Effects of movement advance information were assessed on the prestimulus amplitude of the lateralized readiness potential~LRP!, on the contingent negative variation~CNV!, and on reaction time~RT!. In a precuing paradigm with movement parameters hand, direction, and force, partial precues provided advance information about either hand alone, hand plus force, or hand plus direction, and the full precue specified all response parameters. The full precue produced the shortest RTs and the largest CNV amplitude, precuing hand and force or hand and movement direction produced somewhat slower RTs and a somewhat smaller CNV amplitude, and precuing only hand yielded slowest RTs and the smallest CNV amplitude. In contrast, the LRP amplitude was largest for the full precue and was the same for the remaining precues. The CNV appears to index the central assembling of a motor program, and the LRP represents the implementation of the program at more peripheral levels. The introduction of event-related brain potentials~ERPs! in the study of movement preparation has provided new approaches and insights into what had previously been an exclusively behavioral field. The most successful approach in cognitive psychology to analyze the nature of movement preparation employs the precuing technique developed by Rosenbaum~1980, 1983!. This technique is a variant of a choice reaction time~RT! task, in which each of the possible responses is associated with a single imperative stimulus. Before the onset of the stimulus, a precue conveys information about certain movement parameters. Usually, RT decreases with the amount of advance information provided. From the relation between advance information and the corresponding RT saving, cognitive psychologists hoped to learn more about motoric preparation and the nature of motor programs~e.g., Rosenbaum, 1980!. However, this approach was criticized by Goodman and Kelso~1980! who argued that the RT saving observed with this technique does not reflect a genuine motor effect but rather the facilitation of response selection at a premotoric level. The debate on whether the RT saving reflects a genuine motoric effect could not be settled with the traditional behavioral RT measure because the motoric portion of RT is not directly observable.In resolving this controversy, a new measure, the lateralized readiness potential~LRP!, has recently been used~Leuthold, Sommer, & Ulrich, 1996!; there is strong evidence that the LRP provides a specific index to trace the time course of motor activatioñ cf. Coles, Gratton, & Donchin, 1988;De Jong, Wierda, Mulder, & Mulder, 1988;Miller & Hackley, 1992!. Experiments employing LRP often involve a two-choice RT task in which a precue informs the participant about the responding hand and a subsequent imperative stimulus tells the participant that the response should now be made. During the interval between the precue and the imperative stimulus, the motor readiness potential exhibits greater negativity over the motor cortex contralateral to the responding hand,...
P300 latency is commonly thought to provide a chronometric index of the duration of perceptual processing. Because the evidence in favor of this assumption is controversial, we examined whether P300 latency is influenced by perceptual processes, response selection, and by motoric processes in two experiments using a two-choice spatial stimulus-response compatibility (SRC) task. Both experiments revealed additive effects of perceptual difficulty with spatial SRC in reaction time and P300 latency. In addition, Experiment 2 showed that P300 latency measured in average waveforms is insensitive to motoric processes. The influence of spatial SRC on P300 latency disagrees with the view that P300 latency is sensitive only to stimulus evaluation processes. However, P300 latency may be used to discriminate between influences on premotoric and motoric processing stages. A response conflict account for the SRC effect on P300 latency is suggested.
P300 amplitude and reaction time (RT) are strongly affected by the sequence of events preceding the eliciting stimulus. Sommer, Leuthold and Soetens (1999) found that robust sequential effects in P300 amplitude could be dissociated from more variable sequential effects in RTs. However, global changes in P300 amplitude and topography gave rise to the suggestion that sequential effects are specific for a subcomponent of P300 that is separate from and anterior to the classical parietal P300. Here, confirming evidence for dissociable subcomponents of P300 is reported from two experiments. Independent component analysis separated a centrally distributed sequence-sensitive subcomponent from a more parietal subcomponent. Subsequent dipole source analysis indicated a deep mesial source for the sequence-sensitive subcomponent. Overlap with reafferent somatosensory activity appears to be responsible for an apparent lateralization of this component towards the hemisphere ipsilateral to the responding hand.
Subjective cognitive decline (SCD), as expressed by older adults, is associated with negative affect, which, in turn, is a likely risk factor for Alzheimer’s Disease (AD). This study assessed the associations between negative affective burden, cognitive functioning, and functional connectivity in networks vulnerable to AD in the context of SCD. Older participants (60–90 years) with SCD (n = 51) and healthy controls (n = 50) were investigated in a cross-sectional study. Subclinical negative affective burden, quantified through a composite of self-reported negative affective factors, was related to cognitive functioning (self-perceived and objective) and functional connectivity. Seed-to-voxel analyses were carried out in default mode network (DMN) and salience network (SAL) nodes using resting-state functional magnetic resonance imaging. Greater negative affective burden was associated with lower self-perceived cognitive functioning and lower between-network functional connectivity of DMN and SAL nodes in the total sample. In addition, there was a significant moderation of SCD status. Greater negative affective burden related to higher functional connectivity within DMN (posterior cingulate-to-precuneus) and within SAL (anterior cingulate-to-insula) nodes in the SCD group, whereas in controls the inverse association was found. We show that negative affective burden is associated with functional brain alterations in older adults, regardless of SCD status. Specifically in the SCD phenotype, greater negative affective burden relates to higher functional connectivity within brain networks vulnerable to AD. Our findings imply that negative affective burden should be considered a potentially modifiable target for early intervention.
Electroencephalography (EEG) is widely used in cognitive neuroscience due to high temporal resolution. Typically eventrelated potentials (ERPs) are obtained by averaging single EEG trials synchronized to the onsets of stimuli or responses, with the assumption that each single trial contains more or less the same sequence of sub-processes and ERP components, and the residues between the average and the single trials are noise. However, strong latency variability pervades cognitive EEG responses across single trials. This trial-to-trial variability may strongly smear and mix ERP components and diminish their amplitudes, impeding proper identification of the spatiotemporal representation of brain activities reflecting specific cognitive sub-processes. Furthermore, rich dynamic information about single trials is lost in averaged ERPs. Though it has been recognized for a long time, previous attempts have not succeeded in establishing a latency-variable model as a paradigm for ERP analysis.Here we present a new method RIDE (residue iteration decomposition), which combines the advantages but overcomes the limitations of previous methods, to firmly establish the new paradigm of ERP analysis. The new paradigm simultaneously captures two essential features of neurocognitive processing consisting in several sub-processes, carried out reliably but with more or less trial-to-trial variability, reflected in latency and amplitude variations of the corresponding ERP components. With the new framework, assuming temporally overlapping components with variable latencies and associated with different cognitive events, RIDE allows to extract the ERP components for particular subprocesses. RIDE provides a latency estimation scheme for components without explicit latency information and uses iteration to realize L1-norm minimization to prevent slow wave amplification and distortion typical for conventional temporal decomposition methods. Thus RIDE can be applied to experiments with or without response markers.In the present talk, we describe the principles of RIDE, contrast it to other temporal and spatial ERP decomposition methods both in simulation data and test its applicability in several experimental datasets. RIDE can reconstruct ERP waveforms as most probably observed in single trials and obtain the distributions of latencies and amplitudes of each component among single trials. Applying RIDE, EEG data can now be explored in a much broader scope to study brain-behavior relations by using (1) latency-corrected reconstructed ERPs, (2) separated components for different neurocognitive processes in greater detail and specificity, and (3) information about variability in single trials.Background: In order to deal with the issue of distortion and smearing of ERP components by trial-to-trial latency variability inherent in cognitive task processing studies, RIDE (residue iteration decomposition) method and toolbox were developed to decompose ERP into different component clusters with different latency variability and to represent the E...
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