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Astronauts on interplanetary missions - such as to Mars - will be exposed to space radiation, a spectrum of highly-charged, fast-moving particles that includes 56 Fe and 28 Si. Earth-based preclinical studies show space radiation decreases rodent performance in low- and some high-level cognitive tasks. Given astronaut use of touchscreen platforms during training and space flight and given the ability of rodent touchscreen tasks to assess functional integrity of brain circuits and multiple cognitive domains in a non-aversive way, here we exposed 6-month-old C57BL/6J male mice to whole-body space radiation and subsequently assessed them on a touchscreen battery. Relative to Sham treatment, 56 Fe irradiation did not overtly change performance on tasks of visual discrimination, reversal learning, rule-based, or object-spatial paired associates learning, suggesting preserved functional integrity of supporting brain circuits. Surprisingly, 56 Fe irradiation improved performance on a dentate gyrus-reliant pattern separation task; irradiated mice learned faster and were more accurate than controls. Improved pattern separation performance did not appear to be touchscreen-, radiation particle-, or neurogenesis-dependent, as 56 Fe and 28 Si irradiation led to faster context discrimination in a non-touchscreen task and 56 Fe decreased new dentate gyrus neurons relative to Sham. These data urge revisitation of the broadly-held view that space radiation is detrimental to cognition.

The space radiation environment contains protons and (56)Fe, which could pose a significant hazard to space flight crews during and after missions. The space environment involves complex radiation exposures, thus, the effects of a dose of protons might be modulated by a dose of heavy-ion radiation. The brain, and particularly the hippocampus, may be susceptible to space radiation-induced changes. In this study, we first determined the dose-response effect of proton radiation (150 MeV) on hippocampus-dependent cognition 1 and 3 months after exposure. Based on those results, we subsequently exposed mice to protons alone (150 MeV, 0.1 Gy), (56)Fe alone (600 MeV/n, 0.5 Gy) or combined proton and (56)Fe radiations (protons first) with the two exposures separated by 24 h. At one month postirradiation, all animal groups showed novel object recognition. However, at three months postirradiation, mice exposed to either protons or combined proton and (56)Fe radiations showed impaired novel object recognition, which was not observed in mice irradiated with (56)Fe alone. The mechanisms in these impairments might involve inflammation. In mice irradiated with protons alone or (56)Fe alone three months earlier, there was a negative correlation between a measure of novel object recognition and the number of newly born activated microglia in the dentate gyrus. Next, cytokine and chemokine levels were assessed in the hippocampus. At one month after exposure the levels of IL-12 were higher in mice exposed to combined radiations compared with sham-irradiated mice, while the levels of IFN-γ were lower in mice exposed to (56)Fe radiation alone or combined radiations. In addition, IL-4 levels were lower in (56)Fe-irradiated mice compared with proton-irradiated mice and TNF-α levels were lower in proton-irradiated mice than in mice receiving combined radiations. At three months after exposure, macrophage-derived chemokine (MDC) and eotaxin levels were lower in mice receiving combined radiations. The levels of MDC and eotaxin correlated and the levels of MDC, but not eotaxin, correlated with the percentage of newly born activated microglia in the blades of the dentate gyrus. Finally, hippocampal IL-6 levels were higher in mice receiving combined radiations compared with mice receiving (56)Fe radiation alone. These data demonstrate the sensitivity of novel object recognition for detecting cognitive injury three months after exposure to proton radiation alone, and combined exposure to proton and (56)Fe radiations, and that newly-born activated microglia and inflammation might be involved in this injury.

Word-production theories argue that during language production, a concept activates multiple lexical candidates in left temporal cortex, and the intended word is selected from this set. Evidence for theories on spoken-word production comes, for example, from the picture-word interference task, where participants name pictures superimposed by congruent (e.g., picture: rabbit, distractor “rabbit”), categorically related (e.g., distractor “sheep”), or unrelated (e.g., distractor “fork”) words. Typically, whereas congruent distractors facilitate naming, related distractors slow down picture naming relative to unrelated distractors, resulting in semantic interference. However, the neural correlates of semantic interference are debated. Previous neuroimaging studies have shown that the left mid-to-posterior STG (pSTG) is involved in the interference associated with semantically related distractors. To probe the functional relevance of this area, we targeted the left pSTG with focal repetitive transcranial magnetic stimulation (rTMS) while subjects performed a picture-word interference task. Unexpectedly, pSTG stimulation did not affect the semantic interference effect but selectively increased the congruency effect (i.e., faster naming with congruent distractors). The facilitatory TMS effect selectively occurred in the more difficult list with an overall lower name agreement. Our study adds new evidence to the causal role of the left pSTG in the interaction between picture and distractor representations or processing streams, only partly supporting previous neuroimaging studies. Moreover, the observed unexpected condition-specific facilitatory rTMS effect argues for an interaction of the task- or stimulus-induced brain state with the modulatory TMS effect. These issues should be systematically addressed in future rTMS studies on language production.

Optogenetic techniques are used widely to perturb and interrogate neural circuits in behaving animals, but illumination can have additional effects, such as the activation of endogenous opsins in the retina. We found that illumination, delivered deep into the brain via an optical fiber, evoked a behavioral artifact in mice performing a visually guided discrimination task. Compared with blue (473 nm) and yellow (589 nm) illumination, red (640 nm) illumination evoked a greater behavioral artifact and more activity in the retina, the latter measured with electrical recordings. In the mouse, the sensitivity of retinal opsins declines steeply with wavelength across the visible spectrum, but propagation of light through brain tissue increases with wavelength. Our results suggest that poor retinal sensitivity to red light was overcome by relatively robust propagation of red light through brain tissue and stronger illumination of the retina by red than by blue or yellow light. Light adaptation of the retina, via an external source of illumination, suppressed retinal activation and the behavioral artifact without otherwise impacting behavioral performance. In summary, long wavelength optogenetic stimuli are particularly prone to evoke behavioral artifacts via activation of retinal opsins in the mouse, but light adaptation of the retina can provide a simple and effective mitigation of the artifact.

Experimental studies of cognitive detriments in mice and rats after proton and heavy ion exposures have been performed by several laboratories to investigate possible risks to astronauts exposed to cosmic rays in space travel and patients treated for brain cancers with proton and carbon beams in Hadron therapy. However, distinct radiation types and doses, cognitive tests and rodent models have been used by different laboratories, while few studies have considered detailed dose-response characterizations, including estimates of relative biological effectiveness (RBE). Here we report on the first quantitative meta-analysis of the dose response for proton and heavy ion rodent studies of the widely used novel object recognition (NOR) test, which estimates detriments in recognition or object memory. Our study reveals that linear or linear-quadratic dose-response models of relative risk (RR) do not provide accurate descriptions. However, good descriptions for doses up to 1 Gy are provided by exponentially increasing fluence or dose-response models observed with an LET dependence similar to a classical radiation quality response, which peaks near 100–120 keV/µm and declines at higher LET values. Exponential models provide accurate predictions of experimental results for NOR in mice after mixed-beam exposures of protons and 56Fe, and protons, 16O and 28Si. RBE estimates are limited by available X-ray or gamma-ray experiments to serve as a reference radiation. RBE estimates based on use of data from combined gamma-ray and high-energy protons of low-LET experiments suggest modest RBEs, with values <8 for most heavy ions, while higher values <20 are based on limited gamma-ray data. In addition, we consider a log-normal model for the variation of subject responses at defined dose levels. The log-normal model predicts a heavy ion dose threshold of approximately 0.01 Gy for NOR-related cognitive detriments.

We studied the effects of light and non-specific sound stimulation of domestic chick embryos on their filial preference as well as on the expression of two transcriptional factors c-Fos and Egr-1 and neurotrophin BDNF in the embryo brain. Prenatal light stimulation increased preference of the “natural” object, thus producing a priming effect. In the brain of E19 embryos, c-Fos and Egr-1 were expressed at a high basal level and neither light nor sound stimulation affected the number of cells expressing these factors. BDNF mRNA was also present in a number of brain areas of non-stimulated embryos, but light and sound stimulation enhanced the expression of BDNF mRNA in brain structures associated with filial imprinting. These findings suggest that BDNF is probably involved in the effects of prenatal priming on the development of species-specific behavior.

Wireless internet (Wi-Fi) electromagnetic waves (2.45 GHz) have widespread usage almost everywhere, especially in our homes. Considering the recent reports about some hazardous effects of Wi-Fi signals on the nervous system, this study aimed to investigate the effect of 2.4 GHz Wi-Fi radiation on multisensory integration in rats. This experimental study was done on 80 male Wistar rats that were allocated into exposure and sham groups. Wi-Fi exposure to 2.4 GHz microwaves [in Service Set Identifier mode (23.6 dBm and 3% for power and duty cycle, respectively)] was done for 30 days (12 h/day). Cross-modal visual-tactile object recognition (CMOR) task was performed by four variations of spontaneous object recognition (SOR) test including standard SOR, tactile SOR, visual SOR, and CMOR tests. A discrimination ratio was calculated to assess the preference of animal to the novel object. The expression levels of M1 and GAT1 mRNA in the hippocampus were assessed by quantitative real-time RT-PCR. Results demonstrated that rats in Wi-Fi exposure groups could not discriminate significantly between the novel and familiar objects in any of the standard SOR, tactile SOR, visual SOR, and CMOR tests. The expression of M1 receptors increased following Wi-Fi exposure. In conclusion, results of this study showed that chronic exposure to Wi-Fi electromagnetic waves might impair both unimodal and cross-modal encoding of information.

The neural basis of consciousness remains incompletely understood. While cortical mechanisms of conscious perception have been extensively investigated in humans, the role of subcortical structures, including the thalamus, remains less explored. Here, we elucidate the causal contributions of different thalamic regions to conscious perception using transcranial low-intensity focused ultrasound (LIFU) neuromodulation. We hypothesize that modulating distinct thalamic regions alters perceptual outcomes derived from Signal Detection Theory. We apply LIFU to healthy human anterior (transmodal-dominant) and posterior (unimodal-dominant) thalamic regions, further subdivided into ventral and dorsal regions, during a near-threshold visual perception task. We show that high duty cycle modulation of the ventroanterior (VA) part of thalamus enhances object recognition sensitivity. Sensitivity enhancement magnitude correlates with the core-matrix cell compositions of the stimulated thalamic region. Connectivity analysis of a large-scale functional magnetic resonance imaging dataset confirms strong transmodal connectivity of VA thalamus with frontoparietal and default-mode networks. We also demonstrate target-invariant effects of high duty cycle LIFU disrupting object categorization accuracy. These findings provide causal insight into the cytoarchitectural and functional organization of the thalamus that shape human visual experience, especially the role of matrix-cell-rich, transmodal-dominant VA thalamus. Using low-intensity focused ultrasound, the authors show that targeted modulation of specific thalamic subregions alters human visual perception, revealing a causal role of the anterior thalamus in shaping conscious experience.

Infrared imaging technology relies on detecting the electromagnetic waves emitted by an object's spontaneous thermal radiation for imaging. It can overcome the adverse effects of complex lighting conditions on the detection of pedestrians and vehicles on the road. To address the issues of low accuracy and missed detection in visual detection under complex traffic conditions, such as during rain, snow, or at night, a pedestrian and vehicle detection model using infrared imaging has been proposed. This model improves the neck network and incorporates an attention mechanism. First, by adding a multi-scale feature fusion small-object detection layer to the model's neck, enhancing the capture of detailed information about small infrared objects and reducing missed detections. Second, a novel dual-layer routing attention mechanism is designed, allowing the model to focus on the most relevant feature areas and improving the detection accuracy of small infrared objects. Next, the CARAFE upsampling method is used for adaptive upsampling and context information fusion, which enhances the model's ability to reorganize features and capture details. Finally, a lightweight CSPPC module is constructed using partial convolutions to replace the C2f module in the neck network, which improves the model's frame rate. Experimental results show that, compared to the baseline model, BCC-YOLOv8n improves precision, recall, mAP@0.5, and mAP@0.5:0.95 by 1.4%, 4.8%, 5.3%, and 4.5%, respectively, while reducing the number of parameters by approximately 7%. Additionally, a frame rate of 70.8 FPS was achieved, satisfying the requirements for real-time detection.

Aiming at the problems of edge loss due to down-sampling-up-sampling operations of encoder decoder networks and the difficulty of extracting global features from networks due to the difficulty of obtaining a large receptive field for traditional convolution, a highly efficient encoder decoder convolutional neural network HEDCNN based on multi-scale edge enhancement and dilated convolution is proposed. HEDCNN uses a multi-scale feature learnable edge enhancement block to extract the multi-scale edge information of the original image and fuses it into the network through dense connections, improving the network's ability to recover edge information. Hybrid dilated convolution expands the receptive field of the network, allowing the network to capture broader contextual information while also focusing on local detail information. A compound loss function combining Huber loss and SSIM loss overcomes the over-smoothing problem of the model and further preserves the details of the denoised image. In the 2016 NIH AAPM-Mayo Clinic Low-Dose CT Challenge data sets, compared with other state-of-the-art LDCT denoising models, HEDCNN obtains the best PSNR and SSIM. At the same time, the denoising image is closest to the NDCT image in terms of visual effect.