Behavioural brain research
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Ageing of the central nervous system (CNS) is the major risk factor for Alzheimer's disease (AD), a type of neurodegeneration that is associated with deficits in cognition and memory and clinically manifested as severe senile dementia. Numerous mental processes underline cognition, including attention, producing and understanding language, learning, reasoning, problem solving, decision making and memory formation. In the past, neurones or their parts have been considered to be the exclusive cellular sites of memory and cognitive processes. ⋯ Astroglia exhibit cytoplasmic excitability that engages ions (such as Ca2+ and Na+) and second messengers (such as cAMP). These ions/molecules contribute to the reception of extracellular signals and coordinate the secretion of glio-signalling molecules, including peptides such as apolipoporotein E, which participates in lipid transport between glia and neurones. In this setting, astrocytes are positioned as spatio-temporal integrators of neural network coordination, which disintegrates during progression of AD.
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Peripheral electrical stimulation (PES) modulates corticomotor excitability but its effect on motor performance has not been thoroughly investigated. The purpose of this study was to assess whether increases and/or decreases in corticomotor excitability, induced by PES, influenced motor performance using a visuomotor adaptation task. Three PES interventions (motor stimulation, sensory stimulation or sham) were delivered to the first dorsal interosseous (FDI) in 30 healthy participants matched for age, gender and handedness. ⋯ The rate of visuomotor adaptation was greater following motor PES compared to sham, but not sensory, with no difference observed between sensory and sham. However, visuomotor adaptation performance overall (the total change in performance from beginning to end) was similar across intervention groups. These findings suggest that motor PES applied prior to task acquisition can facilitate the speed of adaptation.
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Metabotropic glutamate receptor 1 (mGluR1) blockade has been shown to decrease impulsive choice, as measured in delay discounting. However, several variables are known to influence an animal's discounting, including sensitivity to delayed reinforcement and sensitivity to reinforcer magnitude. The goal of this experiment was to determine the effects of mGluR1, as well as mGluR5, antagonism on these parameters. ⋯ Specifically, JNJ decreased sensitivity to reinforcer magnitude in rats trained on the descending schedule only. MPEP did not alter sensitivity to reinforcer magnitude or sensitivity to delayed reinforcement. These results show that mGluR1 is an important mediator of impulsive choice, and they provide further evidence that delay order presentation is an important variable that influences drug effects in delay discounting.
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Zinc is an important element in all cells of the body, having structural, enzymatic, and regulatory functions. In some neurons, zinc is loaded into synaptic vesicles by zinc transporter 3 (ZnT3) and released into the synaptic cleft, where it can modulate neuronal function. ZnT3 knockout (KO) mice lack ZnT3 and thus lack synaptic zinc. ⋯ This is the first study to show a behavioural phenotype specifically for female ZnT3 KO mice. Comparing our results to previous studies, it appears that there may be sex-specific effects of eliminating ZnT3. Female ZnT3 KO mice exhibit abnormalities in locomotion and at skilled motor learning, but we were unable to detect spatial or fear learning deficits previously described in male ZnT3 KO mice.
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The Lateral Habenula (LHb) plays an important role in emotion and cognition. Recent experiments suggest that LHb has functional interaction with the hippocampus and plays an important role in spatial learning. LHb is reciprocally connected with midbrain monoaminergic brain areas such as the ventral tegmental area (VTA). ⋯ We found that both D1R agonist and antagonist impaired the acquisition of contextual fear memory in rats. D1R agonist or antagonist also impaired long term potentiation (LTP) in hippocampal CA3-CA1 synapses in freely moving rats and attenuated learning induced phosphorylation of α-amino-3-hydroxy-5-methyl-4-isoxazole-propionic acid receptor (AMPAR) subunit 1 (GluA1) at Ser831 and Ser845 in hippocampus. Taken together, our results suggested that dysfunction of D1R in LHb affected the function of hippocampus.