Aprendendo com feedback: um estudo sobre como o cérebro utiliza informação para aprender

Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Filosofia e Ciências Humanas. Programa de Pós-Graduação em Psicologia.Para aprender, é necessário extrair e integrar informações de diferentes fontes. A informação que resulta das próprias ações do ser humano é chamada de feedback, que pode ser definido como o resultado da ação que são capturadas pelos sentidos. Na presente tese, o objetivo foi analisar como diferentes características do feedback são processadas no cérebro, incluindo a resolução do feedback (contínuo vs. categórico), a magnitude do feedback (erros grandes vs. pequenos), a categoria do feedback (correto vs. incorreto) e o timing do feedback (imediato vs. atrasado). Para investigar como o cérebro processa tais atributos, utilizou-se o eletroencefalograma (EEG). Quatro estudos foram conduzidos para responder a quatro questões centrais: 1) Quais as diferenças no processamento de feedback indicando erros pequenos e grandes? 2) Como os correlatos neurais do feedback categórico indicando acerto e erro estão associados à aprendizagem? Quais as diferenças nos substratos neurais da aprendizagem utilizando feedback graduado e categórico? Quais as diferenças nos correlatos neurais do processamento de feedback imediato vs. atrasado e como que os mesmos interagem com os níveis de ativação? Os correlatos neurais foram analisados utilizando diferentes técnicas, incluindo: potenciais relacionados ao evento (ERPs), representações de tempo-frequência (TFRs), conectividade (sincronização entre áreas) e origens de oscilações neurais utilizando abordagem beamformer. Nem todas as técnicas foram utilizadas em todos os estudos, mas aplicadas de acordo com os objetivos secundários de cada pesquisa. Em todos os experimentos, a aprendizagem foi investigada utilizando uma tarefa de produção temporal, que é aprendida implicitamente. Foi verificado que o processamento de erros pequenos provoca maior ativação das áreas motoras do que erros grandes, e também que essa ativação está relacionada com o quanto bem os participantes consolidam o seu desempenho. Observou-se o aumento de oscilações na frequência teta nas áreas médias frontais em resposta ao feedback categórico incorreto sendo esta maior nos indivíduos com melhor aprendizagem. Verificou-se, também, que o processamento de feedback categórico é mediado por substratos neurais relacionados ao sistema de recompensa, especialmente a porção dorsal direita do córtex cingulado anterior.Os padrões de conectividade encontrados indicam que após o feedback, aumentou o fluxo de informação das áreas motoras às áreas médias frontais e que posteriormente as áreas médias se conectam às áreas pré-frontais, provavelmente refletindo a atualização das expectativas com base no feedback. O nível de ativação ou arousal parece aumentar as diferenças em um componente específico do ERP, sugerindo que as respostas cerebrais ao feedback atrasado foram maiores quando a ativação estava alta. Em conjunto, os resultados indicam que embora os sinais associados com o processamento de informação categórica ou de recompensas seja um correlato relevante para como o cérebro sinaliza a presença de erros, a ativação das áreas motoras contralaterais bem como a comunicação dessas com as áreas médias frontais são mais cruciais para a consolidação da habilidade motora aprendida

Aroused with heart: Modulation of heartbeat evoked potential by arousal induction and its oscillatory correlates

Recent studies showed that the visceral information is constantly processed by the brain, thereby potentially influencing cognition. One index of such process is the heartbeat evoked potential (HEP), an ERP component related to the cortical processing of the heartbeat. The HEP is sensitive to a number of factors such as motivation, attention, pain, which are associated with higher levels of arousal. However, the role of arousal and its associated brain oscillations on the HEP has not been characterized, yet it could underlie the previous findings. Here we analysed the effects of high- (HA) and low-arousal (LA) induction on the HEP. Further, we investigated the brain oscillations and their role in the HEP in response to HA and LA inductions. As compared to LA, HA was associated with a higher HEP and lower alpha oscillations. Interestingly, individual differences in the HEP modulation by arousal induction were correlated with alpha oscillations. In particular, participants with higher alpha power during the arousal inductions showed a larger HEP in response to HA compared to LA. In summary, we demonstrated that arousal induction affects the cortical processing of heartbeats; and that the alpha oscillations may modulate this effect

Learning temporal statistics for sensory predictions in mild cognitive impairment.

Training is known to improve performance in a variety of perceptual and cognitive skills. However, there is accumulating evidence that mere exposure (i.e. without supervised training) to regularities (i.e. patterns that co-occur in the environment) facilitates our ability to learn contingencies that allow us to interpret the current scene and make predictions about future events. Recent neuroimaging studies have implicated fronto-striatal and medial temporal lobe brain regions in the learning of spatial and temporal statistics. Here, we ask whether patients with mild cognitive impairment due to Alzheimer's disease (MCI-AD) that are characterized by hippocampal dysfunction are able to learn temporal regularities and predict upcoming events. We tested the ability of MCI-AD patients and age-matched controls to predict the orientation of a test stimulus following exposure to sequences of leftwards or rightwards orientated gratings. Our results demonstrate that exposure to temporal sequences without feedback facilitates the ability to predict an upcoming stimulus in both MCI-AD patients and controls. However, our fMRI results demonstrate that MCI-AD patients recruit an alternate circuit to hippocampus to succeed in learning of predictive structures. In particular, we observed stronger learning-dependent activations for structured sequences in frontal, subcortical and cerebellar regions for patients compared to age-matched controls. Thus, our findings suggest a cortico-striatal-cerebellar network that may mediate the ability for predictive learning despite hippocampal dysfunction in MCI-AD.This work was supported by grants to PB from Birmingham and Solihull Mental Health Foundation Trust Research and Development, and to ZK from the Leverhulme Trust [RF-2011-378] and the [European Community's] Seventh Framework Programme [FP7/2007-2013] under agreement PITN-GA-2011-290011.This is the accepted manuscript. The final version is available at http://www.sciencedirect.com/science/article/pii/S0028393215300506

Learning Temporal Statistics for Sensory Predictions in Aging.

Predicting future events based on previous knowledge about the environment is critical for successful everyday interactions. Here, we ask which brain regions support our ability to predict the future based on implicit knowledge about the past in young and older age. Combining behavioral and fMRI measurements, we test whether training on structured temporal sequences improves the ability to predict upcoming sensory events; we then compare brain regions involved in learning predictive structures between young and older adults. Our behavioral results demonstrate that exposure to temporal sequences without feedback facilitates the ability of young and older adults to predict the orientation of an upcoming stimulus. Our fMRI results provide evidence for the involvement of corticostriatal regions in learning predictive structures in both young and older learners. In particular, we showed learning-dependent fMRI responses for structured sequences in frontoparietal regions and the striatum (putamen) for young adults. However, for older adults, learning-dependent activations were observed mainly in subcortical (putamen, thalamus) regions but were weaker in frontoparietal regions. Significant correlations of learning-dependent behavioral and fMRI changes in these regions suggest a strong link between brain activations and behavioral improvement rather than general overactivation. Thus, our findings suggest that predicting future events based on knowledge of temporal statistics engages brain regions involved in implicit learning in both young and older adults.We would like to thank Matthew Dexter for help with software development and Josie Harding for help with data collection. This work was supported by grants to ZK from the Biotechnology and Biological Sciences Research Council (H012508), the Leverhulme Trust (RF-2011-378), and the (European Community’s) Seventh Framework Programme (FP7/2007-2013) under agreement PITN-GA-2011-290011.This is the final version of the article. It first appeared from MIT Press via http://dx.doi.org/10.1162/jocn_a_0090

Processing graded feedback: Electrophysiological correlates of learning from small and large errors

Feedback processing is important for learning and therefore may affect the consolidation of skills. Considerable research demonstrates electrophysiological differences between correct and incorrect feedback, but how we learn from small versus large errors is usually overlooked. This study investigated electrophysiological differences when processing small or large error feedback during a time estimation task. Data from high-learners and low-learners were analyzed separately. In both high- and low-learners, large error feedback was associated with higher feedback-related negativity (FRN) and small error feedback was associated with a larger P300 and increased amplitude over the motor related areas of the left hemisphere. In addition, small error feedback induced larger desynchronization in the alpha and beta bands with distinctly different topographies between the two learning groups: The high-learners showed a more localized decrease in beta power over the left frontocentral areas, and the low-learners showed a widespread reduction in the alpha power following small error feedback. Furthermore, only the high-learners showed an increase in phase synchronization between the midfrontal and left central areas. Importantly, this synchronization was correlated to how well the participants consolidated the estimation of the time interval. Thus, although large errors were associated with higher FRN, small errors were associated with larger oscillatory responses, which was more evident in the high-learners. Altogether, our results suggest an important role of the motor areas in the processing of error feedback for skill consolidation

Investigating Age-Related Neural Compensation During Emotion Perception Using Electroencephalography

Previous research suggests declines in emotion perception in older as compared to younger adults, but the underlying neural mechanisms remain unclear. Here, we address this by investigating how “face-age” and “face emotion intensity” affect both younger and older participants’ behavioural and neural responses using event-related potentials (ERPs). Sixteen young and fifteen older adults viewed and judged the emotion type of facial images with old or young face-age and with high- or low- emotion intensities while EEG was recorded. The ERP results revealed that young and older participants exhibited significant ERP differences in two neural clusters: the left frontal and centromedial regions (100–200 ms stimulus onset) and frontal region (250–900 ms) when perceiving neutral faces. Older participants also exhibited significantly higher ERPs within these two neural clusters during anger and happiness emotion perceptual tasks. However, while this pattern of activity supported neutral emotion processing, it was not sufficient to support the effective processing of facial expressions of anger and happiness as older adults showed reductions in performance when perceiving these emotions. These age-related changes are consistent with theoretical models of age-related changes in neurocognitive abilities and may reflect a general age-related cognitive neural compensation in older adults, rather than a specific emotion-processing neural compensation

Neural Correlates of Transmitted Light Experience during Meditation: A Pilot Hyperscanning Study

Certain individuals during deep meditative states can transmitt and give out an aura or ‘light, which is perceived by others through some unknown connections, visual, telepathic or other. Despite various anecdotal, historical accounts of such induced light experience (ILE), its underlying neural mechanism is not known. In this pilot study, we investigated the neural correlates of ILE by simultaneously recording the EEGs of an expert Teacher, who is claimed to elicit ILE, and his Pupil (N=2) during joint sessions under various instructions, given separately to the Teacher (transmit/ do not transmit) and to the Pupil (receive/ do not receive). In a further condition both teacher and pupil wear opaque goggles during transmit/receive instruction, limiting the visual/outputinput. We observed a robust increase in the high frequency beta (12-30 Hz) and gamma oscillations (30-70 Hz) in the Teacher’s brain whenever he was instructed to transmit. Electric field tomography analysis localized these effects over several brain regions including the fusiform gyrus, angular gyrus and the cerebellum. Finally, we found that the Teacher’s and Pupil’s brain responses were synchronized, especially in the alpha band (8-12 Hz) during transmit/receive condition, and the information flow was directional, i.e. from the Teacher to the Pupil; interestingly, this enhanced interbrain synchrony disappeared with opaque goggles. These results were interpreted in terms of heightened internally selective attention as manifested by high frequency beta-gamma oscillations and of joint attention as manifested by interbrain alpha synchrony. Altogether, our results provide the first neuroscientific evidence underlying the phenomenological experience of induced light

From learning to creativity: Identifying the behavioural and neural correlates of learning to predict human judgements of musical creativity

Human creativity is strongly linked to acquired knowledge. However, to date learning a new musical style and subsequent creativity have largely been studied in isolation. We introduced a novel experimental paradigm combining behavioural, electrophysiological, and computational methods, to examine the neural correlates of unfamiliar music learning, and to investigate how neural and computational measures can predict human creativity. We investigated music learning by training non-musicians (N = 40) on an artificial music grammar. Participants’ knowledge of the grammar was tested before and after three training sessions by assessing explicit recognition of the notes of the grammar, while additionally recording EEG. After each training session, participants created their own musical compositions, which were later evaluated by human experts. A computational model of auditory expectation was used to quantify the statistical properties of both the grammar and the compositions. Results showed that participants successfully learned the grammar. This was also reflected in the N100, P200, and P3a components, which were higher in response to incorrect than correct notes. Delta band power in response to grammatical notes during first exposure to the grammar positively correlated with learning, suggesting a potential encoding neural mechanism. On the other hand, better learning was associated with lower alpha and higher beta band power after training, potentially reflecting neural mechanisms of retrieval. Importantly, learning was a significant predictor of creativity, as judged by experts. There was also an inverted U-shaped relationship between percentage of correct intervals and creativity, as compositions with an intermediate proportion of correct intervals were associated with the highest creativity. Finally, the P200 in response to incorrect notes was predictive of creativity, suggesting a link between the neural correlates of learning, and creativity. Overall, our findings shed light on the neural mechanisms of learning an unfamiliar music grammar, as well as offering contributions to the associations between learning measures and human evaluation of creativity

Best of both worlds: promise of combining brain stimulation and brain connectome

Transcranial current brain stimulation (tCS) is becoming increasingly popular as a non-pharmacological non-invasive neuromodulatory method that alters cortical excitability by applying weak electrical currents to the scalp via a pair of electrodes. Most applications of this technique have focused on enhancing motor and learning skills, as well as a therapeutic agent in neurological and psychiatric disorders. In these applications, similarly to lesion studies, tCS was used to provide a causal link between a function or behavior and a specific brain region (e.g., primary motor cortex). Nonetheless, complex cognitive functions are known to rely on functionally connected multitude of brain regions with dynamically changing patterns of information flow rather than on isolated areas, which are most commonly targeted in typical tCS experiments. In this review article, we argue in favor of combining tCS method with other neuroimaging techniques (e.g., fMRI, EEG) and by employing state-of-the-art connectivity data analysis techniques (e.g., graph theory) to obtain a deeper understanding of the underlying spatiotemporal dynamics of functional connectivity patterns and cognitive performance. Finally, we discuss the possibilities of using these combined techniques to investigate the neural correlates of human creativity and to enhance creativity

Versão brasileira da Escala de Estresse Percebido: tradução e validação para idosos

OBJECTIVE: To translate the Perceived Stress Scale into Brazilian Portuguese, and to assess its validity for measuring perceived stress of Brazilian elderly. METHODS: The scale was translated and tested in its full version including 14 questions and in a shortened version including ten questions. The whole translation process consisted of translation, back-translation and committee review. The translated version was applied, by means of interview, to 76 elders aged on average 70.04 years (SD=6.34; range: 60-84). The internal consistency was verified by means of the Cronbach's alpha coefficient and the construct validity was analyzed by means of factorial exploratory analysis with varimax rotation. Full and shortened score means were analyzed comparing the perceived stress in terms of self-assessment of health, perceived socioeconomic condition, marital status, and living conditions, among others. RESULTS: As for reliability, the full version has showed similar internal consistency (r=0.82) compared to the shortened one (r=0.83). The factorial analysis found two factors for the full and one factor for the shortened scale. Question 12 showed the lowest factorial loads. When analyzing PSS likelihood of differentiating the perceived stress in terms of the study variables, it was found the full scale had greater differences in perceived stress than the shortened scale. CONCLUSIONS: The Perceived Stress Scale proved to be a clear and reliable tool to measure the perceived stress of Brazilian elderly, showing suitable psychometric performance.OBJETIVO: Traduzir a Escala de Estresse Percebido para a língua portuguesa do Brasil e verificar sua validade para mensurar o estresse percebido de idosos brasileiros. MÉTODOS: A escala foi traduzida e testada em sua versão completa, com 14 questões e na reduzida, com dez questões. A tradução obedeceu às etapas de tradução, tradução reversa e revisão por um comitê. A escala traduzida foi aplicada, por meio de entrevista, a 76 idosos com idade média de 70,04 anos (DP=6,34; mín: 60; máx: 84). A consistência interna foi verificada por meio do coeficiente alfa de Cronbach e a validade de construto, por análise fatorial exploratória com rotação ortogonal pelo método varimax. As médias das versões completa e reduzida foram analisadas comparando o estresse percebido em função da auto-avaliação da saúde, nível econômico percebido, estado civil, condições de residência, entre outras. RESULTADOS: Quanto à confiabilidade, a versão completa apresentou consistência interna semelhante (r=0,82) à reduzida (r=0,83). A análise fatorial revelou a existência de dois fatores para a completa e um para a reduzida. A questão 12 apresentou as menores cargas fatoriais. Ao analisar a possibilidade de a escala diferenciar o estresse percebido em função das variáveis, verificou-se que a versão completa obteve maiores diferenças no estresse do que a reduzida. CONCLUSÕES: A Escala de Estresse Percebido mostrou-se clara e confiável para mensurar o estresse percebido de idosos brasileiros, apresentando qualidades psicométricas adequadas