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1. Influences of both prior knowledge and recent history on visual working memory

   https://doi.org/10.31234/osf.io/ktrsj  

   DeStefano, Isabella; Vul, Edward; Brady, Timothy F. (January 2020, Proceedings of the Annual Conference of the Cognitive Science Society)

   null (Ed.)

   Existing knowledge shapes and distorts our memories, serving as a prior for newly encoded information. Here, we investigate the role of stable long-term priors (e.g. categorical knowledge) in conjunction with priors arising from recently encountered information (e.g. ’serial dependence’) in visual working memory for color. We use an iterated reproduction paradigm to allow a model-free assessment of the role of such priors. In Experiment 1, we find that participants’ reports reliably converge to certain areas of color space, but that this convergence is largely distinct for different individuals, suggesting responses are biased by more than just shared category knowledge. In Experiment 2, we explicitly manipulate trial n-1 and find recent history plays a major role in participants’ reports. Thus, we find that both global prior knowledge and recent trial information have biasing influences on visual working memory, demonstrating an important role for both shortand long-term priors in actively maintained information. 

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2. Long-term climate establishes functional legacies by altering microbial traits

   https://doi.org/10.1093/ismejo/wraf005  

   Broderick, Caitlin M; Benucci, Gian_Maria Niccolò; Bachega, Luciana Ruggiero; Miller, Gabriel D; Evans, Sarah E; Hawkes, Christine V (January 2025, The ISME Journal)

   Abstract Long-term climate history can influence rates of soil carbon cycling but the microbial traits underlying these legacy effects are not well understood. Legacies may result if historical climate differences alter the traits of soil microbial communities, particularly those associated with carbon cycling and stress tolerance. However, it is also possible that contemporary conditions can overcome the influence of historical climate, particularly under extreme conditions. Using shotgun metagenomics, we assessed the composition of soil microbial functional genes across a mean annual precipitation gradient that previously showed evidence of strong climate legacies in soil carbon flux and extracellular enzyme activity. Sampling coincided with recovery from a regional, multi-year severe drought, allowing us to document how the strength of climate legacies varied with contemporary conditions. We found increased investment in genes associated with resource cycling with historically higher precipitation across the gradient, particularly in traits related to resource transport and complex carbon degradation. This legacy effect was strongest in seasons with the lowest soil moisture, suggesting that contemporary conditions—particularly, resource stress under water limitation—influences the strength of legacy effects. In contrast, investment in stress tolerance did not vary with historical precipitation, likely due to frequent periodic drought throughout the gradient. Differences in the relative abundance of functional genes explained over half of variation in microbial functional capacity—potential enzyme activity—more so than historical precipitation or current moisture conditions. Together, these results suggest that long-term climate can alter the functional potential of soil microbial communities, leading to legacies in carbon cycling. 

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3. Neural oscillations promoting perceptual stability and perceptual memory during bistable perception

   https://doi.org/10.1038/s41598-022-06570-4  

   Zhu, Michael; Hardstone, Richard; He, Biyu J. (February 2022, Scientific Reports)

   Abstract Ambiguous images elicit bistable perception, wherein periods of momentary perceptual stability are interrupted by sudden perceptual switches. When intermittently presented, ambiguous images trigger a perceptual memory trace in the intervening blank periods. Understanding the neural bases of perceptual stability and perceptual memory during bistable perception may hold clues for explaining the apparent stability of visual experience in the natural world, where ambiguous and fleeting images are prevalent. Motivated by recent work showing the involvement of the right inferior frontal gyrus (rIFG) in bistable perception, we conducted a transcranial direct-current stimulation (tDCS) study with a double-blind, within-subject cross-over design to test a potential causal role of rIFG in these processes. Subjects viewed ambiguous images presented continuously or intermittently while under EEG recording. We did not find any significant tDCS effect on perceptual behavior. However, the fluctuations of oscillatory power in the alpha and beta bands predicted perceptual stability, with higher power corresponding to longer percept durations. In addition, higher alpha and beta power predicted enhanced perceptual memory during intermittent viewing. These results reveal a unified neurophysiological mechanism sustaining perceptual stability and perceptual memory when the visual system is faced with ambiguous input. 

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4. Skill Preferences: Learning to Extract and Execute Robotic Skills from Human Feedback

   Wang, Xiaofei; Lee, Kimin; Hakhamaneshi, Kourosh; Abbeel, Pieter: Laskin (November 2021, Conference on Robot Learning)

   null (Ed.)

   A promising approach to solving challenging long-horizon tasks has been to extract behavior priors (skills) by fitting generative models to large offline datasets of demonstrations. However, such generative models inherit the biases of the underlying data and result in poor and unusable skills when trained on imperfect demonstration data. To better align skill extraction with human intent we present Skill Preferences (SkiP), an algorithm that learns a model over human preferences and uses it to extract human-aligned skills from offline data. After extracting human-preferred skills, SkiP also utilizes human feedback to solve downstream tasks with RL. We show that SkiP enables a simulated kitchen robot to solve complex multi-step manipulation tasks and substantially outperforms prior leading RL algorithms with human preferences as well as leading skill extraction algorithms without human preferences. 

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5. Decoding contextual influences on auditory perception from primary auditory cortex

   https://doi.org/10.7554/eLife.94296.3  

   Englitz, Bernhard; Akram, Sahar; Elhilali, Mounya; Shamma, Shihab (December 2024, eLife)

   Perception can be highly dependent on stimulus context, but whether and how sensory areas encode the context remains uncertain. We used an ambiguous auditory stimulus – a tritone pair – to investigate the neural activity associated with a preceding contextual stimulus that strongly influenced the tritone pair’s perception: either as an ascending or a descending step in pitch. We recorded single-unit responses from a population of auditory cortical cells in awake ferrets listening to the tritone pairs preceded by the contextual stimulus. We find that the responses adapt locally to the contextual stimulus, consistent with human MEG recordings from the auditory cortex under the same conditions. Decoding the population responses demonstrates that cells responding to pitch-changes are able to predict well the context-sensitive percept of the tritone pairs. Conversely, decoding the individual pitch representations and taking their distance in the circular Shepard tone space predicts theoppositeof the percept. The various percepts can be readily captured and explained by a neural model of cortical activity based on populations of adapting, pitch and pitch-direction cells, aligned with the neurophysiological responses. Together, these decoding and model results suggest that contextual influences on perception may well be already encoded at the level of the primary sensory cortices, reflecting basic neural response properties commonly found in these areas. 

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