Brain imaging in a patient with hemimicropsia

Hemimicropsia is an isolated misperception of the size of objects in one hemifield (objects appear smaller) which is, as a phenomenon of central origin, very infrequently reported in literature. We present a case of hemimicropsia as a selective deficit of size and distance perception in the left hemifield without hemianopsia caused by a cavernous angioma with hemorrhage in the right occipitotemporal area. The symptom occurred only intermittently and was considered the consequence of a local irritation by the hemorrhage. Imaging data including a volume-rendering MR data set of the patient’s brain were transformed to the 3-D stereotactic grid system by Talairach and warped to a novel digital 3-D brain atlas. Imaging analysis included functional MRI (fMRI) to analyse the patient’s visual cortex areas (mainly V5) in relation to the localization of the hemangioma to establish physiological landmarks with respect to visual stimulation. The lesion was localized in the peripheral visual association cortex, Brodmann area (BA) 19, adjacent to BA 37, both of which are part of the occipitotemporal visual pathway. Additional psychophysical measurements revealed an elevated threshold for perceiving coherent motion. which we relate to a partial loss of function in V5, a region adjacent to the cavernoma. In our study, we localized for the first time a cerebral lesion causing micropsia by digital mapping in Talairach space using a 3-D brain atlas and topologically related it to fMRI data for visual motion. The localization of the brain lesion affecting BA 19 and the occipitotemporal visual pathway is discussed with respect to experimental and case report findings about the neural basis of object size perception

Relationship between saccadic eye movements and cortical activity as measured by fMRI: quantitative and qualitative aspects

We investigated the quantitative relationship between saccadic activity (as reflected in frequency of occurrence and amplitude of saccades) and blood oxygenation level dependent (BOLD) changes in the cerebral cortex using functional magnetic resonance imaging (fMRI). Furthermore, we investigated quantitative changes in cortical activity associated with qualitative changes in the saccade task for comparable levels of saccadic activity. All experiments required the simultaneous acquisition of eye movement and fMRI data. For this purpose we used a new high-resolution limbus-tracking technique for recording eye movements in the magnetic resonance tomograph. In the first two experimental series we varied both frequency and amplitude of saccade stimuli (target jumps). In the third series we varied task difficulty; subjects performed either pro-saccades or anti-saccades. The brain volume investigated comprised the frontal and supplementary eye fields, parietal as well as striate cortex, and the motion sensitive area of the parieto-occipital cortex. All these regions showed saccade-related BOLD responses. The responses in these regions were highly correlated with saccade frequency, indicating that repeated processing of saccades is integrated over time in the BOLD response. In contrast, there was no comparable BOLD change with variation of saccade amplitude. This finding speaks for a topological rather than activity-dependent coding of saccade amplitudes in most cortical regions. In the experiments comparing pro- vs anti-saccades we found higher BOLD activation in the "anti" task than in the "pro" task. A comparison of saccade parameters revealed that saccade frequency and cumulative amplitude were comparable between the two tasks, whereas reaction times were longer in the "anti" task than the pro task. The latter finding is taken to indicate a more demanding cortical processing in the "anti" task than the "pro" task, which could explain the observed difference in BOLD activation. We hold that a quantitative analysis of saccade parameters (especially saccade frequency and latency) is important for the interpretation of the BOLD changes observed with visual stimuli in fMRI

Temporary Bonding with Polydimethylglutarimide Based Lift Off Resist as a Layer Transfer Platform

Bonding of lift off resist (LOR) was performed to realize temporary wafer bonding without residue. Bonding process conditions such as spin speed, pre-bake temperature, and bonding temperature were optimized to obtain a large bonded area with high bond strength. Under optimized process conditions, a bonded area covering over 98% of the wafer surface, with a room temperature bond strength of nearly 5 J/m2 is achieved. During razor blade testing, fracture often occurs at the Si wafer. Moreover, debonding using an N-Methyl-2-pyrrolidone (NMP)-based solvent left the wafer surface extremely small amount of residue. Thus, the optimized bonding processed developed in this research is suitable for a clean temporary bonding process

Assessment of Critical Habitats for Recovering the Chesapeake Bay Atlantic Sturgeon Distinct Population Segment

The states of Virginia and Maryland along with Virginia Commonwealth University (VCU), Virginia Institute of Marine Science (VIMS) and University of Maryland Center for Environmental Science (UMCES) partnered to assess critical habitat for recovering the Chesapeake Bay Atlantic sturgeon (Acipenser oxyrinchus oxyrinchus) distinct population segment. The primary objectives were to assess reproductive habitat in the James River, nursery habitat in the James and York Rivers and the degree of dependence of those populations to habitat in the Chesapeake Bay

Divergent functions for airway epithelial matrix metalloproteinase 7 and retinoic acid in experimental asthma.

The innate immune response of airway epithelial cells to airborne allergens initiates the development of T cell responses that are central to allergic inflammation. Although proteinase allergens induce the expression of interleukin 25, we show here that epithelial matrix metalloproteinase 7 (MMP7) was expressed during asthma and was required for the maximum activity of interleukin 25 in promoting the differentiation of T helper type 2 cells. Allergen-challenged Mmp7(-/-) mice had less airway hyper-reactivity and production of allergic inflammatory cytokines and higher expression of retinal dehydrogenase 1. Inhibition of retinal dehydrogenase 1 restored the asthma phenotype of Mmp7(-/-) mice and inhibited the responses of lung regulatory T cells, whereas exogenous administration of retinoic acid attenuated the asthma phenotype. Thus, MMP7 coordinates allergic lung inflammation by activating interleukin 25 while simultaneously inhibiting retinoid-dependent development of regulatory T cells