Behavioural state differentially engages septohippocampal cholinergic and GABAergic neurons in R6/1 Huntington's disease mice

Huntington's disease (HD) is a neurodegenerative condition characterised by progressive motor, psychological and cognitive decline. R6/1 HD transgenic mice model the clinical hippocampal-dependent cognitive deficits observed in patients. Cholinergic and GABAergic septohippocampal projections play important roles in hippocampal-dependent cognition. The current study examined neuronal activity of cholinergic and GABAergic septohippocampal projections in response to arousal elicited during differing behavioural states. The different behavioural states examined were; home cage (controls), acute exploration of a novel enriched environment and either spontaneous wakefulness (dark phase) or spontaneous sleep (light phase). We employed triple-label immunohistochemistry using c-Fos as an indirect marker of neuron activation and parvalbumin and choline acetyltransferase (ChAT) to label GABAergic and cholinergic neurons in the basal forebrain, respectively. The Y-maze was used to assess short-term hippocampal-dependent memory independently during either the dark or light phase and revealed a memory deficit in R6/1 HD mice compared to wild types that was particularly prominent during the dark phase. Three-way ANOVA of basal forebrain cholinergic and GABAergic activity through co-expression of c-Fos revealed overt responses to differing behavioural states. Both genotypes increased cholinergic neuron activity in response to exploring a novel enriched environment and also an increase during the dark phase compared to the light phase. Novel enriched environment exploration caused a larger response of GABAergic neuron activity in R6/1 HD mice, which also failed to increase the activity of GABAergic neurons during the dark phase compared to the light phase as observed for wildtype mice. Basal levels of c-Fos-positive cells were greatly increased in the hippocampal granule cell layer of R6/1 HD mice during both circadian phases. The differential activation of septohippocampal cholinergic and GABAergic neurons in R6/1 HD mice in response to differing behavioural states may be associated with impaired hippocampal-dependent short-term memory.     

Autonomic arousal and relational aggression in heterosexual dating couples

This study investigated the association between romantic relational aggression and autonomic nervous system (ANS) arousal in the context of heterosexual dating couples (N = 115 couples). Results indicated that romantic relational aggression was associated with low resting sympathetic arousal, high resting parasympathetic arousal, and exaggerated fight or flight responses to a conflict discussion (sympathetic activation and parasympathetic withdrawal). However, ANS activity was more strongly associated with romantic relational aggression in the context of low‐quality romantic relationships, and sympathetic activity was more strongly associated with aggression among females, whereas parasympathetic activity was more strongly associated with aggression among males. Results indicate that psychophysiological functioning may serve as a risk factor for the perpetration of relational aggression against romantic partners.     

Bilingualism: consequences for mind and brain

Building on earlier evidence showing a beneficial effect of bilingualism on children's cognitive development, we review recent studies using both behavioral and neuroimaging methods to examine the effects of bilingualism on cognition in adulthood and explore possible mechanisms for these effects. This research shows that bilingualism has a somewhat muted effect in adulthood but a larger role in older age, protecting against cognitive decline, a concept known as 'cognitive reserve'. We discuss recent evidence that bilingualism is associated with a delay in the onset of symptoms of dementia. Cognitive reserve is a crucial research area in the context of an aging population; the possibility that bilingualism contributes to cognitive reserve is therefore of growing importance as populations become increasingly diverse.     

Neural correlates of establishing, maintaining, and switching brain states

Although the study of brain states is an old one in neuroscience, there has been growing interest in brain state specification owing to MRI studies tracing brain connectivity at rest. In this review, we summarize recent research on three relatively well-described brain states: the resting, alert, and meditation states. We explore the neural correlates of maintaining a state or switching between states, and argue that the anterior cingulate cortex and striatum play a critical role in state maintenance, whereas the insula has a major role in switching between states. Brain state may serve as a predictor of performance in a variety of perceptual, memory, and problem solving tasks. Thus, understanding brain states is critical for understanding human performance.     

The social brain meets neuroimaging

Recent neuroimaging studies in humans have indicated that individual differences in social network size correlate with amygdala volume and the volume of brain regions associated with theory of mind. A new article demonstrates that this is also true for monkeys. Taken together, these findings provide crucial support for the social brain hypothesis.     

Social referencing in dog-owner dyads?

Social referencing is the seeking of information from another individual to form one’s own understanding and guide action. In this study, adult dogs were tested in a social referencing paradigm involving their owner and a potentially scary object. Dogs received either a positive or negative message from the owner. The aim was to evaluate the presence of referential looking to the owner, behavioural regulation based on the owner’s (vocal and facial) emotional message and observational conditioning following the owner’s actions towards the object. Most dogs (83%) looked referentially to the owner after looking at the strange object, thus they appear to seek information about the environment from the human, but little differences were found between dogs in the positive and negative groups as regards behavioural regulation: possible explanations for this are discussed. Finally, a strong effect of observational conditioning was found with dogs in the positive group moving closer to the fan and dogs in the negative group moving away, both mirroring their owner’s behaviour. Results are discussed in relation to studies on human–dog communication, attachment and social learning.     

Three-dimensional spatial representation in freely swimming fish

Research on spatial cognition has focused on how animals encode the horizontal component of space. However, most animals travel vertically within their environments, particularly those that fly or swim. Pelagic fish move with six degrees of freedom and must integrate these components to navigate accurately--how do they do this? Using an assay based on associative learning of the vertical and horizontal components of space within a rotating Y-maze, we found that fish (Astyanax fasciatus) learned and remembered information from both horizontal and vertical axes when they were presented either separately or as an integrated three-dimensional unit. When information from the two components conflicted, the fish used the previously learned vertical information in preference to the horizontal. This not only demonstrates that the horizontal and vertical components are stored separately in the fishes' representation of space (simplifying the problem of 3D navigation), but also suggests that the vertical axis contains particularly salient spatial cues--presumably including hydrostatic pressure. To explore this latter possibility, we developed a physical theoretical model that shows how fish could determine their absolute depth using pressure. We next considered full volumetric spatial cognition. Astyanax were trained to swim towards a reward in a Y-maze that could be rotated, before the arms were removed during probe trials. The subjects were tracked in three dimensions as they swam freely through the surrounding cubic tank. The results revealed that fish are able to accurately encode metric information in a volume, and that the error accrued in the horizontal and vertical axes whilst swimming in probe trials was similar. Together, these experiments demonstrate that unlike in surface-bound rats, the vertical component of the representation of space is vitally important to fishes. We hypothesise that the representation of space in the brain of vertebrates could ultimately be shaped by the number of the degrees of freedom of movement that binds the navigating animal.     

Knowing minds, controlling actions: the developmental relations between theory of mind and executive function from 2 to 4 years of age

This longitudinal study examined the concurrent and predictive relations between executive function (EF) and theory of mind (ToM) in 82 preschoolers who were assessed when they were 2, 3, and 4 years old. The results showed that the concurrent relation between EF and ToM, after controlling for age, verbal ability, and sex, was significant at 3 and 4 years of age but not at 2 years of age. Hierarchical regression analyses showed that EF at age 2 significantly predicted ToM at age 3 and that EF at age 3 significantly predicted ToM at age 4, over and above the effects of age, verbal ability, and prior performance on ToM tasks. However, ToM at ages 2 and 3 did not explain a significant amount of variance in EF at age 4. Bootstrap procedures revealed that verbal ability at age 3 fully mediated the relation between ToM at age 2 and EF at age 4.     

Mediating Role of Satisfaction with Growth Opportunities on the Relationship Between Employee Development Opportunities and Citizenship Behaviors and Burnout

Theory and research from disparate areas were integrated to test if satisfaction with growth opportunities would mediate the influence of job‐ and company‐provided development opportunities on citizenship behaviors and employee burnout. In a sample of professional employees, the results of structural equation modeling provided support for partial mediation. Job‐provided development opportunities were significantly related to satisfaction with growth opportunities, which, in turn, was related to the citizenship behaviors of interpersonal helping, personal industry, and loyal boosterism and to the burnout dimension of personal accomplishment. Job‐ and company‐provided development opportunities also had a direct and differential association with forms of citizenship behaviors and burnout dimensions. Implications of the results for theory and practice are discussed. Directions for future research are offered.