1,721,047 research outputs found
Gaussian processes and beyond: From dynamical modeling to statistical signal processing
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205110.pdf (Publisher’s version ) (Open Access)Radboud University, 06 juni 2019Promotor : Medendorp, W.P. Co-promotor : Maris, E.G.G
On the identification, characterization and investigation of phase dependent coupling in neuronal networks
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141050.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 02 juni 2015Promotor : Ullsperger, M. Co-promotor : Maris, E.G.G.185 p
Preparing for perception: On the attentional modulation, perceptual relevance and physiology of oscillatory neural activity
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124938.pdf (Publisher’s version ) (Open Access)Radboud Universiteit Nijmegen, 18 maart 2014Promotor : Ullsperger, M. Co-promotor : Maris, E.G.G.192 p
Automatic Facilitation ofMovements by Tactile Input: Evidence for a Somatomotor Route in Spatial Orienting
No full textlt is well-established that salient stimuli (exogenous cues) facilitate perception. Here, we addressed whether salient stimuli also facilitate action, and through what route this is mediated. Participants responded to a nonspatial imperative response signa! with button press using their left or right thumb. At different intervals prior to the response signa! a left or right tactile, auditory or visual stimulus was presented, whose side was independent from the required response side. To distinguish between influences that do and do not rely on spatial representations participants either held their hands in front of their body midline or to the left or right of it. We observe that only tactile stimuli facilitated movement at the side of the task-irrelevant stimulus, and that this occurred independent of the hand position in extemal space. Whereas previous studies have attributed the influence of salient stimuli on perception to supramodal spatial representations as contained in the fronto-parietal ventral attentional network, our data suggest a complementary, more direct, route through which salient tactile events may trigger orienting responses in action, which relies on direct connections between somatosensory and motor areas of the brain
Do rhythmic patterns in perceptual sensitivit reflect an electro-physiological clocking mechanism linking motor and perceptual processes
No full textAs of late, there has been increasing amounts of evidence for rhythmic processes underlying both
the motor and visual sensory system, and their connection to the effective processing of stimuli in
the environment. Research suggests that motor action is involved in synchronizing the firing of
neurons in the brain, preparing for stimuli in a rhythmic fashion. In this study, we show significant
rhythmic oscillations in the alpha and theta wave band, in both the parietal-occipital cortex and
the frontal cortex, time-locked to movement onset while attending a low-contrast stimulus. This
rhythmicity is most evident over the entire medial cortex between the frontal and occipital lobes.
This hints at a link between rhythmicity in perceptual sensitivity, time-locked to movement onset
and rhythmic oscillations causing phases of higher and lower neuronal excitability
Power-to-Potential Correlations Identify Markers of Response Inhibition in Human EEG
No full textWhile different ERP markers of response inhibition have been documented in the literature, these are usually identified by comparing either executed- versus inhibited responses (the Go/NoGo task) or correctly inhibited- versus incorrectly executed responses (the stop-signal task). Not only are these comparisons confounded with response execution and/or error commission, but they also ignore other information available that can be used to identify traces of response inhibition in human EEG. We designed a novel task that forces participants to continuously prepare a response and then inhibit it in favor of another response, mostly without the need to actually execute a response. Building on the assumption that more strongly prepared responses also require stronger inhibition to be overruled, we index how strongly a previous response was prepared, through the alpha- and beta power decrease over motor channels, and then correlate this index with the ERP during the following response inhibition period, to identify components that scale with the required strength of inhibition. With this approach, unconfounded by response execution or error commission, we identify a frontal negativity and parietal positivity related to response inhibition. Furthermore, we provide some tentative evidence that this topography can also distinguish between successful and unsuccessful response inhibition when motor confounds are eliminated
Mogelijkheden van beperking van statistische uitzuivering binnen schooleffectiviteitsonderzoek
No full textItem does not contain fulltextThe objective of this article is to give a didactic presentation of the contribution of statistics to school effectiviness research. Our advice for the methodology of school effectiviness is not new. The contribution of this article is twofold: (a) precise formulation of the research question and (b) an evaluation of the existing methods as an answer to this question. We start from a precise definition of what we want to compute (estimate): the school effect. To make an unbiased estimate of the school effect, one has to take into account differences between the schools incoming students and differences between the schools in drop-outs. The starting-point for a possible solution for both of these problems in prediction on the basis of covariates. It is not guaranteed that this solution produces an unbiased estimate, but the solution will be better as more covariates are used as a basis for the prediction
A bicycle can be balanced by stochastic optimal feedback control but only with accurate speed estimates
No full textBalancing a bicycle is typical for the balance control humans perform as a part of a whole range of behaviors (walking, running, skating, skiing, etc.). This paper presents a general model of balance control and applies it to the balancing of a bicycle. Balance control has both a physics (mechanics) and a neurobiological component. The physics component pertains to the laws that govern the movements of the rider and his bicycle, and the neurobiological component pertains to the mechanisms via which the central nervous system (CNS) uses these laws for balance control. This paper presents a computational model of this neurobiological component, based on the theory of stochastic optimal feedback control (OFC). The central concept in this model is a computational system, implemented in the CNS, that controls a mechanical system outside the CNS. This computational system uses an internal model to calculate optimal control actions as specified by the theory of stochastic OFC. For the computational model to be plausible, it must be robust to at least two inevitable inaccuracies: (1) model parameters that the CNS learns slowly from interactions with the CNS-attached body and bicycle (i.e., the internal noise covariance matrices), and (2) model parameters that depend on unreliable sensory input (i.e., movement speed). By means of simulations, I demonstrate that this model can balance a bicycle under realistic conditions and is robust to inaccuracies in the learned sensorimotor noise characteristics. However, the model is not robust to inaccuracies in the movement speed estimates. This has important implications for the plausibility of stochastic OFC as a model for motor control
The correction of a formula in the speed-accuracy decomposition technique of Meyer, Irwin, Osman, and Kounios (1988)
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63611.pdf (Publisher’s version ) (Open Access)The speed-accuracy decomposition (SAD) technique was developed by Meyer et al. (Psychol. Rev. 95 (1988) 183) for studying the course of information accumulation during stimulus processing. This technique aims at calculating the so-called sophisticated-guessing probability. In this note, it is shown that Meyer et al. (Psychol. Rev. 95 (1988) 183) used an incorrect formula for calculating the sophisticated-guessing probability. The correct formula is derived and the implications for the SAD technique are discussed. (C) 2003 Elsevier Inc. All rights reserved
The role of orthographic and phonological codes in the word and the pseudoword superiority effect: an analysis by means of multinomial processing tree models
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269021.pdf (Publisher’s version ) (Open Access)23 p
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