A daytime nap enhances visual working memory performance and alters event-related delay activity

Working memory (WM) is impaired following sleep loss and may be improved after a nap. The goal of the current study was to better understand sleep-related WM enhancement by: (1) employing a WM task that assesses the ability to hold and report visual representations as well as the fidelity of the reports on a fine scale, (2) investigating neurophysiological properties of sleep and WM capacity as potential predictors or moderators of sleep-related enhancement, and (3) exploring frontal and occipital event-related delay activity to index the neural processing of stimuli in WM. In a within-subjects design, 36 young adults (M_age = 20, 20 men, 16 women) completed a 300-trial, continuous-report task of visual WM following a 90-min nap opportunity and an equivalent period of wakefulness. Mixed-effect models were used to estimate the odds of successful WM reports and the fidelity of those reports. The odds of a successful report were approximately equal between nap and wake conditions for the start of the task, but by the end, the odds of success were 1.26 times greater in the nap condition. Successful WM reports were more accurate after a nap, independent of the time on task. Neither WM capacity nor any of the sleep variables measured were found to significantly moderate the nap effect on WM. Lastly, napping resulted in amplitude changes for frontal and occipital delay activity relative to the wake condition. The findings are discussed in relation to contemporary models of visual WM and the role of sleep in sustained attention.     

Functional interaction of mGlu5 and NMDA receptors in aversive learning in rats

Metabotropic glutamate receptor 5 (mGlu5) has been implicated in a variety of learning processes and is important for inhibitory avoidance and conditioned taste aversion learning. MGlu5 receptors are physically connected with NMDA receptors and they interact with, and modulate, the function of one another in several brain regions. The present studies used systemic co-administration of an mGlu5 receptor positive allosteric modulator, 3-cyano-N-(1,3-diphenyl-1H-pyrazol-5-yl)benzamide (CDPPB) and an NMDA receptor antagonist dizocilpine maleate (MK-801) to characterize the interactions of these receptors in two aversive learning tasks. Male Sprague-Dawley rats were trained in a single-trial step-down inhibitory avoidance or conditioned taste aversion task. CDPPB (3 or 10mg/kg, s.c.), delivered by itself prior to the conditioning trial, did not have any effect on performance in either task 48 h after training. However, CDPPB (at 3mg/kg) attenuated the MK-801 (0.2mg/kg, i.p.) induced learning deficit in both tasks. CDPPB also reduced MK-801-induced hyperactivity. These results underlie the importance of mGlu5 and NMDA receptor interactions in modulating memory processing, and are consistent with findings showing the efficacy of positive allosteric modulators of mGlu5 receptors in reversing the negative effects of NMDA receptor antagonists on other behaviors such as stereotypy, sensorimotor gating, or working, spatial and recognition memory.     

Effects of tonic and phasic respiratory sinus arrhythmia on affective stress responses

Adaptive affective responses in the face of environmental challenges require flexible physiological responding. The present study examined the extent to which tonic respiratory sinus arrhythmia (RSA)-a putative marker of regulatory capacity-moderated the association between stress-related changes in RSA (i.e., phasic RSA) and concurrent changes in affect. Ninety-eight healthy, young adults completed ratings of affect during a resting baseline and following the recall of a recent stressor. Tonic RSA moderated the association of phasic RSA with stress-related change in positive affect (PA), such that change in RSA had a positive association with PA for individuals with higher tonic RSA and a negative association for those with lower tonic RSA. Examination of specific aspects of PA indicated that phasic RSA was positively associated with changes in ratings of attentive engagement among individuals with higher tonic RSA. These findings inform our understanding of phasic RSA and support the notion that flexible parasympathetic nervous system functioning is an important component of adaptive stress regulation.     

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.     

Affect networks: a structural analysis of the relationship between work ties and job-related affect

The relationship between organizational networks and employees' affect was examined in 2 organizations. In Study 1, social network analysis of work ties and job-related affect for 259 employees showed that affect converged within work interaction groups. Similarity of affect between employees depended on the presence of work ties and structural equivalence. Affect was also related to the size and density of employees' work networks. Study 2 used a 10-week diary study of 31 employees to examine a merger of 2 organizational divisions and found that negative changes in employees' affect were related to having fewer cross-divisional ties and to experiencing greater reductions in network density. The findings suggest that affect permeates through and is shaped by organizational networks.     

Imitation in shadowing words

Imitation of shadowed words was evaluated using Goldinger's (1998) AXB paradigm. The first experiment was a replication of Goldinger's experiments with different tokens. Experiment 1's AXB tests showed that shadowed words were judged to be better imitations of target words than were baseline (read) counterparts more often than chance (.50). Order of presentation of baseline and shadowed words in the AXB test also significantly influenced judgments. Degree of prior exposure to token words did not significantly influence judgments of imitation. Experiment 2 employed modified target tokens with extended voice onset times (VOTs). In addition to AXB tests, VOTs of response tokens were compared across baseline and shadowing conditions. The AXB tests revealed shadowed words to be better imitations of target tokens than baseline, without an influence of AXB presentation order. Differences between baseline and shadowing VOTs were greater when VOTs were extended. The implications of spontaneous imitation in nonsocial settings are considered.     

Do speakers avoid ambiguities during dialogue?

What affects speakers' production of ambiguous utterances in dialogue? They might consider ease of production for themselves, or ease of comprehension for their addressees. Previous research has demonstrated that ease of production plays a role in speakers' syntactic choices, but that ease of comprehension does not. However, such studies have not employed dialogues that involve role swapping on a turn-by-turn basis. In our experiment, participants alternated in giving and following instructions to move objects around on a grid. They tended to repeat the syntactic form just used by their interlocutor, reflecting sensitivity to ease of production. More interestingly, they were more likely to disambiguate their utterances when the visual context was potentially ambiguous than when it was not, reflecting sensitivity to ease of comprehension. We conclude that speakers pay attention to their beliefs about their addressees' ease of comprehension, in addition to considering ease of production for themselves.     

Assessment of Rorschach dependency measures in female inpatients diagnosed with borderline personality disorder

The psychometric properties and predictive validity of the Dependency Index (DI; Hilsenroth & Bornstein, 2002) and the Rorschach Oral Dependency Scale (ROD; Masling, Rabie, & Blondheim, 1967) were examined to determine if these implicit measures of dependency predict observable attachment-seeking behavior in 66 female inpatients diagnosed with borderline personality disorder. Results indicate that both scales produce excellent reliability estimates. The DI and ROD yield adequate base rates, and the distributions of scores approximate normal distributions. The DI was predictive of nursing staff observation of positive attachment/treatment compliance (r = .28, p = .02) but not excessive isolation. By contrast, the ROD predicted positive attachment/treatment compliance (r = .38, p = .002) and excessive isolation (r = -.35, p = .004). Texture responses predicted excessive isolation (r = -.25, p = .05). Discriminant validity was supported when neither dependency measure predicted hostile interactions or self-destructive behaviors. Hierarchical regression analyses revealed that the ROD demonstrated incremental validity over the DI and select Comprehensive System (Exner, 1993) variables associated with dependency.     

Factor structure of the Penn State Worry Questionnaire: examination of a method factor

The Penn State Worry Questionnaire (PSWQ) was originally designed as a unifactorial measure of pathological trait worry. However, recent studies supported a two-factor solution with positively worded items loading on the first factor and reverse-scored items loading on a second factor. The current study compared this two-factor model to a negative wording method factor solution among college students. A method factor model with all PSWQ items loading on a single worry factor and reverse-scored items loading on a negative wording method factor provided as good a fit as the two-factor model. This method factor alone did not predict a generalized anxiety disorder diagnosis. Finally, the psychometric properties of an abbreviated scale containing only positively worded items were examined. The PSWQ appears to measure a single unitary construct, but response patterns differ between positively worded and reverse-scored items. Theoretical implications for pathological worry and assessment-related issues are discussed.