Failure to develop a conditional reflex by stimulation of the cephalad portion of the severed vagosympathetic trunk: Its significance in terms of the central connections of the vagus

Stimulation of the central stump of either vagosympathetic trunk in the dog, the contralateral nerve remaining intact, regularly provoked deep respiratory movements with forceful expiration, followed by a period of apnea, and a fall in blood pressure, systolic and diastolic, of 20–60 mm/Hg. Stimulation of the cephalad portion of the left nerve provoked brief acceleration of heart rate during the period of hyperventilation, followed by bradycardia; when the stimulus was applied to the central stump of the right nerve heart rate remained relatively unchanged. When a 12-second tone as a conditional stimulus (CS) was reinforced during its last six seconds with such stimulation of the vagosympathetic trunk as an unconditional stimulus (US), despite the striking visceromotor responses elicited by the US, no conditional reflex was established even after more than 3,400 trials in 16 dogs (34–781 trials per animal).     

Age and gender differences in negative affect—Is there a role for emotion regulation?

Elderly people report less negative affect than the young, and women report more negative affect than men. This study investigated whether age and gender differences in negative affect could be explained by emotion regulation, measured as defensiveness and rumination, while controlling for the influence of life events. One-hundred-and-ninety-five young (20–35 years) and 302 elderly (70–85 years) men and women completed the Emotional Control Questionnaire-Rehearsal, Marlowe–Crowne Social Desirability Scale, Profile of Mood States, Beck’s Depression Inventory and List of Recent Experiences. Hierarchical regressions with negative affects as dependent variables showed that age was reduced to non-significance when controlling for defensiveness, and gender was reduced to non-significance when controlling for the interaction between age and gender, which in turn was reduced when entering rumination. Life events also influenced the association between age and negative affect. The results indicate that age differences in negative affect are mediated by defensiveness and life events and that when these two influences are accounted for elderly people score higher on sadness. Gender differences in negative affect were due to the young women’s higher scores on negative affect and this is partly explained by rumination.     

Extinction of a conditioned emotional response: massed and distributed exposures

Using the lick-suppression methodology of Jacobs, Buttrick & Kennedy (Pavlovian Journal of Biological Science, 23, 29-34, 1988), a conditioned emotional response (CER) was established in 24 rats using off-the-baseline pairings of a light (the conditional stimulus) and brief footshock (the unconditioned stimulus). Following conditioning, the rats were assigned to one of three extinction groups differing in whether they received massed or distributed off-the-baseline exposure to the conditional stimulus. The effects of differential treatment were assessed on-the-baseline on test days, when the extinction of the CER was monitored. Rats receiving a single, long exposure to the conditional stimulus showed greater resistance to extinction than the rats in the distributed groups. They also showed a difference pattern of CER extinction. The results were discussed and compared to similar studies that have explored the massed vs distributed dimension, both in CER and avoidance-extinction (using response prevention or flooding). The relation of animal studies to parallel human studies using exposure therapy was also discussed.