43 resultados para PRT - ERP
Resumo:
Processing of discrepant information is an important part in our everyday life. According to the social attributes of information, it can be categorized into two parts: social discrepancy and nonsocial discrepant information. The researches focused on nonsocial discrepancy are much mature than those of social discrepancy processing. This serial study employed three ERP experiments to explore the attributes of social discrepancy cognition. Experiment one compared the ERP differences between social and nonsocial discrepancy processing, experiment two adopted single stimulus paradigm to explore the negativity attention biases of social emotions, experiment three investigated the affective mechanism of emotions to social discrepancy information with cue-target paradigm, based on the experiment one and two. We invited healthy undergraduates to participate in our researches, in which social gender words and affective images were stimuli to explore the temporal sequences, activated modes and affective mechanisms of social discrepancy. The results were as below: 1. The differences of attention resource distributions between social and nonsocial information processing exhibited as early as 200 ms, since which P2 was evoked in both blocks. The larger P2 in nonsocial block represented the more attention to physical and nonsocial attributes of objects. N300/400 indicated the differences of evaluating systems in each block. The cognitive mechanisms of social and nonsocial tasks were specific, based on the fact: (1) the discrepancy evaluating system was activated earlier in nonsocial block than that of social block; (2) the social cognition performed right hemisphere advantage, but nonsocial task did not so. 2. Social emotions also could raise a negativity bias on attention. The latency of P2 evoked by social sad images was shorter than that of social happiness and neutral images. The latencies of P2 indicated that sad emotions attracted attention earlier, and possessed a processing advantage. The phenomenon that the larger N2 was evoked by social sadness showed that people was easily moved by sad emotions and sympathized the sadness. 3. Emotions affected social discrepancy processing. Positive affective mood magnified the discrepancy effect, based on the smaller latencies of difference N400 and larger amplitudes. Persons with happy mood synthesized social stereotypes to accelerate the social tasks. 4. Three experiments all showed the right hemisphere advantages of social cognition and social emotions, offered more proof in laterality hypothesis of social cognition. Above all, social cognition had essential distinctions with nonsocial cognition; they two had their own specific characteristics. The fact that social cognition was prone to be affected by different emotional mood made it more complex.
Resumo:
As a species of internal representation, how is mental imagery organized in the brain? There are two issues related to this question: the time course and the nature of mental imagery. On the nature of mental imagery, today's imagery debate is influenced by two opposing theories: (1) Pylyshyn’s propositional theory and (2) Kosslyn’s depictive representation theory. Behavioural studies indicated that imagery encodes properties of the physical world, such as the spacial and size information of the visual world. Neuroimaging and neuropsychological data indicated that sensory cortex; especially the primary sensory cortex, is involved in imagery. In visual modality, neuroimaging data further indicated that during visual imagery, spatial information is mapped in the primary visual, providing strong evidences for depictive theory. In the auditory modality, behavioural studies also indicated that auditory imagery represents loudness and pitch of sound; this kind of neuroimaging evidence, however, is absent. The aim of the present study was to investigate the time course of auditory imagery processing, and to provide the neuroimaging evidence that imaginal auditory representations encode loudness and pitch information, using the ERP method and a cue-imagery (S1)-S2 paradigm. The results revealed that imagery effects started with an enhancement of the P2, probably indexing the top-down allocation of attention to the imagery task; and continued into a more positive-going late positive potentials (LPC), probably reflecting the formation of auditory imagery. The amplitude of this LPC was inversely related to the pitch of the imagined sound, but directly related to the loudness of the imagined sound, which were consistent with auditory perception related N1 component, providing evidences that auditory imagery encodes pitch and loudness information. When the S2 showed difference in pitch of loudness from the previously imagined S1, the behavioral performance were significantly worse and accordingly a conflict related N2 was elicited; and the high conflict elicited greater N2 amplitude than low conflict condition, providing further evidences that imagery is analog of perception and can encode pitch and loudness information. The present study suggests that imagery starts with an mechanism of top-down allocation of attention to the imagery task; and continuing into the step of imagery formation during which the physical features of the imagined stimulus can be encoded, providing supports to Kosslyn’s depictive representation theory.
Resumo:
The relationship between exogenous attention and endogenous attention is still unclear. We conclude the result of previous studies and our experiments by proposing a convergence hypothesis. A lot of evidences from ERP and fMRI proved the distinction between exogenous and endogenous attention. The distinction is fit for the complicated surroundings. Some studies found that exogenous and endogenous attention activated some common brain areas but if there’s any common function in these areas was still unclear. Previous studies failed to disentangle the relationship between these two mechanisms in detail, and most of the previous studies compared these two mechanisms separately. We used the cue-target paradigm, controlled the SOA and the cue validity to separate endogenous and exogenous attention. We try to figure out the relationship between endogenous and exogenous attention. We found that, in the exogenous attention condition, the amplitude of the P1 component was larger and the amplitude of N1 was smaller than that in the invalid trials. In the endogenous attention condition, the amplitudes of the P1 and N1 components in valid trials were both larger than that in the invalid trials. The difference wave of endogenous and exogenous attentions showed that at the beginning of their process endogenous and exogenous attentions were separate and then the process was going to converge. The stimuli appear in the visual field will activate the “external trigger” in exogenous attention processing, and then the signal will be transferred to next stage, in the endogenous attention processing, when the observer want to attend, the “inner trigger” will be activated and the signal will be transfered. The difference between “external trigger” and “inner trigger” in endogenous and exogenous attention was significant, so the difference at the beginning of the process was significant. When the signal was transferred to the next processing stage, the difference between the endogenous and exogenous attention became diminished, and it was a convergence process. We used the cue-target paradigm, let the central cue and peripheral cue appear in one trial, try to investigate the relationship between endogenous and exogenous attention under different perceptual load conditions. The result from of difference wave showed that the relationship between the two attentions was consistent with the convergence hypothesis. We also found that under different perceptual load conditions, the relationship between endogenous and exogenous attention was different. The perceptual load has influence on the “external trigger” and “inner trigger”. A cue-target paradigm was used to investigate the relationship between attention, age and perceptual load, we found that the function of visual attention was decrease in the old group, they need more attentional resource when they face the issue. The aging effect has influence on the “external trigger” and “inner trigger”. The effects of age and perceptual load were much higher in exogenous attention condition.
Resumo:
Previous researches has shown that two components of the event- related brain potential, the feedback negativity (FRN) and P300, are related to outcome evaluation. So far, the nature of the outcome evaluation reflected by FRN and the significance of P300 remains unknown. Some studies found that the process of outcome evaluation may be related to the expectation, and the FRN may be affected by the intensity levels of the expectation for the outcome. To address these issues, the present study will start on two aspects: (1)This study required 39 participants to make attribution about their performance during a task, the aim was to assess the levels of the expectations for the outcome under four conditions in the attribution task. The main finding is that, the expectations for monetary reward under four conditions are scaled. (2)Based on the results of the first study, this study also required 16 participants to make attribution about their performance during a task. A functional dissociation was observed, with the FRN affected by the intensity levels of the expectation for the outcome, while the P300 sensitive to the degree of emotion the participants experienced. Dipole source location analysis showed that the most likely neural generator of FRN and P300 is the cingulate cortex, suggesting that FRN might reflect cognitive conflict when the actual outcome is different from the expectation, and P300 is related to the emotion processing of outcome stimuli. These results suggest that there is a functional dissociation between FRN and P300.
Resumo:
Although the influence of emotional states on immune function has been generally recognized, researches on the effects of negative emotion on individual SIgA levels have reported mixed findings. Our study aimed to elucidate the relationship between changes in EEG activity and cognitive and psychological mechanisms to the immune changes induced by negative emotion. In experiment one, we investigated how the negative emotional arousal that was induced by watching a number of unpleasant pictures altered the concentration of secretory immunoglobulin A (SIgA). Although our results found discrepancies in the changing tendency of SIgA concentration among participants (some participants’ SIgA decreased after watching unpleasant pictures, whereas others increased), further analysis revealed a coherency among the changing of SIgA concentration, participants’ general coping styles and their actual emotion regulation strategies in perceiving unpleasant pictures, and the event-related potentials (ERPs) associated with the watching of unpleasant pictures. The participants whose SIgA increased after watching unpleasant pictures (the increasers) had higher positive coping scores in the Trait Coping Styles Questionnaire (TCSQ) than those whose SIgA decreased (the decreasers). Also, relative to the decreasers, the increasers tended to use more emotion regulation strategies especially when the presented pictures were extremely negative and exhibited a reverse dissociation pattern between the extremely negative pictures and the moderately negative ones in the amplitude of late positive potential (LPP) that was related to the cognitive evaluation of stimuli’s meaning. On this basis, Event-related potentials were recorded first while participants passively viewed unpleasant pictures, and then during an emotion regulation block in which participants were instructed to reappraise unpleasant pictures in the experiment two. We also collected the immune index before and after the passive viewing block and the emotion regulation block. Our study proved that participants felt a less intense emotional response to unpleasant pictures that followed a reappraisal instruction. The decreasing emotional responding to unpleasant pictures decreased the amplitude of the LPP. But larger N2 was induced in the emotion regulation block, because the participants needed to obtained more attentional resources to detect and integrate more stimulus features to use the cognitive reappraisal strategy effectively. The present study has important theoretic and practical significance. For the theoretic significance, our study elucidated the relationship between changes in EEG activity and cognitive and psychological mechanisms to the immune changes induced by negative emotion by using the technologies of ERP, experimental interview and psychological measurement. Meanwhile, our study also provided an explanation for the different changing tendencies of SIgA induced by negative emotions, and it plays an important role in further studying the cognitive neural mechanisms of immune level in response to emotion. As to the practical significance, our study suggests that individuals who use active emotion regulation in the face of negative emotion stimuli may experience significantly increases in immune system function, subsequently lowering the possibility of infection.
Resumo:
In the history of psychology research, more attention had been focused on the relation between local processing and global processing. For the global information and the local information, which is processed earlier? And which is processed faster? Precedence of the global over the local level in visual perception has been well established by Navon with compound stimuli, and Navon’s original study gave rise to many publications, including replications, generalization to other kinds of stimuli (nonverbal material, digits), populations (infants, children, brain-damaged subjects), and tasks (lateral visual hemifield presentation, copy drawing, memory recognition, and recall), and triggered some debate about the conditions in which global precedence is and is not observed (number, size, sparsity, and goodness of the stimuli, exposure duration, etc.). However, whether there is a global advantage or precedence in other cognitive processes was less tested. Most researches had suggested that there was a functional equivalency between visual perception and visual image processing. However, it’s still unknown whether there will be a global advantage on mental rotation. In the present study, we combined the mental rotation task with the compound stimuli to explore whether the global or local advantage also existed at the mental imagery transformation stages. In two pilot studies, the perceptual global precedence was found to be present in a normal/mirror-image judgment task when the stimuli exposure time was short; while the stimuli exposure time was prolonged (stimuli kept available till subjects’ response) the perceptual global precedence was showed to be eliminated. In all of the subsequent experiments, stimili would be presented till subjects’ response. Then mental rotation was added in normal/mirror-image judgment (some of the stimuli were rotated to certain angles from upright) in normal experiments, experiment 1 and 2 observed a global advantage on mental rotation both with a focused-attention design (Experiment 1) and divided-attention design (Experiment 2). Subjects’ reaction times were increased with rotation angles, and the accuracy was decreased with rotation angles, suggesting that subject need a mental rotation to make a normal/mirror judgment. The most important results were that subjects’ response to global rotation was faster than that to local rotation. The analysis of slope of rotation further indicated that, to some extend, the speed of global rotation was faster than that of local rotation. These results suggest a global advantage on mental rotation. Experiment 3 took advantage of the high temporal resolution of event-related potentials to explore the temporal pattern of global advantage on mental rotation. Event-related potential results indicated the parietal P300 amplitude was inversely related to the character orientation, and the local rotation task delayed the onset of the mental-rotation-related negativity at parietal electrodes. None clear effect was found for occipital N150. All these results suggested that the global rotation was not only processed faster than local rotation, but also occurred earlier than local rotation. Experiments 4 and 5 took the effect size of global advantage as the main dependent variable, and visual angle and exposure duration of the stimuli as independent variables, to examine the relationship between perceptual global precedence and global advantage on mental rotation. Results indicated that visual angle and exposure duration did not influence the effect size of global advantage on mental rotation. The global advantage on mental rotation and the perceptual global advantage seemed to be independent but their effects could be accumulated at some condition. These findings not only contribute to revealing a new processing property of mental rotation, but also deepen our understanding of the problem of global/local processing and shed light on the debate on locus of global precedence.
Resumo:
The nature of individual differences among children is an important issue in the study of human intelligence. There are close relation between intelligence and executive functions. Traditional theories, which are based mainly on the factor analysis, approach the problem only from the perspective of psychometrics. However, they do not study the relation of cognition and neurobiology. Some researchers try to explore the essential differences in intelligence from the basic cognitive level, by studying the relationship between executive function and intelligence. The aim of this study was to do the followings 1) to delineate and separate the executive function in children into measurable constructs; 2) to establish the relationship between executive function and intelligence in children; 3) to find out the difference and its neural mechanism between intellectually-gifted and normal children’s executive function. The participants were 188 children aged 7-12 year old. There were 6 executive function tasks. The results were follows: 1) The latent variables analyses showed that there was no stable construct of executive function in 7-10 year old children. The executive function construct of 11-12 year old children could be separated into updating, inhibition and shifting. And they had grown to be more or less the same as adults in the executive function. There were only moderate correlations between the three types of executive function, but they were largely independent of each other. 2) The correlations between the indices of updating, inhibition, shifting and intelligence were different in 7-12 year old children. The older the age, the more the indices were related to intelligence. The updating and shifting were related to intelligence in 7-10 year old children. There were significant correlations between the updating, inhibition, shifting and intelligence in 11-12 year old children. The correlation between updating and intelligence was higher than the correlation between shifting and intelligence. Furthermore, in structural equation models controlling for the three executive functions correlations, updating was highly related to intelligence, but the relations of inhibition and shifting to intelligence were not significant. 3) Intellectually-gifted children performed better than normal children in executive function tasks. The neural mechanism differences between intellectually gifted and average children were indicated by ERP component P3. The present study helps us to understand the relationship between intelligence and executive function; and throws light on the issue of individual differences in intelligence. The present results can provide theoretical support for the development a culture-free intelligence test and a method to promote the development of intelligence. Our present study lends support to the neural efficient hypothesis.
Resumo:
Developmental dyslexia (DD) is a common kind of learning disorder, which affects 5-18% of people. It seems important to explore the deficit in visual magnocellular pathway in Chinese developmental dyslexia, for many researches demonstrated that one of the core deficits of Chinese developmental dyslexia was orthographic deficit which was associated with the deficit in visual magnocellular pathway. Two studies were done to detect the differences among Chinese developmental dyslexics, average readers of the same chronological age (CA controls) and average readers of the same reading level (RL controls) in reaction time, accuracy and visual mismatch negativity (vMMN) elicited by the moving gratings responded by visual magnocellular pathway. There were two grating-conditions which were low contrast/low spatial frequency condition and high contrast/high spatial frequency condition respectively. In ERP study, a modified “cross-modal delayed response” paradigm was used to elicit the vMMN. The results showed that the developmental dyslexics responded slower than CA controls, had more errors than RL controls, and had smaller amplitudes of vMMNs than the two controls in visual magnocellular pathway condition, but not in control condition. That is to say, Chinese developmental dyslexics had deficits in visual magnocellular pathway.
Resumo:
Zeigarnik effect refers to the enhanced memory performance for unfinished tasks and studies on insight using hemi-visual field presentation technology also find that after failing to solve an problem, hints to the problem are more effective received and lead to insight experience when presented to the left-visual field (Right hemisphere) than presented to the right-visual field, especial when the hints appeared with a delay. Thus, it seems that right hemisphere may play an important role in preserving information of unsolved problems and processing related cues. To further examine the finding above, we introduce an Chinese character chunking task to investigate the brain activities during the stage of failure to resolve problems and of hint presentation using Event-Related Potentials (ERP) and functional MRI technology. Our FMRI results found that bilateral BA10 showed more activation when seeing hints for unsolved problems and we proposed that it may reflect the processes of information to failure problems, howerver, there was no hemispheric difference. The ERP results after the effort to the problems showed that unsolved problems elicited a more positive P150 over the right frontal cortex while solved problems demonstrated a left hemispheric advantage of P150. When hints present, P2 amplitudes of hints were modulated by the status of problem only in the right hemisphere but not in the left hemisphere. Our results confirmed the hypothesis that failure to solve problems would trigger the perseverance processes in right hemisphere, which would make right hemisphere more sensitive to related information of failure problems.
Resumo:
Self-regulation has recently become an important topic in cognitive and developmental domain. According to previous theories and experimental studies, it is shown that self-regulation consist of both a personality (or social) aspect and a behavioral cognitive aspect of psychology. Self-regulation can be divided into self-regulation personality and self-regulation ability. In the present study researches have been carried out from two perspectives: child development and individual differences. We are eager to explore the characteristics of self-regulation in terms of human cognitive development. In the present study, we chose two groups of early adolescences one with high intelligence and the other with normal intelligence. In Study One Questionnaires were used to compare whether the highly intelligent group had had better self-regulation personality than the normal group. In Study Two experimental psychology tasks were used to compare whether highly intelligent children had had better self-regulation cognitive abilities than their normal peers. Finally, in Study Three we combined the results of Study One and Study Two to further explore the neural mechanisms for highly intelligent children with respect to their good self-regulation abilities. Some main results and conclusions are as follows: (1) Questionnaire results showed that highly intelligent children had better self-regulation personalities, and they got higher scores on the personalities related to self-regulation such as, self-reliance, stability, rule-consciousness. They also got higher scores on self-consciousness which meant that they could know their own self better than the normal children. (2) Among the three levels of cognitive difficulties in self-regulation abilities, the highly intelligent children had faster reaction speed than normal children in the primary self-regulation tasks. In the intermediate self-regulation tasks, highly intelligent children’s inhibition processing and executive processing were both better than their normal peers. In the advanced self-regulation tasks, highly intelligent children again had faster reaction speed and more reaction accuracy than their normal peers when facing with conflict and inconsistency experimental conditions,. Regression model’s results showed that primary and advanced self-regulation abilites had larger predictive power than intermediate self-regualation ability. (3) Our neural experiments showed that highly intelligent children had more efficient neural automatic processing ability than normal children. They also had better, faster and larger neural reaction to novel stimuli under pre-attentional condition which made good and firm neural basis for self-regualation. Highly intelligent children had more mature frontal lobe and pariental functions for inhibition processing and executive processing. P3 component in ERP was closely related to executive processing which mainly activated pariental function. There were two time-periods for inhibition processing—first it was the pariental function and later it was the coordination function of frontal and pariental lobes. While conflict control task had pariental N2 and frontal-pariental P3 neural sources, highly intelligent children had much smaller N2 and shorter P3 latency than normal children. Inconsistency conditions induced larger N2 than conditions without inconsistency, and conditions without inconsistency (or Conflict) induced higher P3 amplitudes than with Inconsistency (or Conflict) conditions. In conclusion, the healthy development of self-regulation was very important for children’s personality and cognition maturity, and self-regulation had its own specific characteristics in ways of presentation and ways of development. Better understanding of self-regulation can further help the exploration of the nature of human intelligence and consciousness.
Resumo:
This report mainly focused on methodology of spatiotemporal patterns (STP) of cognitive potentials or event-related potentials (ERP). The representation of STP of brain wave is an important issue in the research of neural assemblies. This paper described methods of parametric 3D head or brain modeling and its corresponding interpolation for functional imaging based on brain waves. The 3D interpolation method is an extension of cortical imaging technique. It can be used with transformed domain features of brain wave on realistic head or brain models. The simulating results suggests that it is a better method in comparison with the global nearest neighbor technique. A stable and definite STP of brainwave referred as microstate may become basic element for comprehending sophisticated cognitive processes. Fuzzy c-mean algorithm was applied to segmentation STPs of ERP into microstates and corresponding membership functions. The optimal microstate number was estimated with both the trends of objective function against increasing clustering number and the decorrelation technique base don microstate shape similarity. Comparable spatial patterns may occur at different moments in time with fuzzy indices and thus the serial processing limit generated from behavioral methods has been break through. High-resolution frequency domain analysis was carried out with multivariate autoregressive model. Bases on a 3D interpolation mentioned above, visualization of dynamical coordination of cerebral network was realized with magnitude-squared partial coherence. Those technique illustrated with multichannel ERP of 9 subjects when they undertook Strop task. Stroop effects involves several regions during post-perception stage with technique of statistical parameter mapping based F-test [SPM(F)]. As SPM(F) suggested task effects occurred within 100 ms after stimuli presentation involved several sensory regions, it may reflect the top-down processing effect.
Resumo:
The purpose of this study was to examine the cognitive and neural mechanism underlying the serial position effects using cognitive experiments and ERPs(the event related potentials), for 11 item lists in very short-term and the continuous-distractor paradigm with Chinese character. The results demonstrated that when the length of list was 11 Chinese character, and the presentation time, the item interval and the retention interval was 400ms, the primacy effect and recency effect belong to the associative memory and absolute memory respectively. The retrieval of the item at the primacy part depended mainly on the context cues, but the retrieval of the item at the recency part depended mainly on the memory trace. The same results was concluded in the continuous-distractor paradigm (the presentation time was 1sec, the item interval is 12sec, and the retention interval was 30sec). Cognitive results revealed the robust serial position effects in the continuous-distractor paradigm. The different retrieval process between items at the primacy part and items at the recency part of the serial position curve was found. The behavioral responses data of ERP illustrated that the responses for the prime and recent items differed neither in accuracy nor reaction time, the retrieval time for the items at the primacy part was longer than that for the items at the recency part. And the accuracy of retrieval for the primacy part item was lower than that for the recency part items. That meant the retrieval of primacy part items needed more cognitive processes. The recent items, compared with the prime items, evoked ERPs that were more positive, this enhanced positivity occurred in a positive component peaking around 360ms. And for the same retrieval direction (forward or backward), the significant positive component difference between the retrieval for prime items and the retrieval for recent items was found. But there was no significant difference between the forward and backward retrieval at both the primacy and recency part of the serial position curve. These revealed the two kind of retrieval (forward and backward) at the same part of the serial position curve belonged to the same property. These findings fit more closely with the notion of the distinct between the associative memory and the absolute memory.