Search results for " motor control"
showing 10 items of 17 documents
Differential contributions of the two human cerebral hemispheres to action timing
2019
Rhythmic actions benefit from synchronization with external events. Auditory-paced finger tapping studies indicate the two cerebral hemispheres preferentially control different rhythms. It is unclear whether left-lateralized processing of faster rhythms and right-lateralized processing of slower rhythms bases upon hemispheric timing differences that arise in the motor or sensory system or whether asymmetry results from lateralized sensorimotor interactions. We measured fMRI and MEG during symmetric finger tapping, in which fast tapping was defined as auditory-motor synchronization at 2.5 Hz. Slow tapping corresponded to tapping to every fourth auditory beat (0.625 Hz). We demonstrate that t…
Cognitive variability in bipolar I disorder: A cluster-analytic approach informed by resting-state data
2019
Abstract Background While the presence of cognitive performance deficits in bipolar disorder I (BD-I) is well established, there is no consensus about which cognitive abilities are affected. Heterogeneous phenotypes displayed in BD-I further suggest the existence of subgroups among the disorder. The present study sought to identify different cognitive profiles among BD-I patients as well as potentially underlying neuronal network changes. Methods 54 euthymic BD-I patients underwent cognitive testing and resting state neuroimaging. Hierarchical cluster-analysis was performed on executive function scores of bipolar patients. The derived clusters were compared against 54 age-, gender- and IQ-m…
Quantifying the contribution of arm postural tremor to the outcome of goal-directed pointing task by displacement measures.
2004
A method for quantifying the outcome of goal-directed postural pointing was presented and used for relating the tremor output to the oscillations of single arm landmarks. The displacement of reflective markers placed on shoulder, upper arm, forearm, and hand were measured by an optoelectronic motion capture system in nine subjects holding a laser penlight pointed at a target. The high signal-to-noise ratio of the measured displacement series (from 7:1 for shoulder marker to 30:1 for hand marker) demonstrated the feasibility of the proposed system to carry out tremor analysis. The track of the laser emission on the target, reconstructed from penlight displacements, was studied as the outcome…
Effects of tinnitus on postural control and stabilization: A pilot study
2015
Introduction: The aim of this study was to evaluate the tinnitus's impacts on postural control. Material and methods: Sixty-six subjects (age: 46,71 ± 15,12 years, height 166,32 ± 8,88 cm, weight 64,85 ± 12,57 kg) with idiopathic tinnitus were recruited for the study and were tested. Each subject underwent to ‘Romberg test’, ‘Static balance’ and ‘posture analysis’. Static balance and posture analysis were performed two times, with open and close eyes, and were measured through the FreeMed posturography system. Results: showed that subjects had worse Baropodometric performances respect to benchmarks; moreover according to literature the results show that these patients had significant differ…
Enhanced Spatial Navigation Skills in Sequence-Space Synesthetes
2018
Contains fulltext : 219554.pdf (Publisher’s version ) (Closed access) Individuals with sequence-space synesthesia (SSS) perceive sequences like months, days and numbers in certain spatial arrangements. Several cognitive benefits have been associated with SSS, such as enhanced mental rotation, more vivid visual imagery and an advantage in spatial processing. The current study aimed to further investigate these cognitive benefits, focusing on spatial navigation skills, to explore if their enhanced sensitivity to spatial relations is reflected in enhanced navigational performance. Synesthetes were distinguished from controls by means of a questionnaire, a consistency test and drawings. A virtu…
Theta power and theta-gamma coupling during formation of novel representations in the infant brain
2021
Item does not contain fulltext Building object representations is crucial for understanding the visual world, but it is not yet understood how infants start to form these representations. In adults, theta power is higher during presentation of stimuli that were later remembered, compared to those later forgotten (Friese et al., 2013), and the coupling between theta phase and gamma amplitude has been shown to be responsible for binding perceptual features to form representations. Theta-gamma coupling has been observed, for example, during the formation of visual associations (Köster, Finger, Graetz, Kater & Gruber, 2018), and was again higher for remembered than forgotten stimuli. Theta-gamm…
Descriptor-type Robust Kalman Filter and Neural Adaptive Speed Estimation Scheme for Sensorless Control of Induction Motor Drive Systems
2012
Abstract This paper deals with robust estimation of speed and rotor flux for sensorless control of motion control systems which use induction motors as actuators. Due to the observability lack of five and six order Extended Kalman Filters, speed is here estimated by means of a Total Least Square algorithm with Neural Adaptive mechanism. This allows the use of a fourth-order Kalman Filter for estimating rotor flux and to filter stator currents. To cope with motor-load parameter variations, a descriptor-type robust Kalman Filter is designed taking explicitly into account these variations. The descriptor-type structure allows direct translation of parameter variations into variations of the co…
A translational paradigm to dtudy the rffects of uncontrollable stress in humans
2020
Theories on the aetiology of depression in humans are intimately linked to animal research on stressor controllability effects. However, explicit translations of established animal designs are lacking. In two consecutive studies, we developed a translational paradigm to study stressor controllability effects in humans. In the first study, we compared three groups of participants, one exposed to escapable stress, one yoked inescapable stress group, and a control group not exposed to stress. Although group differences indicated successful stress induction, the manipulation failed to differentiate groups according to controllability. In the second study, we employed an improved paradigm and co…
Aberrant probabilistic reinforcement learning in first-degree relatives of individuals with bipolar disorder
2020
Contains fulltext : 215845.pdf (Publisher’s version ) (Closed access) Background: Motivational dysregulation represents a core vulnerability factor for bipolar disorder. Whether this also comprises aberrant learning of stimulus-reinforcer contingencies is less clear. Methods: To answer this question, we compared healthy first-degree relatives of individuals with bipolar disorder (n = 42) known to convey an increased risk of developing a bipolar spectrum disorder and healthy individuals (n = 97). Further, we investigated the effects of the behavioral activation system (BAS) on reinforcement learning across the entire sample. All participants were assessed with a probabilistic learning task t…
Integrative Biomimetics of Autonomous Hexapedal Locomotion
2019
Despite substantial advances in many different fields of neurorobotics in general, and biomimetic robots in particular, a key challenge is the integration of concepts: to collate and combine research on disparate and conceptually disjunct research areas in the neurosciences and engineering sciences. We claim that the development of suitable robotic integration platforms is of particular relevance to make such integration of concepts work in practice. Here, we provide an example for a hexapod robotic integration platform for autonomous locomotion. In a sequence of six focus sections dealing with aspects of intelligent, embodied motor control in insects and multipedal robots-ranging from comp…