Information processing, dimensionality reduction and reinforcement learning in the basal ganglia

Bar‐Gad, Izhar; Morris, Genela; Bergman, Hagai

doi:10.1016/j.pneurobio.2003.12.001

Cited by 348 publications

(304 citation statements)

References 290 publications

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“…Current evidence supports a variety of theories purporting that basal ganglia neurons participate in the encoding of information related to reinforcement (Bar-Gad et al, 2003;Kawagoe et al, 1998;Schultz, 1998), expectation of future events , the registration of the presence or absence of salient behavioral stimuli (Hollerman and Schultz, 1998), the mediation of eye and/or limb movements during specific behavioral contexts (Brotchie et al, 1991;Hikosaka and Wurtz, 1983;Jaeger et al, 1993;Kawagoe et al, 2004;Mushiake and Strick, 1995;Turner and Anderson, 2005;van Donkelaar et al, 1999), the integration of sensory cues with motor outputs (Aldridge et al, 1980) and the adaptation of behavior to optimize favorable outcomes (McHaffie et al, 2005;Prescott et al, 2006;Redgrave et al, 1999). Consequently, these types of modulation could underlie our observation of context-dependent responses in the current study.…”

Section: Possible Factors That May Influence Context-dependent Dischargesupporting

confidence: 71%

Signaling patterns of globus pallidus internal segment neurons during forearm rotation

et al. 2007

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We recorded extracellular single unit discharges of globus pallidus internal segment (GPi) neurons in monkeys performing a visually-driven forearm rotation movement task in order to quantify how discharge patterns changed in relation to kinematic parameters. Subjects grasped a handle that rotated about its axis while facing a video screen displaying visual targets. Continuous visual feedback of handle rotation position was provided. Monkeys generated forearm rotation movements of ±35° and ±70° amplitude in order to align the cursor and targets. Trial records were aligned to forearm rotation onset in order to compare the discharge patterns that were associated with movements of different amplitudes, velocities, and directions. In addition, we quantified the depth of modulation of neuronal discharge associated with movements generated in two different task phases. Comparisons of discharge patterns were made between the visually-guided, rewarded phase ("cued movements") and the self-paced, unrewarded phase that returned the monkey to the task start position ("return movements") by quantifying the goodness of fit between neuronal discharge during cued and return movements.Our analyses revealed no systematic relationship between the depth of modulation of GPi neurons and forearm rotation amplitude, direction, or velocity. Further, comparisons between the two behavioral contexts revealed a systematic attenuation of modulation that could not be attributed to differences in movement velocity. Collectively, these findings suggest that the GPi neurons that we studied were not significantly involved in mediating movement kinematics, but may have instead been instrumental in the processing of information about the behavioral context during which movements were generated.

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Section: Possible Factors That May Influence Context-dependent Dischargesupporting

confidence: 71%

Signaling patterns of globus pallidus internal segment neurons during forearm rotation

et al. 2007

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“…Recently, several researchers have pointed out that the simplest version of the standard BG models is inadequate, and that a more advanced dynamic conceptualization of BG function is required, motivating the use of computational modeling (Bar-Gad, Morris, & Bergman, 2003;Brown et al, 2004;Frank, 2005a;Gurney et al, 2001). Others question the most basic assumptions of the standard model, suggesting that the segregation of the "direct" and "indirect" BG pathways is not as clear as once thought (Kawaguchi, Wilson, & Emson, 1990; Levesque & Parent, 2005;Wu, Richard, & Parent, 2000).…”

Section: Overall Bg Network Functionalitymentioning

confidence: 99%

Hold your horses: A dynamic computational role for the subthalamic nucleus in decision making

2006

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The basal ganglia (BG) coordinate decision making processes by facilitating adaptive frontal motor commands while suppressing others. In previous work, neural network simulations accounted for response selection deficits associated with BG dopamine depletion in Parkinson's disease. Novel predictions from this model have been subsequently confirmed in Parkinson patients and in healthy participants under pharmacological challenge. Nevertheless, one clear limitation of that model is in its omission of the subthalamic nucleus (STN), a key BG structure that participates in both motor and cognitive processes. The present model incorporates the STN and shows that by modulating when a response is executed, the STN reduces premature responding and therefore has substantial effects on which response is ultimately selected, particularly when there are multiple competing responses. Increased cortical response conflict leads to dynamic adjustments in response thresholds via cortico-subthalamicpallidal pathways. The model accurately captures the dynamics of activity in various BG areas during response selection. Simulated dopamine depletion results in emergent oscillatory activity in BG structures, which has been linked with Parkinson's tremor. Finally, the model accounts for the beneficial effects of STN lesions on these oscillations, but suggests that this benefit may come at the expense of impaired decision making.

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“…Bar-Gad et al (2003) have proposed that the striatum compresses information relayed to it from cortex, transmitting back the compressed version via the basal ganglia output nuclei. They noted that the two layer network formed by the striatum and the output nuclei can be mapped to standard neural network implementations of principal components analysis, and that these require weak correlation in a layer corresponding to the striatum.…”

Section: Introductionmentioning

confidence: 99%

Dopamine-modulated dynamic cell assemblies generated by the GABAergic striatal microcircuit

2009

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The striatum, principal input structure of the basal ganglia, is crucial to both motor control and learning. It receives convergent input from all over neocortex, hippocampal formation, amygdala and thalamus, and is the primary recipient of dopamine in the brain. Within the striatum is a GABAergic microcircuit that acts upon these inputs, formed by the dominant medium-spiny projection neurons (MSNs) and fast-spiking interneurons (FSIs). There has been little progress in understanding the computations it performs, hampered by the non-laminar structure that prevents identification of a repeating canonical microcircuit. We here begin the identification of potential dynamically-defined computational elements within the striatum. We construct a new three-dimensional model of the striatal microcircuit's connectivity, and instantiate this with our dopamine-modulated neuron models of the MSNs and FSIs. A new model of gap junctions between the FSIs is introduced and tuned to experimental data. We introduce a novel multiple spiketrain analysis method, and apply this to the outputs of the model to find groups of synchronised neurons at multiple time-scales. We find that, with realistic in vivo background input, small assemblies of synchronised MSNs spontaneously appear, consistent with experimental observations, and that the number of assemblies and the time-scale of synchronisation is strongly dependent on the simulated concentration of dopamine. We also show that feed-forward inhibition from the FSIs counter-intuitively increases the firing rate of the MSNs. Such small cell assemblies forming spontaneously only in the absence of dopamine may contribute to motor control problems seen in humans and animals following loss of dopamine cells.

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Information processing, dimensionality reduction and reinforcement learning in the basal ganglia

Cited by 348 publications

References 290 publications

Signaling patterns of globus pallidus internal segment neurons during forearm rotation

Signaling patterns of globus pallidus internal segment neurons during forearm rotation

Hold your horses: A dynamic computational role for the subthalamic nucleus in decision making

Dopamine-modulated dynamic cell assemblies generated by the GABAergic striatal microcircuit

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