FEAST: A flow cytometry-based toolkit for interrogating microglial engulfment of synaptic and myelin proteins.

Although engulfment is a hallmark of microglia function, fully validated platforms that facilitate high-throughput quantification of this process are lacking. Here, we present FEAST (Flow cytometric Engulfment Assay for Specific Target proteins), which enables interrogation of in vivo engulfment of synaptic material by brain resident macrophages at single-cell resolution. We optimize FEAST for two different analyses: quantification of fluorescent material inside live cells and of engulfed endogenous proteins within fixed cells. To overcome false-positive engulfment signals, we introduce an approach suitable for interrogating engulfment in microglia from perfusion-fixed tissue. As a proof-of-concept for the specificity and versatility of FEAST, we examine the engulfment of synaptic proteins after optic nerve crush and of myelin in two mouse models of demyelination (treatment with cuprizone and injections of lysolecithin). We find that microglia, but not brain-border associated macrophages, engulf in these contexts. Our work underscores how FEAST can be utilized to gain critical insight into functional neuro-immune interactions that shape development, homeostasis, and disease.

Dopamine in the songbird auditory cortex shapes auditory preference.

Vocal communication signals can provide listeners with information about the signaler and elicit motivated responses. Auditory cortical and mesolimbic reward circuits are often considered to have distinct roles in these processes, with auditory cortical circuits responsible for detecting and discriminating sounds and mesolimbic circuits responsible for ascribing salience and modulating preference for those sounds. Here, we investigated whether dopamine within auditory cortical circuits themselves can shape the incentive salience of a vocal signal. Female zebra finches demonstrate natural preferences for vocal signals produced by males ("songs"), and we found that brief pairing of passive song playback with pharmacological dopamine manipulations in the secondary auditory cortex significantly altered song preferences. In particular, pairing passive song playback with retrodialysis of dopamine agonists into the auditory cortex enhanced preferences for less-preferred songs. Plasticity of song preferences by dopamine persisted for at least 1 week and was mediated by D1 receptors. In contrast, song preferences were not shaped by norepinephrine. In line with this, while we found that the ventral tegmental area, substantia nigra pars compacta, and locus coeruleus all project to the secondary auditory cortex, only dopamine-producing neurons in the ventral tegmental area differentially responded to preferred versus less-preferred songs. In contrast, norepinephrine neurons in the locus coeruleus increased expression of activity-dependent neural markers for both preferred and less-preferred songs. These data suggest that dopamine acting directly in sensory-processing areas can shape the incentive salience of communication signals.

Motor learning promotes remyelination via new and surviving oligodendrocytes.

Oligodendrocyte loss in neurological disease leaves axons vulnerable to damage and degeneration, and activity-dependent myelination may represent an endogenous mechanism to improve remyelination following injury. Here we report that, while learning a forelimb reach task transiently suppresses oligodendrogenesis, it subsequently increases oligodendrocyte precursor cell differentiation, oligodendrocyte generation and myelin sheath remodeling in the forelimb motor cortex. Immediately following demyelination, neurons exhibit hyperexcitability, learning is impaired and behavioral intervention provides no benefit to remyelination. However, partial remyelination restores neuronal and behavioral function, allowing learning to enhance oligodendrogenesis, remyelination of denuded axons and the ability of surviving oligodendrocytes to generate new myelin sheaths. Previously considered controversial, we show that sheath generation by mature oligodendrocytes is not only possible but also increases myelin pattern preservation following demyelination, thus presenting a new target for therapeutic interventions. Together, our findings demonstrate that precisely timed motor learning improves recovery from demyelinating injury via enhanced remyelination from new and surviving oligodendrocytes.

Developmental auditory exposure shapes responses of catecholaminergic neurons to socially-modulated song.

Developmental sensory experience is critical to the tuning of sensory systems and can shape perceptual abilities and their neural substrates. Neuromodulators, including catecholamines, contribute to sensory plasticity in both older and younger individuals and provide a mechanism for translating sensory experience into changes in brain and behavior. Less well known, however, is whether developmental sensory experience has lasting effects on the neuromodulatory neurons themselves. Here, we used female zebra finches to investigate the degree to which developmental auditory experience can have lasting effects on the density and sensory responsiveness of catecholamine-synthesizing neuron populations. We found that hearing courtship, but not non-courtship, song increased expression of the activity-dependent immediate early gene cFOS in dopamine neurons of the caudal ventral tegmental area (VTA) and this increase was dependent on whether females heard adult song during development. Developmental song exposure also affected the density of dopamine producing neurons in the rostral VTA. In contrast, song-evoked responses in noradrenergic neurons of the Locus Coeruleus were not affected by either developmental song exposure or the social context of the stimulus. These data highlight the lasting effects that developmental auditory experience can have in shaping both the density and sensory responsiveness of dopamine neuron populations.

Delusional ideation during the perinatal period in a community sample.

BACKGROUND: Despite the prevalence of mental health problems during the perinatal period, little research has examined psychotic symptoms in a community sample across pregnancy and the postpartum. Exposure to environmental risk factors, and immigration in particular, are associated with increased risk for psychotic disorders. The current investigation examined whether psychosocial risk and immigrant status would predict levels of delusional ideation across the perinatal period when controlling for depression, anxiety, and demographic factors. METHODS: A community sample of 316 pregnant women was assessed at 12-14 and 32-34weeks gestation during routine clinic visits, and at 7-9weeks postpartum during a home visit. Measures included self-report ratings of psychosocial risk (e.g., history of mental health problems or abuse, stressful life events, lack of social support), pregnancy-related anxiety, depressive symptomatology, and delusional ideation. RESULTS: There was less delusional ideation during the postpartum period than during early pregnancy. Across all time points, levels of delusional ideation were lower than in the general population. Analyses using multilevel modeling indicated significant fixed-effects for the variables time, age, partnership, being religious and prenatal anxiety, but not depressive symptomatology, on delusional ideation. Immigrant status moderated the effect of psychosocial risk such that greater psychosocial risk predicted more symptoms of delusional ideation among immigrants, but not non-immigrants. CONCLUSION: Psychosocial risk factors place immigrant women at an increased likelihood for experiencing delusional ideation during the perinatal period.

Online Health Information Regarding Male Infertility: An Evaluation of Readability, Suitability, and Quality.

BACKGROUND: Many men lack knowledge about male infertility, and this may have consequences for their reproductive and general health. Men may prefer to seek health information online, but these sources of information vary in quality. OBJECTIVE: The objective of this study is to determine if online sources of information regarding male infertility are readable, suitable, and of appropriate quality for Internet users in the general population. METHODS: This study used a cross-sectional design to evaluate online sources resulting from search engine queries. The following categories of websites were considered: (1) Canadian fertility clinics, (2) North American organizations related to fertility, and (3) the first 20 results of Google searches using the terms "male infertility" and "male fertility preservation" set to the search locations worldwide, English Canada, and French Canada. Websites that met inclusion criteria (N=85) were assessed using readability indices, the Suitability Assessment of Materials (SAM), and the DISCERN tool. The associations between website affiliation (government, university/medical, non-profit organization, commercial/corporate, private practice) and Google placement to readability, suitability, and quality were also examined. RESULTS: None of the sampled websites met recommended levels of readability. Across all websites, the mean SAM score for suitability was 45.37% (SD 11.21), or "adequate", while the DISCERN mean score for quality was 43.19 (SD 10.46) or "fair". Websites that placed higher in Google obtained a higher overall score for quality with an r (58) value of -.328 and a P value of .012, but this position was not related to readability or suitability. In addition, 20% of fertility clinic websites did not include fertility information for men. CONCLUSIONS: There is a lack of high quality online sources of information on male fertility. Many websites target their information to women, or fail to meet established readability criteria for the general population. Since men may prefer to seek health information online, it is important that health care professionals develop high quality sources of information on male fertility for the general population.