Understanding 'not': neuropsychological dissociations between hand and head markers of negation in BSL

Simple negation in natural languages represents a complex interrelationship of syntax, prosody, semantics and pragmatics, and may be realised in various ways: lexically, morphologically and prosodically. In almost all spoken languages, the first two of these are the primary realisations of syntactic negation. In contrast, in many signed languages negation can occur without lexical or morphological marking. Thus, in British Sign Language (BSL), negation is obligatorily expressed using face-head actions alone (facial negation) with the option of articulating a manual form alongside the required face-head actions (lexical negation). What are the processes underlying facial negation? Here, we explore this question neuropsychologically. If facial negation reflects lexico-syntactic processing in BSL, it may be relatively spared in people with unilateral right hemisphere (RH) lesions, as has been suggested for other 'grammatical facial actions' [Language and Speech 42 (1999) 307; Emmorey, K. (2002). Language, cognition and the brain: Insights from sign language research. Mahwah, NJ: Erlbaum (Lawrence)]. Three BSL users with RH lesions were specifically impaired in perceiving facial compared with manual (lexical and morphological) negation. This dissociation was absent in three users of BSL with left hemisphere lesions and different degrees of language disorder, who also showed relative sparing of negation comprehension. We conclude that, in contrast to some analyses [Applied Psycholinguistics 18 (1997) 411; Emmorey, K. (2002). Language, cognition and the brain: Insights from sign language research. Mahwah, NJ: Erlbaum (Lawrence); Archives of Neurology 36 (1979) 837], non-manual negation in sign may not be a direct surface realisation of syntax [Language and Speech 42 (1999) 143; Language and Speech 42 (1999) 127]. Difficulties with facial negation in the RH-lesion group were associated with specific impairments in processing facial images, including facial expressions. However, they did not reflect generalised 'face-blindness', since the reading of (English) speech patterns from faces was spared in this group. We propose that some aspects of the linguistic analysis of sign language are achieved by prosodic analysis systems (analysis of face and head gestures), which are lateralised to the minor hemisphere.     

Fluoroscopy fade for embolization of vein of Galen malformation

A fluoroscopy fade technique in the embolization of a vein of Galen malformation in a 10-week-old infant is discussed herein. The availability of the fluoroscopy fade function eliminated the necessity of road mapping during the procedure and permitted minimal usage of contrast material and minimal radiation exposure for the patient. Techniques used during the embolization and the benefits of the fluoroscopy fade feature are also described.     

Mathematical segmentation of grey matter, white matter and cerebral spinal fluid from MR image pairs

The aims of this study were (1) to design a mathematical segmentation technique to allow extraction of grey matter, white matter and cerebral spinal fluid volumes from paired high resolution MR images and (2) to document the statistical accuracy of the method with different image combinations. A series of linear equations were derived that describe proportional tissue volumes in individual image voxels. The equations use estimates of pure tissue values to derive the proportion of each tissue within a single voxel. Repeatability of manual estimations of pure tissue values was assessed both using regions of interest and thresholding techniques. Statistical accuracy of tissue estimations for a variety of image pairs was assessed from measurements of root-mean-square noise and mean grey level intensity. The technique was used to produce parametric images of grey and white matter distribution. The segmentation technique showed greatest statistical accuracy when the first image has high grey/white matter contrast and the second image has little contrast or the rank order of the signal intensities from pure tissue is reversed. A combination of inversion recovery fast spin echo and fast FLAIR images produced a statistical error of 11% for grey matter and 10% for white matter for any given voxel. The effect of increasing sample size improves both of these figures to give a 1% statistical error on a 100 pixel sample.     

Imaging of pediatric pulmonary tumors: A COG Diagnostic Imaging Committee/SPR Oncology Committee White Paper

Pediatric pulmonary malignancy can be primary or metastatic, with the latter being by far the more common. With a few exceptions, there are no well-established evidence-based guidelines for imaging pediatric pulmonary malignancies, although computed tomography (CT) is used in almost all cases. The aim of this article is to provide general imaging guidelines for pediatric pulmonary malignancies, including minimum standards for cross-sectional imaging techniques and specific imaging recommendations for select entities.