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Biomedical subjects

A Mini

Publications and source records attributed to A Mini.

7 recordsLinked to original sources
PubMed2000

Cardiac responses associated with affective processing of unpleasant film stimuli.

The autonomic basis of cardiac reactions to unpleasant film stimuli was investigated. Film clips depicting major surgery, threats of violence, and neutral material were presented to 46 subjects. Self-report measures of emotion were obtained, as well as heart rate, respiration rate, respiratory sinus arrhythmia, T-wave amplitude and skin conductance level. Resting vagal tone was estimated in a paced breathing task prior to film viewing. Spontaneous blink rate was also taken as a measure of visual engagement during film viewing. Coherent increases in sympathetic activation accompanied the film containing violent threats, whereas the surgery film yielded greater electrodermal activation, as well as heart rate deceleration and T-wave increase. These data support the hypothesis of differential autonomic response patterns to specifically unpleasant material. As compared with threat and neutral films, greater blink rate inhibition was observed during the surgery film. Individual differences in parasympathetic cardiac control measured at rest were able to discriminate cardiac response patterns during film viewing.

Adult↗
PubMed1997

The influence of low blood pressure and baroreceptor activity on pain responses.

The influence of baroreceptor modulation on pain perception has been extensively studied in normal and hypertensive subjects, but not in hypotensive subjects. The present experiment was performed to verify the following hypotheses: 1. Hypotensive subjects exhibit an increased pain response following baroreceptor activation compared to normals; 2. unlike the hypotensives, normal subjects, with normal baroreceptor reflexes, would learn to choose more often the baroreceptor activation condition compared to the opposite condition, during painful stimulation; 3. sensory and pain thresholds are correlated with blood pressure. The subjects (39 men), divided according to low and normal blood-pressure groups, participated in an experiment in which electrically-induced pain ratings and pain-evoked potentials were measured. Baroreceptor manipulation was performed by means of the PRES procedure. Whereas hypotensive subjects did not perceive any pain difference between the two baroreceptor conditions, activation and inhibition, normotensive men were able to perceive the baroreceptor activation condition as less painful. Similarly to subjective ratings, pain-evoked potentials of the low blood-pressure group showed a reversed trend compared to normals: larger somatosensory evoked potentials (N150-P260) to the baroreceptor activation condition and the opposite to the baroreceptor deactivation condition. Furthermore, results showed a negative correlation between diastolic blood pressure and sensory perception threshold, and a positive correlation between systolic pressure and pain threshold. Contrary to expectations, the rate of choice of baroreceptor conditions during painful stimulation did not show, in either group, any preference for baroreceptor activation.

Adolescent↗
PubMed1997

Somatotosensory evoked potentials during baroreceptor stimulation in chronic low back pain patients and normal controls.

Nineteen chronic low back pain patients (aged 19-63) and 17 controls (aged 20-41) received electrical pain stimuli during manipulation of their carotid baroreceptors. The non-invasive mechanical manipulation of baroreceptors, using the PRES technique (Phase Related External Suction), simulates the end-effects of phasic blood pressure changes. This technique was developed to assess pain responses induced by changes in blood pressure without the typical shortcomings of pharmacological manipulation or lack of a control condition. During maximum baroreceptor activity, there was an unexpected increase in the amplitude of the somatosensory evoked potentials (SEPs) elicited by the electrical pain stimuli condition (N150-P260 peak-to-peak). In most other studies the opposite effect was found, with decreased pain responses during maximum baroreceptor activity. The chronic pain group reported greater pain during highest baroreceptor activation than did the controls. In addition, the chronic pain group showed lower diastolic blood pressure. To determine whether pain and baroreceptor responses observed in the chronic pain group depended on lower blood pressure levels, a second experiment with a non-clinical sample was performed. Results showed that lower tonic blood pressures are associated with greater baroreceptor activity amplifying pain, while higher blood pressure is associated with pain dampening during high baroreceptor activity. Data suggested that the differences in pain responses found in low back pain patients were associated with their lower tonic blood pressure levels. It is proposed that in general, lower blood pressures may be associated with greater pain during baroreceptor activation.

Adolescent↗
PubMed1997

Visual evoked potentials, heart rate responses and memory to emotional pictorial stimuli.

Although the effects of emotional stimuli on event-related cortical potentials, heart rate, and memory have been extensively studied, the association of these variables in a single study has been neglected. The influence of pleasant, unpleasant, and neutral photographic slides on visual evoked potentials (VEPs), heart rate responses, and free recall, was investigated in 20 normal subjects. VEPs were recorded from Cz and Pz locations, and analyses were performed on both amplitudes and latencies of identifiable endogenous peaks (P2, N2 and P3), and mean amplitude in the 100-200-ms, 400-600-ms, and 600-900-ms latency ranges. An emotional effect was present on VEPs starting from about 282 ms on, as revealed by the N2, P3, and late components. Both pleasant and unpleasant slides yielded larger cortical positivity as compared to neutral ones. Peak latencies did not show any emotional effect. Heart rate data showed a deceleratory response that was larger to unpleasant slides. Free recall of the projected slides showed a better performance for emotional slides compared to neutral ones. VEPs and memory data showed the same pattern: both pleasant and unpleasant slides induced larger positivity in the event-related potentials and were better remembered than neutral slides. Positive correlations were found between the late negative VEPs component (600-900 ms), recorded from Cz, and heart rate deceleration (r = 0.62), and between P3 (at Pz location) and the number of remembered slides (r = 0.53).

Adult↗
PubMed1996

Emotional information processing and visual evoked brain potentials.

Visual evoked potentials to emotional slides presented for 2 sec. were investigated in 13 subjects. 73 emotional slides (pleasant, unpleasant, and neutral) were selected from a standardized set of photographic slides, the 1988 International Affective Picture System of Lang, Ohman, and Vaitl Visual evoked potentials were recorded from three head locations, frontal, central and parietal (Fz, Cz, and Pz). Analyses were performed in the two latency ranges: 300-400 msec. and 400-500 msec. Analyses showed an arousal effect, as indicated by a quadratic trend, indicating that emotional slides (both pleasant and unpleasant) gave higher cortical positivity than neutral ones, for all components. In addition, in the two latency epochs, larger positivities were found at Pz, compared to Fz and Cz, whereas Fz and Cz did not differ from each other.

Adult↗
PubMed1995

Baroreceptor cortical effects, emotions and pain.

The specificity of baroreceptor-dependent inhibition of pain reactions to electrical stimuli was investigated during induction of different emotional states in 27 subjects. Baroreceptors were stimulated through the PRES (Phase Related External Suction) technique, while emotions were induced by means of pleasant, neutral and unpleasant slides. The dependent variables were pain ratings, somatic evoked potentials (N150 and P260) recorded from Fz, Cz and Pz, and skin conductance response (SCR), while heart rate was recorded as a PRES requirement. Valence and arousal ratings were obtained in front of each slide. During suction (external baroreceptor activation) reduced pain ratings, cortical disfacilitation (from Pz, as revealed by N150) and lower SCR were found as compared to pressure (baroreceptor deactivation). Moreover, brain evoked potentials (N150 and P260) reflecting cortical inhibition were found under condition of baroreceptor stimulation during unpleasant slides, but not during pleasant or neutral ones: this result was found in the high blood pressure subjects only. Data showed also a valence effect on pain ratings: pain was evaluated to be higher during unpleasant slides, than neutral and pleasant ones. Results are discussed in the light of "baroreceptor reward" hypothesis, which proposes a learning mechanism for the development of essential hypertension.

Adult↗