Neuroscience
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The impact of treating astrocytes with the astrocytic toxin l-alpha amino adipic acid (L-AAA) on neuronal outgrowth, complexity and synapse formation was assessed, using a model of astrocyte-neuronal interaction. Treatment of rat primary cortical neurons with conditioned media (CM) derived from astrocytes treated with L-AAA reduced neuronal complexity and synapse formation. L-AAA provoked a reduction in the expression of glial fibrillary acid protein (GFAP) and a reduction in ATP-linked mitochondrial respiration in astrocytic cells. ⋯ Furthermore, L-AAA delivery to the pre-limbic cortex (PLC) of mice was found to increase dendritic spine density and treatment with ZL006 reduced this effect. In summary, L-AAA-induced astrocyte impairment leads to a loss of neuronal complexity and synapse loss in vitro and increased dendritic spine density in vivo that may be reversed by inhibitors of the NMDA-R/PSD-95/NOS pathway. The results have implications for understanding astrocytic-neuronal interaction and the search for drug candidates that may provide therapeutic approaches for brain disorders associated with astrocytic histopathology.
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Postnatal ethanol exposure has been shown to cause persistent defects in hippocampal synaptic plasticity and disrupt learning and memory processes. However, the mechanisms responsible for these abnormalities are less well studied. We evaluated the influence of postnatal ethanol exposure on several signaling and epigenetic changes and on expression of the activity-regulated cytoskeletal (Arc) protein in the hippocampus of adult offspring under baseline conditions and after a Y-maze spatial memory (SP) behavior (activity). ⋯ ChIP results suggested that reduced H3K14ac and H4K8ac in the Arc gene promoter is because of impaired CBP, and increased H3K9me2 is due to the enhanced recruitment of G9a. The CB1R antagonist and a G9a/GLP inhibitor, which were shown to rescue postnatal ethanol-triggered synaptic plasticity and learning and memory deficits, were able to prevent the negative effects of ethanol on activity-dependent signaling, epigenetics and Arc expression. Together, these findings provide a molecular mechanism involving signaling and epigenetic cascades that collectively are responsible for the neurobehavioral deficits associated with an animal model of fetal alcohol spectrum disorders (FASD).
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The human brain is known by its ability to modify and update existing memories, mediated by underlying neuronal plasticity. This ability is facilitated by two main phenomena, interference and generalization. ⋯ While each of these two phenomena may be well known separately, we review recent evidence primarily in perceptual and motor skill memory, spanning synaptic, neural systems-level, and behavioral research, suggesting that although the outcomes are different, the underlying neural and behavioral processes responsible for their inducements share numerous commonalities. The reviewed literature may imply a common mechanism underlying these two phenomena, and suggests a unified framework of memory and learning in the human brain.
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In recent years, a growing body of research has addressed the nature and mechanism of material perception. Material perception entails perceiving and recognizing a material, surface quality or internal state of an object based on sensory stimuli such as visual, tactile, and/or auditory sensations. This process is ongoing in every aspect of daily life. ⋯ Our main focus is on vision, but every sensory modality is involved in material perception. Information obtained through different sensory modalities is closely linked in material perception. Such cross-modal processing is another important feature of material perception, and will also be covered in this review.
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The successful recovery from affective loss (i.e., bereavement, relationship breakup) has been linked to adult attachment style (AAS), a personality trait. Up to now, the association between AAS, affective loss experiences and brain gray matter volume is unclear. In 192 healthy subjects we investigated the association between MRI brain gray matter volume, applying voxel based morphometry, AAS (Relationship Scales Questionnaire (RSQ), subscales "avoidance" (AV) and "anxiety" (ANX)), and number of affective losses within the last 5 years (AL; List of Threatening Experiences Questionnaire). ⋯ In additional region-of-interest (ROI) analyses (p < 0.05 FWE-corrected), based on previously reported findings, no significant associations were observed. ANX and AV differently correlate with local volumes of the left insula and pars opercularis of the left inferior frontal gyrus, which are implicated in emotion processing, empathy and emotion regulation among other functions. Our results support the notion that individual attachment styles, which develop in the interplay of genes and social environment, differ in their correlation with brain structure.