Search PubMed⌕ Search

Biomedical subjects

A Ohman

Publications and source records attributed to A Ohman.

At least 19 recordsLinked to original sources
PubMed2001

The face in the crowd revisited: a threat advantage with schematic stimuli.

Schematic threatening, friendly, and neutral faces were used to test the hypothesis that humans preferentially orient their attention toward threat. Using a visual search paradigm, participants searched for discrepant faces in matrices of otherwise identical faces. Across 5 experiments, results consistently showed faster and more accurate detection of threatening than friendly targets. The threat advantage was obvious regardless of whether the conditions favored parallel or serial search (i.e., involved neutral or emotional distractors), and it was valid for inverted faces. Threatening angry faces were more quickly and accurately detected than were other negative faces (sad or "scheming"), which suggests that the threat advantage can be attributed to threat rather than to the negative valence or the uniqueness of the target display.

Adult↗
PubMed2001

Fears, phobias, and preparedness: toward an evolved module of fear and fear learning.

An evolved module for fear elicitation and fear learning with 4 characteristics is proposed. (a) The fear module is preferentially activated in aversive contexts by stimuli that are fear relevant in an evolutionary perspective. (b) Its activation to such stimuli is automatic. (c) It is relatively impenetrable to cognitive control. (d) It originates in a dedicated neural circuitry, centered on the amygdala. Evidence supporting these propositions is reviewed from conditioning studies, both in humans and in monkeys; illusory correlation studies; studies using unreportable stimuli; and studies from animal neuroscience. The fear module is assumed to mediate an emotional level of fear learning that is relatively independent and dissociable from cognitive learning of stimulus relationships.

Animals↗
PubMed2001

Nonconscious fear conditioning, visceral perception, and the development of gut feelings.

When people are presented with backward-masked images of fear-relevant stimuli and only some of these images are paired consistently with electric shocks, they can predict the occurrence of shocks even though they do not consciously know which images they have seen. We postulated that they may use the perception of visceral cues from the conditional fear response to facilitate the prediction of shocks. In this study, ability to detect heartbeats was used to index sensitivity to visceral cues. The results showed that subjects who could detect their heartbeats performed better than chance in predicting whether or not they would receive a shock during the conditioning task. The findings support the notion that hunches, or "gut feelings," are based in part on the perception of visceral cues.

Adolescent↗
PubMed2001

Measuring the negative mood component of stress experiences: description and psychometric properties of a short adjective check-list of stress responses.

Negative Mood (NM) is a 19-items adjective check-list developed to assess negative mood and stress responses. The items of the scale reflect dimensions such as depressed mood, anxiety, anger and time urgency. The data were collected from four different samples, two random population samples and two smaller selective samples. The psychometric properties of the NM showed high internal consistency (Cronbach's Alpha). When analysed with principal components analysis, three factors emerged, anxiety/depression, time pressure, and anger. The factors emerged in all four samples, within samples and between gender. The NM factors were tested for convergent and discriminative validity by correlating them with other more established measures of different aspects of negative mood. The results showed high convergent and discriminative validity for two of the NM factors, i.e., anxiety/depression, and anger, whereas the results for the third factor, time pressure, were more ambiguous. This scale has proven to be useful in capturing some vital dimensions of negative affect across different kinds of populations.

Adult↗
PubMed2000

Fear and anxiety: animal models and human cognitive psychophysiology.

The aim of this paper is to explicate what is special about emotional information processing, emphasizing the neural foundations that underlie the experience and expression of fear. A functional, anatomical model of defense behavior in animals is presented and applications are described in cognitive and physiological studies of human affect. It is proposed that unpleasant emotions depend on the activation of an evolutionarily primitive subcortical circuit, including the amygdala and the neural structures to which it projects. This motivational system mediates specific autonomic (e.g., heart rate change) and somatic reflexes (e.g., startle change) that originally promoted survival in dangerous conditions. These same response patterns are illustrated in humans, as they process objective, memorial, and media stimuli. Furthermore, it is shown how variations in the neural circuit and its outputs may separately characterize cue-specific fear (as in specific phobia) and more generalized anxiety. Finally, again emphasizing links between the animal and human data, we focus on special, attentional features of emotional processing: The automaticity of fear reactions, hyper-reactivity to minimal threat-cues, and evidence that the physiological responses in fear may be independent of slower, language-based appraisal processes.

Animals↗
PubMed1999

A subcortical pathway to the right amygdala mediating "unseen" fear.

Neuroimaging studies have shown differential amygdala responses to masked ("unseen") emotional stimuli. How visual signals related to such unseen stimuli access the amygdala is unknown. A possible pathway, involving the superior colliculus and pulvinar, is suggested by observations of patients with striate cortex lesions who show preserved abilities to localize and discriminate visual stimuli that are not consciously perceived ("blindsight"). We used measures of right amygdala neural activity acquired from volunteer subjects viewing masked fear-conditioned faces to determine whether a colliculo-pulvinar pathway was engaged during processing of these unseen target stimuli. Increased connectivity between right amygdala, pulvinar, and superior colliculus was evident when fear-conditioned faces were unseen rather than seen. Right amygdala connectivity with fusiform and orbitofrontal cortices decreased in the same condition. By contrast, the left amygdala, whose activity did not discriminate seen and unseen fear-conditioned targets, showed no masking-dependent changes in connectivity with superior colliculus or pulvinar. These results suggest that a subcortical pathway to the right amygdala, via midbrain and thalamus, provides a route for processing behaviorally relevant unseen visual events in parallel to a cortical route necessary for conscious identification.

Adult↗
PubMed1999

Behavioral effects of a comprehensive, multifactorial program for lifestyle change after percutaneous transluminal coronary angioplasty: a prospective, randomized controlled study.

A group of 93 coronary patients recently treated with percutaneous transluminal coronary angioplasty (PTCA) were randomly assigned to either an intervention or a control group. Subjects in the intervention group participated in a comprehensive behaviorally oriented program aimed at achieving significant long-term changes in risk factor-related lifestyle behavior. Assessments of lifestyle behaviors, psychological factors, biological risk factors, and rehabilitation as well as secondary prevention endpoints were carried out, at inclusion and after 12 months. Results showed that the intervention patients, as compared with controls, improved significantly on measures assessing smoking, exercise, and diet habits. These self-rated changes were confirmed by weight reductions and improved exercise capacity, as well as by between-group differences in subclinical chest pain during an exercise test. However, few effects were found on the different psychological variables, as well as on morbidity or return to work.

Adult↗
PubMed1999

Fear appears fast: temporal course of startle reflex potentiation in animal fearful subjects.

The temporal course of startle reflex modulation and autonomic response patterns to fear-relevant and fear-irrelevant pictures in subjects with high and low levels of animal fear was investigated. Thirty-eight high-fear and 48 low-fear volunteers viewed photos of snakes and spiders and pictures of neutral and pleasant content. The slides were presented for 6 s or for only 150 ms, depending on the group. Acoustic startle probes were presented at five different times after slide onset. Relative potentiation of the startle responses started 300 ms after onset of snake/spider pictures in fearful subjects. This fear-potentiated startle effect was maintained for the later probe times and was identical in the 150-ms condition. Fear-relevant pictures also prompted a sympathetically dominated autonomic response profile in fearful persons. These data support the idea that fear can be activated very rapidly, requiring only minimal stimulus input.

Adolescent↗
PubMed1999

Two-year results of a controlled study of residential rehabilitation for patients treated with percutaneous transluminal coronary angioplasty. A randomized study of a multifactorial programme.

AIMS: In a multifactorial lifestyle behaviour programme, of 2 years duration, to study the maintenance of achieved behaviour and risk factor-related changes. METHODS AND RESULTS: Out of a consecutive population of 151 patients treated with percutaneous transluminal angioplasty under 65 years of age, 87 were randomly allocated to an intervention group (n=46) or to a control group (n=41). The programme started with a 4 week residential stay, which was focused on health education and the achievement of behaviour change. During the first year of follow-up, a maintenance programme included regular contacts with a nurse, while no further rehabilitative efforts were offered during the second year. One patient died (control). During the second year the proportion of hospitalized patients was lower in the intervention group (4% vs 20%;P<0.05). Patients in the intervention group improved several lifestyle dependent behaviours: diet (index at 0, 12 and 24 months): 10.5+/-3. 4, 12.9+/-2.5 and 12.4+/-2.6 in the intervention group (I) vs 10. 1+/-3.2, 10.7+/-3.0 and 11.8+/-3.2 in the control group (C);P<0.05, exercise sessions per week: 2.5+/-2.3, 4.5+/-1.9 and 4.4+/-2.1 (I) vs 3.1+/-2.2, 3.5+/-2.3 and 3.7+/-2.7 (C);P<0.05, and smoking; 18%, 6% and 9% (I) vs 12%, 21% and 18% (C);P<0.05. This corresponded to improvement in exercise capacity (0, 12 and 24 months): 156+/-42, 174+/-49 and 165+/-47 W (I) vs 164+/-40, 163+/-49 and 156+/-48 watts (C);P<0.05. There were no significant differences between the two groups with regard to serum cholesterol levels at 0 and 24 months: 5. 4+/-0.8 and 5.2+/-0.9 mmol. l(-1)(I) vs 5.4+/-1.0 and 4.9+/-0.9 mmol. l(-1)(C); ns, low density lipoprotein cholesterol level: 3.6+/-0.8 and 3.4+/-0.8 mmol. l(-1)(I) vs 3.7+/-0.9 and 3.3+/-0.7 mmol. l(-1)(C); ns, triglyceride level: 2.2+/-1.6 and 1.8+/-1.3 mmol. l(-1)(I) vs 2.2+/-1.4 and 1.6+/-0.6 mmol. l(-1)(C); ns, body mass index (0, 12 and 24 months): 27.5+/-4.5, 27.0+/-4.3 and 27.4+/- 4.5 kg. m(-2)(I) vs 26.8+/-2.8, 26.9+/-2.7 and 26.9+/- 3.2 kg. m(-2)(C); ns, waist/hip ratio or blood pressure. The two groups did not differ in quality of life, or psychological factors. Return to work after 12 and 24 months was 74% and 78% (I) vs 68% and 61% (C); ns. CONCLUSION: This rehabilitation programme influenced important lifestyle behaviour and reduced some, but not all, important risk factors

Aged↗
PubMed1999

Multifactorial evaluation of a program for lifestyle behavior change in rehabilitation and secondary prevention of coronary artery disease.

A comprehensive, multifactorial lifestyle behavior change program was developed for rehabilitation and secondary prevention of subjects with coronary artery disease. The purpose of the present report is to describe this intervention model and to analyze results achieved in a first group of consecutive participants. Main inclusion criteria for the 292 subjects were a recent history of acute myocardial infarction, coronary artery bypass surgery, or percutaneous transluminal coronary angioplasty. The program commenced with a 4-week residential stay, with the focus on health education and the achievement of behavior change in major lifestyle areas. During the year of follow-up a systematic maintenance program included regular contact with a nurse. Morbidity and mortality was low. Self-reported quality of life improved and there were significant improvements in blood lipids, exercise capacity and body mass index. There were also significant changes both in psychological variables such as Type A behavior, anger, hostility, and in major lifestyle areas such as stress reactions, diet, exercise and smoking. These changes compared favorably with data from relevant samples from the Swedish normal population. This program had a considerable effect on a number of important factors for rehabilitation and secondary prevention of coronary artery disease.

Analysis of Variance↗
PubMed1998

High-potential states of blue and purple copper proteins.

Electrochemical measurements show that there are high-potential states of two copper proteins, Pseudomonas aeruginosa azurin and Thermus thermophilus CuA domain; these perturbed states are formed in guanidine hydrochloride (GuHCl) solution in which the proteins are still blue (azurin) and purple (CuA). In each case, the high-potential state forms reversibly. Absorption (azurin, CuA), visible circular dichroism (azurin, CuA), resonance-Raman (CuA), and EPR (CuA) spectra indicate that the structure of the oxidized copper site of each high-potential form is very similar to that of the native protein. It is proposed that GuHCl perturbs one or more H-bonds in the blue or purple copper active site, thereby allowing Cu(I) to adopt a more favorable coordination structure than that in the rigid cavity of the native protein.

Azurin↗
PubMed1998

NMR study of the conformation and localization of porcine galanin in SDS micelles. Comparison with an inactive analog and a galanin receptor antagonist.

Galanin is a 29/30-residue neuro-endocrine peptide which performs its many important physiological functions via a membrane-bound receptor. By using two-dimensional proton NMR spectroscopy, complete relaxation matrix analysis, and simulated annealing, the conformation of porcine galanin was determined in a membrane-mimicking solvent containing sodium dodecyl sulfate (SDS) micelles. The final family of calculated structures displays three well-defined beta- or gamma-turn regions, comprising residues 1-5, 7-10, and 24-27, but has otherwise a random conformation. The receptor-interacting N-terminal part, residues 1-5, was found to be best defined with a backbone RMSD value of 0.12 A. The mode of association between galanin and the SDS micelle was determined by observing the broadening effect on proton resonances, when spin-labeled 5- and 12-doxyl stearate molecules were added. It was concluded that galanin is located close to the surface of the micelle with two regions, residues 6-9 and 24-29, as well as two single residues, 18 and 21, reaching out into the aqueous solvent. Additional NMR studies were carried out on an inactive analogue, Ala2-galanin, and an antagonist M40. The results show that the proton resonances of galanin and M40 have identical chemical shifts in the N-terminal receptor-interacting region, indicating similar solution structures in this region. For Ala2-galanin, the same region displays a spectral heterogeneity with chemical shifts clearly different from the other two peptides, indicative of different secondary structures. These results may provide a structural background for the antagonist activity of M40 and the hormonal inactivity of Ala2-galanin, as compared to galanin.

Alanine↗
PubMed1998

Conscious and unconscious emotional learning in the human amygdala.

If subjects are shown an angry face as a target visual stimulus for less than forty milliseconds and are then immediately shown an expressionless mask, these subjects report seeing the mask but not the target. However, an aversively conditioned masked target can elicit an emotional response from subjects without being consciously perceived. Here we study the mechanism of this unconsciously mediated emotional learning. We measured neural activity in volunteer subjects who were presented with two angry faces, one of which, through previous classical conditioning, was associated with a burst of white noise. In half of the trials, the subjects' awareness of the angry faces was prevented by backward masking with a neutral face. A significant neural response was elicited in the right, but not left, amygdala to masked presentations of the conditioned angry face. Unmasked presentations of the same face produced enhanced neural activity in the left, but not right, amygdala. Our results indicate that, first, the human amygdala can discriminate between stimuli solely on the basis of their acquired behavioural significance, and second, this response is lateralized according to the subjects' level of awareness of the stimuli.

Adult↗
PubMed1998

Electrodermal activity and obstetric complications in schizophrenia.

The pregnancy and birth records of 79 schizophrenic patients, from whom adult electrodermal data were available, were systematically evaluated for obstetric complications using 34 criteria of nonoptimality in pregnancy, delivery, and postpartum periods. Patients with many obstetric complications had lower levels of electrodermal activity. For frequency of skin conductance responses and spontaneous fluctuations in skin conductance, the association was more evident for women than for men. However, the ratio of stimulus-elicited to spontaneous skin conductance responses showed a reliable association with obstetric complications without any gender differences. The relationship between obstetric complications and electrodermal activity was interpreted in terms of neurodevelopmental insults resulting in structural brain abnormalities interfering with orienting and electrodermal activity.

Adolescent↗
PubMed1998

Emotional conditioning to masked stimuli: expectancies for aversive outcomes following nonrecognized fear-relevant stimuli.

The role of conscious awareness in human Pavlovian conditioning was examined in 2 experiments using masked fear-relevant (snakes and spiders; Experiments 1 and 2) and fear-irrelevant (flowers and mushrooms; Experiment 1) pictures as conditioned stimuli, a mild electric shock as the unconditioned stimulus, and skin conductance responses as the primary dependent variable. The conditioned stimuli were presented briefly (30 ms) and were effectively masked by an immediately following masking stimulus. Experiment 1 demonstrated nonconscious conditioning to fear-relevant but not to fear-irrelevant stimuli. Even though the participants could not recognize the stimuli in Experiment 2, they differentiated between masked stimuli predicting and not predicting shocks in expectancy ratings. However, expectancy ratings were not related to the conditioned autonomic response.

Adult↗
PubMed1997

Relationships between social support, social coping and life events in the relapse of schizophrenic patients.

The vulnerability-stress model for schizophrenia posits that relapses are at least partly determined by interacting triggering and protecting psychosocial factors. This study examined social support and general coping style in 42 consecutively admitted DSM:III schizophrenic patients, who were followed prospectively for up to four years. In a second part of the study, a subgroup of the patients were interviewed using the Life Event and Difficulty Schedule 9 months after discharge or at relapse. Patients contented with low social integration had a higher relapse rate over four years than patients lacking of social provisions, but wanting more. We found an excess of life events three weeks before relapse compared to events reported in the non-relapsing group. Suggesting a buffering effect of social factors, time between life event and relapse was significantly extended among patients with a high availability of attachment and a coping strategy characterised of active support seeking.

Adaptation, Psychological↗
PubMed1997

Prenatal and neonatal risk factors for schizophrenia.

BACKGROUND: The present study examines the effects of independent, single pre- and perinatal risk factors and rates of obstetric complications upon the subsequent development of schizophrenia. METHOD: This study was based on prospectively recorded birth records of 107 cases (82 with schizophrenic disorders and 25 with other psychotic reactions) and 214 controls, individually matched by gender and time and place of birth. Variables univariately associated with significantly elevated risk were entered in a logistic regression model. RESULTS: A high non-optimality summary score (> or = 7 complications of 34 possible) was a significant risk estimate for the total index group (OR 4.58, 95% CI 1.74-12.03) and the 82 schizophrenic patients (OR 3.67, CI 1.30-10.36). Patients with 2-6 complications also had an increased, although lower, risk (OR 1.67, CI 1.02-2.75). A disproportionate birth weight for body length (OR 3.57, CI 1.77-7.19) and a small head circumference (OR 3.93, CI 1.32-11.71) were the strongest independent risk factors. CONCLUSIONS: A contribution of obstetric complications to the risk of schizophrenia was confirmed. Only aberrations in physical size remained as individual independent risk factors.

Adolescent↗