1,721,118 research outputs found
Planning Movements in Visual and Physical Space in Monkey Posterior Parietal Cortex
No full textNeurons in the posterior parietal cortex respond selectively for spatial parameters of planned goal-directed movements. Yet, it is still unclear which aspects of the movement the neurons encode: the spatial parameters of the upcoming physical movement (physical goal), or the upcoming visual limb movement (visual goal). To test this, we recorded neuronal activity from the parietal reach region while monkeys planned reaches under either normal or prism-reversed viewing conditions. We found predominant encoding of physical goals while fewer neurons were selective for visual goals during planning. In contrast, local field potentials recorded in the same brain region exhibited predominant visual goal encoding, similar to previous imaging data from humans. The visual goal encoding in individual neurons was neither related to immediate visual input nor to visual memory, but to the future visual movement. Our finding suggests that action planning in parietal cortex is not exclusively a precursor of impending physical movements, as reflected by the predominant physical goal encoding, but also contains spatial kinematic parameters of upcoming visual movement, as reflected by co-existing visual goal encoding in neuronal spiking. The co-existence of visual and physical goals adds a complementary perspective to the current understanding of parietal spatial computations in primates
Collaborative Research Center SFB 1528 “Cognition of Interaction”
No full textHumans and other primates live in complex environments and social group structures that give rise to multi-faceted interactions with others. Cognitive functions like perception, selective attention, action planning, and decision-making are fundamentally important for successful interactive behaviour. These cognitive capacities have been subject to research for a long time, but were studied neuro-physiologically predominantly in single animals performing solo tasks. Since January 2022, the German Research Foundation (Deutsche Forschungsgemeinschaft DFG) is funding a new Collaborative Research Center (SFB) 1528 “Cognition of Interaction”, to study cognition in the context of dynamic interactions between two or more individuals. The SFB brings together scientists from system and computational neuroscience, behavioural biology, and psychology to address the topic at the behavioural and at the neuronal level. As speaker of the SFB, Alexander Gail, together with vice-speaker Anne Schacht, coordinates the projects at the University of Göttingen, the German Primate Center Göttingen, the University Medical Centers Göttingen and Hamburg-Eppendorf, the Max Planck Institute for Dynamics and Self-Organization, the Göttinger Gesellschaft für Wis-senschaftliche Datenverarbeitung (GWDG) and the Weizmann Institute of Sciences in Rehovot, Israel
Perception-related Modulations of Local Field Potential Power and Coherence in Primary Visual Cortex of Awake Monkey during Binocular Rivalry
No full textCortical synchronization at γ-frequencies (35–90 Hz) has been proposed to define the connectedness among the local parts of a perceived visual object. This hypothesis is still under debate. We tested it under conditions of binocular rivalry (BR), where a monkey perceived alternations among conflicting gratings presented singly to each eye at orthogonal orientations. We made multi-channel microelectrode recordings of multi-unit activity (MUA) and local field potentials (LFP) from striate cortex (V1) during BR while the monkey indicated his perception by pushing a lever. We analyzed spectral power and coherence of MUA and LFP over 4–90 Hz. As in previous work, coherence of γ-signals in most pairs of recording locations strongly depended on grating orientation when stimuli were presented congruently in both eyes. With incongruent (rivalrous) stimulation LFP power was often consistently modulated in consonance with the perceptual state. This was not visible in MUA. These perception-related modulations of LFP occurred at low and medium frequencies (<30 Hz), but not at γ-frequencies. Perception-related modulations of LFP coherence were also restricted to the low–medium range. In conclusion, our results do not support the expectation that γ-synchronization in V1 is related to the perceptual state during BR, but instead suggest a perception-related role of synchrony at low and medium frequencies
Turning decisions into actions
No full textAre selection and control of action serial processes of separate neural modules? A new study in PLOS Biology argues against this and in favor of an integrated process distributed across multiple brain regions, each contributing in a distinct way
Bewegungsplanung in der Großhirnrinde – Signale zur Steuerung von kognitiven Neuroprothesen
No full textZusammenfassung
Mit wachsendem Wissen über die Informationsverarbeitung im Gehirn und verbesserten elektrophysiologischen Methoden rücken neuartige Neuroprothesen in den Bereich des Machbaren. Kinematische Prothesen, die eingeschränkte motorische Fähigkeiten durch künstliche Effektoren kompensieren, können direkt über zentralnervöse, neuronale Steuersignale kontrolliert werden. Bewegungsrelevante Parameter werden im Gehirn in vielfältiger Weise kodiert. So sind unterschiedliche Ansätze denkbar, Bewegungsparameter aus neuronaler Aktivität zu extrahieren. Kognitive Neuroprothesen verfolgen die Idee, die Aktivität der Großhirnrinde hinsichtlich Bewegungsplänen oder -zielen zu interpretieren, anstatt direkte Motorbefehle an das periphere Nervensystem oder deren unmittelbare Vorstufen zu dekodieren. Teilbereiche des parietalen und prämotorischen Kortex kodieren Bewegungsziele für Armbewegungen in unterschiedlichen Koordinatensystemen während der Planungsphase einer Bewegung. Vorteilhaft ist die Verwendung von Steuersignalen, die Bewegungsziele in visuellen, extrinsischen Koordinaten widerspiegeln, da im Fall einer Prothese zwar visuell-sensorische, aber nicht propriozeptive Rückmeldung über die selbst initiierte Prothesenbewegung zur Verfügung steht. Die neuronale Implementierung zielgerichteter Bewegungsplanung ist jedoch in vielen grundlegenden Aspekten noch unverstanden. Untersuchungen, die das Zusammenspiel externer Reize und interner Ziele auf die Bewegungsplanung und -kontrolle zum Gegenstand haben, sind vor dem Hintergrund der Neuroprothetik grundlagen- und anwendungsorientierte Forschung zugleich.</jats:p
Deciding while acting - Mid-movement decisions are more strongly affected by action probability than reward amount
No full textWhen deciding while acting, such as sequentially selecting targets during naturalistic foraging, movement trajectories reveal the dynamics of the unfolding decision process. Ongoing and planned actions may impact decisions in these situations in addition to expected reward outcomes. Here, we test how strongly humans weigh and how fast they integrate individual constituents of expected value, namely the prior probability of an action (PROB) and the prior expected reward amount associated with an action (AMNT), when deciding based on the combination of both together during an ongoing movement. Unlike other decision-making studies, we focus on PROB and AMNT priors, and not final evidence, in that correct actions were either instructed or could be chosen freely. This means, there was no decision-making under risk. We show that both priors gradually influence movement trajectories already before mid-movement instructions of the correct target and bias free-choice behavior. These effects were consistently stronger for PROB compared to AMNT priors. Participants biased their movements towards a high-PROB target, committed to it faster when instructed or freely chosen, and chose it more frequently even when it was associated with a lower AMNT prior than the alternative option. Despite these differences in effect magnitude, the time course of both priors’ effect on movement direction was highly similar. We conclude that prior action probability, and hence the associated possibility to plan actions accordingly, has higher behavioral relevance than prior action value for decisions that are expressed by adjusting already ongoing movements. Significance Statement Natural behavior, like foraging or hunting prey, requires animals and humans to select their next action during ongoing movements, thereby updating movements as the decision process unfolds. Here, we study the magnitude and time course with which prior action probability and prior expectancy of reward amount influence the selection between two competing movements in humans. By simultaneously but independently manipulating both priors in individual decisions, and by avoiding confounds of reward probability, we show that both priors affect the decision process with different magnitude yet comparable time courses. Our results emphasize the prioritized relevance of action probabilities over action values on mid-movement decisions
When adaptive control fails: Slow recovery of reduced rapid online control during reaching under reversed vision
No full textAbstractPrevious studies have shown that short-term exposure to mirror-reversed visual feedback suppresses rapid online control (ROC) of arm movements in response to a sudden target displacement. Here we tested if the reduced ROC under reversed vision can be observed for natural reaches without target perturbations, i.e. without corrective movements that are driven by visual input perturbation. Second, we ask if such ROC reduction generalizes to movement phases without visual feedback of the hand. Subjects were instructed to perform simple reach movements towards a stationary target position either under normal or physically reversed vision of the hand during the late movement phase. We quantified time-resolved ROC via a coefficient of determination of the reach trajectories over the full course of the movement. As for other measures in previous studies, we found that our perturbation-independent ROC was reduced within a few trials after exposure to reversed visual feedback. The reduced ROC was restricted to late movement phases, and was not observed in early movement phases. We further asked if subjects would be able to re-gain ROC with prolonged exposure to the reversed visual input. ROC gradually and incompletely increased over the course of 400 exposure trials, affecting both early and late movement phases. Our results show that under reversed vision ROC is reduced even for perturbation-independent natural reaches aiming at stationary targets
Comparing Open-Source Toolboxes for Processing and Analysis of Spike and Local Field Potentials Data
No full textComplementary encoding of priors in monkey frontoparietal network supports a dual process of decision-making
No full textNeural Dynamics in Monkey Parietal Reach Region Reflect Context-Specific Sensorimotor Transformations
No full textWe investigated the neural dynamics of sensorimotor transformations in the parietal reach region (PRR) of monkeys. To dissociate sensory from motor goal representations, we used a memory-guided anti-reach task. The monkeys had to reach either to a visually instructed, memorized peripheral target position (pro-reach) or to a diametrically opposed position (anti) while keeping central ocular fixation. Pro- and anti-reaches were randomly interleaved and indicated by a color instruction from the beginning of each trial. We analyzed spatiotemporal single-cell tuning and performed time-resolved population decoding to quantify the dynamic representation of the spatial visual cue, the reach goal, and the currently valid task rule (pro/anti mapping). Sensory information regarding the visual cue position was represented weakly during a short period of cue visibility. PRR predominantly encoded the reach goal from the end of the cue period on. The representation of the reach goal in the memory task evolves later for the anti- compared with pro-reaches, consistent with a 40–50 ms difference in reaction time between the two task rules. The task rule could be decoded before the appearance of the spatial cue, which indicates that abstract rule information is present in PRR that is independent of spatial cue or motor goal representations. Our findings support the hypothesis that PRR immediately translates current sensory information into reach movement plans, rather than storing the memorized cue location in the instructed-delay task. This finding indicates that PRR represents integrated knowledge on spatial sensory information combined with abstract behavioral rules to encode the desired movement goal
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