NK and T Cell Immunological Signatures in Hospitalized Patients with COVID-19

Severe acute respiratory syndrome caused by coronavirus 2 emerged in Wuhan (China) in December 2019 and has severely challenged the human population. NK and T cells are involved in the progression of COVID-19 infection through the ability of NK cells to modulate T-cell responses, and by the stimulation of cytokine release. No detailed investigation of the NK cell landscape in clinical SARS-CoV-2 infection has yet been reported. A total of 35 COVID-19 hospitalised patients were stratified for clinical severity and 17 healthy subjects were enrolled. NK cell subsets and T cell subsets were analysed with flow cytometry. Serum cytokines were detected with a bead-based multiplex assay. Fewer CD56dimCD16brightNKG2A+NK cells and a parallel increase in the CD56+CD69+NK, CD56+PD-1+NK, CD56+NKp44+NK subset were reported in COVID-19 than HC. A significantly higher adaptive/memory-like NK cell frequency in patients with severe disease than in those with mild and moderate phenotypes were reported. Moreover, adaptive/memory-like NK cell frequencies were significantly higher in patients who died than in survivors. Severe COVID-19 patients showed higher serum concentrations of IL-6 than mild and control groups. Direct correlation emerged for IL-6 and adaptive/memory-like NK. All these findings provide new insights into the immune response of patients with COVID-19. In particular, they demonstrate activation of NK through overexpression of CD69 and CD25 and show that PD-1 inhibitory signalling maintains an exhausted phenotype in NK cells. These results suggest that adaptive/memory-like NK cells could be the basis of promising targeted therapy for future viral infections.

Memory for medicinal plants remains in ancient and modern environments suggesting an evolved adaptedness

Adaptive memory is the propensity of human memory to easily store and retrieve important information to deal with challenges related to the Pleistocene. Recent evidence shows that humans have had a multiregional evolution across the African continent, including the rainforests and deciduous forests; however, there is little evidence regarding the implications of these origins and the relevant and recurring challenges of these environments on survival processing advantage in memory. In this study, we conducted an experiment with volunteers to analyze whether adaptive memory operates in the retrieval of important information to solve challenges of using medicinal plants to treat diseases in the ancestral environments of the savanna, rainforests, and deciduous forests compared to the modern environments of desert, tundra, coniferous forest, and urban areas. We used simulated survival environments and asked volunteers (30 per simulated scenario) to imagine themselves sick in one of these environments, and needing to find medicinal plants to treat their disease. The volunteers rated the relevance of 32 words to solve this challenge, followed by a surprise memory test. Our results showed no ancestral priority in recalling relevant information, as both ancestral and modern environments showed a similar recall of relevant information. This suggests that the evolved cognitive apparatus allows human beings to survive and can create survival strategies to face challenges imposed in various environments. We believe that this is only possible if the human mind operates through a flexible cognitive mechanism. This flexibility can reflect, for example, the different environments that the first hominids inhabited and the different dangerous situations that they faced.

An adaptive memory method for accurate and efficient computation of the Caputo fractional derivative

A fractional derivative is a temporally nonlocal operation which is computationally intensive due to inclusion of the accumulated contribution of function values at past times. In order to lessen the computational load while maintaining the accuracy of the fractional derivative, a novel numerical method for the Caputo fractional derivative is proposed. The present adaptive memory method significantly reduces the requirement for computational memory for storing function values at past time points and also significantly improves the accuracy by calculating convolution weights to function values at past time points which can be non-uniformly distributed in time. The superior accuracy of the present method to the accuracy of the previously reported methods is identified by deriving numerical errors analytically. The sub-diffusion process of a time-fractional diffusion equation is simulated to demonstrate the accuracy as well as the computational efficiency of the present method.

Developmental change in prefrontal cortex recruitment supports the emergence of value-guided memory

Prioritizing memory for valuable information can promote adaptive behavior across the lifespan, but it is unclear how the neurocognitive mechanisms that enable the selective acquisition of useful knowledge develop. Here, using a novel task coupled with functional magnetic resonance imaging, we examined how children, adolescents, and adults (N = 90) learn from experience what information is likely to be rewarding, and modulate encoding and retrieval processes accordingly. We found that the ability to use learned value signals to selectively enhance memory for useful information strengthened throughout childhood and into adolescence. Encoding and retrieval of high- vs. low-value information was associated with increased activation in striatal and prefrontal regions implicated in value processing and cognitive control. Age-related increases in value-based lateral prefrontal cortex modulation mediated the relation between age and memory selectivity. Our findings demonstrate that developmental increases in the strategic engagement of the prefrontal cortex support the emergence of adaptive memory.

Reliving emotional memories: Episodic recollection elicits affective psychophysiological responses

Episodic recollection allows people to vividly re-experience past events. The remembered information can then inform and guide behavior in the present, especially in the case of emotional events. One way to fulfill this adaptive memory function might be through psychophysiological responses that signal desirable and undesirable outcomes and thereby motivate behavior. However, it remains unknown whether the recollection of past emotional experiences can indeed re-elicit corresponding affective psychophysiological responses. We addressed this question in two experiments (N1 = 48, N2 = 41). Young adults watched positive, negative, and neutral movie clips. One day later, they were instructed to remember these episodes. To index the psychophysiological expression of positive and negative affect, we measured smiling (zygomaticus major) and frowning (corrugator supercilii) responses, respectively. Results revealed that participants smiled more when remembering positive compared to neutral and negative memories. Moreover, they frowned more when remembering negative compared to positive but not neutral memories. Interestingly, the intensity of smiling or frowning during remembering was not related to the intensity during the original experience. Our results suggest that affective psychophysiological responses might play a crucial role in the adaptive function of episodic memories. Therefore, future studies on emotional episodic memory could benefit from incorporating psychophysiological indices.

Basic And Evolutionary Survival Effects In Adaptive Memory Of Younger And Older Adults

Adaptive memory is a memory advantage for stimuli encoded in a survival scenario (e.g., stranded in grasslands) relative to a control scenario (Nairne, Thompson & Pandeirada, 2007). Basic (survival vs. non-survival scenarios) and evolutionary survival effects (high-evolutionary survival vs. low-evolutionary survival scenarios) in adaptive memory were explored in two age groups. Little research has been done with older adults. An extensive pilot study was conducted to select best matched control scenarios. Experiment 1 explored age differences in adaptive memory with a within-subjects manipulation of scenarios and found an age-equivalent basic survival effect. Experiment 2 replicated the basic survival effect in younger adults with a between-subjects design. Considering the age-related preference for processing positive information in older adults, Experiment 3 examined the survival effect with a positive control scenario. Similar results to the previous experiments were found. Overall, the data demonstrated a robust but age equivalent basic survival effect.

Basic And Evolutionary Survival Effects In Adaptive Memory Of Younger And Older Adults

Adaptive memory is a memory advantage for stimuli encoded in a survival scenario (e.g., stranded in grasslands) relative to a control scenario (Nairne, Thompson & Pandeirada, 2007). Basic (survival vs. non-survival scenarios) and evolutionary survival effects (high-evolutionary survival vs. low-evolutionary survival scenarios) in adaptive memory were explored in two age groups. Little research has been done with older adults. An extensive pilot study was conducted to select best matched control scenarios. Experiment 1 explored age differences in adaptive memory with a within-subjects manipulation of scenarios and found an age-equivalent basic survival effect. Experiment 2 replicated the basic survival effect in younger adults with a between-subjects design. Considering the age-related preference for processing positive information in older adults, Experiment 3 examined the survival effect with a positive control scenario. Similar results to the previous experiments were found. Overall, the data demonstrated a robust but age equivalent basic survival effect.