Nouns and verbs in the brain: grammatical class and task specific effects as revealed by fMRI.

The wide variety of techniques and tasks used to study the neural correlates of noun and verb processing has resulted in a body of inconsistent evidence. We performed a functional magnetic resonance imaging (fMRI) experiment to detect grammatical class effects that generalize across tasks. A total of 12 participants undertook a grammatical-class switching task (GCST), in which they were presented with a noun (or a verb) and were asked to retrieve the corresponding verb (or noun), and a classical picture naming task (PNT) widely used in the previous aphasiological and imaging literature. The GCST was explicitly designed to ensure control over confounding variables, such as stimulus complexity or imageability. Conjunction analyses of the haemodynamic responses measured in the two tasks indicated a shared verb-related activation of a dorsal premotor and posterior parietal network, pointing to a strong relationship between verb representation and action-oriented (visuo-)spatial knowledge. On the other hand, no brain area was consistently associated with nouns in both tasks. Moreover, there were task-dependent differences between noun and verb retrieval both at behavioural and at physiological level; the grammatical class that elicited the longest reaction times in both tasks (i.e., verbs in the PNT and nouns in the GCST) triggered a greater activation of the left inferior frontal gyrus. Therefore, we suggest that this area reflects a general increase in task demand rather than verb processing per se.

Neuroimaging abnormalities in adult medulloblastoma undergoing intensified therapy.

We report on radiological abnormalities resembling recurrent tumor in adult medulloblastoma receiving intensified chemotherapy and radiotherapy. Evidence provided in this paper confirms previous reports in the pediatric population and suggests that neuroradiologist and medical oncologists should be aware of new possible radiological findings related to aggressive treatments for brain tumors.

Treatment of a middle cerebral artery giant aneurysm using a covered stent. Case report.

The authors report the case of a 60-year-old man harboring a wide-necked giant aneurysm of the M1 segment of the left middle cerebral artery (MCA); his symptoms included transient ischemic attacks characterized by right hemiparesis and aphasia. The aneurysm was treated by placing a covered stent across the orifice of the aneurysm. The 18-month follow-up examination showed a very good outcome, with perfect left MCA patency, no new ischemic lesion, and minor residual aphasia and right hemiparesis. This is the first report in the literature of an MCA aneurysm treated using a covered stent.

Focal cortical dysplasias: MR imaging, histopathologic, and clinical correlations in surgically treated patients with epilepsy.

BACKGROUND AND PURPOSE: Focal cortical dysplasia (FCD) covers a spectrum of conditions in which the neuropathologic and electroclinic presentations and the surgical outcomes vary. The aim of this study was to identify the MR features of histologic subtypes of FCD that would be useful for differential diagnosis. METHODS: We reviewed the MR data of 49 patients treated surgically for intractable partial epilepsy, who received a histologic diagnosis of FCD not associated with other brain abnormalities except hippocampal sclerosis and who were classified by histologic criteria as having architectural dysplasia (28 patients), cytoarchitectural dysplasia (six patients), or Taylor's FCD (15 patients). RESULTS: From the MR features, it was generally possible to distinguish Taylor's FCD from architectural or cytoarchitectural dysplasias (non-Taylor's FCD). Findings suggesting Taylor's FCD were focal cortical thickening, blurring of the gray-white matter junction, and hyperintensity (on T2-weighted images) of subcortical white matter often tapering toward the ventricle. Focal brain hypoplasia with shrinkage and moderate signal intensity alterations in the white matter core were present in most patients with architectural dysplasia. The lesion was generally extratemporal in Taylor's FCD and temporal in architectural dysplasia. Ipsilateral hippocampal sclerosis was often present in architectural dysplasia (dual abnormality). CONCLUSIONS: In patients with FCD, Taylor's FCD and non-Taylor's FCD can usually be distinguished with MR imaging, although some overlap exists. A provisional MR diagnosis is important for presurgical investigations and surgical planning and may have prognostic implications.