Perceptual reorganization from prior knowledge emerges late in childhood.

Human vision relies heavily on prior knowledge. Here, we show for the first time that prior-knowledge-induced reshaping of visual inputs emerges gradually in late childhood. To isolate the effects of prior knowledge on perception, we presented 4- to 12-year-olds and adults with two-tone images - hard-to-recognize degraded photos. In adults, seeing the original photo triggers perceptual reorganization, causing mandatory recognition of the two-tone version. This involves top-down signaling from higher-order brain areas to early visual cortex. We show that children younger than 7-9 years do not experience this knowledge-guided shift, despite viewing the original photo immediately before each two-tone. To assess computations underlying this development, we compared human performance to three neural networks with varying architectures. The best-performing model behaved much like 4- to 5-year-olds, displaying feature-based rather than holistic processing strategies. The reconciliation of prior knowledge with sensory input undergoes a striking age-related shift, which may underpin the development of many perceptual abilities.

The online world as a means of connection and disconnection during the COVID-19 pandemic: A test of the interpersonal-connections-behaviour framework.

BACKGROUND: The interpersonal-connections-behaviour framework proposes that social media is helpful/unhelpful to the individual to the extent that it facilitates/hinders satisfaction of core needs for acceptance and belonging (connecting and disconnecting pathways). However, little research has, to date, explicitly tested this framework. METHODS: Both pathways were explored in a cross-sectional sample of UK adults at the start of the pandemic (N = 632) and in longitudinal (cross-lagged) analyses (N = 227-240). Participants completed measures of online and offline socialising with friends and family (connecting pathway), and online and offline social comparisons (disconnecting pathway), anxiety, depression and loneliness. RESULTS: In cross-sectional analyses higher levels of online comparisons were associated with poorer mental health, an effect that survived after controlling for offline comparisons, and was partially mediated by loneliness. Counter to our predictions, online socialising was also associated with poorer mental health. Longitudinal analyses did not support predicted directions of causality. LIMITATIONS: Limitations include a lack of testing of individual-level moderators, the use of single item questions to probe some constructs, and an inability to test for effects potentially operating at different time-scales. CONCLUSIONS: The findings reported partially support the interpersonal-connections-behaviour framework in highlighting a disconnecting (but not connecting) pathway between online engagement and mental health. From a clinical perspective they highlight the importance of including people's online lives when considering mental health risk and resilience, particularly (one might argue) during periods of social isolation.

The association between sociodemographic inequalities, COVID-related impacts and mental health.

PURPOSE: There are concerns that the social, economic and health impacts of COVID-19 are unevenly distributed, exacerbating existing inequalities. Here we tested the hypotheses that: (H1) the magnitude of these impacts would be associated with symptoms of depression and anxiety early in the pandemic, and (H2) that these impacts would be associated with a range of sociodemographic risk factors. METHODS: Cross-sectional self-report data were collected from a UK sample (N = 632) between the 16th of May and 21st of July 2020, coinciding with the early stages of the pandemic and first UK lockdown. Data were collected on COVID-19 related impacts including financial and social stressors, symptoms of anxiety and depression, and sociodemographic/economic risk factors operationalised at multiple levels including the individual, familial, household and neighbourhood. RESULTS: Using regression analyses both financial and social impacts were independently associated with anxiety (R2 = 0.23) and depression scores (R2 = 0.24), as well as clinically significant generalised anxiety (R2 = 0.14) and depression (R2 = 0.11). In addition, many sociodemographic factors were associated with elevated levels of COVID-19 related impacts, including being younger, female, having lower educational attainment and lower income. LIMITATIONS: The main limitations of the study were its modest sample size, cross sectional design (which precluded inferences about directions of causality), and the relatively high socioeconomic status of the sample (which limited generalisability). CONCLUSIONS: These findings are consistent with a growing body of evidence that suggests that the pandemic has exacerbated existing inequalities, and further, point to particular groups that should be supported by post-COVID-19 recovery policies and initiatives.

Discrete confidence levels revealed by sequential decisions.

Humans can meaningfully express their confidence about uncertain events. Normatively, these beliefs should correspond to Bayesian probabilities. However, it is unclear whether the normative theory provides an accurate description of the human sense of confidence, partly because the self-report measures used in most studies hinder quantitative comparison with normative predictions. To measure confidence objectively, we developed a dual-decision task in which the correctness of a first decision determines the correct answer of a second decision, thus mimicking real-life situations in which confidence guides future choices. While participants were able to use confidence to improve performance, they fell short of the ideal Bayesian strategy. Instead, behaviour was better explained by a model with a few discrete confidence levels. These findings question the descriptive validity of normative accounts, and suggest that confidence judgments might be based on point estimates of the relevant variables, rather than on their full probability distributions.

The "Use It or Lose It" Dogma in the Retina: Visual Stimulation Promotes Protection Against Retinal Ischemia.

Enriched environment (EE) protects the retina from adult rats against ischemia/reperfusion (I/R) injury; however, how the components of EE contribute to the recovery after retinal ischemic damage remains unclear. We analyzed the contribution of social, cognitive, and visual stimulation on functional and histological alterations induced by I/R. Male Wistar rats were submitted to unilateral ischemia by increasing intraocular pressure to 120 mmHg for 40 min. After ischemia, animals were housed in the following conditions: standard environment (SE), enriched environment (EE), novelty environment (NE), standard social environment (SoE), standard visual environment (SVE), or visual environment (VE). In another set of experiments, rats were submitted to bilateral ischemia and housed in SE or EE. At 2 weeks post-ischemia, rats were subjected to electroretinography and histological analysis. EE (but not SoE or NE) afforded functional and histological protection against unilateral ischemia. EE did not induce protection in animals submitted to bilateral ischemia. VE protected retinal function and histology and increased retinal BDNF levels, while a TrkB receptor antagonist prevented the protective effect of VE against I/R damage. In animals submitted to unilateral ischemia, EE and VE induced an increase in c-fos immunoreactivity in the ipsi and contralateral superior colliculus, whereas in animals submitted to bilateral ischemia, no changes in c-fos-immunoreactivity were observed in either superior colliculus from EE-housed animals. These results support that visual stimulation could be a potent stimulus for driving retinal protection in adult rats through a BDNF/TrkB-dependent mechanism, likely involving the superior colliculus.

Therapeutic benefit of environmental enrichment on optic neuritis.

Optic neuritis (ON) is an inflammatory, demyelinating, neurodegenerative, and presently untreatable condition of the optic nerve which might induce blindness. We analyzed the effect of environmental enrichment (EE) on visual pathway damage provoked by experimental ON induced by a microinjection of bacterial lipopolysaccharide (LPS) into the optic nerve. For this purpose, LPS was microinjected into the optic nerve from male Wistar rats. After injection, one group of animals was submitted to EE, and another group remained in standard environment (SE) for 21 days. EE prevented the decrease in pupil light reflex (PLR), visual evoked potentials, retinal anterograde transport, phosphorylated neurofilament immunoreactivity, myelination (luxol fast blue staining), and axon (toluidine blue staining) and retinal ganglion cell (Brn3a-immunoreactivity) number. EE also prevented microglial/macrophage reactivity (Iba-1- and ED1-immunoreactivity), and astrocytosis (glial fibrillary acidic protein-immunostaining) induced by experimental ON. LPS-injected optic nerves displayed oxidative damage and increased inducible nitric oxide synthase, cyclooxygenase-2, and interleukin-1ß and TNFα mRNA levels which were prevented by EE. EE increased optic nerve brain-derived neurotrophic factor levels. When EE started at 4 (but not 7) days post-injection of LPS, a preservation of the PLR was observed at 21 days post-LPS, which was blocked by the daily administration of ANA-12 from day 4 to day 7 post-LPS. Moreover, EE from day 4 to day 7 post-LPS significantly preserved the PLR at 21 days post-injection. Taken together, our data suggest that EE preserved visual functions and reduced neuroinflammation of the optic nerve. This article is part of the Special Issue entitled "Neurobiology of Environmental Enrichment".

Superior cervical gangliectomy induces non-exudative age-related macular degeneration in mice.

Non-exudative age-related macular degeneration, a prevalent cause of blindness, is a progressive and degenerative disease characterized by alterations in Bruch's membrane, retinal pigment epithelium, and photoreceptors exclusively localized in the macula. Although experimental murine models exist, the vast majority take a long time to develop retinal alterations and, in general, these alterations are ubiquitous, with many resulting from non-eye-specific genetic manipulations; additionally, most do not always reproduce the hallmarks of human age-related macular degeneration. Choroid vessels receive sympathetic innervation from the superior cervical ganglion, which, together with the parasympathetic system, regulates blood flow into the choroid. Choroid blood flow changes have been involved in age-related macular degeneration development and progression. At present, no experimental models take this factor into account. The aim of this work was to analyze the effect of superior cervical gangliectomy (also known as ganglionectomy) on the choroid, Bruch's membrane, retinal pigment epithelium and retina. Adult male C57BL/6J mice underwent unilateral superior cervical gangliectomy and a contralateral sham procedure. Although superior cervical gangliectomy induced ubiquitous choroid and choriocapillaris changes, it induced Bruch's membrane thickening, loss of retinal pigment epithelium melanin content and retinoid isomerohydrolase, the appearance of drusen-like deposits, and retinal pigment epithelium and photoreceptor atrophy, exclusively localized in the temporal side. Moreover, superior cervical gangliectomy provoked a localized increase in retinal pigment epithelium and photoreceptor apoptosis, and a decline in photoreceptor electroretinographic function. Therefore, superior cervical gangliectomy recapitulated the main features of human non-exudative age-related macular degeneration, and could become a new experimental model of dry age-related macular degeneration, and a useful platform for developing new therapies.