fMRI evidence for sensorimotor transformations in human cortex during smooth pursuit eye movements

Smooth pursuit eye movements (SP) are driven by moving objects. The pursuit system processes the visual input signals and transforms this information into an oculomotor output signal. Despite the object's movement on the retina and the eyes' movement in the head, we are able to locate the object in space implying coordinate transformations from retinal to head and space coordinates. To test for the visual and oculomotor components of SP and the possible transformation sites, we investigated three experimental conditions: (I) fixation of a stationary target with a second target moving across the retina (visual), (II) pursuit of the moving target with the second target moving in phase (oculomotor), (III) pursuit of the moving target with the second target remaining stationary (visuo-oculomotor). Precise eye movement data were simultaneously measured with the fMRI data. Visual components of activation during SP were located in the motion-sensitive, temporo-parieto-occipital region MT+ and the right posterior parietal cortex (PPC). Motor components comprised more widespread activation in these regions and additional activations in the frontal and supplementary eye fields (FEF, SEF), the cingulate gyrus and precuneus. The combined visuo-oculomotor stimulus revealed additional activation in the putamen. Possible transformation sites were found in MT+ and PPC. The MT+ activation evoked by the motion of a single visual dot was very localized, while the activation of the same single dot motion driving the eye was rather extended across MT+. The eye movement information appeared to be dispersed across the visual map of MT+. This could be interpreted as a transfer of the one-dimensional eye movement information into the two-dimensional visual map. Potentially, the dispersed information could be used to remap MT+ to space coordinates rather than retinal coordinates and to provide the basis for a motor output control. A similar interpretation holds for our results in the PPC region.     

A CTSA‐Sponsored Program for Clinical Research Coordination: Networking,Education, and Mentoring

Upon receipt of the National Institutes of Health Clinical and Translational Science Award, the University of Iowa’s Institute for Clinical and Translational Science committed to develop an infrastructure for research professionals. Three goals were established: (1) identification of research professionals within the University of Iowa, (2) development of an educational series, including orientation and continuing education, and (3) development of a mentoring system. The purpose of this paper is to describe the process of development, initiation, and outcomes of a successful networking, educational, and mentoring system crafted for research professionals at the University of Iowa. Clin Trans Sci 2011; Volume 4: 42–47     

Mycobacterium avium disease in AIDS patients; diagnosis and therapy]

In eight (25%) of 32 consecutive AIDS patients between 1986 and 1989, Mycobacterium avium infection was diagnosed: in seven disseminated, in one as a local lymph node process. Six patients were treated as consistently as possible with a combination of ethambutol, rifabutine, clofazimine and protionamide (or cycloserine) in relatively large dosages. Median survival of treated patients was 15.5 (4-22) months. Protionamide inhibited most M. avium strains (7 of 8) in vitro, but often caused intolerance (nausea). Treatment of disseminated cytomegalovirus infection in our opinion was necessary in 5 of 6 patients during longterm M. avium therapy. HIV therapy (Zidovudine) during M. avium treatment was not possible due to bone marrow depression. A low maintenance dose of corticosteroids was necessary in 3 of 6 patients (one with adrenal insufficiency) to suppress symptoms such as fever and malaise.     

Temporal profile of T2-weighted MRI distinguishes between pannecrosis and selective neuronal death after transient focal cerebral ischemia in the rat.

Transient middle cerebral artery occlusion (MCAO) by an intraluminal thread leads to primarily subcortical infarctions with little sensorimotor impairment in the Wistar rat strain. We investigated the course of infarct development in this lesion type for 10 weeks using magnetic resonance imaging (MRI) along with histological characterization. MCAO was induced in male Wistar rats (260 to 300 g) for 60 mins. Animals received follow-up T1- and T2-weighted MRI from day 1 until week 10. Separate groups of animals were analyzed histologically after 2, 6, and 10 weeks. Histology included immunohistochemistry for neuronal and astrocytic markers as well as hematoxylin eosin and luxol fast blue-cresyl violet staining. In contrast to lesions involving the cortex, exclusively subcortical infarctions were characterized by a complete resolution of initially increased T1 and T2 relaxation times by 10 weeks. Between 2 and 10 weeks, neuronal death and gliosis as well as a dense inflammatory infiltrate were evident in these lesions, without damage to fiber tracts or development of cystic cavities. Exclusively subcortical lesions in Wistar rats are characterized by normalization of T1 and T2 relaxation times, which might, however, not be mistaken for tissue recovery. Despite this MRI normalization, selective neuronal death and gliosis develop. Although MRI at individual time points might therefore be ambiguous, the temporal profile of relaxation time changes over the chronic time period allows discrimination of the lesion development into selective neuronal death or pannecrosis.