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Reading is one of the most important skills human beings can acquire, but has proven difficult to study naturalistically using functional magnetic resonance imaging (fMRI). We introduce a novel Event-Related Reading (ERR) fMRI approach that enables reliable estimation of the neural correlates of single-word processing during reading of rapidly presented narrative text (200–300ms /word). Application to an fMRI experiment in which subjects read coherent narratives and made no overt responses revealed widespread effects of orthographic, phonological, contextual, and semantic variables on brain activation. Word-level variables predicted activity in classical language areas as well as the inferotemporal visual word form area, specifically supporting a role for the latter in mapping visual forms onto articulatory or acoustic representations. Additional analyses demonstrated that ERR results replicate across experiments and predict reading comprehension. The ERR approach represents a powerful and extremely flexible new approach for studying reading and language behavior with fMRI.

Even though the eyes constantly change position, the location of a stimulus can be accurately represented by a population of neurons with retinotopic receptive fields modulated by eye position gain fields. Recent electrophysiological studies, however, indicate that eye position gain fields may serve an additional function since they have a non-uniform spatial distribution that increases the neural response to stimuli in the straight-ahead direction. We used functional magnetic resonance imaging and a wide-field stimulus display to determine whether gaze modulations in early human visual cortex enhance the blood-oxygenation-level dependent (BOLD) response to stimuli that are straight-ahead. Subjects viewed rotating polar angle wedge stimuli centered straight-ahead or vertically displaced by ±20° eccentricity. Gaze position did not affect the topography of polar phase-angle maps, confirming that coding was retinotopic, but did affect the amplitude of the BOLD response, consistent with a gain field. In agreement with recent electrophysiological studies, BOLD responses in V1 and V2 to a wedge stimulus at a fixed retinal locus decreased when the wedge location in head-centered coordinates was farther from the straight-ahead direction. We conclude that stimulus-evoked BOLD signals are modulated by a systematic, non-uniform distribution of eye-position gain fields.

Recent functional magnetic resonance imaging (fMRI) studies using mixed blocked/event-related designs have shown activity consistent with separable sustained task-related processes and transient trial-related processes. In the mixed design, control blocks are intermixed with task blocks, during which trials are presented at varying intervals. Two studies were conducted to assess the ability of this design to detect and dissociate sustained task-related from transient trial-related activity. Analyses on both simulated and empirical data were performed by using the general linear model with a shape assumed for sustained effects, but not transient effects. In the first study, simulated data were produced with sustained time courses, transient time courses, and the sum of both together. Analyses of these data showed appropriate parsing of sustained and transient activity in all three cases. For the empirical fMRI experiment, counterphase-flickering checkerboard stimuli were constructed to produce sustained, transient, and combined sustained and transient responses in visual cortex. As with the simulation, appropriate parsing of sustained and transient activity was seen in all threecases; i.e., sustained stimuli produced sustained time courses and transient stimuli produced transient time courses. Combined stimuli produced both transient and sustained time courses. Critically, transient stimuli alone did not produce spurious positive sustained responses; sustained stimuli alone produced negligible spurious transient time courses. The results of these two studies along with supplemental simulations provide strong evidence that mixed designs are an effective tool for separating transient, trial-related activity from sustained activity in fMRI experiments. Mixed designs can allow researchers a means to examine brain activity associated with sustained processes, potentially related to task-level control signals.

Volumetric analysis methods continue to enjoy great popularity in the analysis of task-related functional MRI (fMRI) data. Among these methods, the software package FSL (FMRIB, Oxford, UK) is omnipresent throughout the field. However, it remains unknown what advantages might be gained by integrating FSL with alternative preprocessing tools. Here we developed the One-step General Registration and Extraction (OGRE) pipeline to apply FreeSurfer brain extraction for simultaneous registration and motion correction (\"one-step resampling\"), for FSL volumetric analysis of fMRI data. We compared three preprocessing approaches (OGRE, FSL, and fMRIPrep) in a dataset wherein adult human volunteers (N=39) performed a precision drawing task during fMRI scanning. The three approaches produced grossly similar results, but OGRE's preprocessing led to lower inter-individual variability across the brain and greater detected activation in primary motor cortex contralateral to movement. This demonstrates that FreeSurfer tools and one-step resampling can improve FSL's volumetric analysis of fMRI data. The OGRE pipeline provides an off-the-shelf method to apply FreeSurfer-based brain extraction and one-step resampling of motion correction and registration for FSL analysis of task fMRI data.

Blood oxygen level dependent (BOLD) signals characteristically exhibit an overshoot (transient signal increase) at the beginning of fMRI task blocks. This onset transient has often been overlooked as an independent measure of neuronal activity, but it may represent unique functional processes. We examined onset transient responses in normal subjects and individuals with schizophrenia performing three cognitive tasks. These analyses revealed a regionally specific and task specific attenuation of the onset transient in individuals with schizophrenia during performance of a working memory task. Furthermore, this attenuation was often not accompanied by a corresponding population difference in the sustained response, and is missed through conventional fMRI analysis techniques. Relevance of these findings to both an interpretation of the onset transient and the pathology of schizophrenia are discussed.

The distribution of brain aerobic glycolysis (AG) in normal young adults correlates spatially with amyloid-beta (Aβ) deposition in individuals with dementia of the Alzheimer type (DAT) and asymptomatic individuals with brain amyloid deposition. Brain AG decreases with age but the functional significance of this decrease with regard to the development of DAT symptomatology is poorly understood. Using PET measurements of regional blood flow, oxygen consumption and glucose utilization—from which we derive AG—we find that cognitive impairment is strongly associated with loss of the typical youthful pattern of AG. In contrast, amyloid positivity without cognitive impairment was associated with preservation of youthful brain AG, which was even higher than that seen in typical, cognitively unimpaired, amyloid negative adults. Similar findings were not seen for blood flow nor oxygen consumption. Finally, in cognitively unimpaired adults, white matter hyperintensity burden was found to be specifically associated with decreased youthful brain AG. Our results implicate preserved AG as a factor in brain resilience to amyloid pathology and suggest that white matter disease may be a cause and/or consequence of this impaired resilience.

State-of-the-art cloud computing platforms such as Google Earth Engine (GEE) enable regional-to-global land cover and land cover change mapping with machine learning algorithms. However, collection of high-quality training data, which is necessary for accurate land cover mapping, remains costly and labor-intensive. To address this need, we created a global database of nearly 2 million training units spanning the period from 1984 to 2020 for seven primary and nine secondary land cover classes. Our training data collection approach leveraged GEE and machine learning algorithms to ensure data quality and biogeographic representation. We sampled the spectral-temporal feature space from Landsat imagery to efficiently allocate training data across global ecoregions and incorporated publicly available and collaborator-provided datasets to our database. To reflect the underlying regional class distribution and post-disturbance landscapes, we strategically augmented the database. We used a machine learning-based cross-validation procedure to remove potentially mis-labeled training units. Our training database is relevant for a wide array of studies such as land cover change, agriculture, forestry, hydrology, urban development, among many others.

PHOTOS 2 MAP; People line up for food at a roadside chicken stand in Kihei, Hawaii, on Sunday after an earthquake struck, knocking out power. AP photo by Joseph Kaczmarek. Diane George and Stephanie Hart wait in Honolulu International Airport, where planes still arrived after Sunday's quake. AP photo by Luci Pemoni. MAP: Quake measures 6.6 magnitude The earthquake, centered off the northwest coast of the Big island of Hawaii early Sunday, was the strongest to hit the region since 1983, but no tsunami warnings were issued. Hawaii Island Site of earthquake Sources: ESRI, TeleAtlas, USGS Chicago Tribune/Keith Claxton

Background: Transforming growth factor β (TGFβ) has been shown to induce subcapsular plaques in cultured rat lenses as well as in lenses of transgenic mice. In the present study the authors have extended their analysis of these cataract models to determine how closely they mimic human cataract. In particular, they studied the maturation of cataract in the transgenic model to determine if it develops similar features as previously described for anterior subcapsular cataract (ASC) in humans. Furthermore, they investigated whether both of these animal models express the range of molecular markers that have now been shown to be present in human ASC. Methods: Histology and periodic acid Schiff staining were used to study the development and maturation of subcapsular plaques in transgenic mice overexpressing TGFβ1 in the lens. Immunolabelling methods were used to identify the molecular markers for ASC in both the transgenic mouse model and in rat lenses cultured with TGFβ2. Results: Histological analysis showed that the subcapsular plaques that develop in adult transgenic mouse lenses bear a striking similarity to mature human ASC, including the formation of a new epithelial-like layer extending between the subcapsular plaque and the underlying fibre mass. All known molecular markers for human ASC were induced in both rodent models, including collagen types I and III, tenascin, and fibronectin. They also identified the presence of desmin in these plaques, a putative novel marker for human cataract. Conclusions: In both transgenic mouse and rat lens culture models TGFβ induces markers similar to those found in human ASC. Atypical expression of these cataract markers is also characteristic of posterior capsular opacification (PCO). The molecular markers expressed are typical of a myofibroblastic/fibroblastic phenotype and suggest that a common feature of ASC and PCO may be induction of an epithelial-mesenchymal transition by TGFβ.

Incongruous information is better remembered than ordinary information. This result has been attributed both to semantic incongruity and surprise. To determine the contribution of each factor, we performed a functional magnetic resonance imaging study in which participants viewed pictures depicting ordinary and incongruous objects (e.g., head of a wrench fused onto a sheep body). To maximize surprise we administered novel incongruent pictures infrequently in an initial scan. (This scan also included infrequent color-inverted pictures as a control for frequency.) To obtain a pure measure of the effect of incongruity we conducted a second scan in which participants viewed equal numbers of ordinary and incongruous pictures. Signal increases were greater for incongruous versus ordinary and oddball stimuli throughout the ventral and dorsal visual pathways, and in prefrontal cortex bilaterally. Signal decreases were larger for incongruous than for ordinary stimuli bilaterally in lateral parietal regions. A subset of regions near the right frontal operculum and extending laterally responded only to, or more strongly to, infrequent incongruous pictures. A second, purely behavioral, experiment involving a separate group of participants demonstrated that incongruous pictures were better recognized than ordinary pictures. We interpret our results as suggesting that, although correlates of a surprise response can be observed, better memory for incongruous visual information is attributable mainly to more processing and, consequently, better encoding.