Aging is a physiological process that is still poorly understood, especially with respect to effects on the brain. There are open questions about aging that are difficult to answer with an experimental approach. Underlying challenges include the difficulty of recording in vivo single cell and network activity simultaneously with submillisecond resolution, and brain compensatory mechanisms triggered by genetic, pharmacologic, or behavioral manipulations.
View Article and Find Full Text PDFAlthough electroconvulsive therapy (ECT) is one of the most effective treatments for severe mood and psychotic disorders, the mechanisms underlying its therapeutic effects remain unknown. Electroconvulsive stimulation (ECS), the animal model for ECT, can be used to investigate the potential therapeutic mechanisms of ECT in rodents. ECS produces numerous effects in the brain, such as increasing levels of growth factors, inducing dendritic sprouting, and stimulating neurogenesis.
View Article and Find Full Text PDFSudden death by commotio cordis is rare. It is the consequence of a blunt trauma of the chest overlying the heart. The mechanism is a cardiac arrest by ventricular fibrillation in the absence of grossly or microscopically apparent myocardial injury.
View Article and Find Full Text PDFEnvironmental changes alter the sex fate in about 15% of vertebrate orders, mainly in ectotherms such as fish and reptiles. However, the effects of temperature changes on the endocrine and molecular processes controlling gonadal sex determination are not fully understood. Here, we provide evidence that thyroid hormones (THs) act as co-players in heat-induced masculinization through interactions with the stress axis to promote testicular development.
View Article and Find Full Text PDFType 2 diabetes mellitus has steadily increased in prevalence over the past five decades. Among the health risks associated with this disorder are cognitive decline and are increased risk of developing dementia. To further investigate the link between diabetes and cognition, here we test memory performance and hippocampal function in the Goto-Kakizaki (GK) rat, a robust model of diabetes.
View Article and Find Full Text PDFDust grains absorb half of the radiation emitted by stars throughout the history of the universe, re-emitting this energy at infrared wavelengths. Polycyclic aromatic hydrocarbons (PAHs) are large organic molecules that trace millimetre-size dust grains and regulate the cooling of interstellar gas within galaxies. Observations of PAH features in very distant galaxies have been difficult owing to the limited sensitivity and wavelength coverage of previous infrared telescopes.
View Article and Find Full Text PDFBackground: Despite being one of the safest, most effective treatments for severe mood disorders, the therapeutic mechanisms of electroconvulsive therapy remain unknown. Electroconvulsive seizure (ECS) induces rapid, high-level expression of immediate early genes (IEGs) and brain-derived neurotrophic factor (BDNF), in addition to stimulation of neurogenesis and dendritic remodeling of dentate gyrus (DG) neurons. We have previously shown that this upregulation of BDNF fails to occur in the hippocampus of mice lacking the IEG Egr3.
View Article and Find Full Text PDFThe mammalian hippocampus (Hp) can be functionally segregated along its septotemporal axis, with involvement of dorsal hippocampus (dHp) in spatial memory and ventral hippocampus (vHp) in stress responses and emotional behaviour. In the present study, we investigate comparable functional segregation in proposed homologues within the avian brain. Using Japanese quail (Coturnix Japonica), we report that bilateral lesions of the rostral hippocampus (rHp) produce robust deficits in a spatial Y-maze discrimination (YMD) test while sparing performance during contextual fear conditioning (CFC), comparable to results from lesions to homologous regions in mammals.
View Article and Find Full Text PDFHere, we present a protocol for inducing selective lesions in the hippocampal formation of Japanese quail (Coturnix japonica), coupled with associated behavioral testing. We first describe the surgical procedure for aspiration lesions in Japanese quail. We then detail two well-known hippocampus-dependent behavioral tests adapted to birds-foraging array (FA) and spontaneous object recognition (SOR).
View Article and Find Full Text PDFThe hippocampal formation (HF) is a structure critical to navigation and many forms of memory. In mammals, the firing of place cells is widely regarded as the fundamental unit of HF information processing. Supporting homology between the avian and mammalian HF, context-specific patterns of Egr1 have been reported in birds that are comparable to those produced by place cell firing in mammals.
View Article and Find Full Text PDFMore people in the UK are living with cancer than ever before. With an increasingly ethnically diverse population, greater emphasis must be placed on understanding factors influencing cancer outcomes. This review seeks to explore UK-specific variations in engagement with cancer services in minority ethnic groups and describe successful interventions.
View Article and Find Full Text PDFThe mammalian temporal cortex can be functionally segregated into regions that encode spatial information and others that are predominantly responsible for object recognition. In the present study, we report comparable functional segregation in the avian brain. Using Japanese quail, we find that bilateral lesions of the hippocampus (Hp) produce robust deficits in performance in a foraging array (FA) spatial memory task, while sparing spontaneous object recognition (SOR).
View Article and Find Full Text PDFSpontaneous novelty preference is apparent in a wide array of animals, including mammals, birds, reptiles, and fish. This provides a powerful behavioral assay to assess whether an animal can recognize a diverse array of stimuli in a common paradigm. Surprisingly, no research has been conducted in birds using novelty approach under conditions comparable to the spontaneous object recognition (SOR) protocols that have become standard across other animals.
View Article and Find Full Text PDFFront Behav Neurosci
October 2021
Adult-born neurons in the dentate gyrus (DG) make important contributions to learning as they integrate into neuronal networks. Neurogenesis is dramatically reduced by a number of conditions associated with cognitive impairment, including type 2 diabetes mellitus (T2DM). Increasing neurogenesis may thus provide a therapeutic target for ameliorating diabetes-associated cognitive impairments, but only if new neurons remain capable of normal function.
View Article and Find Full Text PDFContextual information is represented in the hippocampus (HPC) partially through the recruitment of distinct neuronal ensembles. It is believed that reactivation of these ensembles underlies memory retrieval processes. Recently, we showed that norepinephrine input from phasic locus coeruleus activation induces hippocampal plasticity resulting in the recruitment of new neurons and disengagement from previously established representations.
View Article and Find Full Text PDFThe 2017 Event Horizon Telescope (EHT) observations of the central source in M87 have led to the first measurement of the size of a black-hole shadow. This observation offers a new and clean gravitational test of the black-hole metric in the strong-field regime. We show analytically that spacetimes that deviate from the Kerr metric but satisfy weak-field tests can lead to large deviations in the predicted black-hole shadows that are inconsistent with even the current EHT measurements.
View Article and Find Full Text PDFNeurobiol Aging
November 2020
Aging is typically accompanied by both memory decline and changes in hippocampal function. Lasting memory is thought to also require recapitulation of recent memory traces during subsequent rest-a phenomenon termed memory trace reactivation or replay. Replay becomes less synchronized in the CA1 region of aged animals, and while subtle, this deficit may have profound physiological consequences for driving plasticity.
View Article and Find Full Text PDFFollowing presentation of a novel food odor on the breath of a conspecific, naïve rats will exhibit a preference for that food, a form of learning called social transmission of food preference (STFP). When tested in isolation, STFPs are robust, persisting for up to a month and overcoming prior aversions. This testing protocol, however, does not account for rats' ecology.
View Article and Find Full Text PDFThe largest clusters of galaxies in the Universe contain vast amounts of dark matter, plus baryonic matter in two principal phases, a majority hot gas component and a minority cold stellar phase comprising stars, compact objects, and low-temperature gas. Hydrodynamic simulations indicate that the highest-mass systems retain the cosmic fraction of baryons, a natural consequence of which is anti-correlation between the masses of hot gas and stars within dark matter halos of fixed total mass. We report observational detection of this anti-correlation based on 4 elements of a 9 × 9-element covariance matrix for nine cluster properties, measured from multi-wavelength observations of 41 clusters from the Local Cluster Substructure Survey.
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