1,720,968 research outputs found
Level of M1 GABAB predicts micro offline consolidation of motor learning during wakefulness
Full text linkThe consolidation process stabilizes a new initially labile memory. This consolidation could operate on a shorter timescale during wakefulness after initial motor learning. Within micro-offline learning states, sequences of simple individual actions learned through interleaved practice are condensed into a unified skill through a time-dependent consolidation process occurring during wakeful periods. While emerging evidence links Glutamate and GABA modulations in the primary motor cortex (M1) to motor learning, its relationship with micro-offline consolidation processes in brief resting states during motor learning is unclear. To investigate this issue, we employed Transcranial magnetic stimulation (TMS) to evaluate whether interindividual variation of different neurotransmitters at rest influences motor learning consolidation in humans. Our results point to the role of GABAB in micro-offline motor consolidation processes during motor learning in M1. This finding could have an important impact on planning neuropharmacology or non-invasive brain stimulation approaches in clinical domains, such as post-stroke rehabilitation
The role of dorsal premotor cortex in joint action stopping
No full textHuman sensorimotor interaction requires mutual behavioral adaptation as well as shared cognitive task representations (Joint Action, JA). Yet, an under-investigated aspect of JA is the neurobehavioral mechanisms employed to stop actions if the context calls for it. Sparse evidence points to the possible contribution of the left dorsal premotor cortex (lPMd) in sculpting movements according to the socio-interactive context. To clarify this issue, we ran two experiments integrating a classical stop signal paradigm with an ecological JA task. The first behavioral study shows longer Stop performance in the JA condition. In the second, we use transcranial magnetic stimulation to inhibit the lPMd or a control site (vertex). Results show that lPMd modulates the JA stopping performance. Action stopping is an important component of JA coordination, and here we provide evidence that lPMd is a key node of a brain network recruited for online mutual co-adaptation in social contexts
Different processes of Concurrent Motor Inhibition are active during Joint Action: Evidence from TMS study
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Parallel fast and slow motor inhibition processes in Joint Action coordination
No full textMotor inhibition is essential to adapt to an ever-changing environment and to noise in state prediction. As a consequence, inhibitory motor control must also play a key role during Joint Action (JA) tasks, where the motor system has to further integrate inferences about others' action. Yet, very little research has been carried out on the contribution of motor inhibition in JA tasks. Here, we used an interactive task in which subjects were required to open a bottle with one hand. The bottle was held and stabilized by a co-actor (JA) or by a mechanical holder (vice clamp, no-JA). A first motion capture study characterized the reaching and grasping kinematics of the two conditions. In a second study, by means of Transcranial Magnetic Stimulation (TMS), we measured (i) corticospinal excitability (CSE), (ii) cortical silent period (cSP) and (iii) short-interval intracortical inhibition (sICI), during the reaching phase of the task. These latter two indexes respectively reflect slow corticospinal (GABAb-mediated) and fast intracortical (GABAa-mediated) inhibition. We found no modulation for CSE, while cSP was increased and intracortical inhibition was downregulated during JA. Interestingly, the cSP correlated with partners' predictability as a whole and with partners’ behaviour in the previous trial. These results, beside showing clear dissociation between fast and slow inhibition during JA, also shed new light on the predictive role played by corticospinal inhibitory mechanisms in online mutual behavioural co-adaptation
Motor overload: GABAergic index of parallel buffer costs
No full textEveryday life actions are continuously adjusted to the context and halted promptly when the environment requires to switch from the current action to a different one. Action changing/adaptation is a multicomponent process that effectively optimizes the chaining of different sub-actions. This process is based on different control strategies that operate on a continuum, adopting either serial (i.e., a task goal is activated after the previous one has been carried out) to parallel (i.e., multiple goals active at the same time or overlay mode) strategies [[1]]. In the parallel strategy, the different task sub-goals share the same limited processing capacity, ultimately hampering response speed. Otherwise, the serial strategy produces no interference between sub-goals. One early component of the action changing process is the preliminary stop of the ongoing action. This stopping has been related to the activity of inhibitory GABAergic circuits in the motor system, that may account for individual differences in action stopping performance [[2],[3]]. However, to date, it is unclear if and how GABAergic neurotransmission relates to individual strategies adopted in action changing
The Neurophysiology of Action Perception
No full textAction perception relies on a parieto-premotor brain network engaged during both perception of actions performed by conspecifics and actual execution of actions. Despite important overlap between neural activations during action observation and action execution, the functional relevance of these activities remains debated. In this chapter, we will discuss how the study of action perception may effectively be enriched by applying core principles of motor control. By doing so, we present evidences in favour of: (i) the presence of a modular control strategy in action observation; (ii) the role of motor inhibition in coping with unpredictable action outcomes. We conclude that reaffirming the strong parallel with motor control would provide important insight into the investigation of action perception mechanisms
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Individual differences in intracortical inhibition predict action control when facing emotional stimuli
Full text linkEfficient inhibitory control in the context of prepotent actions is vital. However, such action inhibition may be profoundly influenced by affective states. Interestingly, research indicates that action control can be either impaired or improved by emotional stimuli. Thus, a great deal of confusion surrounds our knowledge of the complex dynamics subtending emotions and action control. Here, we aimed to investigate whether negative stimuli, even when non-consciously presented and task-irrelevant, can affect action control relative to neutral stimuli. Additionally, we tested whether individual differences in intracortical excitability may predict action control capabilities. To address these issues, we asked participants to complete a modified version of the Stop Signal Task (SST) in which fearful or neutral stimuli were subliminally presented before the go signals as primes. Moreover, we assessed participants' resting-state corticospinal excitability, short intracortical inhibition (SICI), and intracortical facilitation (ICF). Results demonstrated better action control capabilities when fearful stimuli were subliminally presented and interindividual SICI predicted stronger action inhibition capabilities. Taken together, these results shed new light on the intricate dynamics between action, consciousness, and motor control, suggesting that intracortical measures can be used as potential biomarkers of reduced motor inhibition in research and clinical settings
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
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