ERP Amplitudes Research Articles

Brain activity associated with logical inferences in geometry: focusing on students with different levels of ability

Mathematical processing associated with solving short geometry problems requiring logical inference was examined among students who differ in their levels of general giftedness (G) and excellence in mathematics (EM) using ERP research methodology. Sixty-seven male adolescents formed four major research groups designed according to various combinations of G and EM factors, while another group of seven students were considered to be ‘super mathematically gifted’ (S-MG). EM and G factors affected behavioral measures similarly: EM and G students were more accurate than their non-EM and non-G counterparts respectively. At the same time, G and EM factors affected electrophysiological measures differently, with significant interaction between G and EM factors associated with absolute ERP amplitudes at some of the solution stages. S-MG students exhibited significantly lower absolute ERP amplitude values, which we attribute to a neural efficiency effect in this research group. Based on the differences revealed, we suggest that our research demonstrates that G and EM factors are interrelated individual traits which are different in nature. Since the accuracy and strength of electrical potentials associated with solving the problems appeared to be of an accumulative nature, we argue that S-MG is an extreme expression of combined EM and G factors. Taking it one step further, we suggest that ability grouping in school mathematics must take into account both EM and G factors.

Acute effects of theanine, caffeine and theanine–caffeine combination on attention

Objective: l-theanine is a constituent of tea which is claimed to enhance cognitive functions. We aimed to determine whether theanine and theanine–caffeine combination have acute positive effects on cognitive and neurophysiological measures of attention, compared to caffeine (a positive control) and a placebo in healthy individuals.Design: In a placebo-controlled, five-way crossover trial in 20 healthy male volunteers, we compared the effects of l-theanine (200 mg), caffeine (160 mg), their combination, black tea (one cup) and a placebo (distilled water) on cognitive (simple [SVRT] and recognition visual reaction time [RVRT]) and neurophysiological (event-related potentials [ERPs]) measures of attention. We also recorded visual (VEPs) and motor evoked potentials (MEPs) to examine any effects of treatments on peripheral visual and motor conduction, respectively.Results: Mean RVRT was significantly improved by theanine (P = 0.019), caffeine (P = 0.043), and theanine–caffeine combination (P = 0.001), but not by tea (P = 0.429) or placebo (P = 0.822). VEP or MEP latencies or SVRT did not show significant inter-treatment differences. Theanine (P = 0.001) and caffeine (P = 0.001) elicited significantly larger mean peak-to-peak N2-P300 ERP amplitudes than the placebo, whereas theanine–caffeine combination elicited a significantly larger mean N2-P300 amplitude than placebo (P < 0.001), theanine (P = 0.029) or caffeine (P = 0.005). No significant theanine × caffeine interaction was observed for RVRT or N2-P300 amplitude.Discussion: A dose of theanine equivalent of eight cups of back tea improves cognitive and neurophysiological measures of selective attention, to a degree that is comparable with that of caffeine. Theanine and caffeine seem to have additive effects on attention in high doses.

Mismatch negativity and neural adaptation: Two sides of the same coin. Response: Commentary: Visual mismatch negativity: a predictive coding view.

Mismatch negativity and neural adaptation: Two sides of the same coin. Response: Commentary: Visual mismatch negativity: a predictive coding view.

Attention-dependent sound offset-related brain potentials.

When performing sensory tasks, knowing the potentially occurring goal-relevant and irrelevant stimulus events allows the establishment of selective attention sets, which result in enhanced sensory processing of goal-relevant events. In the auditory modality, such enhancements are reflected in the increased amplitude of the N1 ERP elicited by the onsets of task-relevant sounds. It has been recently suggested that ERPs to task-relevant sound offsets are similarly enhanced in a tone-focused state in comparison to a distracted one. The goal of the present study was to explore the influence of attention on ERPs elicited by sound offsets. ERPs elicited by tones in a duration-discrimination task were compared to ERPs elicited by the same tones in not-tone-focused attentional setting. Tone offsets elicited a consistent, attention-dependent biphasic (positive-negative--P1-N1) ERP waveform for tone durations ranging from 150 to 450 ms. The evidence, however, did not support the notion that the offset-related ERPs reflected an offset-specific attention set: The offset-related ERPs elicited in a duration-discrimination condition (in which offsets were task relevant) did not significantly differ from those elicited in a pitch-discrimination condition (in which the offsets were task irrelevant). Although an N2 reflecting the processing of offsets in task-related terms contributed to the observed waveform, this contribution was separable from the offset-related P1 and N1. The results demonstrate that when tones are attended, offset-related ERPs may substantially overlap endogenous ERP activity in the postoffset interval irrespective of tone duration, and attention differences may cause ERP differences in such postoffset intervals.

EEG source activity during processing of neutral stimuli in subjects with anxiety disorders.

Anxiety disorders are a social problem due to their prevalence and consequences. It is crucial to explore the influence of anxiety on cognitive processes. In this study we recorded EEG activity from 73 subjects (35 patients, 38 controls, matched for age and education) during performance of the Continuous Attention Task. We used low resolution electromagnetic tomography (LORETA) for evaluation of mechanisms of impaired cognitive performance in anxiety disorders. Analysis showed that patients with anxiety disorders committed more errors than the controls, had a short latency of P300 and higher amplitude of ERPs at all steps of stimulus processing. Furthermore, we showed that there was a relationship between the scores of Hamilton Anxiety Scale and Beck Depression Inventory, and amplitudes and latencies of ERPs. The results of LORETA analysis showed that enhanced neural responses were found within circuits mediating visual information processing, sustained attention and anxiety. Also, we found higher current density within areas playing an important role in the brain fear network - anterior cingulate and anterior part of insula. Electrophysiological neuroimaging showed greater recruitment of cognitive resources in anxiety disorders, evidenced by higher current density and activation of greater number of brain areas. Despite the strategy employed to compensate for cognitive problems, the anxiety patients did not achieve the same performance as controls. Present study demonstrates that anxiety disorders influence processing of neutral stimuli and this influence is observable at both behavioral and electrophysiological level. The data suggests instability of neural systems responsible for information selection, working memory, engagement and focusing of attention.

Insights into affective word processing and geriatric depression through the combination of Event-Related Potentials with Cortical Brain Network Analysis

Insights into affective word processing and geriatric depression through the combination of Event-Related Potentials with Cortical Brain Network Analysis

When Feelings Arise with Meanings: How Emotion and Meaning of a Native Language Affect Second Language Processing in Adult Learners.

To determine when and how L2 learners start to process L2 words affectively and semantically, we conducted a longitudinal study on their interaction in adult L2 learners. In four test sessions, spanning half a year of L2 learning, we monitored behavioral and ERP learning-related changes for one and the same set of words by means of a primed lexical-decision paradigm with L1 primes and L2 targets. Sensitivity rates, accuracy rates, RTs, and N400 amplitude to L2 words and pseudowords improved significantly across sessions. A semantic priming effect (e.g, prime “driver”facilitating response to target “street”) was found in accuracy rates and RTs when collapsing Sessions 1 to 4, while this effect modulated ERP amplitudes within the first 300 ms of L2 target processing. An overall affective priming effect (e.g., “sweet” facilitating”taste”) was also found in RTs and ERPs (posterior P1). Importantly, the ERPs showed an L2 valence effect across sessions (e.g., positive words were easier to process than neutral words), indicating that L2 learners were sensitive to L2 affective meaning. Semantic and affective priming interacted in the N400 time-window only in Session 4, implying that they affected meaning integration during L2 immersion together. The results suggest that L1 and L2 are initially processed semantically and affectively via relatively separate channels that are more and more linked contingent on L2 exposure.

Facial emotion memory in schizophrenia: From encoding to maintenance-related EEG

ObjectivePersons with schizophrenia exhibit deficits recognizing facial emotions, which may impact social functioning. Whether these deficits reflect aberrant sensory processing, an inability to maintain information in memory, or dysfunctional integration of these two functions remains unclear. MethodsA facial emotion memory paradigm was administered to 38 schizophrenia patients (SZ) and 42 healthy controls (HC). P100, N170 and N250 ERP amplitudes were measured to assess sensory processing. Evoked theta power during the delay interval was quantified to assess memory maintenance. ResultsThe N170 ERP was larger to negative compared to neutral facial expressions in both groups, while SZ exhibited increased evoked theta power during the delay interval. Increased theta power was associated with worse behavioral performance in response to sad and fearful expressions for HC, but this relationship was only found in response to fearful expressions for SZ. Finally, only HC showed consistent correlations between N170 amplitude and theta power during the delay interval. ConclusionsIntegration between measures of sensory processing and memory functioning may be affected in SZ. SignificanceThese findings may indicate that the oscillatory networks subserving emotion processing and sustained attention are intertwined, and comprise part of the social brain network that is affected in schizophrenia.

ERP measures of math anxiety: how math anxiety affects working memory and mental calculation tasks?

There have been several attempts to account for the impact of Mathematical Anxiety (MA) on brain activity with variable results. The present study examines the effects of MA on ERP amplitude during performance of simple arithmetic calculations and working memory tasks. Data were obtained from 32 university students as they solved four types of arithmetic problems (one- and two-digit addition and multiplication) and a working memory task comprised of three levels of difficulty (1, 2, and 3-back task). Compared to the Low-MA group, High-MA individuals demonstrated reduced ERP amplitude at frontocentral (between 180–320 ms) and centroparietal locations (between 380–420 ms). These effects were independent of task difficulty/complexity, individual performance, and general state/trait anxiety levels. Results support the hypothesis that higher levels of self-reported MA are associated with lower cortical activation during the early stages of the processing of numeric stimuli in the context of cognitive tasks.

Ageing effects on word production processes: an ERP topographic analysis

The increasing word-finding difficulty is one of the most investigated characteristics of language ageing. The transmission deficit model postulates an age-related weakening in the pathway from lexicon to phonology, leading to insufficient priming of the complete phonology. To bring neurophysiological evidence of age-related modifications in word production, we investigated the inter-age time course of ERPs in picture naming compared to picture–word verification, where lexical–phonological processes are not involved. Only marginal age-related differences in RTs were found in picture naming. Older adults showed lower accuracy in picture naming, but higher accuracy in picture–word verification. Between-age ERP divergences were observed in an early time window associated with semantic processes. In picture naming, age differences in ERP amplitudes were also observed in a later time window compatible with phonological processing. Results suggest that modifications in word production could stem from age-related changes affecting the processing dynamics in the semantic system.

Rapid cortical dynamics associated with auditory spatial attention gradients

Behavioral and EEG studies suggest spatial attention is allocated as a gradient in which processing benefits decrease away from an attended location. Yet the spatiotemporal dynamics of cortical processes that contribute to attentional gradients are unclear. We measured EEG while participants (n = 35) performed an auditory spatial attention task that required a button press to sounds at one target location on either the left or right. Distractor sounds were randomly presented at four non-target locations evenly spaced up to 180° from the target location. Attentional gradients were quantified by regressing ERP amplitudes elicited by distractors against their spatial location relative to the target. Independent component analysis was applied to each subject's scalp channel data, allowing isolation of distinct cortical sources. Results from scalp ERPs showed a tri-phasic response with gradient slope peaks at ~300 ms (frontal, positive), ~430 ms (posterior, negative), and a plateau starting at ~550 ms (frontal, positive). Corresponding to the first slope peak, a positive gradient was found within a central component when attending to both target locations and for two lateral frontal components when contralateral to the target location. Similarly, a central posterior component had a negative gradient that corresponded to the second slope peak regardless of target location. A right posterior component had both an ipsilateral followed by a contralateral gradient. Lateral posterior clusters also had decreases in α and β oscillatory power with a negative slope and contralateral tuning. Only the left posterior component (120–200 ms) corresponded to absolute sound location. The findings indicate a rapid, temporally-organized sequence of gradients thought to reflect interplay between frontal and parietal regions. We conclude these gradients support a target-based saliency map exhibiting aspects of both right-hemisphere dominance and opponent process models.

Memory, emotion, and pupil diameter: Repetition of natural scenes

Recent studies have suggested that pupil diameter, like the "old-new" ERP, may be a measure of memory. Because the amplitude of the old-new ERP is enhanced for items encoded in the context of repetitions that are distributed (spaced), compared to massed (contiguous), we investigated whether pupil diameter is similarly sensitive to repetition. Emotional and neutral pictures of natural scenes were viewed once or repeated with massed (contiguous) or distributed (spaced) repetition during incidental free viewing and then tested on an explicit recognition test. Although an old-new difference in pupil diameter was found during successful recognition, pupil diameter was not enhanced for distributed, compared to massed, repetitions during either recognition or initial free viewing. Moreover, whereas a significant old-new difference was found for erotic scenes that had been seen only once during encoding, this difference was absent when erotic scenes were repeated. Taken together, the data suggest that pupil diameter is not a straightforward index of prior occurrence for natural scenes.

Biomarkers reflecting the effects of deep brain stimulation on cognitive control

s / Brain Stimulation 8 (2015) 360e377 375 NoGo visual discrimination task with threat-related emotional distractors. During the task, stimulation was switched ON and OFF every few minutes. Repeated Measures Analysis of Variance was carried out for RTs and Go N2-P3 ERP amplitude with Stimulation (ON, OFF) and Emotion (neutral, threat) as within subjects factors. ANT-DBS was associated with enhanced right parietal Go N2-P3 amplitude and increased reaction time in the context of emotional distractors. Threat related distractors increased attention related parietal N2-P3 amplitude and prolonged response speed during ANT-DBS. In summary, stimulating ANT increased attention allocation to negative emotional information. Enhanced attention allocation to negative emotional information, i.e. negativity bias, is linked with depression. The current results show promise for objective behavioral and electrophysiological biomarkers reflecting mood related stimulation effects. Such biomarkers for objective assessment of the stimulation effects on affective functions have major clinical significance with DBS used for treating depression as well as depressive symptoms reported as side effects of ANT-DBS.

Spatiotemporal Neural Pattern Similarity Supports Episodic Memory

Formal computational models of human memory posit a central role of feature representations in episodic memory encoding and retrieval [1-4]. Correspondingly, fMRI studies have found that, in addition to activity level [5, 6], the neural activation pattern similarity across repetitions (i.e., self-similarity) was greater for subsequently remembered than forgotten items [7-9]. This self-similarity has been suggested to reflect pattern reinstatement due to study-phase retrieval [7, 10, 11]. However, the low temporal resolution of fMRI measures could determine neither the temporal precision of study-phase reinstatement nor the processing stage at which the reinstatement supported subsequent memory [12]. Meanwhile, although self-similarity has been shown to correlate with the activity level in the left lateral prefrontal cortex (LPFC) [10, 13], a causal link between left LPFC function and pattern similarity remains to be established. Combining transcranial direct current stimulation (tDCS) and EEG, we found that greater spatiotemporal pattern similarity (STPS) across repetitions of the same item (i.e., self-STPS) during encoding predicted better subsequent memory. The self-STPS located in the right frontal electrodes occurred approximately 500ms after stimulus onset, reflected item-specific encoding, and contributed to memory above and beyond the effects of ERP amplitude and global pattern similarity (i.e., similarity to all other items in memory space). Anodal stimulation over the left LPFC specifically enhanced memory performance and item-specific STPS in the right frontal electrodes. These results support a causal role of LPFC in enhancing STPS and memory and contribute to a mechanistic understanding of memory formation.

Effects of prediction and contextual support on lexical processing: Prediction takes precedence

Readers may use contextual information to anticipate and pre-activate specific lexical items during reading. However, prior studies have not clearly dissociated the effects of accurate lexical prediction from other forms of contextual facilitation such as plausibility or semantic priming. In this study, we measured electrophysiological responses to predicted and unpredicted target words in passages providing varying levels of contextual support. This method was used to isolate the neural effects of prediction from other potential contextual influences on lexical processing. While both prediction and discourse context influenced ERP amplitudes within the time range of the N400, the effects of prediction occurred much more rapidly, preceding contextual facilitation by approximately 100ms. In addition, a frontal, post-N400 positivity (PNP) was modulated by both prediction accuracy and the overall plausibility of the preceding passage. These results suggest a unique temporal primacy for prediction in facilitating lexical access. They also suggest that the frontal PNP may index the costs of revising discourse representations following an incorrect lexical prediction.

Early Auditory Evoked Potential Is Modulated by Selective Attention and Related to Individual Differences in Visual Working Memory Capacity

A growing body of research suggests that the predictive power of working memory (WM) capacity for measures of intellectual aptitude is due to the ability to control attention and select relevant information. Crucially, attentional mechanisms implicated in controlling access to WM are assumed to be domain-general, yet reports of enhanced attentional abilities in individuals with larger WM capacities are primarily within the visual domain. Here, we directly test the link between WM capacity and early attentional gating across sensory domains, hypothesizing that measures of visual WM capacity should predict an individual's capacity to allocate auditory selective attention. To address this question, auditory ERPs were recorded in a linguistic dichotic listening task, and individual differences in ERP modulations by attention were correlated with estimates of WM capacity obtained in a separate visual change detection task. Auditory selective attention enhanced ERP amplitudes at an early latency (ca. 70-90 msec), with larger P1 components elicited by linguistic probes embedded in an attended narrative. Moreover, this effect was associated with greater individual estimates of visual WM capacity. These findings support the view that domain-general attentional control mechanisms underlie the wide variation of WM capacity across individuals.

Reduced ERP amplitudes for animal stimuli in the absence of conscious awareness

and easily extracted; (2) Animal stimuli deviate from non-animal stimuli around 150ms after stimulus onset (ERPs, Thorpe, Fize et al. 1996) Question: (1) Does this remarkable capability function in the absence of awareness? (2) Are there any differences between animal and non-animal in the suppressed condition? (Are animals special?) Introduction Paradigm: CFS (continuous flash suppression) break-through (experiment 1) and plain CFS paradigm (experiment 2,3, EEG) were used.

Electrophysiological explorations of the bilingual advantage: evidence from a Stroop task.

Bilinguals have been shown to exhibit a performance advantage on executive control tasks, outperforming their monolingual counterparts. Although a wealth of research has investigated this ‘bilingual advantage’ behaviourally, electrophysiological correlates are lacking. Using EEG with a Stroop task that manipulated the stimulus onset asynchrony (SOA) of word and colour presentation, the current study addressed two facets of the bilingual advantage. The possibility that bilinguals experience superior conflict processing relative to monolinguals (a ‘conflict-specific advantage’) was investigated by comparing behavioural interference effects as well as the amplitude of the Ninc, a conflict-related ERP component occurring from approximately 300–500 ms after the onset of conflict. In contrast, the hypothesis that bilinguals experience domain-general, conflict-independent enhancements in executive processing (a ‘non-conflict-specific advantage’) was evaluated by comparing the control condition (symbol strings) between groups. There was some significant, but inconsistent, evidence for a conflict-specific bilingual advantage. In contrast, strong evidence emerged for a non-conflict-specific advantage, with bilinguals demonstrating faster RTs and reduced ERP amplitudes on control trials compared to monolinguals. Importantly, when the control stimulus was presented before the colour, ERPs to control trials revealed group differences before the onset of conflict, suggesting differences in the ability to ignore or suppress distracting irrelevant information. This indicates that bilinguals experience superior executive processing even in the absence of conflict and semantic salience, and suggests that the advantage extends to more efficient proactive management of the environment.

Patients with schizophrenia demonstrate reduced cortical sensitivity to auditory oddball regularities

BackgroundIndividuals with schizophrenia demonstrate deficits in context processing. These deficits can be characterized by examining the influence of auditory context on ERP responses to rare target tones. Previous studies demonstrate that target ERP deficits in schizophrenia depend on the number of non-targets that precede the target ERP. Our goal was to extend these findings by examining whether patients with schizophrenia demonstrate a reduced sensitivity to subtle differences in the auditory context preceding rare target stimuli, as quantified by Itti and Baldi's Bayesian prediction error model. MethodsCortical responses to auditory oddball tones were measured within 59 individuals with schizophrenia (SZ) and 59 controls (HC). Individual trial amplitudes were estimated by conducting group ICA on the EEG time series and analyzing the reconstructed individual temporal sources. We quantified the auditory context of target tones using the Bayesian prediction error model and determined whether ERP amplitudes to tones were sensitive to this measure of context, or the number of preceding non-targets directly, within HC and SZ. ResultsIndividuals with schizophrenia show a significant reduction in ERP response amplitudes to targets approximately 244–412ms following target onsets. Individual amplitudes within this window showed significantly greater sensitivity to the modeled prediction error within the controls than in individuals with schizophrenia. These differences approached significance when examining differences in amplitudes as a function of the number of preceding non-targets. ConclusionsThese findings further clarify differences in HC and SZ with regard to their attentional and perceptual sensitivity to subtle environmental regularities.

HETEROGENEITY OF CEREBROSPINAL FLUID BIOMARKER LEVELS IN COGNITIVELY NORMAL INDIVIDUALS WITH A FAMILY HISTORY OF ALZHEIMER'S DISEASE

revealed no differences across groups. The 3 groups performed the same on ITC and ERP measures in the fN400 region and time window. Analysis of recollection revealed significant ITC phase locking to stimulus for mid-aged adults but not for older-adults or patients. ERP analysis revealed older-adults had significantly higher amplitude than the mid-aged and patient groups. Conclusions: Present findings for familiarity indicate no effects with age or pathological change. Findings for recollection show older-adults differ in ERP amplitude compared to the mid-aged and patient groups; while mid-aged differ in ITC compared to older-adults and patients. These findings support the notion that recollection, which requires more integration of information than familiarity, is susceptible to changes in age and pathology. The difference in ITC suggests that while older adults are still able to complete the task, they do so by means than their younger counterparts. One potential explanation for increased amplitude of older-adults, despite their lack of coherence, is the explicit memory task. Olderadults may have implemented a strategy to recruit more resources and complete the task successfully.