Stress-induced Fos-like Immunoreactivity in the Pons and the Medulla Oblongata of Rats

Immunoreactivity of the immediate early gene c-fos was used to investigate changes in the activity of brainstem neurons in response to acute stressors like immobilization, formalin-induced pain, cold exposure, hemorrhage and insulin-induced hypoglycemia. Different stressors induced Fos-like immunoreactivity in different pontine and medullary neurons. A single, 3 hour immobilization was found to be a very strong stimulus that activated brainstem catecholaminergic (tyrosine hydroxylase-immunopositive) neurons and cells in the raphe and certain pontine tegmental nuclei, as well as in the reticular formation. Pain, induced by a subcutaneous injection of formalin was also effective on catecholamine-synthesizing neurons and on others cells in the nucleus of the solitary tract. Cold exposure activated cells mainly in the sensory spinal trigeminal and parabrachial nuclei and in the so-called "pontine thermoregulatory area". Moderate Fos-like immunoreactivity was induced by a hypotonic (25%) hemorrhage in medullary catecholaminergic neurons, the nucleus of the solitary tract and the Barrington nucleus. Among stressful stimuli used, insulin-induced hypoglycemia elicited the smallest Fos activation in the lower brainstem. The present observations indicate that different stressors may use different neuronal pathways in the central organization of the stress response.     

Evidence for altered configural body processing in women at risk of disorders characterized by body image disturbance

Two studies were conducted to assess appearance-related visual processing mechanisms in populations at risk of disorders characterized by body image disturbance. Using inverted stimuli, Experiment 1 assessed visual processing mechanisms associated with body, face, and house viewing in adolescents. Experiment 2 applied the same protocol to assess appearance-related configural processing in high- and low-risk adolescent women, and women recovering from disorders characterized by body image disturbance. Experiment 1 found evidence for typical configural face and body processing, although adolescent women reported higher levels of body image concern (BIC) and self-objectified to a greater extent than adolescent men. In Experiment 2, typical body inversion effects were seen in the low-risk group, whilst there was some evidence to suggest a disruption to the configural processing of body stimuli in high-risk adolescents and in women recovering from body image disorders. Women in recovery were also quicker to respond to all stimuli, whilst high-risk adolescents took longer to respond to bodies than to other stimuli. Configural face processing was intact in all groups, and effects did not directly relate to BIC or self-objectification. These findings have implications for future research looking to inform early interventions and treatment, suggesting that there could be a tendency to visually process individual body parts at the expense of the whole-body form in women at risk of developing body image disorders, as well as those in recovery.     

Bridging a yawning chasm: EEG investigations into the debate concerning the role of the human mirror neuron system in contagious yawning

Ongoing debate in the literature concerns whether there is a link between contagious yawning and the human mirror neuron system (hMNS). One way of examining this issue is with the use of the electroencephalogram (EEG) to measure changes in mu activation during the observation of yawns. Mu oscillations are seen in the alpha bandwidth of the EEG (8–12 Hz) over sensorimotor areas. Previous work has shown that mu suppression is a useful index of hMNS activation and is sensitive to individual differences in empathy. In two experiments, we presented participants with videos of either people yawning or control stimuli. We found greater mu suppression for yawns than for controls over right motor and premotor areas, particularly for those scoring higher on traits of empathy. In a third experiment, auditory recordings of yawns were compared against electronically scrambled versions of the same yawns. We observed greater mu suppression for yawns than for the controls over right lateral premotor areas. Again, these findings were driven by those scoring highly on empathy. The results from these experiments support the notion that the hMNS is involved in contagious yawning, emphasise the link between contagious yawning and empathy, and stress the importance of good control stimuli.     

Within-hemifield posture changes affect tactile–visual exogenous spatial cueing without spatial precision,especially in the dark

We investigated the effects of seen and unseen within-hemifield posture changes on crossmodal visual–tactile links in covert spatial attention. In all experiments, a spatially nonpredictive tactile cue was presented to the left or the right hand, with the two hands placed symmetrically across the midline. Shortly after a tactile cue, a visual target appeared at one of two eccentricities within either of the hemifields. For half of the trial blocks, the hands were aligned with the inner visual target locations, and for the remainder, the hands were aligned with the outer target locations. In Experiments 1 and 2, the inner and outer eccentricities were 17.5º and 52.5º, respectively. In Experiment 1, the arms were completely covered, and visual up–down judgments were better when on the same side as the preceding tactile cue. Cueing effects were not significantly affected by hand or target alignment. In Experiment 2, the arms were in view, and now some target responses were affected by cue alignment: Cueing for outer targets was only significant when the hands were aligned with them. In Experiment 3, we tested whether any unseen posture changes could alter the cueing effects, by widely separating the inner and outer target eccentricities (now 10º and 86º). In this case, hand alignment did affect some of the cueing effects: Cueing for outer targets was now only significant when the hands were in the outer position. Although these results confirm that proprioception can, in some cases, influence tactile–visual links in exogenous spatial attention, they also show that spatial precision is severely limited, especially when posture is unseen.     

Diagnostic accuracy of the MMPI-2 Malingering Discriminant Function Index in the detection of malingering among inmates

The MMPI-2 Malingering Discriminant Function Index (M-DFI) was designed to detect malingerers educated about MMPI-2 validity indicators. However, given current attorney practices, the clinical utility of the M-DFI lies in its ability to detect examinees who are cautioned about the indicators. In this study, we compared 45 inmate simulators cautioned to avoid detection on the MMPI-2 with 46 psychiatric inmates who completed the MMPI-2 under standard instructions. Logistic regression analyses indicated that although the M-DFI performed better than several individual indicators, results were mixed for combinations of indicators, and the M-DFI did not outperform different sets of existing indicators. These findings support existing strategies to detect malingering on the MMPI-2. We discuss considerations concerning the clinical applicability of M-DFI.     

Facilitated processing of visual stimuli associated with the body

Recent work on tactile perception has revealed enhanced tactile acuity and speeded spatial-choice reaction times (RTs) when viewing the stimulated body site as opposed to viewing a neutral object. Here we examine whether this body-view enhancement effect extends to visual targets. Participants performed a speeded spatial discrimination between two lights attached either to their own left index finger or to a wooden finger-shaped object, making a simple distal--proximal decision. We filmed either the finger-mounted or the object-mounted lights in separate experimental blocks and the live scene was projected onto a screen in front of the participants. Thus, participants responded to identical visual targets varying only in their context: on the body or not. Results revealed a large performance advantage for the finger-mounted stimuli: reaction times were substantially reduced, while discrimination accuracy was unaffected. With this finding we address concerns associated with previous work on the processing of stimuli attributed to the self and extend the finding of a performance advantage for such stimuli to vision.     

An MMPI-2 scale to detect malingered depression (Md scale)

A specialized Minnesota Multiphasic Personality Inventory-2 (MMPI-2) validity scale was constructed to detect individuals who are knowledgeable about either depression or MMPI-2 detection strategies and who subsequently attempt to malinger depressive symptoms on the MMPI-2. The Malingered Depression (Md) scale consists of 32 items that discriminated college students who feigned depression from those who were genuinely depressed. Further information about the incremental validity and the utility of the Md scale was obtained in a cross-validation study with additional college students who feigned depression and a sample of students with clinically significant depressive symptoms. The results indicate that the Md scale possesses promising value in detecting malingered symptoms of depression.     

Visuo-tactile links in covert exogenous spatial attention remap across changes in unseen hand posture

We investigated the effect of unseen hand posture on cross-modal, visuo-tactile links in covert spatial attention. In Experiment 1, a spatially nonpredictive visual cue was presented to the left or right hemifield shortly before a tactile target on either hand. To examine the spatial coordinates of any cross-modal cuing, the unseen hands were either uncrossed or crossed so that the left hand lay to the right and vice versa. Tactile up/down (i.e., index finger/thumb) judgments were better on the same side of external space as the visual cue, for both crossed and uncrossed postures. Thus, which hand was advantaged by a visual cue in a particular hemifield reversed across the different unseen postures. In Experiment 2, nonpredictive tactile cues now preceded visual targets. Up/down judgments for the latter were better on the same side of external space as the tactile cue, again for both postures. These results demonstrate cross-modal links between vision and touch in exogenous covert spatial attention that remap across changes in unseen hand posture, suggesting a modulatory role for proprioception.     

Diagnostic Accuracy of the MMPI–2 Malingering Discriminant Function Index in the Detection of Malingering Among Inmates

The MMPI–2 Malingering Discriminant Function Index (M-DFI) was designed to detect malingerers educated about MMPI–2 validity indicators. However, given current attorney practices, the clinical utility of the M-DFI lies in its ability to detect examinees who are cautioned about the indicators. In this study, we compared 45 inmate simulators cautioned to avoid detection on the MMPI–2 with 46 psychiatric inmates who completed the MMPI–2 under standard instructions. Logistic regression analyses indicated that although the M-DFI performed better than several individual indicators, results were mixed for combinations of indicators, and the M-DFI did not outperform different sets of existing indicators. These findings support existing strategies to detect malingering on the MMPI–2. We discuss considerations concerning the clinical applicability of M-DFI.     

Affective responses to body stimuli: comparing male and female bodies with cropped heads and masked faces

Three studies were conducted to determine whether headless bodies evoke affective responses that might confound neuroimaging and electrophysiological findings. In Experiment 1, 224 participants rated pictures, including bodies with cropped heads and masked faces, for disgust, fear, naturalness, valence and arousal. In Experiment 2, 38 participants viewed the same images during a free word association task, whilst in Experiment 3 galvanic skin responses were measured as 57 participants completed a similar rating task to that in Experiment 1. No differences were found between responses elicited by bodies without heads versus bodies with masked faces, although female bodies were thought of more positively than male bodies. This suggests that headless bodies are not abhorrent and are appropriate stimuli for investigating body-selective perceptual processes as they do not evoke face-processing mechanisms. Our findings also suggest that differences between male and female body viewing should be considered when investigating visual body perception.