Electrical stimulation induced self-related auditory hallucinations correlate with oscillatory power change in the default mode network.

Self-related information is crucial in our daily lives, which has led to the proposal that there is a specific brain mechanism for processing it. Neuroimaging studies have consistently demonstrated that the default mode network (DMN) is strongly associated with the representation and processing of self-related information. However, the precise relationship between DMN activity and self-related information, particularly in terms of neural oscillations, remains largely unknown. We electrically stimulated the superior temporal and fusiform areas, using stereo-electroencephalography to investigate neural oscillations associated with elicited self-related auditory hallucinations. Twenty-two instances of auditory hallucinations were recorded and categorized into self-related and other-related conditions. Comparing oscillatory power changes within the DMN between self-related and other-related auditory hallucinations, we discovered that self-related hallucinations are associated with significantly stronger positive power changes in both alpha and gamma bands compared to other-related hallucinations. To ensure the validity of our findings, we conducted controlled analyses for factors of familiarity and clarity, which revealed that the observed effects within the DMN remain independent of these factors. These results underscore the significance of the functional role of the DMN during the processing of self-related auditory hallucinations and shed light on the relationship between self-related perception and neural oscillatory activity.

Prior Knowledge Uses Prestimulus Alpha Band Oscillations and Persistent Poststimulus Neural Templates for Conscious Perception.

Prior knowledge has a profound impact on the way we perceive the world. However, it remains unclear how the prior knowledge is maintained in our brains and thereby influences the subsequent conscious perception. The Dalmatian dog illusion is a perfect tool to study prior knowledge, where the picture is initially perceived as noise. Once the prior knowledge was introduced, a Dalmatian dog could be consciously seen, and the picture immediately became meaningful. Using pictures with hidden objects as standard stimuli and similar pictures without hidden objects as deviant stimuli, we investigated the neural representation of prior knowledge and its impact on conscious perception in an oddball paradigm using electroencephalogram (EEG) in both male and female human subjects. We found that the neural patterns between the prestimulus alpha band oscillations and poststimulus EEG activity were significantly more similar for the standard stimuli than for the deviant stimuli after prior knowledge was provided. Furthermore, decoding analysis revealed that persistent neural templates were evoked after the introduction of prior knowledge, similar to that evoked in the early stages of visual processing. In conclusion, the current study suggests that prior knowledge uses alpha band oscillations in a multivariate manner in the prestimulus period and induces specific persistent neural templates in the poststimulus period, enabling the conscious perception of the hidden objects.SIGNIFICANCE STATEMENT The visual world we live in is not always optimal. In dark or noisy environments, prior knowledge can help us interpret imperfect sensory signals and enable us to consciously perceive hidden objects. However, we still know very little about how prior knowledge works at the neural level. Using the Dalmatian dog illusion and multivariate methods, we found that prior knowledge uses prestimulus alpha band oscillations to carry information about the hidden object and exerts a persistent influence in the poststimulus period by inducing specific neural templates. Our findings provide a window into the neural underpinnings of prior knowledge and offer new insights into the role of alpha band oscillations and neural templates associated with conscious perception.

Genomic divergence and demographic history of Quercus aliena populations.

BACKGROUND: Quercus aliena is a major montane tree species of subtropical and temperate forests in China, with important ecological and economic value. In order to reveal the species' population dynamics, genetic diversity, genetic structure, and association with mountain habitats during the evolutionary process, we re-sequenced the genomes of 72 Q. aliena individuals. RESULTS: The whole chloroplast and nuclear genomes were used for this study. Phylogenetic analysis using the chloroplast genome dataset supported four clades of Q. aliena, while the nuclear dataset supported three major clades. Sex-biased dispersal had a critical role in causing discordance between the chloroplast and nuclear genomes. Population structure analysis showed two groups in Q. aliena. The effective population size sharply declined 1 Mya, coinciding with the Poyang Glaciation in Eastern China. Using genotype-climate association analyses, we found a positive correlation between allele frequency variation in SNPs and temperature, suggesting the species has the capacity to adapt to changing temperatures. CONCLUSION: Overall, this study illustrates the genetic divergence, genomic variation, and evolutionary processes behind the demographic history of Q. aliena.

Mechanically strained osteocyte-derived exosomes contained miR-3110-5p and miR-3058-3p and promoted osteoblastic differentiation.

BACKGROUND: Osteocytes are critical mechanosensory cells in bone, and mechanically stimulated osteocytes produce exosomes that can induce osteogenesis. MicroRNAs (miRNAs) are important constituents of exosomes, and some miRNAs in osteocytes regulate osteogenic differentiation; previous studies have indicated that some differentially expressed miRNAs in mechanically strained osteocytes likely influence osteoblastic differentiation. Therefore, screening and selection of miRNAs that regulate osteogenic differentiation in exosomes of mechanically stimulated osteocytes are important. RESULTS: A mechanical tensile strain of 2500 µÎµ at 0.5 Hz 1 h per day for 3 days, elevated prostaglandin E2 (PGE2) and insulin-like growth factor-1 (IGF-1) levels and nitric oxide synthase (NOS) activity of MLO-Y4 osteocytes, and promoted osteogenic differentiation of MC3T3-E1 osteoblasts. Fourteen miRNAs differentially expressed only in MLO-Y4 osteocytes which were stimulated with mechanical tensile strain, were screened, and the miRNAs related to osteogenesis were identified. Four differentially expressed miRNAs (miR-1930-3p, miR-3110-5p, miR-3090-3p, and miR-3058-3p) were found only in mechanically strained osteocytes, and the four miRNAs, eight targeted mRNAs which were differentially expressed only in mechanically strained osteoblasts, were also identified. In addition, the mechanically strained osteocyte-derived exosomes promoted the osteoblastic differentiation of MC3T3-E1 cells in vitro, the exosomes were internalized by osteoblasts, and the up-regulated miR-3110-5p and miR-3058-3p in mechanically strained osteocytes, were both increased in the exosomes, which was verified via reverse transcription quantitative polymerase chain reaction (RT-qPCR). CONCLUSIONS: In osteocytes, a mechanical tensile strain of 2500 µÎµ at 0.5 Hz induced the fourteen differentially expressed miRNAs which probably were in exosomes of osteocytes and involved in osteogenesis. The mechanically strained osteocyte-derived exosomes which contained increased miR-3110-5p and miR-3058-3p (two of the 14 miRNAs), promoted osteoblastic differentiation.

Task demands modulate pre-stimulus alpha frequency and sensory template during bistable apparent motion perception.

Despite ambiguous environmental inputs, top-down attention biases our subjective perception toward the preferred percepts, via modulating prestimulus neural activity or inducing prestimulus sensory templates that carry concrete internal sensory representations of the preferred percepts. In contrast to frequent changes of behavioral goals in the typical cue-target paradigm, human beings are often engaged in a prolonged task state with only 1 specific behavioral goal. It remains unclear how prestimulus neural signals and sensory templates are modulated in the latter case. To answer this question in the present electroencephalogram study on human subjects, we manipulated sustained task demands toward one of the 2 possible percepts in the bistable Ternus display, emphasizing either temporal integration or segregation. First, the prestimulus peak alpha frequency, which gated the temporal window of temporal integration, was effectively modulated by task demands. Furthermore, time-resolved decoding analyses showed that task demands biased neural representations toward the preferred percepts after the full presentation of bottom-up stimuli. More importantly, sensory templates resembling the preferred percepts emerged even before the bottom-up sensory evidence were sufficient enough to induce explicit percepts. Taken together, task demands modulate both prestimulus alpha frequency and sensory templates, to eventually bias subjective perception toward the preferred percepts.

Pre-stimulus gamma power in human posteromedial cortex shows supra-modal mechanisms in predicting the amplitude and latency of task-induced suppression.

Upon repetitively performing the same well-practiced task on identical bottom-up stimuli, our performance still varies. Although it has been well documented that elevated pre-stimulus baseline activity in the human default-mode network impairs the subsequent task performance, it remains unknown (i) the fine-grained temporal dynamics and (ii) whether the underlying neural dynamics are supra-modal or modality-specific. We utilized intracranial recordings in the human posteromedial cortex (PMC) during a simple visual and an auditory detection task. Our findings suggested that the pre-stimulus gamma power in PMC predicted the subsequent task performance. Critically, the higher the pre-stimulus gamma power, the longer it took for it to be suppressed, and the less suppressed it was during the task performance, which eventually resulted in deleterious effects on task performance, i.e. longer reaction times. These fine-grained temporal dynamics were consistent between the visual and auditory simple detection task. In addition, a direct comparison between the visual and auditory modality showed that the between-modality difference emerged during the recovery period from the maximal gamma suppression back to the baseline. Taken together, the present results contribute novel spatio-temporal mechanisms in human PMC on how simple detection performance varies across multiple repetitions, irrespective of the sensory modality involved.

Cryopreservation-enhanced differentiation capacity of embryogenic cultures of Castanea mollissima.

A cryopreservation protocol has been developed for embryogenic cultures (ECs) of Castanea mollissima, an important economic species of the Castanea genus in China. We achieved 100 % regrowth when ECs were treated with Plant Vitrification Solution 2 (PVS2) for 30, 60 and 90 min on ice. Optimal PVS2 treatment for cryopreservation was determined to be 30 min on ice based on the highest biomass regrowth after thawing. Fluorescein diacetate (FDA) staining could rapidly and reliably determine post-thaw cell viability and its use facilitated the optimization of the cryopreservation protocols. Although the proliferation rate of the re-established ECs remained largely unchanged compared to non-cryopreserved ECs, the capacity of the re-established ECs to differentiate (on two media) into somatic embryos nearly doubled to approximately 2200-2300 globular somatic embryos per 1 g of re-established ECs. Based on cell cluster size analysis, this enhanced growth is primarily attributed to the presence of significantly greater cell clusters with a diameter of 100-200 µm, which have the highest level of differentiation ability. In order to understand the increased embryogenic potential following cryopreservation, we analyzed the expression of key genes related to somatic embryogenesis. Genes CmWUS and CmABP1 were downregulated while CmLEC1, CmAGL15, CmGRF2, and CmFUS3 were upregulated in re-established ECs when compared to non-cryopreserved ECs.

Detection of fluid motion direction based on the rotational Doppler effect of grafted perfect vortex beam.

Vortex beams have attracted much attention due to their unique rotational Doppler effect. With the in-depth study of vortex beams, many new vortex beams have been proposed gradually, while the detection of fluid motion is of great significance for the study of ocean turbulence. Based on the rotational Doppler effect of the grafted perfect vortex beam, we propose a non-embedded optical method for real-time detection of the magnitude and direction of fluid velocity and establish a two-dimensional fluid model for simulation verification. It is proved that the grafted perfect vortex beam can detect the magnitude and direction of the fluid velocity at the same time, which may provide a new way and theoretical support for the detection of fluid motion direction.

Leveraging GPT-4 for food effect summarization to enhance product-specific guidance development via iterative prompting.

Food effect summarization from New Drug Application (NDA) is an essential component of product-specific guidance (PSG) development and assessment, which provides the basis of recommendations for fasting and fed bioequivalence studies to guide the pharmaceutical industry for developing generic drug products. However, manual summarization of food effect from extensive drug application review documents is time-consuming. Therefore, there is a need to develop automated methods to generate food effect summary. Recent advances in natural language processing (NLP), particularly large language models (LLMs) such as ChatGPT and GPT-4, have demonstrated great potential in improving the effectiveness of automated text summarization, but its ability with regard to the accuracy in summarizing food effect for PSG assessment remains unclear. In this study, we introduce a simple yet effective approach,iterative prompting, which allows one to interact with ChatGPT or GPT-4 more effectively and efficiently through multi-turn interaction. Specifically, we propose a three-turn iterative prompting approach to food effect summarization in which the keyword-focused and length-controlled prompts are respectively provided in consecutive turns to refine the quality of the generated summary. We conduct a series of extensive evaluations, ranging from automated metrics to FDA professionals and even evaluation by GPT-4, on 100 NDA review documents selected over the past five years. We observe that the summary quality is progressively improved throughout the iterative prompting process. Moreover, we find that GPT-4 performs better than ChatGPT, as evaluated by FDA professionals (43% vs. 12%) and GPT-4 (64% vs. 35%). Importantly, all the FDA professionals unanimously rated that 85% of the summaries generated by GPT-4 are factually consistent with the golden reference summary, a finding further supported by GPT-4 rating of 72% consistency. Taken together, these results strongly suggest a great potential for GPT-4 to draft food effect summaries that could be reviewed by FDA professionals, thereby improving the efficiency of the PSG assessment cycle and promoting generic drug product development.

The network pharmacology study and molecular docking to investigate the potential mechanism of Acoritataninowii Rhizoma against Alzheimer's Disease.

Alzheimer's Disease is considered as an insidious neurodegenerative progressive disease but its pathogenesis has not been elucidated. Acoritataninowii Rhizoma exhibits anti-dementia effects as a traditional Chinese medicine (TCM), which is linked to its anti- Alzheimer's Disease mechanism. In this study, network pharmacology and molecular docking were used to examine the potential of Acoritataninowii Rhizoma for Alzheimer's Disease. In order to construct PPI networks and drug-component-target-disease networks, disease-related genes and proteins were gathered from the database. Gene ontology (GO), pathway enrichment (KEGG), and molecular docking were used to forecast the potential mechanism of Acoritataninowii Rhizoma on Alzheimer's disease. Therefore, 4 active ingredients and 81 target genes were screened from Acoritataninowii Rhizoma, 6765 specific target genes were screened from Alzheimer's Disease, and 61 drug-disease cross genes were validated. GO analysis showed that Acoritataninowii Rhizoma can regulate processes such as the protein serine/threonine kinase associated with MAPK. KeGG pathway analysis showed that the signaling pathways affected by Acoritataninowii Rhizoma were fluid shear stress and atherosclerosis, AGE-RAGE and other pathways. Molecular docking implied that the pharmacological influences of the bioactive constituents of Acoritataninowii Rhizoma (Cycloaartenol and kaempferol) on Alzheimer's Disease may related to ESR1 and AKT1, respectively. AKT1 and ESR1 may be the core target genes of the treatment for Alzheimer's disease. Kaempferol and Cycloartenol might be core bioactive constituents for treatment.

Tracking objects outside the line of sight using laser Doppler coherent detection.

Based on the laser Doppler coherent detection method, a laser Doppler Non-Line-of Sight imaging technique (LD-NLOS) is proposed to obtain a series of effective information about the detected objects outside the line of sight. According to the analysis of the frequency and light intensity characteristics of the scattered signal, the information of the detected object hidden in the intermediate scattering surface is decoded. Without relying on complicated back-end algorithm processing and expensive experimental detection cost, the proposed LD-NLOS technique can detect the target vibration velocity and stably reconstruct its 2D shape.

Perceptual inference employs intrinsic alpha frequency to resolve perceptual ambiguity.

The brain uses its intrinsic dynamics to actively predict observed sensory inputs, especially under perceptual ambiguity. However, it remains unclear how this inference process is neurally implemented in biasing perception of ambiguous inputs towards the predicted percepts. The process of perceptual inference can be well illustrated by the phenomenon of bistable apparent motion in the Ternus display, in which subjective perception spontaneously alternates between element motion (EM) and group motion (GM) percepts depending on whether two consecutively presented frames are grouped over time or not. The frequency of alpha-band oscillations has long been hypothesized to gate the temporal window of perceptual grouping over time. Under this hypothesis, variation in the intrinsic alpha frequency should predict perceptual outcome of the bistable Ternus display. Moreover, we hypothesize that the perception system employs this prior knowledge on intrinsic alpha frequency to resolve perceptual ambiguity, by shifting perceptual inference towards the predicted percepts. Using electroencephalography and intracranial recordings, we showed that both between and within subjects, lower prestimulus alpha frequencies (PAFs) predicted the EM percepts since the two frames fell in the same alpha cycle and got temporally integrated, while higher PAFs predicted the GM percepts since the two frames fell in different alpha cycles. Multivariate decoding analysis between the EM percepts with lower PAFs and the GM percepts with higher PAFs further revealed a representation of the subsequently reported bistable percept in the neural signals shortly before the actual appearance of the second frame. Therefore, perceptual inference, based on variation in intrinsic PAFs, biases poststimulus neural representations by inducing preactivation of the predicted percepts. In addition, enhanced prestimulus blood-oxygen-level-dependent (BOLD) signals and network dynamics in the frontoparietal network, together with reduced prestimulus alpha power, upon perceiving the EM percepts suggest that temporal grouping is an attention-demanding process.

Influence of watertight optical window with plain glass on receiving field for underwater wireless optical communication.

Underwater wireless optical communication (UWOC) has attracted much attention recently due to its superiority of high transmission speed. In many UWOC applications, to establish communication links easier, the receiver has quite a wide field. However, the performance of the receiving field is affected by watertight encapsulation in practice, especially when the optical window is produced with plain glass. To study such an influence, in this paper, we first establish a theoretical model based on the Monte Carlo method. Then, we analyze the influence with different structure parameters of watertight encapsulation. The simulation results show that to reduce such an impact, the optical window should be thinner, the detector photosurface and optical window surface should be larger, and the space between the detector and optical window should be smaller. In the ideal situation, the largest workable receiving field is about 96° for UWOC. In other situations, the workable receiving field would be smaller. The simulation method and results presented in this paper are pragmatic and useful to UWOC receiver design.

Experimental demonstration of a transmitter with a 50° divergence angle, 50 Mbps rate, and 476 mW optical power for underwater wireless optical communication based on an engineered diffuser.

In practical application of underwater wireless optical communication (UWOC), the transmitter should have a larger divergence angle to make it easier to establish a communication link, besides high modulated rate and high optical power. Laser diodes (LD) are suitable to design such transmitter, thanks to their simpler structure and much faster switching speed. However, it is difficult to implement for widespread use in ocean engineering because of its quite small divergence angle. For this, we present a simple way to enlarge the divergence angle for an LD transmitter based on an engineered diffuser in this paper. First, we design a blue LD transmitter that has 476 mW output power, 50 Mbps rate, and 50° divergence angle. Then, using such transmitter, we establish a UWOC system in a large experimental tank with 13.3 m communication distance and about 0.26m-1 attenuation coefficient of water. The results show that if the deviation of the transmitting direction is up to ±25∘, the communication system is workable. Emission light from the transmitter could cover a 42.5% solid angle of the hemisphere space. The combination performances of speed, angular coverage, and optical power are suitable for ocean engineering. Also, it implies that a light field could be designed by using a suitable engineered diffuser for UWOC. The method presented in this paper is simple and pragmatic, which is useful to reduce the difficulty in establishing communication links and is easy to popularize.

Influence of a watertight optical window with plain glass on the light distribution of an LED transmitter for underwater wireless optical communications.

Underwater wireless optical communication (UWOC) has attracted much attention recently, thanks to its high transmission speed. In many UWOC applications, the transmitter is based on light emitting diodes (LEDs). This is because it has up to a 120° divergence angle, which is helpful with establishing the communication link more easily. However, the light field of such a transmitter is affected by watertight encapsulation in practice. In this paper, we establish a theoretical model based on the Monte Carlo method to study this influence when the watertight optical window is based on plain glass. The results show that both the divergence angle and transmittance become smaller because of the optical window. In order to reduce this influence, the illumination surface, distance from the light source to the optical window, and thickness of the optical window should be smaller, while the optical window surface should be larger. In the ideal situation, the largest divergence angle is 94.4°, which is defined with full width at half-maximum (FWHM). The maximum transmittance is related to the optical materials of the window, while it is 93.54% for quartz glass. When light is modulated with on-off keying (OOK) format, if the signal-to-noise ratio (SNR) is larger than 40 at 0° radiation angle, the UWOC system could work when the angle is up to ±48.7∘. While the SNR reduces, the workable angle range decreases. The simulation model presented in this paper is convenient to analyze the influence of a watertight optical window with plain glass. The simulation results presented in this paper are useful to the UWOC transmitter design.

The potential mechanism of Bupleurum against anxiety was predicted by network pharmacology study and molecular docking.

Bupleurum chinense DC. (Chaihu) is a traditional Chinese medicine (TCM) used in the treatment of anxiety. But the anxiolytic mechanisms of bupleurum are still unclear. Therefore, this unknown is predicted by network pharmacology study with molecular docking in the present study. The components of bupleurum were obtained from the databases. Genes associated with components and disease were also provided by databases. Overlapping genes between components and disease were analyzed. The network of medicine-components-targets-disease was constructed, visualized, and analyzed. Protein-protein interaction (PPI), gene ontology (GO), pathway enrichment (KEGG) and molecular docking were conducted to predict the potential mechanisms of bupleurum on anxiety. A total of 9 bioactive components derived from bupleurum with 80 target genes were involved in anxiety. Neurotransmitter receptor activity, G protein-coupled amine receptor activity, regulation of blood circulation, neuroactive ligand-receptor interaction, calcium signaling pathway and salivary secretion may play significant roles in the anxiolytic of bupleurum. Molecular docking implicated that ACHE and MAOA showed high affinity for stigmasterol. Based on network pharmacology study with molecular docking, multi-component-multi-target-multi-pathway action mode of bupleurum on anxiety was elaborated. Stigmasterol might be the core bioactive component, while ACHE and MAOA might be the core target genes in the pharmacological profile of bupleurum on anxiety.

Exploring the Potential Antidepressant Mechanisms of Pinellia by Using the Network Pharmacology and Molecular Docking.

About 350 million people worldwide suffered from depression, but less than half of the patients received effective and regular treatments. Traditional Chinese Medicine (TCM) such as pinellia has been proven effective for antidepressant treatment with fewer side effects. However, the exact mechanisms remain unclear. Herein, we use the methods of network pharmacology and molecular docking to analyze the effective monomer components of pinellia and reveal the involved signaling pathways to produce antidepressant effects. TCMSP, BATMAN-TCM, and TCMID databases were utilized to analyze the bioactive ingredients and target genes derived from pinellia via the screening the molecular weight (MW), oral bioavailability (OB), blood-brain barrier (BBB) and drug similarity (DL). OMIM, TTD, DisGeNET, GeneCards and DrugBank databases were used to obtain key genes of depression. Then, the networks of protein-protein interaction (PPI) and "medicine-ingredients-targets-pathways" were built. The target signaling pathways were enriched by GO and KEGG by using R language. Furthermore, bioactive ingredients binding of the targets were verified by molecular docking. Nine active monomer ingredients and 96 pivotal gene targets were selected from pinellia. 10,124 disease genes and 87 drug-disease intersecting genes were verified. GO analysis proposed that the receptor activity of neurotransmitter, postsynaptic neurotransmitter, G protein-coupled neurotransmitter, and acetylcholine through the postsynaptic membrane could be modulated by pinellia. KEGG pathway analysis revealed that pinellia influenced depression-related neural tissue interaction, cholinergic synapse, serotonin activated synapse and calcium signaling pathway. Besides, the reliability and accuracy of results obtained from the indirect network pharmacology were validated by molecular docking. The bioactive components of pinellia made significant antidepressant effects by regulating the key target genes/proteins in the pathophysiology of depression.

Molecular cloning, characterization and expression analysis of CXCR3a and CXCR3b from Nile tilapia (Oreochromis niloticus).

The CXC chemokine receptors (CXCRs) are members of the seven transmembrane (7-TM) G-protein-coupled receptor superfamily that involves innate and adaptive immune systems. In this study, CXCR3a and CXCR3b from Nile tilapia (Oreochromis niloticus) were cloned and identified, designated as OnCXCR3a and OnCXCR3b. The open reading frames of OnCXCR3a and OnCXCR3b were 1074 and 1080 bp, encoding the predicted proteins of 357 and 359 amino acids, respectively. Multiple alignment analysis of OnCXCR3a- and OnCXCR3b-deduced protein sequences with the mammalian and bird sequences indicated the presence of typical structural features of chemokine receptors, including a 7-TM domain and conserved motifs. Quantitative real-time PCR analysis revealed that OnCXCR3a and OnCXCR3b were constitutively expressed in a wide range of tissues. When stimulated with Streptococcus agalactiae, Aeromonas hydrophila, polyinosinic:polycytidylic acid and lipopolysaccharide in vivo or in vitro on leukocytes, the mRNA levels of OnCXCR3a and OnCXCR3b were significantly upregulated. Overall, these results indicated that OnCXCR3s might be involved in host immune responses in Nile tilapia.

Apparent Motion Induces Activity Suppression in Early Visual Cortex and Impairs Visual Detection.

Apparent motion (AM) is induced when two stationary visual stimuli are presented in alternating sequence. Intriguingly, AM leads to an impaired detectability of stimuli along the AM path (i.e., AM-induced masking). It has been hypothesized that AM triggers an internal representation of a moving object in early visual cortex, which competes with stimulus-evoked representations of visual stimuli on the motion path in early visual cortex of 25 human adults (16 female). We tested this hypothesis by measuring BOLD responses in early visual cortex during the process of AM-induced masking, using fMRI and population receptive field methods. Surprisingly, and counter to our hypothesis, we showed that AM suppressed, rather than increased, BOLD responses along early visual (V1 and V2) representations of the AM path, including regions that were not directly activated by the AM inducer stimuli. This activity suppression of the visual response predicted the subsequent reduction in detectability of the target that appeared in the middle of the AM path. Our data thereby provide direct empirical evidence for suppressive neural mechanisms underlying AM and suggest that illusory motion can render us blind to objects on the motion path by suppressing neural activity at the earliest cortical stages of visual perception.SIGNIFICANCE STATEMENT When two spatially distinct visual objects are presented in alternating sequence, apparent motion (AM) occurs and impairs detectability of stimuli along its path. The underlying mechanism is thought to be that increased activation in human early visual cortex evoked by AM interferes with the representation of the stimulus. Strikingly, however, we show that AM suppresses neural activity along the motion path, and the strength of activity suppression predicts the subsequent behavioral performance decrement in terms of detecting a stimulus along the AM path. Our findings provide empirical evidence for a suppressive, rather than faciliatory, mechanism underlying AM.

Gaseous environment modulates volatile emission and viability loss during seed artificial ageing.

MAIN CONCLUSION: Modulation of the gaseous environment using oxygen absorbers and/or silica gel shows potential for enhancing seed longevity through trapping toxic volatiles emitted by seeds during artificial ageing. Volatile profiling using non-invasive gas chromatography-mass spectrometry provides insight into the specific processes occurring during seed ageing. Production of alcohols, aldehydes and ketones, derived from processes such as alcoholic fermentation, lipid peroxidation and Maillard reactions, are known to be dependent on storage temperature and relative humidity, but little is known about the potential modulating role of the gaseous environment, which also affects seed lifespan, on volatile production. Seeds of Lolium perenne (Poaceae), Agrostemma githago (Caryophyllaceae) and Pisum sativum (Fabaceae) were aged under normal atmospheric oxygen conditions and in sealed vials containing either oxygen absorbers, oxygen absorbers and silica gel (equilibrated at 60% RH), or silica gel alone. Seeds of A. githago that were aged in the absence of oxygen maintained higher viability and produced fewer volatiles than seeds aged in air. In addition, seeds of A. githago and L. perenne aged in the presence of silica gel were longer lived than those aged without silica, with no effect on seed moisture content or oxygen concentration in the storage containers, but with silica gel acting as a volatile trap. These results indicate that the use of inexpensive oxygen absorbers and silica gel could improve seed longevity in storage for some species and suggests a potential, and previously unidentified, role for silica gel in ultra-dry storage.