Progress in brain research
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When an observer is searching through the environment for a target, what are the consequences of not finding a target in a given environment? We examine this issue in detail and propose that the visual system systematically tags environmental information during a search, in an effort to improve performance in future search events. Information that led to search successes is positively tagged, so as to favor future deployments of attention toward that type of information, whereas information that led to search failures is negatively tagged, so as to discourage future deployments of attention toward such failed information. To study this, we use an oddball-search task, where participants search for one item that differs from all others along one feature or belongs to a different visual category, from the other stimuli in the display. ⋯ Second, we show that the effect is independent of the mode of presentation of stimuli: it happens with both serial and simultaneous stimuli presentation. Third, we show that, when using categorically defined oddballs as the search stimuli (find the face among houses or vice versa), the bias generalizes to unseen members of the "failed" category. Together, these findings support the idea that this inter-trial attentional biases arise from high-level, task-constrained, implicit assessments of performance, involving categorical associations between classes of stimuli and behavioral outcomes (success/failure), which are independent of attentional modality (temporal vs. spatial attention).
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Assessing the level of consciousness of noncommunicative brain-damaged patients is difficult, as one has to make inferences based on the patients' behavior. However, behavioral responses of brain-damaged patients are usually limited not only by their cognitive dysfunctions, but also by their frequent motor impairment. For these reasons, it is essential to resort to para-clinical markers of the level of consciousness. ⋯ Specifically, we emphasize the principled approach provided by the Integrated Information Theory of Consciousness (IITC). We describe the different conditions where the theory predicts markedly reduced states of consciousness, and discuss several technical and conceptual issues limiting its applicability to measuring the level of consciousness of individual patients. Nevertheless, we argue that some of the predictions of the theory are potentially testable using available imaging techniques.
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The locked-in syndrome (LIS) describes patients who are awake and conscious but severely deefferented leaving the patient in a state of almost complete immobility and loss of verbal communication. The etiology ranges from acute (e.g., brainstem stroke, which is the most frequent cause of LIS) to chronic causes (e.g., amyotrophic lateral sclerosis; ALS). In this article we review and present new data on the psychosocial adjustment to LIS. ⋯ Existing evidence supports that biased clinicians provide less-aggressive medical treatment in LIS patients. Thus, psychological treatment for depression, effective strategies for coping with the disease, and support concerning the maintenance of the social network are needed to cope with the disease. Novel communication devices and assistive technology now offers an increasing number of LIS patients to resume a meaningful life and an active role in society.
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Hundreds of thousands around the world have poor vision or no vision at all due to inherited retinal degenerations (RDs) like retinitis pigmentosa (RP). Similarly, millions suffer from vision loss due to age-related macular degeneration (AMD). In both of these allied diseases, the primary target for pathology is the retinal photoreceptor cells that dysfunction and die. ⋯ In summary, no treatments are currently available for severely affected patients with RP and dry AMD. An electrical prosthetic device appears to offer hope in replacing the function of degenerating or dead photoreceptor neurons. Devices with new, sophisticated designs and increasing numbers of electrodes could allow for long-term restoration of functional sight in patients with improvement in object recognition, mobility, independent living, and general QOL.
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Spinal cord injury (SCI) is a serious clinical problem for which no suitable therapeutic strategies have been worked out so far. Recent studies suggest that the SCI and its pathophysiological responses could be altered by systemic exposure to nanoparticles. Thus, SCI when made in animals intoxicated with engineered nanoparticles from metals or silica dust worsened the outcome. ⋯ This indicates that nanoparticles depending on the exposure and its usage could induce both neurotoxicity and neuroprotection. This review discusses the potential adverse or therapeutic utilities of nanoparticles in SCI largely based on our own investigations. In addition, possible mechanisms of nanoparticle-induced exacerbation of cord pathology or enhanced neuroprotection following nanodrug delivery is described in light of recently available data in this rapidly emerging field of nanoneurosciences.