Visual-spatial attention is an essential brain function that enables us to select and preferentially process high priority information in the visual fields. Several brain areas have been shown to participate in the control of spatial attention in humans, but little is known about the underlying selection mechanisms. Non-invasive scalp recordings of event-related potentials (e.r.ps) in humans have shown that attended visual stimuli are preferentially selected as early as 80-90 ms after stimulus onset, but current e.r.p. methods do not permit a precise localization of the participating cortical areas. In this study we combined neuroimaging (positron emission tomography) with e.r.p. recording in order to describe both the cortical anatomy and time course of attentional selection processes. Together these methods showed that visual inputs from attended locations receive enhanced processing in the extrastriate cortex (fusiform gyrus) at 80-130 ms after stimulus onset. These findings reinforce early selection models of attention.
Studies of experience-driven neuroplasticity at the behavioural, ensemble, cellular and molecular levels have shown that the structure and significance of the eliciting stimulus can determine the neural changes that result. Studying such effects in humans is difficult, but professional musicians represent an ideal model in which to investigate plastic changes in the human brain. There are two advantages to studying plasticity in musicians: the complexity of the eliciting stimulus music and the extent of their exposure to this stimulus. Here, we focus on the functional and anatomical differences that have been detected in musicians by modern neuroimaging methods.
Event-related brain potentials (ERPs) were recorded from subjects as they attended to colored bars that were flashed in random order to the left or right of fixation. The task was to detect slightly smaller target bars having a specified color (red or blue) and location (left or right). The ERP elicited by stimuli at an attended location contained a sequence of phasic components (P122/N168/N264) that was highly distinct from the sequence associated with selection on the basis of color (N150·350/P199/P400·500). These findings suggested that spatially focused attention involves a gating or modulation of evoked neural activity in the visual pathways, whereas color selection is manifested by an endogenous ERP complex. When the stimulus locations were widely separated, the ERP signs of color selection were hierarchically dependent upon the prior selection for spatial location. In contrast, when the stimulus locations were adjacent to one another, the ERP signs of color selection predominated over those of location selection. These results are viewed as supporting "early selection" theories of attention that specify the rejection of irrelevant inputs prior to the completion of perceptual processing. The implications of ERP data for theories of multidimensional stimulus processing are considered.
Ischemic stroke is the most common cerebrovascular disease, and its diagnosis, treatment, and study relies on non-invasive imaging. Algorithms for stroke lesion segmentation from magnetic resonance imaging (MRI) volumes are intensely researched, but the reported results are largely incomparable due to different datasets and evaluation schemes. We approached this urgent problem of comparability with the Ischemic Stroke Lesion Segmentation (ISLES) challenge organized in conjunction with the MICCAI 2015 conference. In this paper we propose a common evaluation framework, describe the publicly available datasets, and present the results of the two sub-challenges: Sub-Acute Stroke Lesion Segmentation (SISS) and Stroke Perfusion Estimation (SPES). A total of 16 research groups participated with a wide range of state-of-the-art automatic segmentation algorithms. A thorough analysis of the obtained data enables a critical evaluation of the current state-of-the-art, recommendations for further developments, and the identification of remaining challenges. The segmentation of acute perfusion lesions addressed in SPES was found to be feasible. However, algorithms applied to sub-acute lesion segmentation in SISS still lack accuracy. Overall, no algorithmic characteristic of any method was found to perform superior to the others. Instead, the characteristics of stroke lesion appearances, their evolution, and the observed challenges should be studied in detail. The annotated ISLES image datasets continue to be publicly available through an online evaluation system to serve as an ongoing benchmarking resource (www.isles-challenge.org).
Acquiring the meaning of a new word in a foreign language can be achieved either by rote memorizing or, similar to meaning acquisition during infancy, by extracting it from context. Little is known about the brain mechanisms involved in word learning. Here we demonstrate, using event-related brain potentials, the rapid development of a brain signature related to lexical and semantic processing during contextual word learning. Healthy volunteers engaged in a simple word-learning task were required to discover the meaning of a novel word from a context during silent reading. After 3 exposures, brain potentials to novel words in meaningful contexts were indistinguishable from real words, although this acquisition effect was not observed for novel words, for which sentence contexts allowed no meaning derivation. Furthermore, when the learned novel words were presented in isolation, an activation of their corresponding meaning was observed, although this process was slower than for real words.
IMPORTANCE Limbic encephalitis with leucine-rich, glioma-inactivated 1 (LGI1) antibodies is one of the most frequent variants of autoimmune encephalitis with antibodies targeting neuronal surface antigens. However, the neuroimaging pattern and long-term cognitive outcome are not well understood. OBJECTIVE To study cognitive outcome and structural magnetic resonance imaging (MRI) alterations in patients with anti-LGI1 encephalitis.
In previous studies, it was shown that there is a need for efficient motor rehabilitation approaches. For this purpose, we evaluated a music-supported training program designed to induce an auditory-sensorimotor co-representation of movements in 20 stroke patients (10 affected in the left and 10 in the right upper extremity). Patients without any previous musical experience participated in an intensive step by step training, first of the paretic extremity, followed by training of both extremities. Training was applied 15 times over 3 weeks in addition to conventional treatment. Fine as well as gross motor skills were addressed by using either a MIDI-piano or electronic drum pads. As a control, 20 stroke patients (10 affected left and 10 right) undergoing exclusively conventional therapies were recruited. Assignment to the training and control groups was done pseudo-randomly to achieve an equal number of left- and right-affected patients in each group. Pre- and post-treatment motor functions were monitored using a computerized movement analysis system (Zebris) and an established array of motor tests (e. g., Action Research Arm Test, Box & Block Test). Patients showed significant improvement after treatment with respect to speed, precision and smoothness of movements as shown by 3D movement analysis and clinical motor tests. Furthermore, compared to the control subjects, motor control in everyday activities improved significantly. In conclusion, this innovative therapeutic strategy is an effective approach for the motor skill neurorehabilitation of stroke patients.
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