Henrique Sequeira

Affective picture processing: An integrative review of ERP findings

The review summarizes and integrates findings from 40 years of event-related potential (ERP) studies using pictures that differ in valence (unpleasant-to-pleasant) and arousal (low-to-high) and that are used to elicit emotional processing. Affective stimulus factors primarily modulate ERP component amplitude, with little change in peak latency observed. Arousal effects are consistently obtained, and generally occur at longer latencies. Valence effects are inconsistently reported at several latency ranges, including very early components. Some affective ERP modulations vary with recording methodology, stimulus factors, as well as task-relevance and emotional state. Affective ERPs have been linked theoretically to attention orientation for unpleasant pictures at earlier components (<300 ms). Enhanced stimulus processing has been associated with memory encoding for arousing pictures of assumed intrinsic motivational relevance, with task-induced differences contributing to emotional reactivity at later components (>300 ms). Theoretical issues, stimulus factors, task demands, and individual differences are discussed.

Modulation of cognitive processing by emotional valence studied through event-related potentials in humans.

This experiment investigated whether the emotional content of a stimulus could modulate its cognitive processing. Particularly, we focused on the influence of the valence dimension on the cognitive processing triggered by a non emotional oddball task. To this end, event-related potentials (ERPs) were recorded from 25 sites during a visual oddball paradigm. Three sets of pictures (unpleasant, neutral and pleasant) with low arousal values served as rare target items. Subjects were simply asked to realize a standard/target categorization task, irrespective of the picture valence. A temporal principal component analysis allowed us to identify several evoked components (i.e. P1, P2, N2, P3a and P3b). Emotional effects observed on P1, P2 and P3b showed that the valence content of the stimulus modulates the cognitive processes at several points in the information processing stream.

Electrical autonomic correlates of emotion.

This paper focussed on how electrophysiological autonomic data may contribute to better understand neural substrates of emotional processing. The utility of autonomic electrophysiological markers for assessing emotional and cognitive processes is presented in the context of an important bodily arousal interface. Components of general autonomic control are reviewed and relevant neural modulations of specific autonomic variables were discussed. The role of autonomic feedback on central processes is emphasized and neural influences on autonomic activities as an index of arousal dimension, the electrodermal activity (EDA), are outlined. An overview of brain mechanisms governing generation and control of EDA is presented, and the contribution of electrodermal parameters as indices of emotional activation illustrated by data related to diurnal emotional reactivity and to non consciously subjective emotionality. Conclusions highlight the role of electrical autonomic expressions as tools to explore emotional components of mind-body-mind relationships.

Event-related P3a and P3b in response to unpredictable emotional stimuli

In natural situations, unpredictable events processing often interacts with the ongoing cognitive activities. In a similar manner, the insertion of deviant unpredictable stimuli into a classical oddball task evokes both the P3a and P3b event-related potentials (ERPs) components that are, respectively, thought to index reallocation of attentional resources or inhibitory process and memory updating mechanism. This study aims at characterising the influence of the emotional arousal and valence of a deviant and unpredictable non-target stimulus on these components. ERPs were recorded from 28 sites during a visual three-stimulus oddball paradigm. Unpleasant, neutral and pleasant pictures served as non-target unpredictable items and subjects were asked to realize a perceptually difficult standard/target discrimination task. A temporal principal component analysis (PCA) allowed us to show that non-target pictures elicited both a P3a and a P3b. Moreover, the P3b component was modulated by the emotional arousal and the valence of the pictures. Thus, the memory updating process may be modulated by the affective arousal and valence of unpredictable disturbing stimuli, even if the task does not require any explicit emotional categorization.

Neurobiological correlates of high (HAB) versus low anxiety-related behavior (LAB): differential Fos expression in HAB and LAB rats

BACKGROUND Two Wistar rat lines selectively bred for either high (HAB) or low (LAB) anxiety-related behavior were used to identify neurobiological correlates of trait anxiety. METHODS We used Fos expression for mapping of neuronal activation patterns in response to mild anxiety-provoking challenges. RESULTS In both lines, exposure to an open field (OF) or the open arm (OA) of an elevated plus-maze induced Fos expression in several brain areas of the anxiety/fear circuitry. Rats of the HAB type, which showed signs of a hyperanxious phenotype and a hyperreactive hypothalamic-pituitary-adrenal axis compared with LAB rats, exhibited a higher number of Fos-positive cells in the paraventricular nucleus of the hypothalamus, the lateral and anterior hypothalamic area, and the medial preoptic area in response to both OA and OF. Less Fos expression was induced in the cingulate cortex in HAB than in LAB rats. Differential Fos expression in response to either OA or OF was observed in few brain regions, including the thalamus and hippocampus. CONCLUSIONS The present data indicate that the divergent anxiety-related behavioral response of HAB versus LAB rats to OF and OA exposures is associated with differential neuronal activation in restricted parts of the anxiety/fear circuitry. Distinct hypothalamic regions displayed hyperexcitability, and the cingulate cortex showed hypoexcitability, which suggests that they are main candidate mediators of dysfunctional brain activation in pathologic anxiety.

Peripherally Presented Emotional Scenes: A Spatiotemporal Analysis of Early ERP Responses

Recent findings from event-related potentials (ERPs) studies provided strong evidence that cen- trally presented emotional pictures could be used to assess affective processing. Moreover, several studies showed that emotionally charged stimuli may automatically attract attention even if these are not consciously identified. Indeed, such perceptive conditions can be compared to those typical of the peripheral vision, particularly known to have low spatial resolution capacities. The aim of the present study was to characterize at behavioral and neural levels the impact of emotional visual scenes presented in peripheral vision. Eighteen participants were asked to categorize neutral and unpleasant pictures presented at central (0°) and peripheral eccentricities (−30 and +30°) while ERPs were recorded from 63 electrodes. ERPs were analysed by means of spatio-temporal principal component analyses (PCA) in order to evaluate influences of the emotional content on ERP components for each spatial position (central vs. peripheral). Main results highlight that affective modulation of early ERP components exists for both centrally and peripherally presented pictures. These findings suggest that, for far peripheral eccentricities as for central vision, the brain engages specific resources to process emotional information.

Cortical and Hypothalamo-Limbic Control of Electrodermal Responses

Hughlings (1869) was among the first authors to report cortical influences upon the autonomic nervous system. Following Jackson’s studies, cardiovascular changes were elicited by stimulation of the frontal cortex (Danilewsky, 1875; Bochefontaine, 1876). At the beginning of this century, some authors (Bechterew, 1905; Karplus and Kreidl, 1909) also obtained an increase of sweating in the foot-pads of the cat, evoked by stimulating the sensorimotor cortex. During the next decades, other reports approached the role of cortical areas in the regulation of autonomic responses (see reviews of Kaada, 1951; Delgado, 1960; Hoff et al., 1963).

Cortical control of somato-cardiovascular integration: Neuroanatomical studies

This paper will discuss experiments dedicated to the exploration of pathways linking the sensorimotor cortex (SMC) and the main bulbar nuclei involved in cardiovascular control: the nucleus tractus solitarius (NTS), the dorsal nucleus of the vagus (DMV) and the rostral ventrolateral medulla (RVLM). Results obtained through neurofunctional and neuroanatomical methods are presented in order to bring new answers to relevant points concerning somato-cardiovascular integration: firstly to show the ability of the SMC to influence neurons in bulbar cardiovascular nuclei, and secondly to identify pathways that transmit such influences. The neurofunctional approach, based on the identification of Fos-like immunoreactive neurons, indicated that the SMC has functional connections with cardiovascular bulbar nuclei. The neuroanatomical approach, which employed retrograde and anterograde axonal tracing methods, provided evidence of direct projections from the SMC to NTS/DMV and RVLM. Furthermore, experiments showed clearly that corticospinal neurons sent collaterals to bulbar cardiovascular nuclei, especially to the RVLM. Direct cortical projections to the NTS/DMV and the RVLM provide the anatomical basis for cortical influences on the baroreceptor reflex and sympathetic vasomotor mechanisms for blood pressure control, and support the hypothesis of cortical commands coupling somatic and cardiovascular outputs for action.

Diurnal variations of tonic electrodermal activity.

Diurnal variability of skin conductance level (SCL) was examined in two complementary experiments, simultaneously with variability of skin temperature (ST) and that of simple reaction time (RT) which was recorded as a behavioural index of arousal. In Experiment I, 6 subjects spent 6 days in the laboratory in homogeneous conditions. Three recording sessions, each lasting 2 h, began, respectively, at 9:00 a.m. (morning), 1:00 p.m. (afternoon) and 5:00 p.m. (evening). Results indicated that SCL increased linearly throughout the day. Experiment II was undertaken to test whether this effect could still be observed in more heterogeneous conditions. Subjects (n = 12) attended to their own activities between the two 30-min sessions beginning, respectively, at 9:30 a.m. and 6:00 p.m. during a single experimental day. Again, SCL was higher in the evening than in the morning. In both experiments the SCL pattern seemed to be asynchronous with ST and RT variations. Taken as a whole, these data bring additional evidence of temporal electrodermal variation, a phenomenon which should be further taken into account in EDA research.

An ERP investigation of emotional processing in European and Japanese individuals

This article examined neural time course differences in the processing of emotional pictures in European and Asian individuals. Event-related potentials (ERPs) were recorded in 15 French and 15 Japanese volunteers during the presentation of neutral and emotional pictures in their own country. ERPs were analyzed by means of spatio-temporal Principal Component Analysis (PCA) and allow to evaluate cultural influences on emotional processing along three temporal windows: 105 to 140 ms, 176 to 230 ms and 255 to 455 ms. Main results highlight that (1) early ERP components coded emotional charge but were not modulated by cultural background, (2) later components showed a significant decrease of amplitudes at parieto-occipital areas for Japanese participants compared to French ones in emotional condition. These findings suggest that, in both populations, similar neurocognitive processes are involved in the early stage of the emotional stimuli processing and effects observed on later components may reflect a poorer engagement of parietal areas, known to be involved in emotional arousal dimension. Considering that cognitive judgments were similar in both populations, electrophysiological findings suggest that cultural influences on later stage of emotional processing could be related to the known lower level of emotionally expressive behavior in Japanese than in Caucasians.