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Research on the role of affect in decision-making indicates that both predecisional current and expected affective valence predict choice. However, the exact role of current and expected affect for recurrent decision-making is still a matter of debate. We used a generalised mixed effect model to predict gambling responses in an experience-based learning task from ratings of current and expected affective valence. Results indicate that current and expected affective valence interact to predict choice. While expected valence had the biggest effect size, current valence and the interaction still contributed significantly to the prediction of choice. Resolving the interaction showed that participants relied more on the current valence if expectations were unclear or positive. These findings are discussed in the context of dual-process accounts and the affective signalling hypothesis. In conclusion, current and expected valence depend on one another and interact to predict choice in recurrent decision tasks.
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Afeto , Jogo de Azar , Afeto/fisiologia , HumanosRESUMO
Introduction: The present study was conducted to verify a promising experimental setup which demonstrated an inversed Stroop-effect (much faster responses for incongruent relative to congruent Stroop trials) following a mismatching tone. In the matching condition, which was an almost exact replication of the original study, participants were required to indicate whether word color and word meaning were matching, whereas in the response conflict condition, instruction was the same as in a classical Stroop task and required the participants to respond to the word color. As in the original study, each trial was preceded by a sine tone which was deviant in pitch in 20% of the trials. Results: The main result was that the Stroop effect was not inversed after deviant tones, neither under the matching task instruction nor under the response conflict task instruction. The Stroop effect was unaffected by the previous "conceptual mismatch." Conclusion: The current study failed to replicate the astonishing concept of "conflict priming" reported in previous work and does not open the doors for a new window on sequences of conflicts. Nevertheless, the failed replication is valuable for future research, since it demonstrated that "Conflict Priming" as a facilitation of processing of conflict trials following deviant tones, is not an confirmed finding.
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There is empirical evidence that expected yet not current affect predicts decisions. However, common research designs in affective decision-making show consistent methodological problems (e.g., conceptualization of different emotion concepts; measuring only emotional valence, but not arousal). We developed a gambling task that systematically varied learning experience, average feedback balance and feedback consistency. In Experiment 1 we studied whether predecisional current affect or expected affect predict recurrent gambling responses. Furthermore, we exploratively examined how affective information is represented on a neuronal level in Experiment 2. Expected and current valence and arousal ratings as well as Blood Oxygen Level Dependent (BOLD) responses were analyzed using a within-subject design. We used a generalized mixed effect model to predict gambling responses with the different affect variables. Results suggest a guiding function of expected valence for decisions. In the anticipation period, we found activity in brain areas previously associated with valence-general processing (e.g., anterior cingulate cortex, nucleus accumbens, thalamus) mostly independent of contextual factors. These findings are discussed in the context of the idea of a valence-general affective work-space, a goal-directed account of emotions, and the hypothesis that current affect might be used to form expectations of future outcomes. In conclusion, expected valence seems to be the best predictor of recurrent decisions in gambling tasks.
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BACKGROUND: About 6.2 million adults in Germany cannot read and write properly despite attending school for several years. They are considered to be functional illiterates (FI). Since the ability to read and write is crucial for being employed and socially accepted, we developed a special literacy training to overcome these deficits. METHODS: In this study, we investigate training-related changes in intrinsic functional connectivity (iFC) at rest in a group of 20 FI and 20 adult normal readers using resting state functional magnetic resonance imaging (rsfMRI). We used independent component analysis (ICA) to define different networks. RESULTS: Before training, the between group analysis showed increased iFC in FI in a left-fronto-parietal network (LFPN; anterior insula, medial frontal cortex, lateral and frontal parietal regions) and in the Basal Ganglia network (BGN: thalamus, caudate, putamen, pallidum, amygdala, supplementary motor cortex and cingulate gyrus). Furthermore, the Visual Network-1 (VN1; temporal occipital fusiform gyrus, lateral occipital cortex, occipital pole, lingual gyrus, thalamus) showed decreased iFC in FI. After training the FI group showed reversal of the "hyperconnectivity" in middle frontal gyrus and in the frontal orbital cortex and between supramarginal gyrus and the BGN. Furthermore, functional connectivity increased in FI VN1 (lateral occipital cortex, insular cortex). These changes in connectivity correlated with gains in reading speed and spelling accuracy. CONCLUSIONS: These findings show that poor reading and writing abilities are associated with abnormalities in iFC in several brain areas subserving cognitive processes important for reading. Intensive literacy training induces changes in the functional connectivity between and within neural networks important for literacy skills.
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There is sufficient evidence to believe that variations in the error-related negativity (ERN) are linked to dispositional characteristics in individuals. However, explanations of individual differences in the amplitude of the ERN cannot be derived from functional theories of the ERN. The ERN has a counterpart that occurs after correct responses (correct-response negativity, CRN). Based on the assumption that ERN and CRN reflect an identical cognitive process, variations in CRN might be associated with dispositional characteristics as well. Higher CRN amplitudes have been found to reflect task engagement. In the present study, a simple-choice-reaction task was used to investigate ERN and CRN amplitudes in relation to their score on a conscientiousness scale. The task consisted of a simple rule that required pressing the left or right key when a circle or square appeared, respectively. During alternative conditions that occur infrequently, participants were instructed to violate or reverse the previously established response rules. Smaller ΔERN amplitudes (manifested in almost equal CRN and ERN amplitudes) and a tendency of better task performance from participants scoring high on the conscientiousness scale might indicate a greater focus on the task and higher motivation of responding correctly. In addition, higher Pc amplitudes directly following the CRN indicated that the response monitoring system of less conscientious participants showed a higher disengagement. The role of individual differences in CRN amplitude should be studied in future experiments on performance monitoring.
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BACKGROUND: Many researchers have tried to investigate pain by studying brain responses. One method used to investigate pain-related brain responses is continuous electroencephalography (EEG). The objective of the current study is to add on to our understanding of EEG responses during pain, by differentiation between EEG patterns indicative of (i) the noxious stimulus intensity and (ii) the subjective pain sensation. METHODS: EEG was recorded during the administration of tonic experimental pain, consisting of six minutes of contact heat applied to the leg via a thermode. Two stimuli above pain threshold, one at pain threshold and two non-painful stimuli were administered. Thirty-six healthy participants provided a subjective pain rating during thermal stimulation. Relative EEG power was calculated for the frequency bands alpha1, alpha2, beta1, beta2, delta, and theta. RESULTS: Whereas EEG activity could not be predicted by stimulus intensity (except in one frequency band), subjective pain sensation could significantly predict differences in EEG activity in several frequency bands. An increase in the subjective pain sensation was associated with a decrease in alpha2, beta1, beta2 as well as in theta activity across the midline electrodes. CONCLUSION: The subjective experience of pain seems to capture unique variance in EEG activity above and beyond what is captured by noxious stimulus intensity.
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Potenciais Somatossensoriais Evocados/fisiologia , Hiperalgesia/fisiopatologia , Percepção da Dor/fisiologia , Limiar da Dor/fisiologia , Dor/fisiopatologia , Adulto , Feminino , Temperatura Alta/efeitos adversos , Humanos , Masculino , Medição da Dor , Estimulação Física/efeitos adversos , Análise de Regressão , Adulto JovemRESUMO
Developmental dyslexia is a specific deficit in reading and spelling that often persists into adulthood. In the present study, we used slow event-related fMRI and independent component analysis to identify brain networks involved in perception of audio-visual speech in a group of adult readers with dyslexia (RD) and a group of fluent readers (FR). Participants saw a video of a female speaker saying a disyllabic word. In the congruent condition, audio and video input were identical whereas in the incongruent condition, the two inputs differed. Participants had to respond to occasionally occurring animal names. The independent components analysis (ICA) identified several components that were differently modulated in FR and RD. Two of these components including fusiform gyrus and occipital gyrus showed less activation in RD compared to FR possibly indicating a deficit to extract face information that is needed to integrate auditory and visual information in natural speech perception. A further component centered on the superior temporal sulcus (STS) also exhibited less activation in RD compared to FR. This finding is corroborated in the univariate analysis that shows less activation in STS for RD compared to FR. These findings suggest a general impairment in recruitment of audiovisual processing areas in dyslexia during the perception of natural speech.
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Dislexia/diagnóstico por imagem , Dislexia/fisiopatologia , Imageamento por Ressonância Magnética , Percepção de Movimento/fisiologia , Percepção da Fala/fisiologia , Adulto , Encéfalo/diagnóstico por imagem , Encéfalo/fisiopatologia , Mapeamento Encefálico/métodos , Feminino , Humanos , Masculino , Percepção Social , Adulto JovemRESUMO
The present experiment was designed to enhance our understanding of how response effects with varying amounts of useful information influence implicit sequence learning. We recorded event-related brain potentials, while participants performed a modified version of the serial reaction time task (SRTT). In this task, participants have to press one of four keys corresponding to four letters on a computer screen. Unknown to participants, in some parts of the experimental blocks, the stimuli appear in a repetitive (structured) deterministic sequence, whereas in other parts, stimuli were determined randomly. Four groups of participants differing in the presentation of tones after each response performed the SRTT. In the no tone group, no tones were presented after a response. The other three groups differed with respect to the melody generated by the key presses: in the unmelodic group, one out of four different tones was chosen randomly and presented immediately after a response. In the consistent melody group, the press of a response key always resulted in the production of the same tone, resulting in a repetitive melody during structured parts of the sequence (consistent redundant effect). In the inconsistent melody group, the "melody" produced in the sequenced parts of the blocks was identical to the consistent melody group, but the same response could produce two different tones depending on the actual position in the stimulus sequence. Thus, during structured sequences, subjects heard the same melody as in the consistent melody group, but every key press could be followed by one out of two different tones. To disentangle effects of sequence awareness from our experimental manipulations, all analyses were restricted to implicit learners. All four groups showed sequence learning, but to a different degree: in general, every kind of tone improved sequence learning relative to the no tone group. However, unmelodic tones were less beneficial for learning than tones forming a melody. Tones mapped consistently to response keys improved learning faster than tones producing the same melody, but not mapped consistently to keys. However, at the end of the learning phase, the two melody groups did not differ in the amount of sequence learning. The error-related negativity (ERN) increased with sequence learning (larger ERN at the end of the experiment for trials following the sequence compared to random trials) and this effect was more pronounced for the groups that showed more learning. These findings indicate that response effects containing useful information foster sequence learning even if the same response can produce different effects. Furthermore, we replicated earlier results showing that the importance of an error with respect to the task at hand modulates the activity of the human performance monitoring system.
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Percepção Auditiva/fisiologia , Potenciais Evocados/fisiologia , Função Executiva/fisiologia , Música , Desempenho Psicomotor/fisiologia , Aprendizagem Seriada/fisiologia , Adulto , Potenciais Evocados P300/fisiologia , Feminino , Humanos , Masculino , Adulto JovemRESUMO
Dyslexia is an impairment of reading and spelling that affects both children and adults even after many years of schooling. Dyslexic readers have deficits in the integration of auditory and visual inputs but the neural mechanisms of the deficits are still unclear. This fMRI study examined the neural processing of auditorily presented German numbers 0-9 and videos of lip movements of a German native speaker voicing numbers 0-9 in unimodal (auditory or visual) and bimodal (always congruent) conditions in dyslexic readers and their matched fluent readers. We confirmed results of previous studies that the superior temporal gyrus/sulcus plays a critical role in audiovisual speech integration: fluent readers showed greater superior temporal activations for combined audiovisual stimuli than auditory-/visual-only stimuli. Importantly, such an enhancement effect was absent in dyslexic readers. Moreover, the auditory network (bilateral superior temporal regions plus medial PFC) was dynamically modulated during audiovisual integration in fluent, but not in dyslexic readers. These results suggest that superior temporal dysfunction may underly poor audiovisual speech integration in readers with dyslexia.
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Percepção Auditiva/fisiologia , Dislexia/fisiopatologia , Percepção da Fala/fisiologia , Fala/fisiologia , Lobo Temporal/fisiopatologia , Mapeamento Encefálico/métodos , HumanosRESUMO
About 7.5million adults in Germany cannot read and write properly despite attending school for several years. They are considered to be functional illiterates. Since the ability to read and write is crucial for being employed and socially accepted, we developed a literacy training to overcome these deficits. In this study, we investigate the structural changes induced by the training. A group of 20 functional illiterates and 20 adult normal readers participated in the study. Group differences as well as intervention-related changes in gray (voxel-based morphometry, VBM) and white matter (Tract-Based Spatial Statistics, TBSS, applied to fractional anisotropy, FA, obtained with diffusion tensor imaging, DTI) were assessed in functional illiterates and normal reading controls. VBM analyses revealed decreased gray matter intensities in functional illiterates compared to normal readers before training in several reading-related brain regions such as the superior temporal gyrus, supramarginal gyrus, and angular gyrus. Using TBSS, functional illiterates showed reduced FA values in the genu of the corpus callosum. After training, both the gray matter intensities and FA values increased in functional illiterates and were no longer statistically different from controls' pre-test data. Moreover, the increase was positively correlated with reading and writing skills. The findings suggest that poor literacy skills are associated with several structural abnormalities in reading-related brain areas. In addition, we showed that while literacy skills of functional illiterates improved after training, the structural differences to controls disappeared.
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Encéfalo/diagnóstico por imagem , Educação não Profissionalizante , Substância Cinzenta/diagnóstico por imagem , Alfabetização , Substância Branca/diagnóstico por imagem , Adulto , Imagem de Tensor de Difusão , Feminino , Humanos , Imageamento Tridimensional , Testes de Linguagem , Imageamento por Ressonância Magnética , Masculino , Pessoa de Meia-Idade , Plasticidade Neuronal , Leitura , Resultado do Tratamento , RedaçãoRESUMO
The Broaden-and-Build Theory states that positive emotions broaden cognition and therefore build personal resources. However, missing theoretical precision regarding the interaction of the cognitive processes involved offers a variety of possible explanations for the mechanisms of broadening and building. In Experiment 1 we tested the causality assumption which states that positive emotions first broaden visual attention which in turn leads to broadened cognition. We examined the effects of a broadened, narrowed or neutral attentional scope of 72 subjects (30 men) on their momentary thought-action repertoire. Results showed that there were no significant differences between groups regarding the breadth or the content of the thought-action repertoire. In Experiment 2 we studied the non-causality hypothesis which assumes a non-causal relationship between cognitive processes. We did so by investigating the effects of negative, neutral, and positive affect on the visual attentional scope of 85 subjects (41 men) in Experiment 2a, as well as on the thought-action repertoire of 85 participants (42 men) in Experiment 2b. Results revealed an attentional broadening effect in Experiment 2a but no differences between groups concerning the breadth of the thought-action repertoire in Experiment 2b. However, a theory driven content analysis showed that positive affect promoted social actions. Thus, our results favor the non-causality assumption. Moreover, results indicate that positive emotions do not target personal resources in general but rather resources associated with social behavior. In conclusion, we argue that the Broaden-and-Build Theory should be refined.
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BACKGROUND: Event-related brain potentials (ERPs) were used to investigate training-related changes in fast visual word recognition of functionally illiterate adults. Analyses focused on the left-lateralized occipito-temporal N170, which represents the earliest processing of visual word forms. Event-related brain potentials were recorded from 20 functional illiterates receiving intensive literacy training for adults, 10 functional illiterates not participating in the training and 14 regular readers while they read words, pseudowords or viewed symbol strings. Subjects were required to press a button whenever a stimulus was immediately repeated. RESULTS: Attending intensive literacy training was associated with improvements in reading and writing skills and with an increase of the word-related N170 amplitude. For untrained functional illiterates and regular readers no changes in literacy skills or N170 amplitude were observed. CONCLUSIONS: Results of the present study suggest that the word-related N170 can still be modulated in adulthood as a result of the improvements in literacy skills.
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Encéfalo/fisiologia , Escolaridade , Aprendizagem/fisiologia , Percepção Visual/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados/fisiologia , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Leitura , Adulto JovemRESUMO
BACKGROUND: Recent research on the "embodiment of emotion" implies that experiencing an emotion may involve perceptual, somatovisceral, and motor feedback aspects. For example, manipulations of facial expression and posture appear to induce emotional states and influence how affective information is processed. The present study investigates whether performance monitoring, a cognitive process known to be under heavy control of the dopaminergic system, is modulated by induced facial expressions. In particular, we focused on the error-related negativity, an electrophysiological correlate of performance monitoring. METHODS/PRINCIPAL FINDINGS: During a choice reaction task, participants held a Chinese chop stick either horizontally between the teeth ("smile" condition) or, in different runs, vertically ("no smile") with the upper lip. In a third control condition, no chop stick was used ("no stick"). It could be shown on a separate sample that the facial feedback procedure is feasible to induce mild changes in positive affect. In the ERP sample, the smile condition, hypothesized to lead to an increase in dopaminergic activity, was associated with a decrease of ERN amplitude relative to "no smile" and "no stick" conditions. CONCLUSION: Embodying emotions by induced facial expressions leads to a changes in the neural correlates of error detection. We suggest that this is due to the joint influence of the dopaminergic system on positive affect and performance monitoring.
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Mapeamento Encefálico , Emoções/fisiologia , Expressão Facial , Neurônios/fisiologia , Adulto , Afeto/fisiologia , Potenciais Evocados , Feminino , Humanos , Masculino , Processos Mentais , Pessoa de Meia-Idade , Tempo de Reação/fisiologia , Reprodutibilidade dos Testes , Inquéritos e QuestionáriosRESUMO
The present study examines the influence of induced affective state on performance monitoring. The electroencephalogram was recorded while human participants engaged in a speeded choice-reaction time task commonly used to examine performance monitoring processes. Prior to the experiment, participants were randomly allocated to receive either encouraging or derogatory feedback during task execution. Feedback was based on each participant's reaction times. Affective state was assessed prior and after the experiment with a state questionnaire. Although participants of both feedback groups loaded high on items describing tiredness in the state questionnaire, only those with derogatory feedback loaded higher on negative state items and lower on positive state items after completion of the experiment. The error-related negativity (ERN) as an index of performance monitoring was increased after derogatory feedback; this difference was not seen at the beginning of the experiment. Negative state correlated significantly with ERN amplitude. The error positivity, a later component following errors, did not differ between feedback groups. This study provides further evidence that changes in affective state influence how we monitor ongoing behavior.
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Afeto/fisiologia , Mapeamento Encefálico , Potenciais Evocados Visuais/fisiologia , Retroalimentação Psicológica/fisiologia , Monitorização Fisiológica , Comportamento Verbal/fisiologia , Adulto , Análise de Variância , Eletroencefalografia/métodos , Feminino , Humanos , Modelos Lineares , Testes Neuropsicológicos , Estimulação Luminosa , Tempo de Reação/fisiologia , Inquéritos e Questionários , Fatores de Tempo , Adulto JovemRESUMO
The present study investigates whether performance monitoring and its electrophysiological indices in a choice reaction time task are modulated by affective information presented briefly prior to the critical stimuli. A flanker task known to elicit a sufficient number of performance errors was used and prior to each flanker stimulus a neutral, pleasant or unpleasant picture from the International Affective Picture System (IAPS) was shown. While behavioral performance to the flanker stimuli was hardly affected by the preceding affective information, the error-related negativity (ERN) of the event-related potential was modulated by affective information: Unpleasant IAPS pictures preceding a performance error led to an increased ERN amplitude compared to trials with neutral and pleasant IAPS pictures. These trial-by-trial modulations of electrophysiological markers of performance monitoring are discussed in terms of the possible influence of affective stimuli on monaminergic neuromodulatory transmitter systems.
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Afeto/fisiologia , Comportamento de Escolha/fisiologia , Variação Contingente Negativa/fisiologia , Potenciais Evocados Visuais/fisiologia , Adulto , Mapeamento Encefálico , Eletroencefalografia/métodos , Feminino , Humanos , Testes Neuropsicológicos , Estimulação Luminosa , Tempo de Reação/fisiologia , Fatores de Tempo , Adulto JovemRESUMO
BACKGROUND: Detecting malingering or exaggeration of impairments in brain function after traumatic brain injury is of increasing importance in neuropsychological assessment. Lawyers involved in brain injury litigation cases routinely coach their clients how to approach neuropsychological testing to their advantage. Thus, it is important to know how robust assessment methods are with respect to symptom malingering or exaggeration. METHODS: The influence of different coaching methods on the simulated malingering of memory impairments is investigated in neurologically healthy participants using the Short-Term-Memory Test from the Bremer Symptom-Validierung (STM-BSV). Cut-offs were derived from patients with mild to severe traumatic brain injury. For comparison purposes, the German adaptation of the Rey Auditory Verbal Learning Test (AVLT), and the Rey 15 Items Test (FIT) were additionally administered. Four groups of neurologically healthy subjects were instructed to (1) perform as best as they can, (2) simulate brain injury, (3) simulate brain injury and received additional information about the sequelae of head trauma, (4) simulate brain injury and received additional information on how to avoid detection. Furthermore, a group of patients with mild to severe closed head injury performed the tests with best effort. RESULTS: The naïve simulator and the symptom coached groups were the easiest to detect, whereas the symptom plus test coached group was the hardest to detect. The AVLT and the FIT were not suited to detect simulators (sensitivities from 0% to 50.8% at 75% specificity) whereas the STM-BSV detected simulators with 67% - 88% sensitivity at a specificity of 73%. However, the STM-BSV was not robust to coaching. CONCLUSION: The present investigation shows that symptom validity testing as implemented in the BSV-STM is one clinically useful element in the detection of memory malingering. However, clinicians have to be aware that coaching influences performance in the test.
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Lesões Encefálicas/diagnóstico , Simulação de Doença/diagnóstico , Transtornos da Memória/diagnóstico , Testes Neuropsicológicos , Análise de Variância , Percepção Auditiva/fisiologia , Lesões Encefálicas/psicologia , Diagnóstico Diferencial , Alemanha , Humanos , Testes de Inteligência , Simulação de Doença/psicologia , Transtornos da Memória/psicologia , Memória de Curto Prazo/fisiologia , Variações Dependentes do Observador , Psicometria/métodos , Sensibilidade e Especificidade , Aprendizagem Verbal/fisiologiaRESUMO
BACKGROUND: The use of self-generated and externally provided information in performance monitoring is reflected by the appearance of error-related and feedback-related negativities (ERN and FRN), respectively. Several authors proposed that ERN and FRN are supported by similar neural mechanisms residing in the anterior cingulate cortex (ACC) and the mesolimbic dopaminergic system. The present study is aimed to test the functional relationship between ERN and FRN. Using an Eriksen-Flanker task with a moving response deadline we tested 17 young healthy subjects. Subjects received feedback with respect to their response accuracy and response speed. To fulfill both requirements of the task, they had to press the correct button and had to respond in time to give a valid response. RESULTS: When performance monitoring based on self-generated information was sufficient to detect a criterion violation an ERN was released, while the subsequent feedback became redundant and therefore failed to trigger an FRN. In contrast, an FRN was released if the feedback contained information which was not available before and action monitoring processes based on self-generated information failed to detect an error. CONCLUSION: The described pattern of results indicates a functional interrelationship of response and feedback related negativities in performance monitoring.
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Encéfalo/fisiologia , Retroalimentação Psicológica/fisiologia , Desempenho Psicomotor/fisiologia , Adulto , Eletroencefalografia , Potenciais Evocados , Feminino , Humanos , Masculino , Estimulação Luminosa , Tempo de ReaçãoRESUMO
BACKGROUND: The present study used event-related brain potentials to investigate semantic, phonological and syntactic processes in adult German dyslexic and normal readers in a word reading task. Pairs of German words were presented one word at a time. Subjects had to perform a semantic judgment task (house-window; are they semantically related?), a rhyme judgment task (house-mouse; do they rhyme?) and a gender judgment task (das-Haus [the-house]; is the gender correct? [in German, house has a neutral gender: das Haus]). RESULTS: Normal readers responded faster compared to dyslexic readers in all three tasks. Onset latencies of the N400 component were delayed in dyslexic readers in the rhyme judgment and in the gender judgment task, but not in the semantic judgment task. N400 and the anterior negativity peak amplitudes did not differ between the two groups. However, the N400 persisted longer in the dyslexic group in the rhyme judgment and in the semantic judgment tasks. CONCLUSION: These findings indicate that dyslexics are phonologically impaired (delayed N400 in the rhyme judgment task) but that they also have difficulties in other, non-phonological aspects of reading (longer response times, longer persistence of the N400). Specifically, semantic and syntactic integration seem to require more effort for dyslexic readers and take longer irrespective of the reading task that has to be performed.
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Dislexia/fisiopatologia , Potenciais Evocados/fisiologia , Leitura , Reconhecimento Psicológico , Semântica , Adulto , Análise de Variância , Eletroencefalografia , Feminino , Humanos , Masculino , Estimulação Luminosa/métodos , Distribuição Aleatória , Tempo de Reação/fisiologia , Fatores de TempoRESUMO
Event-related brain potentials (ERPs) elicited by recalled and non-recalled words were recorded from 18 female subjects to investigate primacy and recency effects in free memory recall. The typical pattern of a serial position curve (SPC) was obtained with words presented at first and final positions in a list recalled better than words presented in the middle of a list. A marked positivity is seen in the ERPs for words on Primacy, but not on Recency positions at frontocentral electrodes. In contrast, ERP amplitudes on parietal electrodes resemble the SPC seen in behavioral data: P300 amplitude is largest for words on Primacy and Recency positions and attenuated on Plateau positions. Furthermore, subjects with a clear Primacy effect in behavioral data show a distinct frontal positive slow wave for Primacy words only, whereas subjects without a clear primacy effect show a frontal "difference due to subsequent memory" (DM) effect for Primacy and Plateau words. These results are discussed in the framework of working memory and distinctiveness.
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Eletroencefalografia , Rememoração Mental/fisiologia , Aprendizagem Seriada/fisiologia , Adulto , Atenção/fisiologia , Mapeamento Encefálico , Córtex Cerebral/fisiologia , Potenciais Evocados P300/fisiologia , Potenciais Evocados/fisiologia , Feminino , Humanos , Memória de Curto Prazo/fisiologia , Retenção Psicológica/fisiologia , Semântica , Processamento de Sinais Assistido por ComputadorRESUMO
BACKGROUND: Previous research has demonstrated a relationship between memory recall and P300 amplitude in list learning tasks, but the variables mediating this P300-recall relationship are not well understood. In the present study, subjects were required to recall items from lists consisting of 12 words, which were presented in front of pictures taken from the IAPS collection. One word per list is made distinct either by font color or by a highly arousing background IAPS picture. This isolation procedure was first used by von Restorff. Brain potentials were recorded during list presentation. RESULTS: Recall performance was enhanced for color but not for emotional isolates. Event-related brain potentials (ERP) showed a more positive P300-component for recalled non-isolated words and color-isolated words, compared to the respective non-remembered words, but not for words isolated by arousing background. CONCLUSION: Our findings indicate that it is crucial to take emotional mediator variables into account, when using the P300 to predict later recall. Highly arousing environments might force the cognitive system to interrupt rehearsal processes in working memory, which might benefit transfer into other, more stable memory systems. The impact of attention-capturing properties of arousing background stimuli is also discussed.