Neuroscience
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Fluoxetine (Flx) is the most commonly used antidepressant to treat major depressive disorder. However, its molecular mechanisms of action are not defined as yet. A comparative proteomic approach was used to identify proteome changes in the prefrontal cortex (PFC) cytosolic and non-synaptic mitochondria (NSM)-enriched fractions of adult male Wistar rats following chronic social isolation (CSIS), a rat model of depression, and Flx treatment in CSIS and control rats, using liquid chromatography online tandem mass spectrometry. ⋯ The presence of cytochrome c in the cytosol may suggest compromised mitochondrial membrane integrity. Flx treatment in CSIS rats downregulated protein involved in oxidative phosphorylation, such as complex III and manganese superoxide dismutase, and upregulated vesicle-mediated transport and synaptic signaling proteins in the cytosol, and neuronal calcium-binding protein 1 in NSM. Our study identified PFC modulated proteins and affected biochemical pathways that may represent potential markers/targets underlying CSIS-induced depression and effective Flx treatment, and highlights the role of protein systems involved in NSM and various metabolic pathways potentially involved in neuronal plasticity.
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The history of our actions and their outcomes represent important information, informing choices and efficiently guiding future behavior. While unsuccessful (S-) outcomes are expected to lead to more explorative motor states and increased behavioral variability, successful (S+) outcomes are expected to reinforce the use of the previous action. ⋯ Using electroencephalography, we show that theta band oscillations of the prefrontal cortex are most prominent during changes in two consecutive outcomes, potentially reflecting the need for enhanced cognitive control. Our results suggest that S+ experiences 'overwrite' previous motor states to a greater extent than S- experiences and that modulations in neural oscillations in the prefrontal cortex play a potential role in encoding changes in movement variability state during reinforcement motor learning.
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Response time (RT) distributions are histograms of the observed RTs for discriminative choices, comprising a rich source of empirical information to study perceptual processes. The drift-diffusion model (DDM), a mathematical formulation predicting decision tasks, reproduces the RT distributions, contributing to our understanding of these processes from a theoretical perspective. Notably, although the mouse is a popular model system for studying brain function and behavior, little is known about mouse perceptual RT distributions, and their description from an information-accumulation perspective. ⋯ The large number of empirical observations that we collected for this study allowed us to achieve accurate convergence for the model fit. Therefore, changes in the experimental conditions were mirrored by changes in model parameters, suggesting the participation of relevant brain areas in the decision-making process. This approach could help interpret future studies involving attention, discrimination, and learning in adult mice.
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During speech comprehension, the ongoing context of a sentence is used to predict sentence outcome by limiting subsequent word likelihood. Neurophysiologically, violations of context-dependent predictions result in amplitude modulations of the N400 event-related potential (ERP) component. While the N400 is widely used to measure semantic processing and integration, no publicly-available auditory stimulus set is available to standardize approaches across the field. ⋯ With 20 neurotypical adults, we validated that this set elicits robust N400's, as well as two additional semantically-related ERP components: the recognition potential (∼ 250 ms) and the late positivity component (∼ 600 ms). This stimulus set (https://doi.org/10.5061/dryad.9ghx3ffkg) and the 20 high-density (128-channel) electrophysiological datasets (https://doi.org/10.5061/dryad.6wwpzgmx4) are made publicly available to promote data sharing and reuse. Future studies that use this stimulus set to investigate sentential semantic comprehension in both control and clinical populations may benefit from the increased comparability and reproducibility within this field of research.
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In general, catechins contained in green tea are believed to have positive effects on the human body and mental health. The intake of epigallocatechin gallate (EGCG), a major polyphenol in green tea, is known to be effective for retinal protection; however, whether green tea and/or EGCG affect visual function remains unknown. In the present study, we investigated the effect of green tea and EGCG on visual motion processing by measuring optokinetic responses (OKRs) in young adult and aging mice. ⋯ We found that the OKRs of young and aging mice after green tea intake and after EGCG administration showed higher temporal sensitivity than those of control mice. The visual ability to detect moving objects was enhanced in young and aging mice upon intake of green tea or EGCG. From the above results, the visual motion processing for optokinetic responses by ingesting green tea was enhanced, which may be related to the effect of EGCG.