Epinephrine administration increases neural impulses propagated along the vagus nerve: Role of peripheral beta-adrenergic receptors

A significant number of animal and human studies demonstrate that memories for new experiences are encoded more effectively under environmental or laboratory conditions which elevate peripheral concentrations of the hormone epinephrine and in turn, induce emotional arousal. Although this phenomenon has been replicated across several learning paradigms, understanding of how this arousal related hormone affects memory processing remains obscure because epinephrine does not freely enter into the central circulation to produce any direct effects on the brain. This study examined whether epinephrine's actions on the CNS may be mediated by the initial activation of peripheral vagal fibers that project to the brain. The vagus was selected as a candidate for this role since it is densely embedded with beta-adrenergic receptors and the peripheral endings of this nerve innervate a broad spectrum of sensory organs that are directly affected by epinephrine release. Electrophysiological recordings of cervical vagal activity was measured over 110 min in urethane-anesthetized Sprague-Dawley rats given saline, epinephrine (0.3 mg/kg), the peripherally acting beta-adrenergic antagonist sotalol (2.0 mg/kg), or a combination of sotalol followed 15 min later by an injection of epinephrine. Epinephrine produced a significant increase in vagal nerve firing 10 min post-injection (p < .05) relative to controls and neural impulses recorded from the vagus remained significantly elevated for the remaining 55 min collection period. The excitatory actions of epinephrine were not observed in groups given an identical dose of the hormone after peripheral beta-adrenergic receptor blockade with sotalol. These findings demonstrate that neural discharge in vagal afferent fibers is increased by elevations in peripheral concentrations of epinephrine and the significance of these findings in understanding how epinephrine modulates brain limbic structures to encode and store new information into memory is discussed.     

Moderator effects of cognitive ability and social support on the relation between race-related stress and quality of life in a community sample of black Americans

The current study examined the combined moderating effects of cognitive ability and social support on the relation between race-related stress and quality of life in a sample of Black Americans. Participants (N = 323) were administered the Wonderlic Personnel Test (WPT; E. F. Wonderlic Associates, Inc., 1983), the Multidimensional Social Support Scale (MDSS; Winefield, Winefield, & Tiggemann, 1992), the Index of Race-Related Stress-Brief (Utsey, 1999), and the WHOQOL-BREF (The WHO Group, 1998). The findings indicated that cognitive ability and social support, conjointly, moderated the relation between individual and cultural race-related stress and quality of life for Black Americans in the current sample. The paper concludes by discussing the study's findings, limitations, and by offering recommendations for future research related to this area of inquiry.     

Motion in the mind’s eye: Comparing mental and visual rotation

Mental rotation is among the most widely studied visuospatial skills in humans. The processes involved in mental rotation have been described as analogous to seeing an object physically rotate. We used functional magnetic resonance imaging of the whole brain and localized motion-sensitive hV5/MT1 to compare brain activation for stimuli when they were mentally or visually rotated. The results provided clear evidence for activation in hV5/MT1 during both mental and visual rotation of figures, with increased activation for larger rotations. Combined with the overall similarities between mental and visual rotation in this study, these results suggest that mental rotation recruits many of the same neural substrates as observing motion.     

Externalizing and internalizing subtypes of combat-related PTSD: a replication and extension using the PSY-5 scales

This study replicated and extended prior findings of internalizing and externalizing subtypes of posttraumatic response (M. W. Miller, J. L. Greif, & A. A. Smith, 2003). Cluster analyses of the Minnesota Multiphasic Personality Inventory--2 Personality Psychopathology--Five (MMPI-2 PSY-5; A. R. Harkness, J. L. McNulty, Y. S. Ben-Porath, 1995) profiles obtained from 736 veterans with posttraumatic stress disorder (PTSD) partitioned the sample into a low pathology cluster defined by personality scores in the normal range, an externalizing cluster characterized by low constraint and high negative emotionality, and an internalizing cluster with high negative emotionality and low positive emotionality. Externalizers showed the highest rates of alcohol-related and antisocial personality disorders; internalizers, the highest rates of panic and major depressive disorder. These findings support the development of a personality-based typology of posttraumatic response designed to account for heterogeneity in the expression of PTSD and associated psychopathology.     

Generalization of deferred imitation during the first year of life

Infants first generalize across contexts and cues at 3 months of age in operant tasks but not until 12 months of age in imitation tasks. Three experiments using an imitation task examined whether infants younger than 12 months of age might generalize imitation if conditions were more like those in operant studies. Infants sat on a distinctive mat in a room in their home (the context) while an adult modeled actions on a hand puppet (the cue). When they were tested 24 h later, 6-month-olds generalized imitation when either the mat or the room (but not both) differed, whereas 9-month-olds generalized when both the mat and the room differed. In addition, 9-month-olds who imitated immediately also generalized to a novel test cue, whereas 6-month-olds did not. These results parallel results from operant studies and reveal that the similarity between the conditions of encoding and retrieval-not the type of task-determines whether infants generalize. The findings offer further evidence that memory development during infancy is a continuous function.     

Incidental visual memory for targets and distractors in visual search

We explored incidental retention of visual details of encountered objects during search. Participants searched for conjunction targets in 32 arrays of 12 pictures of real-world objects and then performed a token discrimination task that examined their memory for visual details of the targets and distractors from the search task. The results indicate that even though participants had not been instructed to memorize the objects, the visual details of search targets and distractor objects related to the targets were retained after the search. Distractor objects unrelated to the search target were remembered more poorly. Eye-movement measures indicated that the objects that were remembered were looked at more frequently during search than those that were not remembered. These results provide support that detailed visual information is included incidentally in the visual representation of an object after the object is no longer in view.     

Suicidality in African American men: the roles of southern residence, religiosity, and social support

The rise in suicide by African Americans in the United States is directly attributable to the dramatic, nearly three-fold increase in suicide rates of African American males. Gibbs (1997) hypothesized high social support, religiosity, and southern residence are protective factors against suicidality for Black people. This hypothesis was tested among 5,125 participants from the National Comorbidity Survey; 299 were African American males. In this study we hypothesized that there would be significantly lower suicidality in the South, and social support and religiosity would mediate this relationship. Our results indicate that Southern region is indeed a significant predictor of suicidal symptoms in African American men, such that suicidal symptoms were lower in the South, but religiosity and social support did not account for this effect. Other potential mediators were also examined.     

The incremental validity of the MMPI-2: when does therapist access not enhance treatment outcome?

The present study examined whether therapist access to the Minnesota Multiphasic Personality Inventory (MMPI-2) predicted favorable treatment outcome, above and beyond other assessment measures. A manipulated assessment design was used, in which patients were randomly assigned either to a group in which therapists had access to their MMPI-2 data or to a group without therapist access to such information. Illness severity, improvement ratings, number of sessions attended, and premature termination were indicators of therapy outcome. Results indicated that therapist access to the MMPI-2 data did not add to the prediction of positive treatment outcome beyond that predicted by other measures in this setting. Findings from this initial study suggest that, compared with other resources, perhaps in clinical settings with an emphasis on diagnosis-based and evidence-based treatment, the MMPI-2 may not provide incrementally valid information. However, these effects warrant replication across different settings and samples. Guidelines for future studies are discussed.