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Decomposing hot executive function: Decision making under ambiguity in preschoolers
Get PDFHot executive function (EF) is a critical skillset involving the ability to make decisions when there are motivational or emotional influences present. The present study examined three- and four-year-old preschooler performance across three hot EF tasks. Associations between the measures, which included the Preschool Gambling Task (PGT), a Delay of Gratification (DoG) hybrid wait-choice paradigm, and the Trash to Treasure passive avoidance task, were also explored. A sample of 144 preschoolers
(including 85 four-year-old children) completed the three hot EF tasks. The results revealed age differences on all three tasks. Furthermore, performance on Trash to Treasure and DoG were associated with different stages of decision making in the PGT, supporting the idea of differences in decision making when preschoolers have no knowledge of the task contingencies versus decision making when they have some knowledge. These findings suggest that age sensitive hot EF tasks have the potential to contribute to the assessment of developmental disorders that include EF impairments, such as autism or conduct disorder. Future studies should consider individual differences in EF development, increase the Trash to Treasure task sensitivity to age, and incorporate a larger sample
Exploring the effects of imagining the future self on delay of gratification on preschoolers
Get PDFThe ability to delay gratification is observed beginning in early childhood and due to the positive outcomes associated with this ability, there is growing interest in mechanisms that can be used to facilitate the development of this skill. The current study aims to investigate whether encouraging preschoolers to imagine their future selves improves delay of gratification. In the first study, 64 children, 36 three-year-olds and 28 four-yearolds (28 males and 36 females), completed a delay of gratification task. Fifty-seven
children, 23 three-year-olds and 34 four-year-olds (31 males and 26 females) participated in the second study. There were four conditions across the two studies, where children were primed to imagine their present selves, their future selves, their present selves in conjunction with their future selves, and not primed to engage in imagining the self. Results indicated that preschoolers made significantly more choices to delay when they were primed to imagine their future selves. These results suggest that
engaging in future-oriented thinking of the self may be employed as a strategy to help children delay gratification
The effect of cold exposure on glutamate transmission and neuronal excitability in the dorsomedial hypothalamus of male rats
Get PDFThe dorsomedial hypothalamus (DMH) is a key brain region involved in thermoregulation, in part through activation of brown adipose tissue (BAT). The DMH functionally connects thermoreceptors in the skin to the sympathetic nervous system, which activates BAT and generates heat during cold exposure in mammals. While it is known that the DMH is essential for BAT activation, how cold exposure affects neuronal communication and excitability in the DMH remains unknown. We hypothesized that cold exposure affects synaptic communication in the DMH by altering glutamate transmission and neuronal excitability. To examine the potential effects of cold exposure on DMH synapses, we subjected young male Sprague Dawley rats to a two-hour cold exposure (2 - 4°C). To control for the effects of stress during cold exposure experiments, control (stress) experiments were performed with replicated procedures excluding the change in temperature. Patch clamp electrophysiology was then used to study glutamate signaling and excitability in the DMH of naive, cold-exposed, and stressed animals. We observed a decrease in baseline glutamate transmission in the DMH of cold exposed animals. This suggests that decreased glutamate transmission in the DMH may be involved in signaling cold temperatures and activating thermogenic processes regulated by the DMH. A long-term depression at glutamate synapses was observed in the DMH of both cold-exposed and stressed animals. As the long-term depression was also seen in stressed animals, who experienced similar environmental manipulation without a change in temperature, the observed depression was likely caused by stress and not cold exposure. There was no difference in action potential firing observed across naive, cold-exposed, and stressed animals, suggesting a two-hour cold exposure does not alter the excitability of DMH neurons. This study is the first to demonstrate that glutamate transmission is decreased in the DMH during cold exposure, representing a potential important neuronal mechanism involved in activating thermoregulatory strategies such as BAT thermogenesis
High-throughput well plate approach illustrates strain specific variation in picocyanobacteria nitrogen and phosphorus usage
Get PDFIn the wake of water body eutrophication influenced by major nutrient influxes from agriculture and urban runoff, there have been global increases in the growth of phytoplankton species. The environments created appear to favour the growth of cyanobacteria in comparison to other primary producers. The smallest group of these organisms, known as picocyanobacteria, is uniquely adapted to grow and dominate aquatic environments following a period of nutrients saturation. Due to the small nature of these organisms’ identification outside of genomic testing can be a difficult task, as such minor morphological differences can be hard to identify using microscopic techniques. Despite being closely related and similarly classified, many picocyanobacteria have been highly specialized in their environment based on conditions such as salinity, nutrient availability, and light. This study implemented the use of a high-throughput well plate design to expose three strains of picocyanobacteria to a fully crossed experimental matrix of five phosphorus concentrations (0 μM, 0.5 μM, 3.0 μM, 5.0 μM, and 7.0 μM), four nitrogen concentrations (0 μM, 5.0 μM, 30.0 μM, and 70.0 μM), and three-light levels (30, 100 or 300 μmol photons m-2 s-1), to determine if niche determination based on nutrients and light is an effective method of understanding and characterizing the growth of picocyanobacteria strains. Cyanobium sp. CZS25K, Cyanobium sp. CZS48M, and Synechocystis sp. PCC6803 were examined for this study. Statistical modelling demonstrated distinct strain-specific variations between the uses of nutrients and light for
growth. Nitrogen and phosphorus concentrations were demonstrated to influence the growth of CZS25K. Nitrogen and light levels were essential for the growth of CZS48M. In contrast, PCC6803 growth rates were most sensitive to environmental nitrogen availability. These results may help support and inspire studies examining phytoplankton growth and adaptation mechanisms. This knowledge is becoming increasingly valuable for global monitoring and management of accelerated phytoplankton growth
A dual process account: The effect of context congruency on identification and detection processes in a change detection task
Get PDFThe goal of this study was to investigate the underlying processes involved in complex scene perception and, more specifically, the influence of context congruency on change detection performance. In two separate experiments, participants were asked to detect changing objects embedded in contextually congruent and incongruent scenes. In the first experiment, participants were faster and made fewer errors detecting incongruent objects than congruent objects. In the second experiment, participants were given valid and invalid cues for the target objects. In this case, participants were faster and made fewer errors detecting incongruent objects when the cue did not accurately describe the target object. This incongruency benefit, however, was eliminated when the cue accurately described the target object. These findings support a dual process account of complex scene perception, wherein task constraints can lead to incongruency benefits in some cases, but not others
Synthesis and characterization of novel iminophosphineplatinum(II) complexes containing aliphatic groups
Get PDFSix novel iminophosphines were synthesized following the addition of the appropriate alkyl amine to 2-(diphenylphosphino)benzaldehyde and subsequent coordination to platinum. All compounds were fully characterized by FT-IR and multinuclear NMR spectroscopy. Melting point determination was carried out on solid compounds. An X-ray diffraction studied was performed on dicholoro-[(2-(diphenylphosphino)benzilidene)hexylamine]platinum(II) (Pt1). Future work will focus on characterizing platinum complexes using elemental analysis and screening the bioactivity
Cladoceran body size as a metric of environmental change in New Brunswick lakes
Get PDFCladocerans are a widespread order of zooplankton frequently used as bioindicators of aquatic conditions and environmental change. Shifts in cladoceran body size, at both the taxon and assemblage level, can occur as a response to environmental stressors. A standardized body size metric was developed for cladoceran taxa commonly observed in lakes of eastern Canada to provide an assessment method for understanding body size responses to environmental change. The metric was then applied to dated sediment records of five New Brunswick lakes that experienced severe DDT contamination in the mid-20th century. Body sizes of Bosmina sp. and Daphnia sp. remains were also measured from two lakes to determine whether size trends based on the metric occurred at a taxon level. A decline in body sizes in two lakes initially associated with historical DDT inputs has remained to present, and suggests that past and contemporary stressors, such as climate change, may structure both assemblage composition and body sizes of cladocerans. The shift towards smaller body sizes during the DDT impact period was reflected at both the assemblage (via the size metric) and taxon levels. The agreement in the metric and
measurements of cladoceran remains from the sediment record suggests that the metric accurately tracks trends in average cladoceran body size through time. Overall, the body size metric provides a tool to further assess the impact of environmental stressors on cladocerans and determine potential implications for aquatic food webs
Finding a place for affordable accessible housing
Get PDFStudying affordable housing is like exploring the ocean; it is inadequate to examine one section of the area in depth without contextualizing its broader environment, nor is it preferable in only understanding the ocean at a surface level. There is no one affordable housing crisis, nor is there one solution to these crises. The depth and breadth of the study of affordable housing is perhaps why municipal governments see affordable housing as a brick wall, such as planners I have spoken to over my two years of deep sea diving through this complex topic. During this time I have learned that affordable housing is about more than funding for social housing projects and rent subsidies. There exists opportunities to supply much needed affordable accessible housing (AAH) at the market level by enabling developers to reach this undersupplied demographic of homeowner or renter
The effect of endocannabinoids on glutamate synaptic transmission in the rat dorsomedial hypothalamus
Get PDFEndogenous cannabinoids (eCBs) are a class of neurotransmitters that modulate the release of other classical neurotransmitters, such as glutamate and GABA, onto their target neurons by activating type I cannabinoid (CB1) receptors on presynaptic terminals. eCBs stimulate appetite, but the mechanisms are not entirely understood. The dorsomedial hypothalamus (DMH) is a key appetite-regulatory center, and research shows that CB1Rs are expressed in this region. eCBs have been reported to decrease the release of GABA onto DMH neurons in rats, but there are no reports of their effects on glutamate release in the DMH, despite observations that eCBs modulate glutamate release elsewhere in the brain. We hypothesized that eCBs would alter glutamate release onto rat DMH neurons with the prediction that eCBs will decrease glutamate release. To test this, we used young male Sprague Dawley rats and performed patch clamp electrophysiology to record glutamate-mediated currents in living DMH neurons. Here we show that activation of CB1R with a synthetic agonist decreases glutamate release onto DMH neurons, confirming that CB1R are present on glutamate terminals in the DMH. Surprisingly, when eCB
release from DMH neurons was induced with depolarization or high frequency stimulation of DMH synapses, we did not observe a decrease in glutamate release. Accumulating evidence suggests that another transmitter, nitric oxide, can interfere with eCB signaling, so we repeated the HFS experiment but with NO synthesis inhibited to determine if eCBs would then trigger a long-term decrease in glutamate release. Under these conditions, we observed a significant decrease in glutamate release that was mediated by CB1R activation. This research could enhance our understanding of the mechanisms by which eCBs control appetite
Age-related differences in spatial relational perception
Get PDFDeficits in episodic memory are prevalent in older adults (OA). Episodic memory involves binding event details to spatial contexts, thus, well-formed scene representations support memory for these associations. Furthermore, episodic memory and spatial processing share a neural underpinning: the hippocampus (HC). Episodic memory decline in aging is associated with HC degradation, suggesting a possibility that OA’s memory deficits may arise from an inability to process coherent spatial representations due to HC degradation. Although OA show impairments in spatial cognition, it is unclear whether these occur during early stages of scene processing, i.e., visual perception. We present a novel study which investigated age differences in spatial relational perception. We predicted that OA would perform worse than younger adults (YA) at identifying changes in object location, but not object identity. Although results revealed no differences in accuracy, OA were significantly slower than YA when identifying changes in object location, and not identity. Our findings therefore support the hypothesis, revealing an age-related impairment in visuospatial relational perception. We posit that this is due to degradation of the HC, endorsing its role in scene perception. Further research into this age-related impairment may reveal important links between episodic memory and visuospatial perception