ganglia are also involved in neural and behavioural inhibition in the motor and non-motor domains. We then distinguish between goal-directed and habitual (also known as automatic) inhibition mediated by fronto-striato-subthalamic-pallido-thalamo-cortical networks. We also suggest that imbalance between goal-directed and habitual action and inhibition contributes to some manifestations of Parkinson's disease, Tourette syndrome and obsessive-compulsive disorder. Finally, we propose that basal ganglia surgery improves these disorders by restoring a functional balance between facilitation and inhibition.
439 citations
TL;DR: The results support the theory that key basal ganglia output neurons serve as an inhibitory gate over motor output that can be opened or closed by striatal direct and indirect pathways, respectively.
Abstract: The direct and indirect efferent pathways from striatum ultimately reconverge to influence basal ganglia output nuclei, which in turn regulate behavior via thalamocortical and brainstem motor circuits. However, the distinct contributions of these two efferent pathways in shaping basal ganglia output are not well understood. We investigated these processes using selective optogenetic control of the direct and indirect pathways, in combination with single-unit recording in the basal ganglia output nucleus substantia nigra pars reticulata (SNr) in mice. Optogenetic activation of striatal direct and indirect pathway projection neurons produced diverse cellular responses in SNr neurons, with stimulation of each pathway eliciting both excitations and inhibitions. Despite this response heterogeneity, the effectiveness of direct pathway stimulation in producing movement initiation correlated selectively with the subpopulation of inhibited SNr neurons. In contrast, effective indirect pathway-mediated motor suppression was most strongly influenced by excited SNr neurons. Our results support the theory that key basal ganglia output neurons serve as an inhibitory gate over motor output that can be opened or closed by striatal direct and indirect pathways, respectively.
340 citations
Cites background from "Canceling actions involves a race b..."
...A recent study observed very similar pauses in SNr activity just before initiation of lateral head movements; these pauses were observed in a sector of SNr that projects to SC, and did not occur when movements were canceled (Schmidt et al., 2013)....
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References
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Book•
01 Jan 1983
TL;DR: This paper presents a meta-analyses of the determinants of earthquake-triggered landsliding in the Czech Republic over a period of 18 months in order to establish a probabilistic framework for estimating the intensity of the earthquake.
Abstract: Preface. Acknowledgements. Introduction. References. List of Structures. Index of Abbreviations. Diagrams.
57,116 citations
TL;DR: A model in which specific types of basal ganglia disorders are associated with changes in the function of subpopulations of striatal projection neurons is proposed, which suggests that the activity of sub Populations of Striatal projections neurons is differentially regulated by striatal afferents and that different striatal projections may mediate different aspects of motor control.
5,094 citations
Book•
01 Jan 2007
TL;DR: A circular cribbage board having a circular base plate on which a circular counter disc, bearing a circular scale having 122 divisions numbered consecutively from 0, is mounted for rotation.
Abstract: From the Publisher:
Dramatically updating and extending the first edition, published in 1995, the second edition of The Handbook of Brain Theory and Neural Networks presents the enormous progress made in recent years in the many subfields related to the two great questions: How does the brain work? and, How can we build intelligent machines?
Once again, the heart of the book is a set of almost 300 articles covering the whole spectrum of topics in brain theory and neural networks. The first two parts of the book, prepared by Michael Arbib, are designed to help readers orient themselves in this wealth of material. Part I provides general background on brain modeling and on both biological and artificial neural networks. Part II consists of "Road Maps" to help readers steer through articles in part III on specific topics of interest. The articles in part III are written so as to be accessible to readers of diverse backgrounds. They are cross-referenced and provide lists of pointers to Road Maps, background material, and related reading.
The second edition greatly increases the coverage of models of fundamental neurobiology, cognitive neuroscience, and neural network approaches to language. It contains 287 articles, compared to the 266 in the first edition. Articles on topics from the first edition have been updated by the original authors or written anew by new authors, and there are 106 articles on new topics.
3,487 citations
TL;DR: The postulated role of excessive activity in the subthalamic nucleus in Parkinson's disease is supported by the effects of lesions evaluated in monkeys rendered parkinsonian by treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine.
Abstract: Although it is known that Parkinson's disease results from a loss of dopaminergic neurons in the substantia nigra, the resulting alterations in activity in the basal ganglia responsible for parkinsonian motor deficits are still poorly characterized. Recently, increased activity in the subthalamic nucleus has been implicated in the motor abnormalities. To test this hypothesis, the effects of lesions of the subthalamic nucleus were evaluated in monkeys rendered parkinsonian by treatment with 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). The lesions reduced all of the major motor disturbances in the contralateral limbs, including akinesia, rigidity, and tremor. This result supports the postulated role of excessive activity in the subthalamic nucleus in Parkinson's disease.
1,848 citations
TL;DR: These findings establish a critical role for basal ganglia circuitry in the bidirectional regulation of motor behaviour and indicate that modulation of direct-pathway circuitry may represent an effective therapeutic strategy for ameliorating parkinsonian motor deficits.
Abstract: Neural circuits of the basal ganglia are critical for motor planning and action selection. Two parallel basal ganglia pathways have been described, and have been proposed to exert opposing influences on motor function. According to this classical model, activation of the 'direct' pathway facilitates movement and activation of the 'indirect' pathway inhibits movement. However, more recent anatomical and functional evidence has called into question the validity of this hypothesis. Because this model has never been empirically tested, the specific function of these circuits in behaving animals remains unknown. Here we report direct activation of basal ganglia circuitry in vivo, using optogenetic control of direct- and indirect-pathway medium spiny projection neurons (MSNs), achieved through Cre-dependent viral expression of channelrhodopsin-2 in the striatum of bacterial artificial chromosome transgenic mice expressing Cre recombinase under control of regulatory elements for the dopamine D1 or D2 receptor. Bilateral excitation of indirect-pathway MSNs elicited a parkinsonian state, distinguished by increased freezing, bradykinesia and decreased locomotor initiations. In contrast, activation of direct-pathway MSNs reduced freezing and increased locomotion. In a mouse model of Parkinson's disease, direct-pathway activation completely rescued deficits in freezing, bradykinesia and locomotor initiation. Taken together, our findings establish a critical role for basal ganglia circuitry in the bidirectional regulation of motor behaviour and indicate that modulation of direct-pathway circuitry may represent an effective therapeutic strategy for ameliorating parkinsonian motor deficits.
1,614 citations