articlesThe optic flow 1 that is generated when a person moves through the environment can be locally decomposed into several basic components, including radial, circular, translation and sheer motion 2,3 . Neurons in the dorsal portion of the medial superior temporal cortex (MSTd) of macaque monkeys respond selectively to these components, alone or in combination [4][5][6][7] . Microstimulation can influence the direction of heading of a behaving monkey 8 , which demonstrates the functional importance of MST to heading. In the adjacent area MT (or V5), neurons also respond to motion and are highly directionally selective, but they do not show specific selectivity to circular or radial trajectories 9 . The neurophysiology findings are reinforced by psychophysical studies suggesting the existence of analogous neural units in humans that integrate local-motion signals along complex flow trajectories 10,11 . In agreement with the neurophysiological studies, these units have very large receptive fields 12 and sum information over periods of one or two seconds (L. Santoro and D.C. Burr, Perception 28, 90c, 1999). There is also some evidence in humans for selectivity along the 'cardinal directions' of optic flow (radial and circular) 13 , although this issue is somewhat controversial 14 .A very strong motion-selective response at the boundary of Brodmann's areas 19 and 37 is shown by human imaging [15][16][17][18][19][20][21][22][23] . This area is generally thought to be the human analogue of monkey V5/MT-MST regions, and is referred to as 'V5/MT complex' (MT+). Other motion-sensitive areas have been identified: a dorsal region referred to as V3A 16,21,22,24 and a ventral region, seemingly activated by motion boundaries and second-order motion 20,21 . Here, using fMRI, we examined the response to optic-flow stimuli, and showed selective activation of a large area within the V5/MT complex to radial and circular motion, very different from the area activated by translational motion. Activation in response to optic flow occurred only when the direction of optic flow changed-abruptly or gradually-during the presentation period; continuous radial or circular motion produced no reliable activation in any area when measured against a matched random control. RESULTS Response to optic flowWe created dynamic displays of circular, radial, spiral and translational motion from random-dot patterns. The control stimuli were locally identical to the active stimuli; each dot moved along independent, randomly chosen trajectories ( Fig. 1; Methods). Responses of subjects to flow motion were measured against these random controls, with both active and control stimuli reversing direction every two seconds. There was a clear and specific activation in the temporal-occipital cortex, with no response in V1 or any other cortical area (example, Fig. 2a). The response extended for more than 1 cm along the sulcus that separates Brodmann's area 19 and 37, within the region that is usually referred to the human analogue of V5/MT complex [15][16][...

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Infective endocarditis (IE) in chronic haemodialysis (HD) is significantly more common and causes greater morbidity and mortality than in the general population, being second only to cardiovascular disease as the leading cause of death in this group of patients. Because of the peculiarity of this group of patients, it has been recently proposed to add a fifth category (health-care associated and HD-associated IE) in the actually four categories classification of IE (namely, native valve IE, prosthetic valve IE, IE in e.v. drug users, and nosocomial IE). Given that rates of acceptance into HD are increasing (including a higher proportion of older patients in whom valvular calcification is virtually ubiquitous), and along with improved survival in HD patients, the incidence of IE in this subset of patients will probably increase with significant diagnostic and therapeutic implications. In particular cardiac, diagnostic, echocardiographic, and surgical expertises are required to correctly identify patients at higher risk and who may benefit from surgical treatment. The aim of this review is to clarify the peculiar features of chronic HD patients with regard to pathogenesis, diagnosis, current therapeutic options, and determinants of prognosis of IE.

(a) MRI abnormalities in phenylketonuria are the result of a distinctive alteration of white matter suggesting the intracellular accumulation of a hydrophilic metabolite, which leaves unaffected white matter architecture and structure. (b) White matter abnormalities do not seem to reflect the mechanisms involved in the derangement of mental development in PKU. (c) Our data do not support the usefulness of conventional brain MRI examination in the clinical monitoring of phenylketonuria patients.

Area prostriata is a cortical area at the fundus of the calcarine sulcus, described anatomically in humans [1-5] and other primates [6-9]. It is lightly myelinated and lacks the clearly defined six-layer structure evident throughout the cerebral cortex, with a thinner layer 4 and thicker layer 2 [10], characteristic of limbic cortex [11]. In the marmoset and rhesus monkey, area prostriata has cortical connections with MT+ [12], the cingulate motor cortex [8], the auditory cortex [13], the orbitofrontal cortex, and the frontal polar cortices [14]. Here we use functional magnetic resonance together with a wide-field projection system to study its functional properties in humans. With population receptive field mapping [15], we show that area prostriata has a complete representation of the visual field, clearly distinct from the adjacent area V1. As in the marmoset, the caudal-dorsal border of human prostriata-abutting V1-represents the far peripheral visual field, with eccentricities decreasing toward its rostral boundary. Area prostriata responds strongly to very fast motion, greater than 500°/s. The functional properties of area prostriata suggest that it may serve to alert the brain quickly to fast visual events, particularly in the peripheral visual field.

These preliminary data underline the importance of long-term surveillance of transplant recipients, choice of immunosuppressive treatment, and careful donor selection.

BACKGROUND AND PURPOSE Polymicrogyria is a malformation of cortical development that is often identified in children with epilepsy or delayed development. We investigated in vivo the potential of 7T imaging in characterizing polymicrogyria to determine whether additional features could be identified. MATERIALS AND METHODS Ten adult patients with polymicrogyria previously diagnosed by using 3T MR imaging underwent additional imaging at 7T. We assessed polymicrogyria according to topographic pattern, extent, symmetry, and morphology. Additional imaging sequences at 7T included 3D T2* susceptibility-weighted angiography and 2D tissue border enhancement FSE inversion recovery. Minimum intensity projections were used to assess the potential of the susceptibility-weighted angiography sequence for depiction of cerebral veins. RESULTS At 7T, we observed perisylvian polymicrogyria that was bilateral in 6 patients, unilateral in 3, and diffuse in 1. Four of the 6 bilateral abnormalities had been considered unilateral at 3T. While 3T imaging revealed 2 morphologic categories (coarse, delicate), 7T susceptibility-weighted angiography images disclosed a uniform ribbonlike pattern. Susceptibility-weighted angiography revealed numerous dilated superficial veins in all polymicrogyric areas. Tissue border enhancement imaging depicted a hypointense line corresponding to the gray-white interface, providing a high definition of the borders and, thereby, improving detection of the polymicrogyric cortex. CONCLUSIONS 7T imaging reveals more anatomic details of polymicrogyria compared with 3T conventional sequences, with potential implications for diagnosis, genetic studies, and surgical treatment of associated epilepsy. Abnormalities of cortical veins may suggest a role for vascular dysgenesis in pathogenesis.

EVL given at higher exposure for 6 months plus very low CsA concentration may obtain low acute rejection rate and good graft survival in De novo renal transplantation. However, there was no difference between groups in CrCl.