Putaminal Activity for Simple Reactions or Self-Timed Movements

2003 ◽  
Vol 89 (5) ◽  
pp. 2528-2537 ◽  
Author(s):  
Irwin H. Lee ◽  
John A. Assad
Keyword(s):  
Basal Ganglia ◽  
Neuronal Activity ◽  
Time Window ◽  
Important Determinant ◽  
Reaction Times ◽  
Variable Delay ◽  
Cortical Circuits ◽  
Movement Initiation ◽  
The Difference

To examine the role of basal ganglia-cortical circuits in movement initiation, we trained monkeys to make the same arm movements in two ways—in immediate reaction to a randomly timed external cue (cued movements) and also following a variable delay without an explicit initiation signal (self-timed movements). The two movement types were interleaved and balanced in overall timing to allow a direct comparison of activity before and during the movement. Posterior putaminal neurons generally had phasic, movement-related discharges that were comparable for cued and self-timed movements. On cued movements, neuronal activity increased sharply following cue onset. However, for self-timed movements, there was a slow build-up in activity that preceded the phasic discharge. This slow build-up was time-locked to movement and restricted to a narrow time window hundreds of milliseconds before movement. The difference in premovement activity between cued and self-timed trials was present before the earliest cue-onset times and was not related to any differences in the overall time-to-move between the two types of trials. These features suggest that activity evolving in the basal ganglia-cortical circuitry may drive the initiation of movements by increasing until an activity threshold is exceeded. The activity may increase abruptly in response to an external cue or gradually when the timing of movements is determined by the animals themselves rather than an external cue. In this view, small changes in activity that occur in advance of the much larger perimovement neuronal activity may be an important determinant of when movement occurs. In support of this hypothesis, we found that even for cued movements, faster reaction times were associated with slightly higher levels of activity hundreds of milliseconds before movement.

scholarly journals Globus pallidus dynamics reveal covert strategies for behavioral inhibition

2020 ◽  
Author(s):  
Bon-Mi Gu ◽  
Robert Schmidt ◽  
Joshua D. Berke
Keyword(s):  
Basal Ganglia ◽  
State Space ◽  
Globus Pallidus ◽  
Behavioral Inhibition ◽  
Reaction Times ◽  
Proactive Inhibition ◽  
Strategic Positioning ◽  
Movement Initiation ◽  
Population Activity ◽  
Flexible Behavior

AbstractFlexible behavior requires restraint or cancellation of actions that are no longer appropriate. This behavioral inhibition critically relies on frontal cortex - basal ganglia circuits. A central node within the basal ganglia, the globus pallidus pars externa (GPe), has been hypothesized to mediate “proactive” inhibition: being prepared to stop an action if needed. Here we investigate the population dynamics of rat GPe neurons during preparation-to-stop, stopping, and going. Rats could selectively engage proactive inhibition towards one specific action, as shown by slowed reaction times (RTs) for that action. While proactive inhibition was engaged, GPe population activity occupied state-space locations farther from the trajectory followed during normal movement initiation. Furthermore, the specific state-space location was predictive of distinct types of errors: failures to stop, failures to go, and incorrect choices. The slowed RTs on correct proactive trials reflected a starting bias towards the alternative action, which was overcome before making progress towards action initiation. Our results demonstrate that rats can exert cognitive control via strategic positioning of their GPe network state.

scholarly journals The enhancement of activity rescues the establishment of Mecp2 null neuronal phenotypes

2020 ◽  
Author(s):  
Linda Scaramuzza ◽  
Giuseppina De Rocco ◽  
Genni Desiato ◽  
Clementina Cobolli Gigli ◽  
Martina Chiacchiaretta ◽  
...  
Keyword(s):  
Rett Syndrome ◽  
Neuronal Activity ◽  
Time Window ◽  
Early Time ◽  
Brain Maturation ◽  
Transcriptional Program ◽  
Brain Functions ◽  
Reduced Activity

AbstractMecp2 deficiency, the gene responsible for Rett syndrome (RTT), affects brain maturation by impairing neuronal activity, transcription and morphology. These three elements are physiologically linked in a feed-forward cycle where neuronal activity modulates transcription and morphology to further increase network maturity. We hypothesized that the reduced activity displayed by maturing Mecp2 null neurons during development could perturb such cycle, sustaining an improper transcriptional program that, ultimately, impairs neuronal maturation. Accordingly, we show that by enhancing activity within an early time window, Ampakine redirects, in vitro, the development of null neuronal networks towards more physiological routes. Similarly, the administration of the drug to newborn null offspring delays the progression of symptoms, significantly prolonging life span. Our data highlights the role of altered neuronal activity during the establishment of Mecp2 null networks and the importance of such early defects to the typically poor maturity of RTT brain functions in adulthood. We propose the existence of an “early molecular phase” of Rett syndrome, a detailed description of which might disclose relevant targets for new rescue treatments.

scholarly journals What, If, and When to Move: Basal Ganglia Circuits and Self-Paced Action Initiation

2019 ◽  
Vol 42 (1) ◽  
pp. 459-483 ◽  
Author(s):  
Andreas Klaus ◽  
Joaquim Alves da Silva ◽  
Rui M. Costa
Keyword(s):  
Basal Ganglia ◽  
Prediction Errors ◽  
Movement Initiation ◽  
Reward Prediction ◽  
Behavioral Transitions ◽  
Main Input ◽  
Action Initiation

Deciding what to do and when to move is vital to our survival. Clinical and fundamental studies have identified basal ganglia circuits as critical for this process. The main input nucleus of the basal ganglia, the striatum, receives inputs from frontal, sensory, and motor cortices and interconnected thalamic areas that provide information about potential goals, context, and actions and directly or indirectly modulates basal ganglia outputs. The striatum also receives dopaminergic inputs that can signal reward prediction errors and also behavioral transitions and movement initiation. Here we review studies and models of how direct and indirect pathways can modulate basal ganglia outputs to facilitate movement initiation, and we discuss the role of cortical and dopaminergic inputs to the striatum in determining what to do and if and when to do it. Complex but exciting scenarios emerge that shed new light on how basal ganglia circuits modulate self-paced movement initiation.

scholarly journals Globus pallidus dynamics reveal covert strategies for behavioral inhibition

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Bon-Mi Gu ◽  
Robert Schmidt ◽  
Joshua D Berke
Keyword(s):  
Basal Ganglia ◽  
State Space ◽  
Globus Pallidus ◽  
Behavioral Inhibition ◽  
Reaction Times ◽  
Proactive Inhibition ◽  
Movement Initiation ◽  
Population Activity ◽  
Occupied State ◽  
Flexible Behavior

Flexible behavior requires restraint of actions that are no longer appropriate. This behavioral inhibition critically relies on frontal cortex - basal ganglia circuits. Within the basal ganglia, the globus pallidus pars externa (GPe) has been hypothesized to mediate selective proactive inhibition: being prepared to stop a specific action, if needed. Here we investigate population dynamics of rat GPe neurons during preparation-to-stop, stopping, and going. Rats selectively engaged proactive inhibition towards specific actions, as shown by slowed reaction times (RTs). Under proactive inhibition, GPe population activity occupied state-space locations farther from the trajectory followed during normal movement initiation. Furthermore, the state-space locations were predictive of distinct types of errors: failures-to-stop, failures-to-go, and incorrect choices. Slowed RTs on correct proactive trials reflected starting bias towards the alternative action, which was overcome before progressing towards action initiation. Our results demonstrate that rats can exert cognitive control via strategic adjustments to their GPe network state.

scholarly journals Testing Basal Ganglia Motor Functions Through Reversible Inactivations in the Posterior Internal Globus Pallidus

2008 ◽  
Vol 99 (3) ◽  
pp. 1057-1076 ◽  
Author(s):  
M. Desmurget ◽  
R. S. Turner
Keyword(s):  
Basal Ganglia ◽  
Globus Pallidus ◽  
Reaction Times ◽  
Movement Direction ◽  
Visually Guided ◽  
Movement Initiation ◽  
Internal Globus Pallidus ◽  
On Line ◽  
Motor Loop ◽  
Target Locations

To test current hypotheses on the contribution of the basal ganglia (BG) to motor control, we examined the effects of muscimol-induced inactivations in the skeletomotor region of the internal globus pallidus (sGPi) on visually directed reaching. Injections were made in two monkeys trained to perform four out-and-back reaching movements in quick succession toward four randomly selected target locations. Following sGPi inactivations the following occurred. 1) Peak velocity and acceleration were decreased in nearly all sessions, whereas movement duration lengthened inconsistently. 2) Reaction times were unaffected on average, although minor changes were observed in several individual sessions. 3) Outward reaches showed a substantial hypometria that correlated closely with bradykinesia, but directional accuracy was unaffected. 4) Endpoint accuracy was preserved for the slow visually guided return movements. 5) No impairments were found in the rapid chaining of out-and-back movements, in the selection or initiation of four independent reaches in quick succession or in the quick on-line correction of initially misdirected reaches. 6) Inactivation-induced reductions in the magnitude of movement-related muscle activity (EMG) correlated with the severity of slowing and hypometria. There was no evidence for inactivation-induced alterations in the relative timing of EMG bursts, excessive cocontraction, or impaired suppression of antagonist EMG. Therefore disconnecting the BG motor pathway consistently produced bradykinesia and hypometria, but seldom affected movement initiation time, feedback-mediated guidance, the capacity to produce iterative reaches, or the ability to abruptly reverse movement direction. These results are discussed with reference to the idea that the BG motor loop may regulate energetic expenditures during movement (i.e., movement “vigor”).

Basal Ganglia Orient Eyes to Reward

2006 ◽  
Vol 95 (2) ◽  
pp. 567-584 ◽  
Author(s):  
Okihide Hikosaka ◽  
Kae Nakamura ◽  
Hiroyuki Nakahara
Keyword(s):  
Basal Ganglia ◽  
Brain Stem ◽  
Neuronal Activity ◽  
Behavioral Measure ◽  
Learning Theories ◽  
The Gaze ◽  
Cognitive Activities ◽  
Cortical Inputs ◽  
The Brain

Expectation of reward motivates our behaviors and influences our decisions. Indeed, neuronal activity in many brain areas is modulated by expected reward. However, it is still unclear where and how the reward-dependent modulation of neuronal activity occurs and how the reward-modulated signal is transformed into motor outputs. Recent studies suggest an important role of the basal ganglia. Sensorimotor/cognitive activities of neurons in the basal ganglia are strongly modulated by expected reward. Through their abundant outputs to the brain stem motor areas and the thalamocortical circuits, the basal ganglia appear capable of producing body movements based on expected reward. A good behavioral measure to test this hypothesis is saccadic eye movement because its brain stem mechanism has been extensively studied. Studies from our laboratory suggest that the basal ganglia play a key role in guiding the gaze to the location where reward is available. Neurons in the caudate nucleus and the substantia nigra pars reticulata are extremely sensitive to the positional difference in expected reward, which leads to a bias in excitability between the superior colliculi such that the saccade to the to-be-rewarded position occurs more quickly. It is suggested that the reward modulation occurs in the caudate where cortical inputs carrying spatial signals and dopaminergic inputs carrying reward-related signals are integrated. These data support a specific form of reinforcement learning theories, but also suggest further refinement of the theory.

Mesial Motor Areas in Self-Initiated Versus Externally Triggered Movements Examined With fMRI: Effect of Movement Type and Rate

1999 ◽  
Vol 81 (6) ◽  
pp. 3065-3077 ◽  
Author(s):  
Marie-Pierre Deiber ◽  
Manabu Honda ◽  
Vicente Ibañez ◽  
Norihiro Sadato ◽  
Mark Hallett
Keyword(s):  
Anterior Cingulate ◽  
Visual Signals ◽  
Visual Signal ◽  
Movement Initiation ◽  
Movement Type ◽  
The Difference ◽  
The Right ◽  
Externally Triggered Movements ◽  
Motor Areas

Mesial motor areas in self-initiated versus externally triggered movements examined with fMRI: effect of movement type and rate. The human frontomesial cortex reportedly contains at least four cortical areas that are involved in motor control: the anterior supplementary motor area (pre-SMA), the posterior SMA (SMA proper, or SMA), and, in the anterior cingulate cortex, the rostral cingulate zone (RCZ) and the caudal cingulate zone (CCZ). We used functional magnetic resonance imaging (fMRI) to examine the role of each of these mesial motor areas in self-initiated and visually triggered movements. Healthy subjects performed self-initiated movements of the right fingers (self-initiated task, SI). Each movement elicited a visual signal that was recorded. The recorded sequence of visual signals was played back, and the subjects moved the right fingers in response to each signal (visually triggered task, VT). There were two types of movements: repetitive (fixed) or sequential (sequence), performed at two different rates: slow or fast. The four regions of interest (pre-SMA, SMA, RCZ, CCZ) were traced on a high-resolution MRI of each subject’s brain. Descriptive analysis, consisting of individual assessment of significant activation, revealed a bilateral activation in the four mesial structures for all movement conditions, but SI movements were more efficient than VT movements. The more complex and more rapid the movements, the smaller the difference in activation efficiency between the SI and the VT tasks, which indicated an additional processing role of the mesial motor areas involving both the type and rate of movements. Quantitative analysis was performed on the spatial extent of the area activated and the percentage of change in signal amplitude. In the pre-SMA, activation was more extensive for SI than for VT movements, and for fast than for slow movements; the extent of activation was larger in the ipsilateral pre-SMA. In the SMA, the difference was not significant in the extent and magnitude of activation between SI and VT movements, but activation was more extensive for sequential than for fixed movements. In the RCZ and CCZ, both the extent and magnitude of activation were larger for SI than for VT movements. In the CCZ, both indices of activation were also larger for sequential than for fixed movements, and for fast than for slow movements. These data suggest functional specificities of the frontomesial motor areas with respect not only to the mode of movement initiation (self-initiated or externally triggered) but also to the movement type and rate.

The Role of Feedback in Learning Spatially Incompatible Choice Reaction Tasks: Does it Have one?

1993 ◽  
Vol 37 (19) ◽  
pp. 1320-1324
Author(s):  
Addie Dutta ◽  
Robert W. Proctor
Keyword(s):  
Compatibility Effect ◽  
Reaction Times ◽  
Response Compatibility ◽  
Stimulus Response ◽  
Response Deadline ◽  
Extended Practice ◽  
Stimulus Response Compatibility ◽  
The Difference ◽  
Speed Accuracy

Stimulus-response compatibility effects have been shown to persist even after extended practice. In the present study, two experiments were conducted to see if the effects persist when knowledge of results that allows subjects to set performance goals is provided. In the first experiment, summary feedback about mean accuracy and mean reaction time was provided after each block of 40 trials of practice in a two-choice spatial compatibility task. Subjects practiced the task for 2,400 trials, yet the compatibility effect was not eliminated. Compared to previous experiments, reaction times were faster overall, but the degree of change was the same for both compatible and incompatible assignments. In the second experiment, a response deadline was imposed on each trial. If the subject did not respond within the time limit, which was reduced as the experiment progressed, auditory feedback was presented. Summary feedback was also presented as in Experiment 1. Again, 2,400 trials of practice reduced but did not eliminate the compatibility effect. The greater reduction in the difference in reaction times for compatible and incompatible assignments, relative to other experiments, could be attributed to speed-accuracy tradeoff. The results indicate that the persistence of stimulus-response compatibility effects with extended practice is not due to poorer motivation to perform with the incompatible assignment. The results suggest that training will be insufficient to overcome difficulties in performance resulting from spatially incompatible assignments.

Frontal-striatal circuit functions: Context, sequence, and consequence

2003 ◽  
Vol 9 (1) ◽  
pp. 103-128 ◽  
Author(s):  
JEAN A. SAINT-CYR
Keyword(s):  
Information Processing ◽  
Basal Ganglia ◽  
Cortical Circuits ◽  
Research Strategies ◽  
Learning Functions ◽  
Cue Salience ◽  
Sequential Information ◽  
Encoding Strategies ◽  
Behavioral Constraint

The exact role of the basal ganglia in both the motor and non-motor domains has proven elusive since it is virtually impossible to refer to its function in isolation of cortical, and especially frontal cortical circuits. The result is that we often speak of frontal-striatal circuits and functions but this still leaves us in the dark when trying to specify basal ganglia information processing. A critical review of the data from both basic science and clinical studies suggests that we should break down processing along a temporal continuum, including the domains of context, sequential information processing, and feedback or reinforcement (i.e., the consequences of action). This analysis would cut across other theoretical constructs, such as attention, central executive, memory, and learning functions, traditionally employed in the neuropsychological literature. Under specified behavioral constraint, the basal ganglia can then be seen to be involved in fundamental aspects of attentional control (often covert), in the guidance of the early stages of learning (especially reinforcement-based, but also encoding strategies in explicit paradigms), and in the associative binding of reward to cue salience and response sequences via dopaminergic mechanisms. Parkinson's disease is considered to offer only a limited view of basal ganglia function due to partial striatal depletion of dopamine and the potential involvement of other structures and transmitters in its pathology. It is hoped that the present formulation will suggest new heuristic research strategies for basal ganglia research, permitting a closer link to be established between neurophysiological, functional imaging and neuropsychological paradigms. (JINS, 2003, 9, 103–128.)

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