Pleasant Stimuli Research Articles

Cerebral blood flow changes associated with attribution of emotional valence to pleasant, unpleasant, and neutral visual stimuli in a PET study of normal subjects.

To assist in the development of a model for the psychopathology of emotions, the present study sought to identify the neural circuits associated with the evaluation of visual stimuli for emotional valence. Seventeen healthy individuals were shown three sets of emotionally laden pictures carrying pleasant, unpleasant, and neutral content. While subjects evaluated the picture set for emotional valence, regional cerebral blood flow was measured with the use of [15O] water positron emission tomography. Subjective ratings of the emotional valence of the picture sets were recorded. Data were analyzed by comparing the images acquired during the neutral condition with the unpleasant and pleasant image sets and the unpleasant and pleasant conditions with each other. Processing of pleasant stimuli was associated with increased blood flow in the dorsal-lateral, orbital, and medial frontal cortex relative to the unpleasant condition and in the cingulate, precuneus, and visual cortex relative to the neutral condition. Evaluation of unpleasant stimuli activated the amygdala, visual cortex, and cerebellum relative to the pleasant condition and the nucleus accumbens, precuneus, and visual cortex relative to the neutral condition. Observing and assigning emotional value to unpleasant stimuli produced activations in subcortical limbic regions, whereas evaluation of pleasant stimuli produced activations in cortical limbic areas. These findings are consistent with the notion of a subcortical and archaic danger recognition system and a system detecting pleasantness in events and situations that is phylogenetically younger, involving primarily the prefrontal cortex.

The role of depression in coronary artery disease.

The concept of depression encompasses a series of psychopathological disorders that differ in regard to symptomatology, severity, course and prognosis. It is important to individualize these disorders for a better understanding of the following studies and of their diagnostic management. Major depressive disorder, as defined by CID X 1 and DSM IV , may have different clinical characteristics (table I). A specifier that may be employed in diagnosing the major depressive episode is the presence of melancholic symptoms (melancholia), whose main characteristic is the loss of interest and pleasure in all or almost all activities and a lack of reactivity to usually pleasant stimuli. In these circumstances, the depressive mood does not improve, not even temporarily, when something positive happens. Yet, at least three of the following symptoms should be present for the diagnosis of major depression to be made: depressive mood qualitatively different from the normal, worsening in the morning, terminal insomnia (to wake up at least two hours before the usual time), psychomotor retardation or agitation, anorexia or significant weight loss (5% of the body weight per month), excessive or inappropriate guilt. Sometimes, however, the depressive disorder is atypical with mood reactivity, i.e., enhancement of the mood in response to real or potential positive events, significant weight gain, increase in appetite, hypersomnia, sensation of heaviness in the upper and lower limbs, in addition to a prolonged pattern of sensitivity to interpersonal rejection resulting in significant social or occupational impairment . The dysthymic disorder (dysthymia) is characterized by a chronically depressed mood lasting for most of the day, for the majority of days, and lasting for at least two years . The individual may note significant reduction in usual interests and in self-criticism, frequently seeing himself or herself as uninteresting and incapable. As these symptoms become part of daily life, usually they are not mentioned by the patient unless directly inquired about by Andre Luiz Langer Manica, Carolina Garcia Soares Leaes, Benicio Noronha Frey, Mario Francisco Juruena

Affective startle modulation in clinical depression: preliminary findings

Background: Modulation of the startle reflex by affective foreground stimuli was investigated in a group receiving inpatient treatment for major depressive episodes (n = 14) and an age and gender matched nondepressed group (n = 14).Methods: Participants viewed 27 pleasant, neutral, and unpleasant pictures chosen from the International Affective Picture System. Acoustic startle probes were presented during picture viewing, and participants also rated the affective qualities of the pictures.Results: While ratings of the pictures were largely similar between the depressed and nondepressed groups, they displayed dissimilar patterns of startle modulation. In the nondepressed group, blinks elicited during unpleasant pictures were significantly larger than during pleasant pictures, whereas the depressed group failed to show this effect. Analyses, which separated the depressed participants into moderate and severe groups based on Beck Depression Inventory scores, revealed that while the moderately depressed group also showed a normal pattern of startle modulation, the severely depressed showed potentiated startles during the pleasant pictures.Conclusions: These preliminary results suggest that severely depressed patients may respond to some pleasant stimuli as if they are aversive, possibly because such stimuli are seen as signals of frustrative nonreward.

Psychomotor retardation and anhedonia in depression.

Anhedonia, the inability to experience pleasure, and observed changes in psychomotor performance are frequent psychopathological phenomena in major depression with possible common neurobiological mechanisms. Interest, pleasure and reactivity to pleasurable stimuli contribute to movement generation and observable behaviour. Therefore the relationship between anhedonia and psychomotor retardation was studied in 48 depressed patients. Subjectively experienced anhedonia correlated with self-rated but not with observer-rated global severity of depression. There was a significant correlation between anhedonia and psychomotor retardation assessed with the Widöcher Retardation Scale. The results suggest the existence of an empirical relationship between reduced ability to experience pleasure and observable psychomotor retardation in depression. Specific measures of psychomotor phenomena may provide further insights into the relationship between observable behaviour and self-experienced symptoms in depression.

The representation of pleasant touch in the brain and its relationship with taste and olfactory areas.

Although there has been much investigation of brain pathways involved in pain, little is known about the brain mechanisms involved in processing somatosensory stimuli which feel pleasant. Employing fMRI it was shown that pleasant touch to the hand with velvet produced stronger activation of the orbitofrontal cortex than affectively neutral touch of the hand with wood. In contrast, the affectively neutral but more intense touch produced more activation of the primary somatosensory cortex than the pleasant stimulus. This indicates that part of the orbitofrontal cortex is concerned with representing the positively affective aspects of somatosensory stimuli, and in further experiments it was shown that this orbitofrontal area is different from that activated by taste and smell. The finding that three different primary or unlearned types of reinforcer (touch, taste, and smell) are represented in the orbitofrontal cortex helps to provide a firm foundation for understanding the neural basis of emotions, which can be understood in terms of states elicited by stimuli which are rewarding or punishing.

Galanin: a significant role in depression?

This paper describes a hypothesis that attempts to account for how changes in noradrenergic systems in the brain can affect depression-related behaviors and symptoms. It is hypothesized that increased activity of the locus coeruleus (LC) neurons, the principal norepinephrine (NE)-containing cells in the brain, causes release of galanin (GAL) in the ventral tegmentum (VTA) from LC axon terminals in which GAL is colocalized with NE. It is proposed that GAL release in VTA inhibits the activity of dopaminergic cell bodies in this region whose axons project to forebrain, thereby resulting in two of the principal symptoms seen in depression, decreased motor activation and decreased appreciation of pleasurable stimuli (anhedonia). The genesis of this hypothesis, which derives from studies using an animal model of depression, is described as well as recent data consistent with the hypothesis. The formulation proposed suggests that GAL antagonists may be of therapeutic benefit in the treatment of depression.

Repressive/Defensive Coping and Identification Thresholds for Pleasant and Unpleasant Words

This study examined the relationship between repressive/defensive coping and identification thresholds for pleasant and unpleasant words. Word identification thresholds were determined by presenting masked words at increasing durations until correct report. Identification thresholds were greater for unpleasant than for pleasant words. When the difference between identification thresholds for unpleasant and pleasant words was standardized, high-defensive participants showed this effect to a greater degree than low-defensive participants. One possible interpretation of the findings is that avoidance of unpleasant stimuli takes place, and that repressive/defensive participants are more prone to it. Alternatively, the findings may reflect a general perceptual bias for pleasant stimuli that is greater for high defensive participants. Such a perceptual bias for pleasant stimuli may facilitate avoidance of unpleasant ones.

Neglect syndrome for aversive stimuli in a macaque monkey with dorsomedial frontal cortex lesion

After a session of unit activity recording, one of our monkeys presented an epileptic attack, which provoked contralateral tilting movements. The following days, the animal performed saccades and fixation tasks correctly in all directions, while contralateral arm reaching movements were severely impaired. To establish if the neurological lesion had changed the orienting performance we considered two types of stimuli, pleasant and aversive. Pleasant stimuli, presented in the ipsilateral or contralateral hemifield, readily drew the attention of the animal. If the same stimuli were presented simultaneously in both hemifields, the monkey oriented itself only toward the ipsilateral one. Aversive stimuli evoked an aggressive reaction only when the stimulus was localized in the ipsilateral hemifield. The animal clearly neglected the aversive stimulus presented in the contralateral hemifield. The animal recovered completely in 30 days. The postmortem examination revealed a lesion in the dorsomedial frontal cortex. The combined attentional and motor deficits suggest that this area may be involved in the preparation and execution of movements triggered by the affective meaning of the stimulus.

Affective Valence and Arousal in ADHD and Normal Boys During a Startle Habituation Experiment

To measure two dimensions of emotion (affective valence and arousal) in 29 boys with attention-deficit hyper-activity disorder (ADHD) and 32 normal boys. After a startle habituation experiment during which these subjects heard 40 startling sounds while watching a silent interesting movie, they were asked 12 questions (categorized a priori into questions relating to affective valence and to arousal) about their emotional reactions to these putatively unpleasant and pleasurable stimuli. Responses were recorded for the two dimensions of emotion, using two cartoon strips in each of which five expressions of a cartoon character varied linearly from happy to unhappy (affective valence dimension) and calm to excited (arousal dimension). Factor analyses of the 12 responses revealed four factors in which the highest loadings were for affective valence to the startle responses, affective valence to the silent movie, arousal, and scary feelings. Relative to the normal group, the responses of the ADHD group were significantly biased toward pleasurable valence to the startling stimuli and to the silent movie, with a trend toward hypoarousal. Startle magnitude and habituation were similar in both groups. The normal tonic heart rate acceleration throughout the experimental session was not sustained in the ADHD group. The self-reports of affective valence biased in the direction of pleasure and away from displeasure and the trend toward hypoarousal suggest an emotional dysfunction in ADHD.

Aversive smoking for smoking cessation.

Aversion therapy pairs the pleasurable stimulus of smoking a cigarette with some unpleasant stimulus. The objective is to extinguish the urge to smoke. This review has two aims. First, to determine the efficacy of rapid smoking and other aversive methods in helping smokers stop smoking. Second, to determine whether there is a dose-response effect on smoking cessation at different levels of aversive stimulation. We searched the Cochrane Tobacco Addiction Group trials register for studies which evaluated any technique of aversive smoking. Randomised trials which compared aversion treatments with 'inactive' procedures or which compared aversion treatments of different intensity for smoking cessation. Trials must have reported follow-up of least 6 months from beginning of treatment. We extracted data in duplicate on the study population, the type of aversion treatment, the outcome measure, method of randomisation and completeness of follow-up. The outcome measure was abstinence from smoking at maximum follow-up, using the strictest measure reported by the authors. Subjects lost to follow-up were regarded as smokers. Where appropriate, we performed meta-analysis using a fixed effects model. Twenty four trials met the inclusion criteria. Ten included rapid smoking and ten used other aversion methods. Ten trials included two or more conditions allowing assessment of a dose-response to aversive stimulation. The odds ratio for abstinence following rapid smoking compared to control was 2.08 (95% confidence interval 1.39 to 3.12). Several factors suggest that this finding should be interpreted cautiously. A funnel plot of included studies was asymmetric, due to the relative absence of small studies with negative results. Most trials had a number of serious methodological problems likely to lead to spurious positive results. The only trial using biochemical validation of all self reported cessation gave a non significant result. Other aversion methods were not shown to be effective (odds ratio 1.19, 95% confidence interval 0.77 to 1.83). There was a borderline dose-response to the level of aversive stimulation (odds ratio 1.66, 95% confidence interval 1.00 to 2.78). The existing studies provide insufficient evidence to determine the efficacy of rapid smoking, or whether there is a dose-response to aversive stimulation. Milder versions of aversive smoking seem to lack specific efficacy. Rapid smoking is an unproven method with sufficient indications of promise to warrant evaluation using modern rigorous methodology.

Psychological stress in people with profound mental retardation.

Does emotional stress in people with profound mental retardation occur and does it result from simple stimuli of daily living? Can this be measured by recording vital signs? To obtain answers, the histories of stress and stress diseases, and the behavioral characteristics of 163 institutionalized adults with developmental disabilities were evaluated; vital signs, temperatures and bodily expressions of 35 subjects from this sample were monitored. All but two of the 35 subjects had elevations of heart rate, blood pressure, respiration rate, core body temperature, and changes in peripheral temperature. Reactions occurred with unpleasant and pleasurable stimuli, and were greatest at clinical examinations and when the subjects were stared at. Responses were best demonstrated by heart rate, respiration rate, blood pressure and temperature. Such reactions result from the insecurity of people whose disabilities prevent them from adjusting to perceived threats.

Individual differences in the excitation transfer effect

Excitation transfer refers to the main effect of an arousing experience (e.g. exercise) on subsequent emotional reactions (e.g. reactions to emotional photographs). Residual arousal from the earlier task is said to “transfer” to the latter task, with the arousal being misattributed to subsequent stimuli. Studies examining individual differences in excitation transfer have focused on physical characteristics, such as cardiovascular fitness. However, because excitation transfer involves both arousal and hedonic tone, it may be that personality dimensions relevant to arousability or emotional reactivity may predict individual differences in the excitation transfer effect. Several hypotheses were proposed based upon differing personality theories. Results supported the notion that excitation transfer is strongest for the hedonically-valenced emotions with which the person has relatively less experience. Extraversion predicted excitation transfer to unpleasant (but not pleasant) stimuli, and Neuroticism predicted excitation transfer to pleasant (but not unpleasant) stimuli. Results are discussed in terms of processing bodily information more during unfamiliar than familiar affective states.

Pleasure heals. The role of social pleasure--love in its broadest sense--in medical practice

THE THERAPEUTIC benefits of love and hope, and of trusted physicians and clergymen, can be explained by the physiologic healing effects of pleasurable stimuli.¹Those effects may also underlie the placebo effect, some nonspecific therapeutic effects of corticoids, and sleep's facilitation of healing and growth. Organisms experience stimuli as painful, pleasurable, or both as they respond to them. Those experiences are mediated by midline systems in the central nervous system²that help determine the objective intensity of the responses at the time and the subjective "emotionality" associated with those stimuli, both then and in the future. <h3>THE BASIC NEUROPHYSIOLOGIC SYSTEMS</h3><h3>Pain/Avoidance and Pleasure/Approach</h3> The midline system concerned with pain is called "self-preservative" or ergotropic (energy-turning or energy-releasing)³because it mediates activities involved with safety and survival, removing stress, and emergency "fight or fight"—ie, with pain and eliminating its causes.<i>Avoidance</i>of painful stimuli, the basic movement involved, involves

Pleasure Heals

THE THERAPEUTIC benefits of love and hope, and of trusted physicians and clergymen, can be explained by the physiologic healing effects of pleasurable stimuli.¹Those effects may also underlie the placebo effect, some nonspecific therapeutic effects of corticoids, and sleep's facilitation of healing and growth. Organisms experience stimuli as painful, pleasurable, or both as they respond to them. Those experiences are mediated by midline systems in the central nervous system²that help determine the objective intensity of the responses at the time and the subjective "emotionality" associated with those stimuli, both then and in the future. <h3>THE BASIC NEUROPHYSIOLOGIC SYSTEMS</h3><h3>Pain/Avoidance and Pleasure/Approach</h3> The midline system concerned with pain is called "self-preservative" or ergotropic (energy-turning or energy-releasing)³because it mediates activities involved with safety and survival, removing stress, and emergency "fight or fight"—ie, with pain and eliminating its causes.<i>Avoidance</i>of painful stimuli, the basic movement involved, involves

Emotion, novelty, and the startle reflex: habituation in humans.

Previous research with both animal and human subjects has shown that startle reflex magnitude is potentiated in an aversive stimulus context, relative to responses elicited in a neutral or appetitive context. In the present experiment, the same pleasant, unpleasant, and neutral picture stimuli were repeatedly presented to human subjects. Startle reflex habituation was assessed in each stimulus context and was compared with the habituation patterns of heart rate, electrodermal, and facial corrugator muscle responses. All systems showed initial differentiation among affective picture contents and general habituation over trials. The startle reflex alone, however, continued to differentiate among pleasant, neutral, and unpleasant pictures throughout the presentation series. These results suggest that (a) the startle probe reflex is relatively uninfluenced by stimulus novelty, (b) the startle modulatory circuit (identified with amygdala-reticular connections in animals) varies systematically with affective valence, and (c) the modulatory influence is less subject to habituation than is the obligatory startle pathway or responses in other somatic and autonomic systems.

Facial expressions in severely demented patients—a stimulus–response study of four patients with dementia of the Alzheimer type

AbstractThe ability to exhibit facial expressions was studied in four patients with severe dementia of the Alzheimer type (SDAT), by means of the Facial Action Coding System (FACS) and physiological responses (heart rate, respiration, skin temperature) under pleasant and unpleasant stimulus conditions. Complex facial expressions that could be interpreted as expressions of emotions were not seen. An increase in the number of facial movements and changes in the physiological responses were seen most markedly under the unpleasant stimulus condition. The patients' reactions during the assumed pleasant stimulus conditions indicated comfort. Different reactions were obtained among the patients. The importance of developing further methods to identify and interpret facial movements in nurse‐patient relationships is emphasized.

To Adopt the Intentional Stance?

To Adopt the Intentional Stance?

Pupillary responses in recognizing awareness in persons with profound mental retardation.

Pupil-size changes have been shown to indicate positive or negative reactions to several sensory and psychologic stimuli in normal persons. Whether this could be extended to mentally retarded patients who lack ability for verbal or motor behavior was tested by pupillary responses to several visual, tactile, and auditory stimuli. 24 institutionalized severely and profoundly retarded patients were examined by video camera in their usual environments rather than in a controlled laboratory setting. The videotapes were later projected onto a screen for pupil-size measurements. Pupils dilated with pleasant stimuli, including visualizing a familiar person, soft touch to the arm, music, and soft compliments. There was constriction with presenting an unfamiliar person, rough grasp of the arm, and abrasive noise and harsh commands. The findings demonstrate the existence of pupil reactivity in profoundly retarded persons and suggest such testing as a means of determining which elements of their environment are pleasing or aversive to them.

Colour-identification of differentially valenced words in anxiety

Abstract Two groups of individuals, one high in trait anxiety and the other low in trait anxiety, performed a Stroop task in which threat, neutral, and pleasant words were presented. The results indicated clear differences between the high- and low-trait groups in their performance on this task. The low-trait group's performance was similar for all three types of sitmuli, whereas the high-trait group's responses were fastest for pleasant stimuli and slowest for threat-related stimuli. A recognition task to examine incidental learning of the “irrelevant” Stroop words showed that whilst the high-trait group had a stronger tendency to respond positively to all trials (critical and distractor) than the low-trait group, there were no differences in sensitivity between the two groups.

An EEG-mapping study of "laughing": coherence and brain dominances.

The human expressive behavior termed laughter is triggered by pleasurable psychoemotional stimuli (Moody, 1978) and is possessed of a certain healing potential. According to split-brain studies (Sperry, 1966), psychoemotional stimuli are bound up with emotional activity in the right side of the brain. The idea thus suggests itself to study laughter generated by different sources with regard to the attendant electric brain activity between the right and left hemispheres. The present study was undertaken first with subjects in a state of normal consciousness and subsequently-given the possibility of increased affect stimulation in connection with laughter-under hypnosis. Having familiarized ourselves in our earlier work on brain dominances with the brain mapping EEG and having convinced ourselves of its greater efficiency in comparison with conventional EEG (Bick, 1985), we have had recourse to this method in the present study on approaches to the neurophysiological processes in the brain connected with laughter.