Lennart Mucke
Jun 1, 2000; 20:4050-4058
Cellular

Cristopher M. Niell
Jul 23, 2008; 28:7520-7536
BehavioralSystemsCognitive

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Far-right groups and individuals in the United States are exploiting the COVID-19 pandemic to promote disinformation, hate, extremism and authoritarianism. "COVID-19 has been seized by far-right groups as an opportunity to call for extreme violence," states a report from ISD, based on a combination of natural language processing, network analysis and ethnographic online research.

A prominent theory claims that the right temporoparietal junction (rTPJ) is especially associated with embodied processes relevant to perspective-taking. In the present study, we use high-definition transcranial direct current stimulation to provide evidence that the rTPJ is causally associated with the embodied processes underpinning perspective-taking. Eighty-eight young human adults were stratified to receive either rTPJ or dorsomedial PFC anodal high-definition transcranial direct current stimulation in a sham-controlled, double-blind, repeated-measures design. Perspective-tracking (line-of-sight) and perspective-taking (embodied rotation) were assessed using a visuo-spatial perspective-taking task that required understanding what another person could see or how they see it, respectively. Embodied processing was manipulated by positioning the participant in a manner congruent or incongruent with the orientation of an avatar on the screen. As perspective-taking, but not perspective-tracking, is influenced by bodily position, this allows the investigation of the specific causal role for the rTPJ in embodied processing. Crucially, anodal stimulation to the rTPJ increased the effect of bodily position during perspective-taking, whereas no such effects were identified during perspective-tracking, thereby providing evidence for a causal role for the rTPJ in the embodied component of perspective-taking. Stimulation to the dorsomedial PFC had no effect on perspective-tracking or taking. Therefore, the present study provides support for theories postulating that the rTPJ is causally involved in embodied cognitive processing relevant to social functioning.

SIGNIFICANCE STATEMENT The ability to understand another's perspective is a fundamental component of social functioning. Adopting another perspective is thought to involve both embodied and nonembodied processes. The present study used high-definition transcranial direct current stimulation (HD-tDCS) and provided causal evidence that the right temporoparietal junction is involved specifically in the embodied component of perspective-taking. Specifically, HD-tDCS to the right temporoparietal junction, but not another hub of the social brain (dorsomedial PFC), increased the effect of body position during perspective-taking, but not tracking. This is the first causal evidence that HD-tDCS can modulate social embodied processing in a site-specific and task-specific manner.

Human ventral temporal cortex (VTC) is critical for visual recognition. It is thought that this ability is supported by large-scale patterns of activity across VTC that contain information about visual categories. However, it is unknown how category representations in VTC are organized at the submillimeter scale and across cortical depths. To fill this gap in knowledge, we measured BOLD responses in medial and lateral VTC to images spanning 10 categories from five domains (written characters, bodies, faces, places, and objects) at an ultra-high spatial resolution of 0.8 mm using 7 Tesla fMRI in both male and female participants. Representations in lateral VTC were organized most strongly at the general level of domains (e.g., places), whereas medial VTC was also organized at the level of specific categories (e.g., corridors and houses within the domain of places). In both lateral and medial VTC, domain-level and category-level structure decreased with cortical depth, and downsampling our data to standard resolution (2.4 mm) did not reverse differences in representations between lateral and medial VTC. The functional diversity of representations across VTC partitions may allow downstream regions to read out information in a flexible manner according to task demands. These results bridge an important gap between electrophysiological recordings in single neurons at the micron scale in nonhuman primates and standard-resolution fMRI in humans by elucidating distributed responses at the submillimeter scale with ultra-high-resolution fMRI in humans.

SIGNIFICANCE STATEMENT Visual recognition is a fundamental ability supported by human ventral temporal cortex (VTC). However, the nature of fine-scale, submillimeter distributed representations in VTC is unknown. Using ultra-high-resolution fMRI of human VTC, we found differential distributed visual representations across lateral and medial VTC. Domain representations (e.g., faces, bodies, places, characters) were most salient in lateral VTC, whereas category representations (e.g., corridors/houses within the domain of places) were equally salient in medial VTC. These results bridge an important gap between electrophysiological recordings in single neurons at a micron scale and fMRI measurements at a millimeter scale.

The detection and segmentation of meaningful figures from their background is one of the primary functions of vision. While work in nonhuman primates has implicated early visual mechanisms in this figure–ground modulation, neuroimaging in humans has instead largely ascribed the processing of figures and objects to higher stages of the visual hierarchy. Here, we used high-field fMRI at 7 Tesla to measure BOLD responses to task-irrelevant orientation-defined figures in human early visual cortex (N = 6, four females). We used a novel population receptive field mapping-based approach to resolve the spatial profiles of two constituent mechanisms of figure–ground modulation: a local boundary response, and a further enhancement spanning the full extent of the figure region that is driven by global differences in features. Reconstructing the distinct spatial profiles of these effects reveals that figure enhancement modulates responses in human early visual cortex in a manner consistent with a mechanism of automatic, contextually driven feedback from higher visual areas.

SIGNIFICANCE STATEMENT A core function of the visual system is to parse complex 2D input into meaningful figures. We do so constantly and seamlessly, both by processing information about visible edges and by analyzing large-scale differences between figure and background. While influential neurophysiology work has characterized an intriguing mechanism that enhances V1 responses to perceptual figures, we have a poor understanding of how the early visual system contributes to figure–ground processing in humans. Here, we use advanced computational analysis methods and high-field human fMRI data to resolve the distinct spatial profiles of local edge and global figure enhancement in the early visual system (V1 and LGN); the latter is distinct and consistent with a mechanism of automatic, stimulus-driven feedback from higher-level visual areas.

Nitric oxide (NO) is an important signaling molecule that fulfills diverse functional roles as a neurotransmitter or diffusible second messenger in the developing and adult CNS. Although the impact of NO on different behaviors such as movement, sleep, learning, and memory has been well documented, the identity of its molecular and cellular targets is still an area of ongoing investigation. Here, we identify a novel role for NO in strengthening inhibitory GABA_A receptor-mediated transmission in molecular layer interneurons of the mouse cerebellum. NO levels are elevated by the activity of neuronal NO synthase (nNOS) following Ca²⁺ entry through extrasynaptic NMDA-type ionotropic glutamate receptors (NMDARs). NO activates protein kinase G with the subsequent production of cGMP, which prompts the stimulation of NADPH oxidase and protein kinase C (PKC). The activation of PKC promotes the selective strengthening of α3-containing GABA_ARs synapses through a GABA receptor-associated protein-dependent mechanism. Given the widespread but cell type-specific expression of the NMDAR/nNOS complex in the mammalian brain, our data suggest that NMDARs may uniquely strengthen inhibitory GABAergic transmission in these cells through a novel NO-mediated pathway.

SIGNIFICANCE STATEMENT Long-term changes in the efficacy of GABAergic transmission is mediated by multiple presynaptic and postsynaptic mechanisms. A prominent pathway involves crosstalk between excitatory and inhibitory synapses whereby Ca²⁺-entering through postsynaptic NMDARs promotes the recruitment and strengthening of GABA_A receptor synapses via Ca²⁺/calmodulin-dependent protein kinase II. Although Ca²⁺ transport by NMDARs is also tightly coupled to nNOS activity and NO production, it has yet to be determined whether this pathway affects inhibitory synapses. Here, we show that activation of NMDARs trigger a NO-dependent pathway that strengthens inhibitory GABAergic synapses of cerebellar molecular layer interneurons. Given the widespread expression of NMDARs and nNOS in the mammalian brain, we speculate that NO control of GABAergic synapse efficacy may be more widespread than has been appreciated.

Neonatal stroke is as frequent as stroke in the elderly, but many pathophysiological injury aspects are distinct in neonates, including immune signaling. While myeloid cells can traffic into the brain via multiple routes, the choroid plexus (CP) has been identified as a uniquely educated gate for immune cell traffic during health and disease. To understand the mechanisms of myeloid cell trafficking via the CP and their influence on neonatal stroke, we characterized the phenotypes of CP-infiltrating myeloid cells after transient middle cerebral artery occlusion (tMCAO) in neonatal mice of both sexes in relation to blood-brain barrier permeability, injury, microglial activation, and CX3CR1-CCR2 signaling, focusing on the dynamics early after reperfusion. We demonstrate rapid recruitment of multiple myeloid phenotypes in the CP ipsilateral to the injury, including inflammatory CD45⁺CD11b⁺Ly6c^highCD86⁺, beneficial CD45⁺CD11b⁺Ly6c^lowCD206⁺, and CD45⁺CD11b⁺Ly6c^lowLy6g^high cells, but only minor leukocyte infiltration into acutely ischemic-reperfused cortex and negligible vascular albumin leakage. We report that CX3CR1-CCR2-mediated myeloid cell recruitment contributes to stroke injury. Considering the complexity of inflammatory cascades triggered by stroke and a role for TLR2 in injury, we also used direct TLR2 stimulation as an independent injury model. TLR2 agonist rapidly recruited myeloid cells to the CP, increased leukocytosis in the CSF and blood, but infiltration into the cortex remained low over time. While the magnitude and the phenotypes of myeloid cells diverged between tMCAO and TLR2 stimulation, in both models, disruption of CX3CR1-CCR2 signaling attenuated both monocyte and neutrophil trafficking to the CP and cortex.

SIGNIFICANCE STATEMENT Stroke during the neonatal period leads to long-term disabilities. The mechanisms of ischemic injury and inflammatory response differ greatly between the immature and adult brain. We examined leukocyte trafficking via the choroid plexus (CP) following neonatal stroke in relation to blood-brain barrier integrity, injury, microglial activation, and signaling via CX3CR1 and CCR2 receptors, or following direct TLR2 stimulation. Ischemia-reperfusion triggered marked unilateral CX3CR1-CCR2 dependent accumulation of diverse leukocyte subpopulations in the CP without inducing extravascular albumin leakage or major leukocyte infiltration into the brain. Disrupted CX3CR1-CCR2 signaling was neuroprotective in part by attenuating monocyte and neutrophil trafficking. Understanding the migratory patterns of CP-infiltrating myeloid cells with intact and disrupted CX3CR1-CCR2 signaling could identify novel therapeutic targets to protect the neonatal brain.

All over the world local varieties of fruit, vegetables and grain are grown. Many are seemingly forgotten or are underutilized despite having outstanding nutritional or taste qualities. Some have good commercial potential and could be an excellent cash crop for a smallscale or family farmers, aimed at the local, regional or international market. Here are six traditional crops and six facts [...]

Whether we categorize uneaten food as “lost” or “wasted” depends on where it goes out of the food supply chain. Imagine how everything we eat travels across a food supply chain, a complex journey that stretches from farm to table. Studies show that an astounding 1/3 of all the food we produce for human consumption never actually reaches our plates. Most [...]

What happens when money is given directly to people living in dire conditions? Will children be better nourished? Will families be more productive or will they become dependent? Will economies grow stronger? Today, some 70 percent of the world population, most of which live in rural areas, have no access to adequate social protection measures. For this reason, FAO has [...]

Bees pollinate a third of what we eat and play a vital role in sustaining the planet’s ecosystems. Some 84% of the crops grown for human consumption need bees or other insects to pollinate them to increase their yields and quality. Bee pollination not only results in a higher number of fruits, berries or seeds, it may also give a [...]

Pulses are being celebrated in 2016 all over the world since they are nutritious, suited for use in a variety of dishes, easy on the budget  and good for the health of the soil. From food security and nutrition to ensuring biodiversity and mitigating the effects of climate change, pulses contribute to sustainable development. Here is how.  1.     Nutritional benefits of pulses   Pulses [...]

Illegal, Unreported and Unregulated fishing, also known as IUU, robs the world’s oceans of 26 million tonnes of seafood annually, bringing financial losses to a staggering US$ 23 billion a year. Illegal fishing severely affects the livelihoods of fishers and other fisher-sector stakeholders and exacerbates poverty and food insecurity. It undermines the accuracy of fisheries’ stock assessments and threatens the [...]

The digital revolution has changed the way we work, access information and connect with each other. It offers opportunities to those who can use the new technologies, but also presents new challenges for those who are left behind. Often referred to collectively as Information and Communications Technologies or ICTs, these technologies are any method of electronically sharing or storing data: telephones, [...]

With the health of our oceans at stake, illegal, unreported and unregulated (IUU) fishing has quickly become a monumental problem. The term “IUU fishing” is used for any fishing activities that operate outside of the law. There are many types of IUU fishing, for example, fishing without license or authorization, not accurately reporting the fish caught, fishing in prohibited areas [...]

Many of us look back on our childhoods with warm feelings. But for more than 150 million girls and boys between the ages of 5 and 17 around the world, childhood means something else: poverty, a lack of education and working long hours in dangerous conditions.  

Growing crops, fishing, harvesting fruits and nuts from the forests are just some examples of the activities that millions of people do daily to get food to eat or to earn a living. But when their rights to that land or those natural resources aren’t recognized, livelihoods and food sources can disappear from one day to the next.    

A review of FAO’s fight against hunger and malnutrition and challenges ahead with the participation of José Graziano da Silva, Director-General of FAO. 

Where: Sheikh Zayed Centre at FAO headquarters 

When: Friday, 26th [...]

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