Endocannabinoid signaling within the basolateral amygdala integrates multiple stress hormone effects on memory consolidation

Item does not contain fulltextGlucocorticoid hormones are known to act synergistically with other stress-activated neuromodulatory systems, such as norepinephrine and corticotropin-releasing factor (CRF), within the basolateral complex of the amygdala (BLA) to induce optimal strengthening of the consolidation of long-term memory of emotionally arousing experiences. However, as the onset of these glucocorticoid actions appear often too rapid to be explained by genomic regulation, the neurobiological mechanism of how glucocorticoids could modify the memory-enhancing properties of norepinephrine and CRF remained elusive. Here, we show that the endocannabinoid system, a rapidly activated retrograde messenger system, is a primary route mediating the actions of glucocorticoids, via a glucocorticoid receptor on the cell surface, on BLA neural plasticity and memory consolidation. Furthermore, glucocorticoids recruit downstream endocannabinoid activity within the BLA to interact with both the norepinephrine and CRF systems in enhancing memory consolidation. These findings have important implications for understanding the fine-tuned crosstalk between multiple stress hormone systems in the coordination of (mal)adaptive stress and emotional arousal effects on neural plasticity and memory consolidation

The hippocampal sharp wave–ripple in memory retrieval for immediate use and consolidation

Various cognitive functions have long been known to require the hippocampus. Recently, progress has been made in identifying the hippocampal neural activity patterns that implement these functions. One such pattern is the sharp wave-ripple (SWR), an event associated with highly synchronous neural firing in the hippocampus and modulation of neural activity in distributed brain regions. Hippocampal spiking during SWRs can represent past or potential future experience, and SWR-related interventions can alter subsequent memory performance. These findings and others suggest that SWRs support both memory consolidation and memory retrieval for processes such as decision-making. In addition, studies have identified distinct types of SWR based on representational content, behavioural state and physiological features. These various findings regarding SWRs suggest that different SWR types correspond to different cognitive functions, such as retrieval and consolidation. Here, we introduce another possibility - that a single SWR may support more than one cognitive function. Taking into account classic psychological theories and recent molecular results that suggest that retrieval and consolidation share mechanisms, we propose that the SWR mediates the retrieval of stored representations that can be utilized immediately by downstream circuits in decision-making, planning, recollection and/or imagination while simultaneously initiating memory consolidation processes

Faunal assemblages of seagrass ecosystems

Seagrass habitats support diverse animal assemblages and while there has been considerable progress in the study of these fauna over the last few decades, large knowledge gaps remain. There are biases in our knowledge of taxonomic and functional information that favour the temperate regions over the tropics, some seagrass genera over others, shallow habitats compared to deeper meadows and larger animals over smaller ones, with many invertebrate communities poorly described. In many areas of Australia, invertebrate identification to low taxonomic resolution is difficult due to a lack of resources, but new approaches, such as genetic barcoding, may one day surpass traditional methods of classification and overcome this issue. Many studies have demonstrated greater biodiversity of fauna in seagrass compared to adjacent bare habitats with explanations for this ranging from habitat and seascape processes to food availability and trophic interactions. Within seagrass ecosystems, meadows can be highly heterogeneous, and habitat factors such as structural complexity, patch size, edges, gaps and corridors influence associated faunal communities. Broader seascape processes that occur across multiple connected habitats, including seagrass meadows, bare sediments, mangroves, saltmarshes and coral and rocky reefs, influence faunal productivity and/or diversity through the movement of organisms for recruitment and migration, and the transport of detritus and nutrients. The study of seagrass food webs has highlighted the importance of bottom-up processes in shaping the faunal assemblages through assessments of the role of invertebrate prey in influencing the productivity of consumer species and manipulative experiments that show prey resources affecting spatial patterns of predators. In addition, top-down consumptive and non-consumptive effects of predators such as their modification of prey behaviour also affect the structure of faunal communities. A large number of natural and anthropogenic perturbations to seagrass meadows influence their resident animals. These disturbances can modify seagrass-associated fauna in several ways; directly where seagrass fauna are more sensitive to perturbation than their seagrass habitat, indirectly through habitat modification, and additionally through interventions that reduce connectivity between habitats that fauna use for part of their life cycle. Animals can also play a significant role in structuring seagrass meadows through processes such as herbivory and bioturbation that can have both positive and negative effects on seagrass habitat