603 research outputs found

    Generalized lapse of responding in trait impulsivity indicated by ERPs: the role of energetic factors in inhibitory control

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    Impaired inhibitory control is one of the still debated underlying mechanisms of trait impulsivity. The Cognitive Energetic Model accounts for the role of energetic factors mediating task performance. The aim of the present study was to compare inhibitory control functions of adults with high and low impulsivity by using a modified Eriksen flanker task. Adults were classified as impulsive (n = 15) and control (n = 15) participants based on the Barratt Impulsiveness Scale. Flanker trials had three levels of required effort manipulated by visual degradation. We analyzed RT, accuracy, and ERPs time-locked to the flanker stimuli. Reaction time of impulsive participants was generally slower than that of controls', but accuracy was similar across groups. N2c showed that monitoring of response conflict was modulated by task requirements independent of impulsivity. The P3 latency was delayed in the impulsive group indicating slower stimulus evaluation. The P3 amplitude was reduced in the control group for moderately degraded incongruent trials suggesting that the attentional resources were employed less. The Lateralized Readiness Potential (LRP) peaked later in the impulsive group irrespective of experimental effects. The amplitude of the positive-going LRP recorded in the incongruent condition was comparable across groups, but the latency was delayed partly supporting a stronger susceptibility to stimulus interference of impulsive participants. Their delayed incongruent negative-going LRP reflected a weaker response inhibition and a slower correct response organization. In conclusion, impaired inhibitory functions in impulsivity could not be unequivocally demonstrated, but we found a generalized lapse of motor activation

    Investigating The Relationship between Event-Related Potentials and Response Kinematics

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    Movement is one of the most important functions of our nervous system. Recent research has shown that cognitive and perceptual functions ranging from our perception of others’ emotions to the planning of goal-directed behaviors depends critically on brain areas once thought to be primarily motor in nature. Given the important role our motor system plays in understanding and interacting with the world around us, it is surprising that the majority of cognitive neuroscience research using electroencephalogram (EEG) has focused primarily on perception and cognition irrespective of its relationship(s) to the execution of movement. One possible explanation for this is that EEG and event-related potential (ERP) studies typically rely on simplistic motor responses and ERP averaging techniques that do not afford an analysis of these dynamic relationships. Combining a novel method for tracking dynamic cursor movement and single-trial EEG analysis, the current study addressed this limitation in the field via assessment of younger and older adults’ goal-directed movements during a task-set switching procedure. Our results demonstrate that ERPs conventionally interpreted with respect to cognition and perception are in fact related to the kinematics of motor responses

    Investigating the modulation of cognition and event-related potentials relating to visual attention, working memory, and executive control in habitual videogame players

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    The overall objective of this thesis was to produce a document that investigated whether habitual videogame playing modulated cognitive processes related to visual processing and where in the processing stream these modulations occur. In this thesis, the term ‘cognitive modulation’ refers to any neurological differences (as identified through ERP) between videogame players and non-videogame players that theoretically may have been a result of videogame playing. Using this method, I am able to ascertain whether differences between the two groups are observed in early sensory ERPs, in which case VGPs might possess an advantage in bottom-up visual processing, later selective attention which might indicate alterations in top-down attentional processing, motor-response waveforms that may indicate difference in stimulus response mappings, and finally any differences in working memory capacity that might be the underlying cause of supposed attentional differences. An example of cognitive modulation was observed by Wu et al., (2012) and discussed in more detail in the introduction of this thesis. Indeed these modulations should also be accompanied by a behavioural difference between the two groups. As ERP was the primary source of neurophysiological recordings in this thesis, modulations could occur in the amplitude, mean activity, or peak latency of ERP waveforms.The paradigms employed in this thesis were chosen and designed so that in combination they provide a measure of potential cognitive modulation across the entire processing stream. That is, from early sensory ERPs, through selective attentional ERPs, including executive control ERPs and concluding at ERPs related to motor response priming. As these studies primarily focused on attentional processes, an ERP chapter towards the end of this thesis was included to identify whether any modulations in attentional ERPs were an indirect result of modulated working memory.Chapters 2 and 3 in this thesis focus on attentional control, resources, and the inhibitory processes of attention. Specifically, these chapters related to the attentional control each group employed when being presented with distracting items. Indeed, I observed modulated cognitive processes in chapter 3 related inhibitory processing in both attention and executive control related processes. In addition to this, the flanker task in Chapter 3 also allowed me to measure and modulation in motor priming between videogame players and non-videogame players.Chapters 4 and 5 looked more closely at ERPs related to selective attention such as the N2pc and P3, alongside early sensory ERPs (N1, P1, etc.). In response to observing differences in how each group processed distractors (related to the N2pc in Chapter 4), Chapter 5 employed a very specific test in order to split the N2pc into its component parts to further investigate whether any cognitive modulation between groups was a result of altered priority on processing targets or inhibiting distractors.Chapter 6 in this thesis sought to identify whether any differences observed in the attentional processing stream was actually the result of modulations in working memory, a cognitive process theoretically closely related to selective attention. Chapter 6 measured the contralateral delay activity, a neurological waveform that correlates with items held in visual working memory.Chapter 7 provided further exploratory psychophysical testing to identify whether any potential behavioural between-group differences extend beyond the usual visual field our groups would play videogames in. This involved testing the crowding phenomenon whereby participants are unable to identify a stimulus when closely flanked by distractors.This these concludes with Chapter 8, an overall discussion of each chapters results and how these theoretically synthesise with one another in relation to the two objectives of this thesis; does videogame playing modulate cognitive, and where in the attentional processing stream does this occur

    The N400/FN400 and Lateralized Readiness Potential Neural Correlates of Valence and Origin of Words’ Affective Connotations in Ambiguous Task Processing

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    Recent behavioral studies revealed an interesting phenomenon concerning the influence of affect on the interpretation of ambiguous stimuli. In a paradigm, where the participants’ task was to read a word, remember its meaning for a while, and then choose one of two pictorial-alphabet-like graphical signs best representing the word sense, we observed that the decisions involving trials with reflective-originated verbal stimuli were performed significantly longer than decisions concerning other stimuli (i.e., automatic-originated). The origin of an affective reaction is a dimension which allows speaking of an affect as automatic (you feel it in your guts) or reflective (you feel it comes from your mind). The automatic affective reaction represents the immediate and inescapable as opposed to the reflective, i.e., the delayed and controllable affective responses to stimuli. In the current experiment, we investigated the neural correlates of performance in an QR-signs-selection ambiguous task. We found the effects of valence and origin in the N400/FN400 potential by means of a stimuli-locked analysis of the initial part of the task, that is, the remembering of a certain word stimulus in a working memory. The N400/FN400 effects were separated in space on scalp distribution. Reflective originated stimuli elicited more negative FN400 than other conditions, which means that such stimuli indeed are associated with conceptual incongruence or higher affective complexity of meaning, but distinct from purely cognitive concreteness. Moreover, the amplitude of the potential preceding the decision, analyzed in the response-locked way, was shaped by the origin of an affective state but not valence. Trials involving decisions concerning reflective-originated words were characterized by a more negative amplitude than trials involving automatic-originated and control word stimuli. This corresponds to the observed pattern of response latencies, where we found that latencies for reflective stimuli were longer than for automatic originated or control ones. Additionally, this study demonstrates that the proposed new ambiguous paradigm is useful in studies concerning the influence of affect on decisions

    The neurocognitive underpinnings of the Simon effect: An integrative review of current research

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    Published online: 7 October 2020For as long as half a century the Simon task – in which participants respond to a nonspatial stimulus feature while ignoring its position – has represented a very popular tool to study a variety of cognitive functions, such as attention, cognitive control, and response preparation processes. In particular, the task generates two theoretically interesting effects: the Simon effect proper and the sequential modulations of this effect. In the present study, we review the main theoretical explanations of both kinds of effects and the available neuroscientific studies that investigated the neural underpinnings of the cognitive processes underlying the Simon effect proper and its sequential modulation using electroencephalogram (EEG) and event-related brain potentials (ERP), transcranial magnetic stimulation (TMS), and functional magnetic resonance imaging (fMRI). Then, we relate the neurophysiological findings to the main theoretical accounts and evaluate their validity and empirical plausibility, including general implications related to processing interference and cognitive control. Overall, neurophysiological research supports claims that stimulus location triggers the creation of a spatial code, which activates a spatially compatible response that, in incompatible conditions, interferes with the response based on the task instructions. Integration of stimulus-response features plays a major role in the occurrence of the Simon effect (which is manifested in the selection of the response) and its modulation by sequential congruency effects. Additional neural mechanisms are involved in supporting the correct and inhibiting the incorrect response.This research was supported by the Basque Government through the BERC 2018-2021 program and by the Spanish State Research Agency through BCBL Severo Ochoa excellence accreditation SEV-2015-0490 This study was also funded by Juan de la Cierva-Incorporación (Spanish government; JC) and European Commission (Marie Skłodowska-Curie actions 838536_BILINGUALPLAS; JC), by post-doctoral funding of the University of Bremen (DG; ZF 11/876/08), and by an ERC Advanced Grant (BH: ERC-2015-AdG-694722)

    An electroencephalographic investigation of the impact of eye movements in a change detection task

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    openIn studies involving Event-Related Potentials (ERPs), ocular artifacts such as blinks and saccades can compromise the quality of the recorded neural signals. To address this issue, researchers often manually reject epochs (that is a specific time-window extracted from the continuous EEG signal) containing these artifacts. However, this procedure consistently reduces the number of epochs that can be used for extracting ERPs. An alternative solution is to use Independent Component Analysis (ICA), which can preserve more epochs for analysis by removing only the artifact from the EEG recording. However, the reliability of ICA in neurocognitive studies of lateralized ERP components, such as the Sustained Posterior Contralateral Negativity (SPCN) related to visual working memory load, remains unclear, particularly in contexts where subjects are more likely to make saccades during the task. Furthermore, by using ICA, we are assuming that ocular movements do not interact with the neural signal, which has yet to be confirmed. For this reason, in the present experiment, all the participants were asked to perform a change detection task under two conditions: a ‘free gaze/saccade’ condition, where they were allowed to move their eyes to look at the lateralized stimuli, and a ‘fixation’ condition, where they were required to maintain the gaze on the center of the monitor. The subjects were also split into two groups, each performing the same experiment but with different stimulus presentation times (100 ms and 500 ms) to investigate whether saccades could differently affect the ERP in these conditions. The SPCN components were then extracted using both the Independent Component Analysis (ICA) correction and epoch-rejection methods. The results revealed that ICA correction is a robust and reliable method for experimental paradigms with a short presentation time of the stimuli (100 ms). By removing only the saccades, the features of the SPCN are preserved, suggesting that with this method we can retain a higher number of epochs for the ERP extraction with the certainty that saccades do not alter the neural signal.In studies involving Event-Related Potentials (ERPs), ocular artifacts such as blinks and saccades can compromise the quality of the recorded neural signals. To address this issue, researchers often manually reject epochs (that is a specific time-window extracted from the continuous EEG signal) containing these artifacts. However, this procedure consistently reduces the number of epochs that can be used for extracting ERPs. An alternative solution is to use Independent Component Analysis (ICA), which can preserve more epochs for analysis by removing only the artifact from the EEG recording. However, the reliability of ICA in neurocognitive studies of lateralized ERP components, such as the Sustained Posterior Contralateral Negativity (SPCN) related to visual working memory load, remains unclear, particularly in contexts where subjects are more likely to make saccades during the task. Furthermore, by using ICA, we are assuming that ocular movements do not interact with the neural signal, which has yet to be confirmed. For this reason, in the present experiment, all the participants were asked to perform a change detection task under two conditions: a ‘free gaze/saccade’ condition, where they were allowed to move their eyes to look at the lateralized stimuli, and a ‘fixation’ condition, where they were required to maintain the gaze on the center of the monitor. The subjects were also split into two groups, each performing the same experiment but with different stimulus presentation times (100 ms and 500 ms) to investigate whether saccades could differently affect the ERP in these conditions. The SPCN components were then extracted using both the Independent Component Analysis (ICA) correction and epoch-rejection methods. The results revealed that ICA correction is a robust and reliable method for experimental paradigms with a short presentation time of the stimuli (100 ms). By removing only the saccades, the features of the SPCN are preserved, suggesting that with this method we can retain a higher number of epochs for the ERP extraction with the certainty that saccades do not alter the neural signal

    Cortical Components of Reaction-Time during Perceptual Decisions in Humans

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    The mechanisms of perceptual decision-making are frequently studied through measurements of reaction time (RT). Classical sequential-sampling models (SSMs) of decision-making posit RT as the sum of non-overlapping sensory, evidence accumulation, and motor delays. In contrast, recent empirical evidence hints at a continuous-flow paradigm in which multiple motor plans evolve concurrently with the accumulation of sensory evidence. Here we employ a trial-to-trial reliability-based component analysis of encephalographic data acquired during a random-dot motion task to directly image continuous flow in the human brain. We identify three topographically distinct neural sources whose dynamics exhibit contemporaneous ramping to time-of-response, with the rate and duration of ramping discriminating fast and slow responses. Only one of these sources, a parietal component, exhibits dependence on strength-of-evidence. The remaining two components possess topographies consistent with origins in the motor system, and their covariation with RT overlaps in time with the evidence accumulation process. After fitting the behavioral data to a popular SSM, we find that the model decision variable is more closely matched to the combined activity of the three components than to their individual activity. Our results emphasize the role of motor variability in shaping RT distributions on perceptual decision tasks, suggesting that physiologically plausible computational accounts of perceptual decision-making must model the concurrent nature of evidence accumulation and motor planning
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