P300 Amplitude Research Articles

Similarity Distractors Increase the Burden of Chinese Character Selection and Updating in Working Memory.

Attentional mechanisms are the primary processes for performing working memory (WM) tasks and can prevent distractors from interfering with the content representations stored in WM. However, our understanding of the mechanisms by which attention affects WM remains limited. As such, we analyzed ERPs of the character n-back task to investigate Chinese character selection, updating, and maintenance in WM. In Experiment 1, we collected electroencephalography data from 27 participants aged 18-25 years to explore the influence of false-character interference and symbol interference on a neural activity in the character n-back task. The results suggest that RT was longer in the false-character interference condition. The N2pc and P300 amplitudes were smaller; however, the slow wave amplitude did not differ significantly. In Experiment 2, we used a single-symbol interference and a multiple-symbol interference to establish whether the number of interferences affected the neural activity in the character n-back task. Thirty participants (aged 19-25 years) took part in the experiment. The findings imply that a longer RT and a larger N2pc amplitude occurred in the multiple-symbol interference condition, but not in the P300 and slow wave conditions. Our findings indicate that distractors that are similar to characters may produce greater interference in character recognition and affect the subsequent updating, whereas the number of distractors may only interfere with early character selection, but not with updating and maintenance phases.

P1 evoked by facial expression images is enhanced in Parkinson’s disease patients with depressive symptoms

IntroductionDepressive symptoms are most common non-motor symptoms in Parkinson’s disease (PD), which is often overlooked due to absence of rapid and objective diagnostic biomarkers. Electroencephalography (EEG)-based event-related potentials (ERPs) is commonly used to assess emotional processes. The aim of this study was to investigate changes in ERPs in PD patients exhibiting depressive symptoms and to provide a reliable biomarker for assisting in the diagnosis of PD with depressive symptoms.MethodsWe conducted a case–control study involving 30 PD patients with (dPD group) or without depressive symptoms (nPD group) and 13 age matched healthy controls (HC). We recorded EEG of the patients during the emotional picture stimulation task and analyzed the difference in the early ERPs potentials (P1, N170, early posterior negativity) and their correlation with the severity of symptoms in PD patients.ResultsOur results found that P1 amplitude in the occipital region of the dPD group in response to emotional faces was significantly higher than that of nPD and HC group, and it was positively correlated with severity of depressive symptoms in PD patients.ConclusionOur study shows that facial expression-induced enhancement of P1 amplitude can be utilized as a rapid and objective indicator to screen for depressive symptoms in PD.

Expert and Novice Teachers’ Cognitive Neural Differences in Understanding Students’ Classroom Action Intentions

Objectives: Teachers’ intention understanding ability reflects their professional insight, which is the basis for effective classroom teaching activities. However, the cognitive process and brain mechanism of how teachers understand students’ action intention in class are still unclear. Methods: This study used event-related potential (ERP) technology to explore the cognitive neural differences in intention understanding ability among teachers with different levels of knowledge and experience. The experiment used the comic strips paradigm to examine the ability of expert and novice teachers to understand students’ normative and non-normative classroom actions under different text prompts (“how” and “why”). Results: The results revealed that in the late time window, expert teachers induced larger P300 and LPC amplitudes when they understood students’ classroom action intentions, while the N250 amplitudes induced by novice teachers in the early time window were significantly larger. In addition, for both types of teachers, when understanding the intentions behind students’ normative actions, the N250 amplitude was the most significant, while the P300 and LPC amplitudes were more significant for non-normative actions. Conclusions: This study found that teachers at varying professional development stages had different time processing processes in intention understanding ability, which supported teachers’ brain electrophysiological activities related to social ability.

Low frequency-repetitive transcranial magnetic stimulation combined with Xingnao Kaiqiao acupuncture improves post-stroke cognitive impairment and has better clinical efficacy.

Enhancing post-stroke cognitive impairment (PSCI) is a key aspect of prognosis for stroke patients. Low-frequency repetitive transcranial magnetic stimulation (LF-rTMS) is currently a widely utilised method for treating PSCI. With the increasing promotion of traditional Chinese medicine, Xingnao Kaiqiao (XNKQ) acupuncture has been progressively incorporated into clinical treatment. This paper observes the effect of LF-rTMS with XNKQ acupuncture on patients with PSCI. Totally, 192 patients with PSCI were consecutively recruited and treated either with LF-rTMS and XNKQ acupuncture (observation group) or LF-rTMS only (control group) for 4 weeks. The pre- and post-treatment Mini-Mental State Examination (MMSE) and Montreal Cognitive Assessment (MoCA) scores, P300 latency and amplitude, inflammatory factor levels were compared and clinical efficacy was assessed. Both groups exhibited increased MMSE/MoCA scores, and P300 amplitude, and shortened P300 latency, and the observation group had higher scores and P300 amplitude, and shorter P300 latency than the control group. Both groups displayed decreased inflammatory factor levels (Tumour necrosis factor-α, interleukin (IL)-6, IL-10, IL-1β) after treatment, which were lower in the observation group than the control group. Inflammatory factor levels in PSCI patients were negatively interrelated with MMSE, MoCA score and P300 amplitude, and positively with P300 latency. The observation group showed an increased number of patients showing cured and significantly effective results, a decreased number of patients showing effective and invalid results, and an observably elevated total effective rate. LF-rTMS with XNKQ acupuncture can improve cognitive function and reduce inflammatory immune response, and has better clinical efficacy in PSCI patients.

Effects of a Functional Cone Mushroom (Termitomyces fuliginosus) Protein Snack Bar on Cognitive Function in Middle Age: A Randomized Double-Blind Placebo-Controlled Trial

Background: Due to the rising prevalence of cognitive impairment in the middle-aged and elderly population, combined with consumer demand for functional foods to improve health and well-being. Objective: This study aimed to formulate a functional cone mushroom (Termitomyces fuliginosus) (FCM) protein snack bar and evaluate its amino acid profile, phytochemical contents, biological activity and impact on cognitive function. Methods: A total of 26 middle-aged male and female participants were randomized and divided into placebo, FCM1 and FCM2 groups. Continuous consumption was performed for 6 weeks. Demographic data, body composition, cognitive function and memory were evaluated at baseline and at the end of the study period (6 weeks). Results: The event-related potential (ERP) analysis results showed a significant increase in N100 and P300 amplitude at the Fz location in participants who consumed the functional cone mushroom protein snack bar at a dose of 1 g compared to the placebo group (p = 0.015). Additionally, subjects who consumed the functional cone mushroom protein snack bar at a dose of 2 g showed a significantly increased P300 amplitude and percent accuracy of numeric working memory (p = 0.048) compared to those in the placebo group (p = 0.044). The possible underlying mechanism may involve AChE and MAO suppression activity alongside antioxidant activity. Conclusions: These data suggest that FCM can improve cognitive function and memory and may be considered for use in natural supplementation products with possible health benefits.

Neurofeedback Reduces P300 Amplitudes to Intensely Emotive Pictures in Depressed Cancer Patients.

Objective. Electroencephalographic neurofeedback (EEG NF) or its effects on event-related potentials (ERPs) in quantitative EEG have not yet been systematically studied in cancer patients. The aim of this study was to investigate the emotional arousal and valence effects on the event-related P300 in a visual oddball paradigm by an individualized EEG alpha and theta/beta NF intervention in cancer patients and survivors (N = 18, age between 31 and 73 years). Methods. ERPs to low and high arousal target stimuli with either emotional positive or negative content and depressive state were obtained in cancer patients before and after a five-week NF intervention in a waitlist paradigm, following the consensus on the reporting and experimental design of clinical and cognitive-behavioral NF studies (CRED-nf checklist). Results. Overall, P300 amplitudes decreased significantly (p < .05) from pre to post therapy. Effects concerning high arousal stimuli with negative and positive valences were on the border to significance. Moreover, patients achieved significant relief of depressive symptoms (p < .05). Especially younger participants (<55 yrs.) benefited. Conclusions. P300 observations could reflect a therapeutic effect on brain activity level. EEG NF alleviates depressive symptoms in cancer patients. Significance. Based on these findings, further studies are needed to investigate the effects on event-related potentials by NF therapy.

The recovery of decreased executive attention in Tibetan migrants at high-altitude.

Attention is one of the basic cognitive functions sensitive to high altitude, and most studies have focussed on exposure times of approximately 3 years; however, it is unclear how attention changes in migrants who have lived and worked at high altitude for nearly 20 years. We explored the dynamics of attentional networks and neurophysiological mechanisms in migrants over 3-20 years using the Attentional Network Test combined with Electrocardiograph and Electroencephalography and found a consistent quadratic correlation between exposure and executive control efficiency, P3 amplitude and heart rate variability (HRV), with a decrease followed by an increase/relative stability, with approximately 10 years being the breakpoint. However, neither linear nor quadratic trajectories were observed for the alerting and orienting network. Mediation analysis revealed that the P3 amplitude mediated the decrease and increase in executive control efficiency with exposure time depends on the breakpoint. Correlations between HRV and executive control efficiency and P3 amplitude suggest that U-shaped changes in executive control in migrants may be related to body homeostasis maintained by the autonomic nervous system, and that P3 amplitude may serve as a neurophysiological marker of migrants' adaptation/recovery from high-altitude exposure.

EEG Responses to the Number of Objects in Partially Occluded and Uncovered Scenes.

Perceptual completion is ubiquitous when estimating properties such as the shape, size, or number of objects in partially occluded scenes. Behavioral experiments showed that the number of hidden objects is underestimated in partially occluded scenes compared with an estimation based on the density of visible objects and the amount of occlusion. It is still unknown at which processing level this (under)estimation of the number of hidden objects occurs. We studied this question using a passive viewing task in which observers viewed a game board that was initially partially occluded and later was uncovered to reveal its hidden parts. We simultaneously measured the electroencephalographic responses to the partially occluded board presentation and its uncovering. We hypothesized that if the underestimation is a result of early sensory processing, it would be observed in the activities of P1 and N1, whereas if it is because of higher level processes such as expectancy, it would be reflected in P3 activities. Our data showed that P1 amplitude increased with numerosity in both occluded and uncovered states, indicating a link between P1 and simple stimulus features. The N1 amplitude was highest when both the initially visible and uncovered areas of the board were completely filled with game pieces, suggesting that the N1 component is sensitive to the overall Gestalt. Finally, we observed that P3 activity was reduced when the density of game pieces in the uncovered parts matched the initially visible parts, implying a relationship between the P3 component and expectation mismatch. Overall, our results suggest that inferences about the number of hidden items are reflected in high-level processing.

Group empathy for pain is stronger than individual empathy for pain in the auditory modality.

Humans live in collective groups and are highly sensitive to perceived emotions of a group, including the pain of a group. However, previous research on empathy for pain mainly focused on the suffering of a single individual ("individual empathy for pain"), with limited understanding of empathy for pain to a group ("group empathy for pain"). Thus, the present study aimed to investigate the cognitive neural mechanisms of group empathy for pain in the auditory modality. The study produced group painful voices to simulate the painful voices made by a group, and recruited 34 participants to explore differences between their responses to group painful voices and individual painful voices using the event-related potential (ERP) techniques. The results revealed that group painful voices were rated with higher pain intensity, more negative affective valence, and larger P2 amplitudes than individual painful voices. Furthermore, trait affective empathy scores of the participants were positively correlated with their P2 amplitudes of group painful voices. The results suggested that the group empathy for pain may facilitate affective empathetic processing in auditory modality.

The functional activity of the brain in patients with occupational chronic mercury intoxication against background of the treatment of insomnia disorders

Introduction. In patients with chronic mercury intoxication, insomnia disorders are much more common than in the general population. Persistent emotional disorders in combination with severe sleep disturbances may contribute to the progression of cognitive dysfunction in patients in the late post-exposure period of chronic mercury intoxication. The purpose of the study was to analyze the trend in electroencephalography indices and study cognitive evoked potentials in patients with occupational chronic mercury intoxication to optimize the treatment of insomnia. Materials and methods. Two groups of 30 patients with occupational chronic mercury intoxication, who worked at the enterprises of Usolyekhimprom LLC and Sayanskhimplast OJSC, were examined. In the first group of patients received the first treatment option, the average age was 56±0.71 years, in the second group, cases received the second treatment regimen, were of 57.1±3 years. Before and after treatment, there were carried out neurophysiological studies including polysomnography, electroencephalography, and a study of cognitive evoked potentials P300. Results. After the implementation of the treatment regimen in the first group, positive changes in the main indices of polysomnography were revealed as follows: decrease in the time of falling asleep and time of wakefulness in the bed, increase in total sleep time and the representation of delta sleep, increase in the sleep efficiency index, etc., electroencephalography (decrease in the delta index – rhythm and an increase in the alpha rhythm index), and cognitive evoked potentials (decreased latency and increased P300 amplitude). In the second group, there were registered positive alterations only in three neurophysiological indices: a decrease in the latent period of the 1st stage of sleep, a decline in the delta rhythm index and a fall in P300 latency. Limitations. The results cannot be generalized to workers as the group included only men. Conclusion. According to neurophysiological studies, improvement in polysomnography parameters during the treatment of insomnia in patients in the late post-contact period of chronic mercury intoxication was accompanied by an improvement in concentration and an increase in the rate of psychomotor response.

Multifocal electroretinogram changes after panretinal photocoagulation in early proliferative diabetic retinopathy

Background: Panretinal photocoagulation (PRP) impacts macular function in eyes with early proliferative diabetic retinopathy (PDR). Herein, we used the multifocal electroretinogram (mfERG) to objectively investigate this concept. Methods: In this prospective interventional case series, we enrolled patients with treatment-naive early PDR, absence of clinically significant macular edema, and requirement for PRP. All participants underwent detailed ocular examinations. We measured the best-corrected distance visual acuity (BCDVA), conducted optical coherence tomography imaging to measure central macular thickness (CMT), and performed mfERG at baseline and 3 months post-PRP. Amplitude and latency of the mfERG response were evaluated within the innermost four of the five concentric rings. Results: We enrolled 29 eyes of 23 patients with a mean (standard deviation) age of 54.3 (8.8) years and male-to-female ratio of 1:1.3. The mean BCDVA was unchanged post-treatment (P &gt;0.05), and the BCDVA in 26 eyes (89.7%) was either improved or unchanged, whereas in three eyes (10.3%) it decreased. The mean CMT was unchanged post-PRP (P &gt;0.05). Concerning the mfERG, the mean P1 amplitudes decreased significantly in all four concentric rings from the foveola at 3 months post-PRP compared with baseline values (all P &lt;0.05); however, the latencies were unchanged (all P &gt;0.05). At baseline, BCDVA correlated significantly with both the amplitude (r = + 0.55; P &lt;0.05) and latency (r = - 0.38; P &lt;0.05) of the mfERG in the central ring, whereas a significant correlation was detected with only the amplitude at 3 months post-PRP (r = + 0.52; P &lt;0.05). Conclusions: Macular function was decreased 3 months post-PRP in patients with early PDR, as indicated by decreased amplitude of the mfERG, whereas the functional and anatomical parameters were stable. The mfERG served as an objective tool for measuring retinal function and predicting visual outcomes post-PRP in eyes with early PDR. A higher amplitude in the mfERG correlated substantially with a better visual outcome post-PRP. Further multi-center longitudinal studies with robust designs including different PDR severity levels may reveal additional objective aftereffects of PRP.

Changes in P300 amplitude to negative emotional stimuli correlate with treatment responsiveness to sertraline in adolescents with depression

ObjectiveAdolescents with depression is characterized by high rates of recurrence and functional impairment, with a significant association with suicide risk. Antidepressants are commonly prescribed to treat depression, yet few reproducible neurobiological markers for depression and antidepressant treatment response have been identified. Therefore, discovering a stable and reliable neurobiological marker holds significant value for both the clinical diagnosis and treatment of depression in adolescents. MethodsOne hundred and seven patients with major depressive disorder (MDD group, 30 males, 77 females, mean age: 14.80 years), and 25 healthy subjects (HC group, 13 males, 12 females, mean age: 15.72 years) were recruited to perform a two-choice oddball task related to negative emotional cues. All participants completed a self-administered questionnaire to gather demographic information. A trained psychiatrist administered the Hamilton Depression Scale (HAMD-17) to assess depression severity. Of the 107 adolescents with depression, 61 received antidepressant medication for 8 weeks, and 61 of these patients were followed up. Multichannel EEG was recorded continuously from 64 scalp electrodes using the Curry 8 system. EEG signal preprocessing and analysis was performed offline using the EEGLAB toolbox in MATLAB. The ERP component characteristics associated with emotional processing were extracted from the difference waves and statistically analyzed. ResultsAdolescents with depression exhibited significantly larger P300 amplitudes than healthy controls in response to both neutral and negative emotional cues. Following sertraline treatment, both depression scores and P300 amplitudes decreased significantly in adolescents with depression. Moreover, a strong positive correlation was observed between changes in depression scores and changes in P300 amplitude in response to negative emotional cues before and after treatment. ConclusionsChanges in neural reactivity to negative emotional stimuli among adolescents with depression can be selectively modulated by sertraline and are significantly associated with improvements in depressive symptoms. SignificanceChanges in P300 amplitude to negative emotional stimuli significantly correlate with treatment responsiveness to sertraline in adolescents with depression.

Visual placebo and nocebo effects.

Placebo and nocebo effects modulate symptom perception through expectations and learning processes in various domains. Predominantly, their impact has been investigated on pain and physical performance. However, the influence of placebos and nocebos on visual system functionality has yet to be explored. The present study aimed to test whether placebo and nocebo effects can intervene in altering participants' performance outcomes during a novel visual accuracy task and to examine the underlying neural mechanisms through EEG. After performing a baseline session, visual accuracy was said to be enhanced or disrupted by a sham transcranial electrical stimulation over the occipital lobe. Behavioural results showed a significant increase in visual accuracy for the placebo group, from the baseline session to the test session, whereas the nocebo group showed a decrease in visual accuracy. EEG analyses on the event-related potential P300 component, conducted on both a centro-parietal electrode patch and a parieto-occipital, one displayed an increase in the amplitude of P300 for the placebo group, and a decrease in the nocebo group. These findings suggest for the first time that placebo and nocebo effects can influence visual perception and attentional processes linked to it. Overall, the present study contributes to understanding how expectations affect sensory perception beyond pain and the motor system, paving the way for investigating these phenomena in other sensory modalities such as auditory or olfactory perception. KEY POINTS: Placebo and nocebo effects have been studied predominantly in pain and motor performance fields. In a novel visual task, the impact of placebo and nocebo effects on the visual system has been evaluated, in both early components (stimuli-related) and late components (attention-related). The placebo group showed an increase in visual accuracy and EEG-evoked potential amplitudes, whereas the nocebo group showed a decrease in both. This study shows how expectations and the related placebo and nocebo effects can shape basic stimuli sensory perception in the visual domain.

An ERP-based comparison of gender representations elicited by generic masculine role nouns and the German gender star form

There is an ongoing debate about the linguistic gender forms that should be used to elicit fair mental representations of all genders. While most languages with grammatical gender traditionally use the masculine form to refer to people in a gender-independent way, numerous empirical studies have demonstrated that this form leads to a male bias in mental representations. In German, the so-called gender star form has been proposed as an alternative to the masculine form, aimed at better representing persons with nonmale gender identities. To provide empirical data on this claim, we compared the neural processing mechanisms elicited by the gender star form with those elicited by the generically intended masculine form during reference resolution. Participants in the present ERP study read sentence pairs in which a group of people was introduced with a role noun in one of the two gender forms and then revealed to be partly comprised of men or women. Following the masculine form, anaphoric references to women (vs. men) resulted in an increased ERP amplitude in the P600 range. In contrast, following the gender star form, the P600 amplitude was increased for references to men (vs. women), albeit in a slightly different spatio-temporal range. The present data thus indicate that the gender star form and the generically intended masculine form impose partially different demands on the syntactic operations performed by the brain during reference resolution but that, in the end, neither form elicits gender-balanced mental representations of men and women in German.

Adaptation patterns and their associations with mismatch negativity: An electroencephalogram (EEG) study with controlled expectations.

Adaptation refers to the decreased neural response that occurs after repeated exposure to a stimulus. While many electroencephalogram (EEG) studies have investigated adaptation by using either single or multiple repetitions, the adaptation patterns under controlled expectations manifested in the two main auditory components, N1 and P2, are still largely unknown. Additionally, although multiple repetitions are commonly used in mismatch negativity (MMN) experiments, it is unclear how adaptation at different time windows contributes to this phenomenon. In this study, we conducted an EEG experiment with 37 healthy adults using a random stimulus arrangement and extended tone sequences to control expectations. We tracked the amplitudes of the N1 and P2 components across the first 10 tones to examine adaptation patterns. Our findings revealed an L-shaped adaptation pattern characterised by a significant decrease in N1 amplitude after the first repetition (N1 initial adaptation), followed by a continuous, linear increase in P2 amplitude after the first repetition (P2 subsequent adaptation), possibly indicating model adjustment. Regression analysis demonstrated that the peak amplitudes of both the N1 initial adaptation and the P2 subsequent adaptation significantly accounted for variance in MMN amplitude. These results suggest distinct adaptation patterns for multiple repetitions across different components and indicate that the MMN reflects a combination of two processes: the initial adaptation in the N1 and a continuous model adjustment effect in the P2. Understanding these processes separately could have implications for models of cognitive processing and clinical disorders.

Fifty Percent of the Time, Tones Come Every Time: Stronger Prediction Error Effects on Neurophysiological Sensory Attenuation for Self-generated Tones.

The N1/P2 amplitude reduction for self-generated tones in comparison to external tones in EEG, which has recently also been described for action observation, is an example of the so-called sensory attenuation. Whether this effect is dependent on motor-based or general predictive mechanisms is unclear. Using a paradigm, in which actions (button presses) elicited tones in only half the trials, this study examined how the processing of the tones is modulated by the prediction error in each trial in a self-performed action compared with action observation. In addition, we considered the effect of temporal predictability by adding a third condition, in which visual cues were followed by external tones in half the trials. The attenuation result patterns differed for N1 and P2 amplitudes, but neither showed an attenuation effect beyond temporal predictability. Interestingly, we found that both N1 and P2 amplitudes reflected prediction errors derived from a reinforcement learning model, in that larger errors coincided with larger amplitudes. This effect was stronger for tones following button presses compared with cued external tones, but only for self-performed and not for observed actions. Taken together, our results suggest that attenuation effects are partially driven by general predictive mechanisms irrespective of self-performed actions. However, the stronger prediction-error effects for self-generated tones suggest that distinct motor-related factors beyond temporal predictability, potentially linked to reinforcement learning, play a role in the underlying mechanisms. Further research is needed to validate these initial findings as the calculation of the prediction errors was limited by the design of the experiment.

Neural encoding for spatial release from informational masking and its correlation with behavioral metrics.

The central auditory system encompasses two primary functions: identification and localization. Spatial release from masking (SRM) highlights speech recognition in competing noise and improves the listening experience when a spatial cue is introduced between noise and target speech. This assessment focuses on the integrity of auditory function and holds clinical significance. However, infants or pre-lingual subjects sometimes provide less reliable results. This study investigates the value of cortical auditory evoked potentials (CAEPs) onset and acoustic change complex (ACC) as an objective measurement of SRM. Thirty normal-hearing young adults (11 males) were recruited. We found the spatial separation of signals and noise (±90° symmetrically) resulted in a signal-to-noise ratio (SNR) improvement of 9.00 ± 1.71 dB behaviorally. It significantly enhanced cortical processing at all SNR levels, shortened CAEP latencies, and increased amplitudes, resulting in a greater number of measurable peaks for ACC. SRM showed mild to moderate correlations with the differences between two conditions in CAEP measures. The regression model combining N1'-P2' amplitude at 5 dB SNR (R2 = 0.26), P1 amplitude at 0 dB SNR (R2 = 0.14), and P1 latency at -5 dB SNR (R2 = 0.15), explained 45.3% of the variance in SRM. Our study demonstrates that introducing spatial cues can improve speech perception and enhance central auditory processing in normal-hearing young adults. CAEPs may contribute to predictions about SRM and hold potential for practical application.NEW & NOTEWORTHY The neural encoding of spatial release from masking (SRM) can be observed in normal-hearing young adults. Spatial separation between target and masker improves speech perception in noise and enhances central auditory processing. The behavioral results showed mild-to-moderate correlations with electrophysiological measures, with acoustic change complex (ACC) amplitude being a better indicator than onset components. Cortical auditory evoked potentials (CAEPs) may contribute to predictions about spatial release from masking, especially when behavioral tests are less reliable.

The impact of social comparison on self-deception: An event-related potentials study.

Self-deception refers to an individual holding inflated beliefs about their abilities, and it plays a crucial role in human behavior and decision-making. The present study employed event-related potentials (ERPs) technique to explore the neural responses to the impacts of social comparison direction and comparison gap on self-deceptive behavior. They were instructed to predict their performance in the forward-looking paradigm. Behavioral responses and neural reactions during the decision-making process were documented. The behavioral results indicated that, in contrast to the downward comparison condition, participants engaged in upward comparison exhibited more occurrences of self-deception. However, within the context of upward comparison, participants demonstrated a higher frequency of self-deception in the large gap condition compared with the small gap condition. The ERP results showed that induced self-deception under conditions with a large comparative gap between participants and their paired counterparts stimulated larger P300 and smaller N400 amplitude than under conditions with a small gap. However, when participants were in the upward comparison situation, the late positive potential (LPP) amplitude induced by self-deception behavior in the condition of a large comparison gap between participants and paired opponents was larger than that in the condition of a small comparison gap. These results indicated that individuals in the large gap group feel strong unfairness and negative emotions. More importantly, the self-deception induced by the large gap group in the upward comparison situation used fewer cognitive resources than the small gap condition, whereas the individuals in the downward comparison situation did not show the difference in cognitive resources.

Direct evidence for logarithmic magnitude representation in the central nervous system

Fechner’s law proposes a logarithmic relationship between the physical intensity and perceived magnitude of a stimulus. The principle of logarithmic magnitude representation has been extensively utilized in various theoretical frameworks. Although the neural correlates of Weber’s law have been considered as possible evidence for Fechner’s law, there is still a lack of direct evidence for a logarithmic representation in the central nervous system. In our study, participants were asked to reproduce the time intervals between two circles and ignore their spatial distances while electroencephalogram (EEG) signals were recorded synchronously. Behavioral results showed that a Bayesian model, which assumes a logarithmic representation of spatiotemporal information, was better at predicting production times than a model relying on a linear representation. The EEG results revealed that P2 and P3b amplitudes increased linearly with the logarithmic transformation of spatiotemporal information, and these event-related potentials were localized in the parietal cortex. Our study provides direct evidence supporting logarithmic magnitude representation in the central nervous system.

Spatial Contextual Information Modulates Affordance Processing and Early Electrophysiological Markers of Scene Perception.

Scene perception allows humans to extract information from their environment and plan navigation efficiently. The automatic extraction of potential paths in a scene, also referred to as navigational affordances, is supported by scene-selective regions (SSRs) that enable efficient human navigation. Recent evidence suggests that the activity of these SSRs can be influenced by information from adjacent spatial memory areas. However, it remains unexplored how these contextual information could influence the extraction of bottom-up information, such as navigational affordances, from a scene and the underlying neural dynamics. Therefore, we analyzed ERPs in 26 young adults performing scene and spatial memory tasks in artificially generated rooms with varying numbers and locations of available doorways. We found that increasing the number of navigational affordances only impaired performance in the spatial memory task. ERP results showed a similar pattern of activity for both tasks, but with increased P2 amplitude in the spatial memory task compared with the scene memory. Finally, we reported no modulation of the P2 component by the number of affordances in either task. This modulation of early markers of visual processing suggests that the dynamics of SSR activity are influenced by a priori knowledge, with increased amplitude when participants have more contextual information about the perceived scene. Overall, our results suggest that prior spatial knowledge about the scene, such as the location of a goal, modulates early cortical activity associated with SSRs, and that this information may interact with bottom-up processing of scene content, such as navigational affordances.