Co-Planar Stereotaxic Atlas of the Human Brain—3-Dimensional Proportional System: An Approach to Cerebral Imaging, J. Talairach, P. Tournoux. Georg Thieme Verlag, New York (1988), 122 pp., 130 figs. DM 268

Threshold-free cluster enhancement: Addressing problems of smoothing, threshold dependence and localisation in cluster inference

In this paper we report the set-up and results of the Multimodal Brain Tumor Image Segmentation Benchmark (BRATS) organized in conjunction with the MICCAI 2012 and 2013 conferences Twenty state-of-the-art tumor segmentation algorithms were applied to a set of 65 multi-contrast MR scans of low- and high-grade glioma patients—manually annotated by up to four raters—and to 65 comparable scans generated using tumor image simulation software Quantitative evaluations revealed considerable disagreement between the human raters in segmenting various tumor sub-regions (Dice scores in the range 74%–85%), illustrating the difficulty of this task We found that different algorithms worked best for different sub-regions (reaching performance comparable to human inter-rater variability), but that no single algorithm ranked in the top for all sub-regions simultaneously Fusing several good algorithms using a hierarchical majority vote yielded segmentations that consistently ranked above all individual algorithms, indicating remaining opportunities for further methodological improvements The BRATS image data and manual annotations continue to be publicly available through an online evaluation system as an ongoing benchmarking resource

/pdf/the-multimodal-brain-tumor-image-segmentation-benchmark-2gfraj98dk.pdf

The Multimodal Brain Tumor Image Segmentation Benchmark (BRATS)

Cerebral small vessel disease (SVD) is a common accompaniment of ageing. Features seen on neuroimaging include recent small subcortical infarcts, lacunes, white matter hyperintensities, perivascular spaces, microbleeds, and brain atrophy. SVD can present as a stroke or cognitive decline, or can have few or no symptoms. SVD frequently coexists with neurodegenerative disease, and can exacerbate cognitive deficits, physical disabilities, and other symptoms of neurodegeneration. Terminology and definitions for imaging the features of SVD vary widely, which is also true for protocols for image acquisition and image analysis. This lack of consistency hampers progress in identifying the contribution of SVD to the pathophysiology and clinical features of common neurodegenerative diseases. We are an international working group from the Centres of Excellence in Neurodegeneration. We completed a structured process to develop definitions and imaging standards for markers and consequences of SVD. We aimed to achieve the following: first, to provide a common advisory about terms and definitions for features visible on MRI; second, to suggest minimum standards for image acquisition and analysis; third, to agree on standards for scientific reporting of changes related to SVD on neuroimaging; and fourth, to review emerging imaging methods for detection and quantification of preclinical manifestations of SVD. Our findings and recommendations apply to research studies, and can be used in the clinical setting to standardise image interpretation, acquisition, and reporting. This Position Paper summarises the main outcomes of this international effort to provide the STandards for ReportIng Vascular changes on nEuroimaging (STRIVE).

https://www.thelancet.com/pdfs/journals/laneur/PIIS1474-4422(13)70124-8.pdf

Neuroimaging standards for research into small vessel disease and its contribution to ageing and neurodegeneration

Over the past 20 years, neuroimaging has become a predominant technique in systems neuroscience. One might envisage that over the next 20 years the neuroimaging of distributed processing and connectivity will play a major role in disclosing the brain's functional architecture and operational principles. The inception of this journal has been foreshadowed by an ever-increasing number of publications on functional connectivity, causal modeling, connectomics, and multivariate analyses of distributed patterns of brain responses. I accepted the invitation to write this review with great pleasure and hope to celebrate and critique the achievements to date, while addressing the challenges ahead.

/pdf/functional-and-effective-connectivity-a-review-s5oik3vige.pdf

Functional and effective connectivity: a review.

The amount of light reaching the eyes can be affected by changes in the level of illumination or by changes in the reflectance of external surfaces. It is well known that, at the retinal level, such a distinction loses its meaning, since there are only changes in luminous flux and spectral composition at this level. However, information about the two types of changes is recovered by the visual system at the perceptual level, allowing us e.g. to easily distinguish between self-luminous and reflecting surfaces. Surprisingly, the neural mechanisms underlying this distinction are largely unknown, even though the perceptual correlates are compelling. Using fMRI, we investigated in twelve healthy volunteers the neural basis for the perception of elements of the visual field which appear to be self-luminous (sources of light), as distinct from those elements which appear to reflect light. Stimuli were cross-like figures with luminance-gradients, as introduced first by Zavagno (Perception,1999, 28: 835-8) and Zavagno and Caputo (Perception, 2001, 30: 209-22). These stimuli can be modulated so that they produce a percept of luminosity or reflectance without changes in the luminance of the area which is seen as self-luminous or reflecting. Additional stimulus types were used to control for effects induced by the use of luminance gradients, and to distinguish possible luminosity-sensitive regions from brain regions that are sensitive to general luminance differences. Data were analysed with SPM'99. A group analysis revealed bilateral activation in the posterior part of the occipito-temporal sulcus that was specific for glowing stimuli. Individual analysis showed bilateral activation in 8 and unilateral activation in 4 of the 12 subjects. We conclude that a region in the human posterior occipito-temporal sulcus seems to be specifically activated by glowing objects. This region does not increase its activity with increasing luminance.

A cortical region for luminosity perception - An fMRI study

Here, the functions of the angular gyrus (AG) are evaluated in the light of current evidence from transcranial magnetic/electric stimulation (TMS/TES) and EEG/MEG studies. 65 TMS/TES and 52 EEG/MEG studies were examined in this review. TMS/TES literature points to a causal role in semantic processing, word and number processing, attention and visual search, self-guided movement, memory, and self-processing. EEG/MEG studies reported AG effects at latencies varying between 32 and 800 ms in a wide range of domains, with a high probability to detect an effect at 300–350 ms post-stimulus onset. A three-phase unifying model revolving around the process of sensemaking is then suggested: (1) early AG involvement in defining the current context, within the first 200 ms, with a bias toward the right hemisphere; (2) attention re-orientation and retrieval of relevant information within 200–500 ms; and (3) cross-modal integration at late latencies with a bias toward the left hemisphere. This sensemaking process can favour accuracy (e.g. for word and number processing) or plausibility (e.g. for comprehension and social cognition). Such functions of the AG depend on the status of other connected regions. The much-debated semantic role is also discussed as follows: (1) there is a strong TMS/TES evidence for a causal semantic role, (2) current EEG/MEG evidence is however weak, but (3) the existing arguments against a semantic role for the AG are not strong. Some outstanding questions for future research are proposed. This review recognizes that cracking the role(s) of the AG in cognition is possible only when its exact contributions within the default mode network are teased apart. 

Mohamed L. Seghier

Papers

A cortical region for luminosity perception - An fMRI study

Multiple functions of the angular gyrus at high temporal resolution

Demystifying desk rejection: A call to action for our authors

fMRI on patients with lesions involving language areas: implications for neurosurgery

Illusory contours have retinotopic representations in V1