What goes up can come down? A preliminary investigation of emotion reactivity and emotion recovery in bipolar disorder

Background

How is emotion disrupted in bipolar disorder? Two studies are presented that adopt a multi-method approach to investigate emotion reactivity and emotion recovery in bipolar I disorder.

Methods

Across both studies, individuals with inter-episode bipolar disorder and healthy controls were shown three emotion-eliciting films (neutral, happy, and sad) and experiential and physiological responses were measured. In Study 1, bipolar (BD; n = 23) and non-clinical control (NC; n = 24) participants' emotional reactivity during film clips was assessed. In Study 2, a separate sample of BD (n = 23) and NC (n = 25) participants' emotion recovery was assessed after the film clips were assessed.

Results

Results indicated that the BD group exhibited increased self-reported positive emotion and respiratory sinus arrhythmia across all films compared to the NC group. There were no group differences in emotion recovery.

Discussion

Taken together, these results suggest that bipolar disorder is associated with increased positive emotion reactivity, but not emotion recovery, across contexts.     

Children’s perceptions of emotion regulation strategy effectiveness: links with attachment security

Six- and nine-year-old children (N = 97) heard illustrated stories evoking anger in a story character and provided evaluations of the effectiveness of eight anger regulation strategies. Half the stories involved the child’s mother as social partner and the other half involved a peer. Attachment security was assessed via the Security Scale. Children reported greater effectiveness for seeking support from adults and peers in the peer context than the mother context, but perceived venting as more effective with mothers. Children with higher security scores were more likely to endorse problem solving and less likely to endorse aggression in both social contexts than those with lower security scores. Early evidence for gender differences was found in that boys endorsed the effectiveness of distraction while girls endorsed venting their emotion.     

Moving up or moving down? Malpositioned cerebellar unipolar brush cells in reeler mouse

Cerebellar morphogenesis occurs through a complex interplay of cell proliferation and migration that in mouse and rat begins about midgestation and ends in the third postnatal week. Cerebellar cells derive from germinative matrices in the ventricular zone and the external granular layer. Like granule cells, unipolar brush cells (UBCs) are excitatory interneurons situated in the granular layer of the cortex and innervated by mossy fibers. While granule cells are produced from the external granular layer, the generation of UBCs is still controversial. We utilized the reeler mutant mouse, which has widespread misplacement of neurons due to lack of Reelin protein, to ascertain the origin of UBCs. In the reeler cerebellum, which is small and lacks foliation, Purkinje cells are greatly reduced in number and in large part are located ectopically in deep cerebellar masses. Granule cells are also reduced in number and form an irregular granule cell layer. In this study we demonstrate that the reeler mutation influences the positioning of UBCs and also significantly reduces their number. Both subsets of UBCs identified in normal mouse, the calretinin-positive and the metabotropic glutamate receptor 1alpha-positive subsets, are affected in the reeler. About 40% of the calretinin-positive UBCs are ectopically situated in the deep cerebellar regions and the immediate vicinity of the ependyma of the fourth ventricle. Ectopic UBCs have discrete, although somewhat looser brushes than granular layer UBCs, but form synaptic junctions with complex axon terminals, possibly belonging to mossy fibers and UBC axons, like their normally situated counterpart. The observed displacement of UBCs in the reeler suggests that they originate from the ventricular zone.     

Anterior cingulate cortex volume and emotion regulation: is bigger better?

Emotion dysregulation is a key feature of mood and anxiety disorders. Many of these disorders also involve volumetric reductions in brain regions implicated in emotion regulation, including the dorsal anterior cingulate cortex (dACC). Investigating this relationship in healthy individuals may clarify the link between emotion regulation and volumetric reductions in this key brain region. High-resolution anatomical MRI images were used to calculate dACC volumes in 50 healthy female subjects. Trait measures of emotion regulation (cognitive reappraisal and expressive suppression) and negative affect were also obtained. As predicted, cognitive reappraisal was positively related to dACC volume, but not the volume of a control region, the ventral ACC. Expressive suppression, negative affect, and age were not related to dACC volume. These findings indicate that individual differences in cognitive reappraisal are related to individual differences in dACC volume in healthy participants.     

Quantitative trait locus mapping: fishing strategy or replicable results?

Genomewide scan, as shown by recently published linkage studies on the behavior of mice or in psychiatry, provides evidence for replicated quantitative trait loci (QTL). Several studies of Alzheimer's disease have demonstrated the promise of moving from clinical diagnoses to biological signs for psychiatric investigations. Empirical studies also demonstrate that genetic background, differences in environment, epistatic effects, and definition of the phenotype (including psychiatric diagnosis) all actively contribute to limit the duplication of QTL.     

Response latency in Canis familiaris: mental ability or mental strategy?

Animal studies of cognitive aging typically use measures of response accuracy (RA) to evaluate cognitive function, which declines with age. Human aging studies, by contrast, frequently measure response latency (RL), with faster responses being indicative of superior performance. To examine the influence of age on RL in an animal model, the authors assessed RA with RL in young and aged beagle dogs (Canis familiaris) tested on a 3-component delayed nonmatching-to-position task, which comprised 3 subtests. Young dogs displayed significantly slower RLs and higher RAs and showed RL slowing with greater complexity, compared with aged dogs. In addition, the slower responding young dogs made fewer errors. Thus, RL appears to reflect the learning strategy applied, rather than the level of mental ability.     

Molecular mimicry reflected through database screening: serendipity or survival strategy?

Protein databases have been growing fast, and there has been considerable improvement in the computer software used to explore them. Subsequently, database screening commonly yields evidence of molecular mimicry between unrelated proteins. Here, Chantal Roudier and colleagues analyse the statistical significance of such sequence identities.     

Slowing down after a mild traumatic brain injury: a strategy to improve cognitive task performance?

Long-term persistent attention and memory difficulties following a mild traumatic brain injury (TBI) often go undetected on standard neuropsychological tests, despite complaints by mild TBI individuals. We conducted a visual Repetition Detection working memory task to digits, in which we manipulated task difficulty by increasing cognitive load, to identify subtle deficits long after a mild TBI. Twenty-six undergraduate students with a self-report of one mild TBI, which occurred at least 6 months prior, and 31 non-head-injured controls took part in the study. Participants were not informed until study completion that the study's purpose was to examine cognitive changes following a mild TBI, to reduce the influence of "diagnosis threat" on performance. Neuropsychological tasks did not differentiate the groups, though mild TBI participants reported higher state anxiety levels. On our working memory task, the mild TBI group took significantly longer to accurately detect repeated targets on our task, suggesting that slowed information processing is a long-term consequence of mild TBI. Accuracy was comparable in the low-load condition and, unexpectedly, mild TBI performance surpassed that of controls in the high-load condition. Temporal analysis of target identification suggested a strategy difference between groups: mild TBI participants made a significantly greater number of accurate responses following the target's offset, and significantly fewer erroneous distracter responses prior to target onset, compared with controls. Results suggest that long after a mild TBI, high-functioning young adults invoke a strategy of delaying their identification of targets in order to maintain, and facilitate, accuracy on cognitively demanding tasks.     

Functional biomimetic analogs help remineralize apatite-depleted demineralized resin-infiltrated dentin via a bottom–up approach

Natural biominerals are formed through metastable amorphous precursor phases via a bottom–up, nanoparticle-mediated mineralization mechanism. Using an acid-etched human dentin model to create a layer of completely demineralized collagen matrix, a bio-inspired mineralization scheme has been developed based on the use of dual biomimetic analogs. These analogs help to sequester fluidic amorphous calcium phosphate nanoprecursors and function as templates for guiding homogeneous apatite nucleation within the collagen fibrils. By adopting this scheme for remineralizing adhesive resin-bonded, completely demineralized dentin, we have been able to redeposit intrafibrillar and extrafibrillar apatites in completely demineralized collagen matrices that are imperfectly infiltrated by resins. This study utilizes a spectrum of completely and partially demineralized dentin collagen matrices to further validate the necessity for using a biomimetic analog-containing medium for remineralizing resin-infiltrated partially demineralized collagen matrices in which remnant seed crystallites are present. In control specimens in which biomimetic analogs are absent from the remineralization medium, remineralization could only be seen in partially demineralized collagen matrices, probably by epitaxial growth via a top–down crystallization approach. Conversely, in the presence of biomimetic analogs in the remineralization medium, intrafibrillar remineralization of completely demineralized collagen matrices via a bottom–up crystallization mechanism can additionally be identified. The latter is characterized by the transition of intrafibrillar minerals from an inchoate state of continuously braided microfibrillar electron-dense amorphous strands to discrete nanocrystals, and ultimately into larger crystalline platelets within the collagen fibrils. Biomimetic remineralization via dual biomimetic analogs has the potential to be translated into a functional delivery system for salvaging failing resin–dentin bonds.     

Different time course of emotion regulation towards odors and pictures: Are odors more potent than pictures?

The present study assessed emotion regulation in response to chemosensory and visual stimuli. Using cognitive reappraisal, 40 female participants regulated their emotions in response to disgusting pictures and odors, while the startle reflex was elicited and emotion ratings were assessed. Participants reported feeling less negative, and less aroused, while down-regulating their emotions towards both odors and pictures. Although being rated as equally negative and arousing, odor presentations were accompanied by larger startle responses than picture presentations. Furthermore, as compared to pictures emotion regulation towards odors followed a strikingly different time course suggesting less effective emotion regulation in response to disgusting odors. Questionnaire data show that differences between emotion regulation outcome towards odors was not attributable to different regulation strategies used. Thus, the current data suggest a unique role of olfaction in emotion perception, and show that cognitive emotion regulation - although being generally effective - may also be limited.     

Sensory regulation of quadrupedal locomotion: a top-down or bottom-up control system?

Propriospinal pathways are thought to be critical for quadrupedal coordination by coupling cervical and lumbar central pattern generators (CPGs). However, the mechanisms involved in relaying information between girdles remain largely unexplored. Using an in vitro spinal cord preparation in neonatal rats, Juvin and colleagues (Juvin et al. 2012) have recently shown sensory inputs from the hindlimbs have greater influence on forelimb CPGs than forelimb sensory inputs on hindlimb CPGs, in other words, a bottom-up control system. However, results from decerebrate cats suggest a top-down control system. It may be that both bottom-up and top-down control systems exist and that the dominance of one over the other is task or context dependent. As such, the role of sensory inputs in controlling quadrupedal coordination before and after injury requires further investigation.     

BP regulation VI: elevated sympathetic outflow with human aging: hypertensive or homeostatic?

Though conventional wisdom suggests that a rise in blood pressure is a reality of advancing age, in fact, it appears that progressive elevation in sympathetic activity, not necessarily accompanied by increased blood pressure, is intrinsic to cardiovascular aging in humans. The mechanism behind this elevation would seem to reside in homeostatic cardiovascular regulation; nonetheless, the balance of factors that result in elevated sympathetic outflow with age remains elusive. Age-related increases in sympathetic nervous outflow cannot be fully explained by increases in body mass, body adiposity, or other metabolic factors; interrelations among cardiac output, peripheral resistance, and blood pressure may not reflect a determinative hemodynamic interrelation but rather parallel phenomena; and there is no simple linear relationship between baroreflex control and resting levels of sympathetic activity. In contrast to systemic relationships, available data suggest that elevated sympathetic outflow may derive from the inter-relationship between centrally driven sympathoexcitation and a decline in the ability of sympathetic outflow to effect peripheral vascular responses. This review aims to integrate the current knowledge of mechanisms underlying elevated sympathetic outflow with age. It seeks to synthesize these data in the context of proposing that an age-related decline in the ability of sympathetic outflow to effect regional vascular responses incites a compensatory elevation in resting sympathetic activity to maintain homeostatic balance, presumably to maintain adequate control of blood pressure.