Sound level context modulates neural activity in the human brainstem

Optimal perception requires adaptation to sounds in the environment. Adaptation involves representing the acoustic stimulation history in neural response patterns, for example, by altering response magnitude or latency as sound-level context changes. Neurons in the auditory brainstem of rodents are sensitive to acoustic stimulation history and sound-level context (often referred to as sensitivity to stimulus statistics), but the degree to which the human brainstem exhibits such neural adaptation is unclear. In six electroencephalography experiments with over 125 participants, we demonstrate that the response latency of the human brainstem is sensitive to the history of acoustic stimulation over a few tens of milliseconds. We further show that human brainstem responses adapt to sound-level context in, at least, the last 44 ms, but that neural sensitivity to sound-level context decreases when the time window over which acoustic stimuli need to be integrated becomes wider. Our study thus provides evidence of adaptation to sound-level context in the human brainstem and of the timescale over which sound-level information affects neural responses to sound. The research delivers an important link to studies on neural adaptation in non-human animals

Pathophysiological link between Alzheimer’s disease and type 2 diabetes mellitus: novel therapeutic applications of anti-diabetic drugs

This review aims to distinguish type 2 diabetes (T2D) and Alzheimer’s disease (AD) as independent illnesses, while also highlighting the relationship of insulin resistance (IR) between the two conditions. Elucidating a similar mechanism of IR in T2D and AD may uncover the potential for diabetic therapies to treat AD. The cause of AD is unknown, although it is established that T2D is a major risk factor. The focus of this review will be to: 1. examine the mechanistic cross-talk between insulin-mediated signalling pathways in both T2D and AD; 2. highlight the similar cellular structural changes in the brain associated with cognitive impairments in both T2D and AD; and, 3. assess the effectiveness of diabetic therapies to ameliorate AD-related cognitive impairments. AD has been described as a brain-specific diabetes due to the presence of IR within regions of the brain exhibiting high insulin signalling and insulin receptor expression (e.g., the hippocampus). IR is associated with decreased hippocampal glucose metabolism in AD and T2D, leading to cognitive impairments. Future longitudinal studies should be conducted on AD-predisposed populations, or individuals exhibiting early signs of AD, to assess the effectiveness of diabetic therapies on outcomes associated with cognitive impairments before irreversible complications arise.</p

Sustained neural activity correlates with rapid perceptual learning of auditory patterns

Repeating structures forming regular patterns are common in sounds. Learning such patterns may enable accurate perceptual organization. In five experiments, we investigated the behavioral and neural signatures of rapid perceptual learning of regular sound patterns. We show that recurring (compared to novel) patterns are detected more quickly and increase sensitivity to pattern deviations and to the temporal order of pattern onset relative to a visual stimulus. Sustained neural activity reflected perceptual learning in two ways. Firstly, sustained activity increased earlier for recurring than novel patterns when participants attended to sounds, but not when they ignored them; this earlier increase mirrored the rapid perceptual learning we observed behaviorally. Secondly, the magnitude of sustained activity was generally lower for recurring than novel patterns, but only for trials later in the experiment, and independent of whether participants attended to or ignored sounds. The late manifestation of sustained activity reduction suggests that it is not directly related to rapid perceptual learning, but to a mechanism that does not require attention to sound. In sum, we demonstrate that the latency of sustained activity reflects rapid perceptual learning of auditory patterns, while the magnitude may reflect a result of learning, such as better prediction of learned auditory patterns

Interactions between lemongrass and lavender essential oils in combination with ampicillin influencing antibacterial activity on Sporosarcina ureae and Serratia liquefaciens

The purpose of this study is to determine the effects of various combinations of essential oils (EOs) with antibiotics on bacterial growth. The molecular mechanisms behind the effects of individual phytochemicals in EOs and antibiotics is well understood, unlike the mechanisms behind the interactions between multiple phytochemicals and antibiotics in a mixture. Serratia liquefaciens and Sporosarcina ureae were exposed to various treatments of different combinations of Lavandula officinalis (lavender oil), Cymbopogon citratus (lemongrass oil) with ampicillin. For each treatment group, mean zones of inhibition (ZOI) were measured after exposure for 48 hours. Controls for both species did not yield any ZOI whereas all other treatments resulted in the inhibition of bacterial growth in both Serratia liquefaciens and Sporosarcina ureae. Statistical analyses showed that the combination of lemongrass oil and ampicillin was significantly more effective than all other treatments for Serratia liquefaciens. The lemongrass oil and ampicillin treatment was the only treatment that displayed additive effects. All treatments for Sporosarcina ureae, with the exception of the control and lavender oil treatments, showed a significantly higher mean ZOI when compared to control and lavender oil treatments. It was concluded that lemongrass oil was a better candidate to be included in antibacterial cocktails than lavender oil. However, further investigation is required to elucidate EOs that interact synergistically with ampicillin when acting on Serratia liquefaciens and Sporosarcina ureae. Additionally, further investigation into the molecular mechanisms behind the interactions of the components found in these EOs with ampicillin is required

Maternal fructose consumption pre-pregnancy and during pregnancy and associations with maternal and offspring hepatic fat deposition and whole-body adiposity - a scoping review.

A review to establish the impact of maternal fructose consumption prior to and during pregnancy upon maternal and new born liver and whole body fat deposition