Mapping spatial neglect symptoms in the brain: a preliminary report from a single case.

Background Following injury to the right parietal cortex, patients typically show unilateral spatial neglect, a complex syndrome associated with a reduced capability to orient attentional resources toward the contralateral side of space [1]. Visual extinction is one of the most prominent symptoms of unilateral spatial neglect. In visual extinction, a transient stimulus presented in the right hemifield ‘extinguishes’ from awareness an homologue stimulus simultaneously presented in the left hemifield. This is thought to be a consequence of the residual activity of the left – non damaged – parietal cortex [1-4]. Surprisingly, however, this hypothesis has been largely unexplored to date in real neglect patients. Here we used functional magnetic resonance imaging (fMRI) to identify brain regions contributing to visual extinction in a stroke patient with unilateral spatial neglect and in four healthy controls. Method During fMRI, all participants were presented with a target stimulus (i.e., a black square of 2x2°; 10° apart from the central fixation point), that equiprobably appeared on either the left, right or both hemifields. Participants pressed one of three response buttons to indicate the hemifield(s) of appearance of the target, left, right, or bilateral. Results Behaviourally, we found 100% accuracy in control subjects, irrespective of the target side, left, right or bilateral. By contrast, the neglect patient systematically failed to detect bilateral targets (0% of accuracy). Importantly, “bilateral” targets were perceived by the patient as “right” targets in the great majority of trials (93,75%). Moreover, the patient showed a decreased capability in detecting left (44%) vs. right targets (100%). The fMRI analysis revealed in the patient a greater activation of the left posterior parietal cortex, namely of the left angular gyrus (x, y, z = -44, -68, 30), when comparing detection of bilateral vs. unilateral (left and right) targets. The same comparison revealed no significant activations in the control group. Conclusions Our findings provides empirical evidence that confirm the crucial role played by the left parietal cortex during visual extinction in spatial neglect, providing important insights for the current models of unilateral spatial neglect

Oxidative stress and inflammation in long-term renal transplanted hypertensives.

Introduction: Several studies have shown that chronic renal failure (CRF) is characterized by "accelerated atherosclerosis". More recent studies emphasize that inflammation and oxidative stress play a central role in atherosclerosis, and it is well-established that C-reactive protein (CRP) is a cardiovascular risk marker in the general population, in end-stage renal disease (ESRD) patients and in allograft recipients. Methods: We measured the serum concentration of high sensitivity CRP, TNFα, 8-iso-prostaglandin F2α (8-iso-PGF2α, an in vivo oxidative stress marker) in 15 CRF patients and in 15 transplant recipients. Exclusion criteria were age 65 years, smoking, diabetes mellitus and history of cardiovascular diseases. Immunosuppressive therapy was not withdrawn, and antihypertensive treatment was the same for both groups. Systolic (SBP) and diastolic blood pressure (DBP), serum creatinine (sCr) and estimated glomerular filtration rate (GFR) were also evaluated. 15 healthy subjects were enrolled as controls. Res ults: The transplanted group showed significantly higher values than controls of CRP (p < 0.05), TNFα (p < 0.05), 8-iso-PGF2α (p < 0.05). The CRF group as well exhibited, in comparison with controls significantly higher concentrations of CRP (p < 0.05), TNFα (p < 0.05), and 8-iso-PGF2α (p < 0.05). SBP, DBP and sCr were not different between transplanted and CRF patients. CRP was higher in transplant recipients than in CRF patients (p < 0.05). No difference in TNFα levels between the 2 groups was found. 8-iso-PGF2α was significantly higher in CRF than in the transplanted group (p < 0.05). In this latter, 8-iso-PGF2α showed a positive correlation with TNFα (p < 0.001), sCr (p < 0.001), SBP (p < 0.05) and DBP (p < 0.05). In the same group both 8-iso-PGF2α and TNFα were negatively correlated with GFR (r = -0.873 and -0.912, respectively, p < 0.001 for both). Conclusion: Our data have shown the coexistence of an increased oxidative stress and an inflammatory state in long-term renal graft recipient