Dyslexia is a severe and persistent reading and spelling disorder caused by impairment to manipulate speech sounds. Here, we combine functional magnetic resonance brain imaging with multi-voxel pattern analysis and functional and structural connectivity analysis to disentangle whether dyslexics' phonological deficits are caused by poor quality of the phonetic representations or by difficulties in accessing intact phonetic representations. We show that phonetic representations are hosted bilaterally in primary and secondary auditory cortices, and that their neural quality is intact in adults with dyslexia. However, the functional and structural connectivity between bilateral auditory cortices and left inferior frontal gyrus (a region involved in higher-level phonological processing) is significantly hampered in dyslexics, suggesting deficient access to otherwise intact phonetic representations.Speech perception involves the mapping of spectrally complex and rapidly changing acoustic signals onto discrete and abstract phonetic sound categories or phonemes (1). Developmental dyslexia is a hereditary neurological disorder characterized by severe and persistent reading and/or spelling impairments (2). Individuals with dyslexia perform poorly on tasks that require phonological awareness, verbal short-term memory and lexical access. Performance on these phonological tasks predicts reading acquisition in both normal and dyslexic readers (3). One view is that success on these tasks reflects the quality of underlying phonological (phonetic) representations (4) and that these representations of speech sounds are distorted or less well specified in individuals with dyslexia (5). An alternative view holds that representations are intact, but access to the representations is problematic in people with dyslexia (6, 7). Here, we combine functional magnetic resonance imaging (fMRI) with multi-voxel pattern analysis (MVPA) (8-10) and functional and structural connectivity analysis to disentangle whether dyslexia is caused by poor quality of the phonetic representation or by difficulties in accessing an intact phonetic representation.We collected whole-brain functional images in 23 adults with a diagnosis of dyslexia and 22 matched normal readers (Table S1, 11-13), while they listened to different versions of four sublexical speech sounds (Fig. S1) and performed an easy phoneme discrimination task. The selection of stimuli allowed us to investigate both vowel and stop consonant discrimination, which relies on spectral versus spectrotemporal acoustic feature processing, respectively. If dyslexia is related to a deficit in the quality of phonetic representations, then we expect that the neural representations would be less robust and distinct in individuals with dyslexia than in normal readers. Given dyslexics' particular problems processing temporal cues, such as those involved in consonant discrimination (11), we expected the most prominent group differences for neural patterns distinguishing between consonants.We analyzed...

Immersive virtual reality has become increasingly popular to improve the assessment and treatment of health problems. This rising popularity is likely to be facilitated by the availability of affordable headsets that deliver high quality immersive experiences. As many health problems are more prevalent in older adults, who are less technology experienced, it is important to know whether they are willing to use immersive virtual reality. In this study, we assessed the initial attitude towards head-mounted immersive virtual reality in 76 older adults who had never used virtual reality before. Furthermore, we assessed changes in attitude as well as self-reported cybersickness after a first exposure to immersive virtual reality relative to exposure to time-lapse videos. Attitudes towards immersive virtual reality changed from neutral to positive after a first exposure to immersive virtual reality, but not after exposure to time-lapse videos. Moreover, self-reported cybersickness was minimal and had no association with exposure to immersive virtual reality. These results imply that the contribution of VR applications to health in older adults will neither be hindered by negative attitudes nor by cybersickness.

Based on lesion mapping studies, the inferior parietal lobule and temporoparietal junction are considered the critical parietal regions for spatial-attentional deficits. Lesion evidence for a key role of the intraparietal sulcus, a region featuring prominently in non-human primate studies and human functional imaging studies of the intact brain, is still lacking, probably due to the exceptional nature of isolated intraparietal sulcus lesions. We combined behavioural testing and functional imaging in two patients with a focal intraparietal sulcus lesion sparing the inferior parietal lobule and temporoparietal junction to examine the critical contribution of the intraparietal sulcus to spatial attention. Case H.H. had a focal ischaemic lesion (1.8 cm3) that was confined to the posterior segment of the left intraparietal sulcus, whereas Case N.V. had a partially reversible lesion of the middle segment of the right intraparietal sulcus extending into the superior parietal lobule (13.8 cm3). The performance of these cases was contrasted with five cases with a classical inferior parietal lesion, as well as with a group of 31 age-matched controls. In the behavioural study, the patients performed an orientation discrimination task on a peripheral target (eccentricity 7.6°) that was preceded by a central spatial cue. We manipulated both the cue validity (17% trials with an invalid spatial cue) and the presence of a competing distracter in the visual field contralateral to the target (17% double stimulation trials). The ability of the patients with an intraparietal sulcus lesion to reorient their spatial focus of attention and to select between competing stimuli was impaired for contralesional targets compared with controls, similarly to what we saw in the inferior parietal group. Furthermore, we could observe that the deficit in Case N.V. resolved with regression of the lesion. To further evaluate the correspondence between spatial-attentional deficits and the intraparietal sulcus lesions, we ascertained the functional integrity of the inferior parietal lobule and temporoparietal junction in Case H.H. using event-related functional magnetic resonance imaging with the same task as in the behavioural study. The intraparietal sulcus lesion of this patient did not affect the task-related activation of the inferior parietal lobule or temporoparietal junction. Additionally, a resting-state functional magnetic resonance imaging study in Case H.H. and 62 controls revealed that the lesion in Case H.H. did not affect the topology of the ventral attention network nor the strength of its main inter- and intrahemispheric connections. Our findings demonstrate that the human superior parietal cortex critically contributes to spatially selective attention.

Computed tomographic (CT) images are widely used for the identification of abnormal brain tissue following infarct and hemorrhage in stroke. Manual lesion delineation is currently the standard approach, but is both time-consuming and operator-dependent. To address these issues, we present a method that can automatically delineate infarct and hemorrhage in stroke CT images. The key elements of this method are the accurate normalization of CT images from stroke patients into template space and the subsequent voxelwise comparison with a group of control CT images for defining areas with hypo- or hyper-intense signals. Our validation, using simulated and actual lesions, shows that our approach is effective in reconstructing lesions resulting from both infarct and hemorrhage and yields lesion maps spatially consistent with those produced manually by expert operators. A limitation is that, relative to manual delineation, there is reduced sensitivity of the automated method in regions close to the ventricles and the brain contours. However, the automated method presents a number of benefits in terms of offering significant time savings and the elimination of the inter-operator differences inherent to manual tracing approaches. These factors are relevant for the creation of large-scale lesion databases for neuropsychological research. The automated delineation of stroke lesions from CT scans may also enable longitudinal studies to quantify changes in damaged tissue in an objective and reproducible manner.