Dataset Information

Are we afraid of different categories of stimuli in identical ways? Evidence from skin conductance responses.

ABSTRACT: Studies have shown that emotional pictures attract more attention than neutral pictures, and pictures of living stimuli have similar advantage in driving attention (vs. nonliving). However, factors of emotion, category and picture context are usually mixed so that whether living and nonliving categories elicit different skin conductance (SC) responses, in both conscious and unconscious conditions, remains to be clarified. In this study, participants were presented with negative and neutral pictures denoting different living and nonliving concepts in conscious (Experiments 1 and 2) and unconscious conditions (40ms, Experiment 3) when their SC responses were measured. The picture context was manipulated in Experiments 2 and 3 as half including human-related information. In three experiments, the emotional levels of different categories were matched in different and identical cohorts of participants. The results showed that living pictures in a negative, high-arousing dimension elicited stronger SC responses than nonliving pictures. When nonhuman animals and inanimate objects were compared, the increased SC responses to animals was obtained only for negative pictures without human contexts in the conscious condition, but regardless of human context in the unconscious condition. These results suggested that contextual information and level of conscious awareness are important to modulate the animate advantage in emotional processing.

SUBMITTER: Tan T

PROVIDER: S-EPMC3770652 | biostudies-literature | 2013

REPOSITORIES: biostudies-literature

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Are we afraid of different categories of stimuli in identical ways? Evidence from skin conductance responses.

Tan Tengteng T Li Han H Wang Yingying Y Yang Jiongjiong J

PloS one 20130911 9

Studies have shown that emotional pictures attract more attention than neutral pictures, and pictures of living stimuli have similar advantage in driving attention (vs. nonliving). However, factors of emotion, category and picture context are usually mixed so that whether living and nonliving categories elicit different skin conductance (SC) responses, in both conscious and unconscious conditions, remains to be clarified. In this study, participants were presented with negative and neutral pictu ...[more]

PMID: 24039879

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Project description:Depressive symptoms are related to abnormalities in the autonomic nervous system (ANS), and physiological signals that can be used to measure and evaluate such abnormalities have previously been used as indicators for diagnosing mental disorder, such as major depressive disorder (MDD). In this study, we investigate the feasibility of developing an objective measure of depressive symptoms that is based on examining physiological abnormalities in individuals when they are experiencing mental stress. To perform this, we recruited 30 patients with MDD and 31 healthy controls. Then, skin conductance (SC) was measured during five 5-min experimental phases, comprising baseline, mental stress, recovery from the stress, relaxation, and recovery from the relaxation, respectively. For each phase, the mean amplitude of the skin conductance level (MSCL), standard deviations of the SCL (SDSCL), slope of the SCL (SSCL), mean amplitude of the non-specific skin conductance responses (MSCR), number of non-specific skin conductance responses (NSCR), and power spectral density (PSD) were evaluated from the SC signals, producing 30 parameters overall (six features for each phase). These features were used as input data for a support vector machine (SVM) algorithm designed to distinguish MDD patients from healthy controls based on their physiological responses. Statistical tests showed that the main effect of task was significant in all SC features, and the main effect of group was significant in MSCL, SDSCL, SSCL, and PSD. In addition, the proposed algorithm achieved 70% accuracy, 70% sensitivity, 71% specificity, 70% positive predictive value, 71% negative predictive value in classifying MDD patients and healthy controls. These results demonstrated that it is possible to extract meaningful features that reflect changes in ANS responses to various stimuli. Using these features, detection of MDD was feasible, suggesting that SC analysis has great potential for future diagnostics and prediction of depression based on objective interpretation of depressive states.

Project description:Psychosocial stressors induce autonomic nervous system (ANS) responses in multiple body systems that are linked to health risks. Much work has focused on the common effects of stress, but ANS responses in different body systems are dissociable and may result from distinct patterns of cortical-subcortical interactions. Here, we used machine learning to develop multivariate patterns of fMRI activity predictive of heart rate (HR) and skin conductance level (SCL) responses during social threat in humans (N = 18). Overall, brain patterns predicted both HR and SCL in cross-validated analyses successfully (rHR = 0.54, rSCL = 0.58, both p < 0.0001). These patterns partly reflected central stress mechanisms common to both responses because each pattern predicted the other signal to some degree (rHR?SCL = 0.21 and rSCL?HR = 0.22, both p < 0.01), but they were largely physiological response specific. Both patterns included positive predictive weights in dorsal anterior cingulate and cerebellum and negative weights in ventromedial PFC and local pattern similarity analyses within these regions suggested that they encode common central stress mechanisms. However, the predictive maps and searchlight analysis suggested that the patterns predictive of HR and SCL were substantially different across most of the brain, including significant differences in ventromedial PFC, insula, lateral PFC, pre-SMA, and dmPFC. Overall, the results indicate that specific patterns of cerebral activity track threat-induced autonomic responses in specific body systems. Physiological measures of threat are not interchangeable, but rather reflect specific interactions among brain systems. SIGNIFICANCE STATEMENT:We show that threat-induced increases in heart rate and skin conductance share some common representations in the brain, located mainly in the vmPFC, temporal and parahippocampal cortices, thalamus, and brainstem. However, despite these similarities, the brain patterns that predict these two autonomic responses are largely distinct. This evidence for largely output-measure-specific regulation of autonomic responses argues against a common system hypothesis and provides evidence that different autonomic measures reflect distinct, measurable patterns of cortical-subcortical interactions.

Dataset Information

Are we afraid of different categories of stimuli in identical ways? Evidence from skin conductance responses.

Publications

Are we afraid of different categories of stimuli in identical ways? Evidence from skin conductance responses.

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