% % This file was created by the Typo3 extension % sevenpack version 0.7.14 % % --- Timezone: CEST % Creation date: 2017-05-23 % Creation time: 10-49-42 % --- Number of references % 40 % @Article { CalcinaghiWJSKWFBMW2013, title = {Multimodal Imaging in Rats Reveals Impaired Neurovascular Coupling in Sustained Hypertension}, journal = {Stroke}, year = {2013}, month = {7}, volume = {44}, number = {7}, pages = {1957-1964}, abstract = {BACKGROUND AND PURPOSE: Arterial hypertension is an important risk factor for cerebrovascular diseases, such as transient ischemic attacks or stroke, and represents a major global health issue. The effects of hypertension on cerebral blood flow, particularly at the microvascular level, remain unknown. METHODS: Using the spontaneously hypertensive rat (SHR) model, we examined cortical hemodynamic responses on whisker stimulation applying a multimodal imaging approach (multiwavelength spectroscopy, laser speckle imaging, and 2-photon microscopy). We assessed the effects of hypertension in 10-, 20-, and 40-week-old male SHRs and age-matched male Wistar Kyoto rats (CTRL) on hemodynamic responses, histology, and biochemical parameters. In 40-week-old animals, losartan or verapamil was administered for 10 weeks to test the reversibility of hypertension-induced impairments. RESULTS: Increased arterial blood pressure was associated with a progressive impairment in functional hyperemia in 20- and 40-week-old SHRs; baseline capillary red blood cell velocity was increased in 40-week-old SHRs compared with age-matched CTRLs. Antihypertensive treatment reduced baseline capillary cerebral blood flow almost to CTRL values, whereas functional hyperemic signals did not improve after 10 weeks of drug therapy. Structural analyses of the microvascular network revealed no differences between normo- and hypertensive animals, whereas expression analyses of cerebral lysates showed signs of increased oxidative stress and signs of impaired endothelial homeostasis upon early hypertension. CONCLUSIONS: Impaired neurovascular coupling in the SHR evolves upon sustained hypertension. Antihypertensive monotherapy using verapamil or losartan is not sufficient to abolish this functional impairment. These deficits in neurovascular coupling in response to sustained hypertension might contribute to accelerate progression of neurodegenerative diseases in chronic hypertension.}, department = {Department Logothetis}, web_url = {http://stroke.ahajournals.org/content/44/7/1957.abstract}, DOI = {10.1161/STROKEAHA.111.000185}, author = {Calcinaghi, N and Wyss, MT and Jolivet, R and Singh, A and Keller, AL and Winnik, S and Fritschy, JM and Buck, A and Matter, CM and Weber, B} } @Article { 6999, title = {Vascularization of Cytochrome Oxidase-Rich Blobs in the Primary Visual Cortex of Squirrel and Macaque Monkeys}, journal = {Journal of Neuroscience}, year = {2011}, month = {1}, volume = {31}, number = {4}, pages = {1246-1253}, abstract = {The close correlation between energy supply by blood vessels and energy consumption by cellular processes in the brain is the basis of blood flow-related functional imaging techniques. Regional differences in vascular density can be detected using high-resolution functional magnetic resonance imaging. Therefore, inhomogeneities in vascularization might help to identify anatomically distinct areas noninvasively in vivo. It was reported previously that cytochrome oxidase-rich blobs in the striate cortex of squirrel monkeys are characterized by a notably higher vascular density (42\% higher than interblob regions). However, blobs have so far never been identified in vivo on the basis of their vascular density. Here, we analyzed blobs of the primary visual cortex of squirrel monkeys and macaques with respect to the relationship between vascularization and cytochrome oxidase activity. By double staining with cytochrome oxidase enzyme histochemistry to define the blobs and collagen type IV immunohistochemistry to quantify the blood vessels, a close correlation between oxidative metabolism and vascularization was confirmed and quantified in detail. The vascular length density in cytochrome oxidase blobs was on average 4.5\% higher than in the interblob regions, a difference almost one order of magnitude smaller than previously reported. Thus, the vascular density that is closely associated with local average metabolic activity is a structural equivalent of cerebral metabolism and blood flow. However, the quantitative differences in vascularization between blob and interblob regions are small and below the detectability threshold of the noninvasive hemodynamic imaging methods of today.}, department = {Department Logothetis}, web_url = {http://www.jneurosci.org/cgi/reprint/31/4/1246}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1523/JNEUROSCI.2765-10.2011}, author = {Keller, AL and Sch{\"u}z, A and Logothetis, NK and Weber, B} } @Article { 6168, title = {Vascular graph model to simulate the cerebral blood flow in realistic vascular networks}, journal = {Journal of Cerebral Blood Flow and Metabolism}, year = {2009}, month = {8}, volume = {29}, number = {8}, pages = {1429-1443}, abstract = {At its most fundamental level, cerebral blood flow (CBF) may be modeled as fluid flow driven through a network of resistors by pressure gradients. The composition of the blood as well as the cross-sectional area and length of a vessel are the major determinants of its resistance to flow. Here, we introduce a vascular graph modeling framework based on these principles that can compute blood pressure, flow and scalar transport in realistic vascular networks. By embedding the network in a computational grid representative of brain tissue, the interaction between the two compartments can be captured in a truly three-dimensional manner and may be applied, among others, to simulate oxygen extraction from the vessels. Moreover, we have devised an upscaling algorithm that significantly reduces the computational expense and eliminates the need for detailed knowledge on the topology of the capillary bed. The vascular graph framework has been applied to investigate the effect of local vascular dilation and occlusion on the flow in the surrounding network.}, department = {Department Logothetis}, web_url = {http://www.nature.com/jcbfm/journal/v29/n8/pdf/jcbfm200958a.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1038/jcbfm.2009.58}, author = {Reichold, J and Stampanoni, M and Keller, AL and Buck, A and Jenny, P and Weber, B} } @Article { 4901, title = {The microvascular system of the striate and extrastriate visual cortex of the macaque}, journal = {Cerebral Cortex}, year = {2008}, month = {10}, volume = {18}, number = {10}, pages = {2318-2330}, abstract = {In functional neuroimaging, neurovascular coupling is used to generate maps of hemodynamic changes that are assumed to be surrogates of regional neural activation. The aim of this study was to characterize the microvascular system of the primate cortex as a basis for understanding the constraints imposed on a region's hemodynamic response by the vascular architecture, density, as well as area- and layer-specific variations. In the macaque visual cortex, an array of anatomical techniques has been applied, including corrosion casts, immunohistochemistry, and cytochrome oxidase (COX) staining. Detailed measurements of regional vascular length density, volume fraction, and surface density revealed a similar vascularization in different visual areas. Whereas the lower cortical layers showed a positive correlation between the vascular and cell density, this relationship was very weak in the upper layers. Synapse density values taken from the literature also displayed a very moderate correlation with the vascular density. However, the vascular density was strongly correlated with the steady-state metabolic demand as measured by COX activity. This observation suggests that although the number of neurons and synapses determines an upper bound on an area's integrative capacity, its vascularization reflects the neural activity of those subpopulations that represent a “default” mode of brain steady state.}, department = {Department Logothetis}, web_url = {http://cercor.oxfordjournals.org/cgi/reprint/18/10/2318}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1093/cercor/bhm259}, author = {Weber, B and Keller, AL and Reichold, J and Logothetis, NK} } @Article { 4288, title = {Quantification of Cerebral Blood Flow in Nonhuman Primates Using Arterial Spin Labeling and a Two-Compartment Model}, journal = {Magnetic Resonance Imaging}, year = {2007}, month = {7}, volume = {25}, number = {6}, pages = {775-783}, abstract = {Noninvasive absolute quantification of cerebral blood flow (CBF) with high spatial resolution is still a challenging task. Arterial spin labeling (ASL) is a promising magnetic resonance imaging (MRI) method for accurate perfusion quantification. However, modeling of ASL data is far from being standardized and has not been investigated in great detail. In this study, two-compartment modeling of monkey ASL data in three physiological conditions (baseline, sensory activated and globally elevated CBF) is reported. Absolute perfusion and arterial transit times were derived for gray matter (GM) and white matter (WM) separately. The uncertainties of the model\&amp;lsquo;s result were determined by Monte Carlo simulations. The fitted CBF values for GM were 133 ml/min/100 ml at baseline condition, 165 ml/min/100 ml during visual stimulation and 234 ml/min/100 ml for globally elevated CBF after intravenous injection of acetazolamide. The ratio of GM to WM CBF was 2.5 at baseline and was found to d ecre ase to 1 .6 after application of acetazolamide. The corresponding arterial transit times decreased from 742 to 607 ms in GM and from 985 to 875 ms in WM. Monte Carlo simulations showed that absolute CBF values can be determined with an error of 11–15\%, while the arterial transit time values have a coefficient of variation of 25–31\%. With an alternative acquisition scheme, the precision of the arterial transit times can be improved significantly. The CBF values in the occipital lobe of the monkey brain quantified with ASL are higher than previously reported in positron emission tomography studies.}, department = {Department Logothetis}, web_url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6T9D-4NNYG0P-1-1\&_cdi=5112\&_user=29041\&_orig=browse\&_coverDate=07\%2F31\%2F2007\&_sk=999749993\&view=c\&wchp=dGLbVtz-zSkWA\&md5=0392}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1016/j.mri.2006.11.028}, author = {Zappe, A-C and Reichold, J and Burger, C and Weber, B and Buck, A and Pfeuffer, J and Logothetis, NK} } @Article { 3827, title = {Spatial specificity of BOLD versus cerebral blood volume fMRI for mapping cortical organization}, journal = {Journal of Cerebral Blood Flow and Metabolism}, year = {2007}, month = {1}, volume = {27}, number = {6}, pages = {1248-1261}, abstract = {Intravascular contrast agents are used in functional magnetic resonance imaging to obtain cerebral blood volume (CBV) maps of cortical activity. Cerebral blood volume imaging with MION (monocrystalline-iron-oxide-nanoparticles) increases the sensitivity of functional imaging compared with the blood oxygenation level-dependent (BOLD) signal (Leite et al, 2002; Mandeville et al, 1998; Vanduffel et al, 2001). It therefore represents an attractive method for obtaining detailed maps of cortical organization (Vanduffel et al, 2001; Zhao et al, 2005). However, it remains to be determined how the spatial profile of CBV maps of cortical activity derived with MION compares with the profile of BOLD activation maps under a variety of different stimulation conditions. We used several stimulation paradigms to compare the spatial specificity of CBV versus BOLD activation maps in macaque area V1 at 4.7 T. We observed that: (1) CBV modulation is relatively stronger in deep cortical layers compared with BOLD, in agreement with studies in cats (Harel et al, 2006) and rodents (Lu et al, 2004; Mandeville and Marota, 1999) and (2) surprisingly, under large surround stimulation conditions, CBV maps extend along the cortical surface to cover large (\&gt;10 mm) regions of the cortex that are devoid of significant BOLD modulation. We conclude that the spatial profiles of BOLD and CBV activity maps do not coregister across all stimulus conditions, and therefore do not necessarily represent equivalent transforms of the neural response. Cerebral blood volume maps should be interpreted with care, in the context of the particular experimental paradigm applied.}, department = {Department Logothetis}, web_url = {http://www.nature.com/jcbfm/journal/v27/n6/pdf/9600434a.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1038/sj.jcbfm.9600434}, author = {Smirnakis, SM and Schmid, MC and Weber, B and Tolias, AS and Augath, M and Logothetis, NK} } @Article { 3793, title = {18F-Choline Images Murine Atherosclerotic Plaques Ex Vivo}, journal = {Arteriosclerosis, Thrombosis, and Vascular Biology}, year = {2006}, month = {3}, volume = {26}, number = {3}, pages = {584-589}, abstract = {Objective— Current imaging modalities of atherosclerosis mainly visualize plaque morphology. Valuable insight into plaque biology was achieved by visualizing enhanced metabolism in plaque-derived macrophages using 18F-fluorodeoxyglucose (18F-FDG). Similarly, enhanced uptake of 18F-fluorocholine (18F-FCH) was associated with macrophages surrounding an abscess. As macrophages are important determinants of plaque vulnerability, we tested 18F-FCH for plaque imaging. Methods and Results— We injected 18F-FCH (n=5) or 18F-FDG (n=5) intravenously into atherosclerotic apolipoprotein E-deficient mice. En face measurements of aortae isolated 20 minutes after 18F-FCH injections demonstrated an excellent correlation between fat stainings and autoradiographies (r=0.842, P}, web_url = {http://atvb.ahajournals.org/cgi/reprint/26/3/584}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1161/01.ATV.0000200106.34016.18}, author = {Matter, C and Wyss, M and Spath, N and von Lukowicz, T and Lohmann, C and Weber, B and de Molina, AR and Ametamey, SM and von Schulthess, GK and Kaufmann, PA and Buck, A} } @Article { 3792, title = {Lateralized and frequency-dependent effects of prefrontal rTMS on regional cerebral blood flow}, journal = {Neuroimage}, year = {2006}, month = {2}, volume = {31}, number = {2}, pages = {641-648}, abstract = {Repetitive transcranial magnetic stimulation (rTMS) is a means to study the function and connectivity of brain areas. The present study addressed the question of hemispheric asymmetry of frontal regions and aimed to further understand the acute effects of high- and low-frequency rTMS on regional cerebral blood flow (rCBF). Sixteen healthy right-handed men were imaged using H215O positron emission tomography (PET) immediately after stimulation. High (10 Hz)- and low (1 Hz)-frequency suprathreshold short-duration rTMS was applied over either the left or right dorsolateral prefrontal cortex (DLPFC). Slow and fast rTMS applied over the left DLPFC significantly increased CBF in the stimulated area. Compared to baseline, slow rTMS induced a significant increase in CBF contralateral to the stimulation site, in the right caudate body and in the anterior cingulum. Furthermore, slow rTMS decreased CBF in the orbitofrontal cortex (OFC, ipsilateral to stimulation side). Fast rTMS applied over the right DLPFC was associat ed with increased activity at the stimulation site, in the bilateral orbitofrontal cortex and in the left medial thalamus compared to 1-Hz rTMS. These results show that rCBF changes induced by prefrontal rTMS differ upon hemisphere stimulated and vary with stimulation frequency. These differential neurophysiological effects of short-train rTMS with respect to side and frequency suggest hemisphere-dependent functional circuits of frontal cortico-subcortical areas.}, web_url = {http://www.sciencedirect.com/science?_ob=MImg\&_imagekey=B6WNP-4JB9MXN-1-5\&_cdi=6968\&_user=29041\&_orig=search\&_coverDate=06\%2F30\%2F2006\&_sk=999689997\&view=c\&wchp=dGLzVzz-zSkzk\&md5=f990af87573458a9cb93aac346649d52\&ie=}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, language = {en}, DOI = {10.1016/j.neuroimage.2005.12.025}, author = {Knoch, D and Treyer, V and Regard, M and M{\"u}ri, R and Buck, A and Weber, B} } @Article { 3654, title = {Laser speckle imaging with an active noise reduction scheme}, journal = {Optics Express}, year = {2005}, month = {11}, volume = {13}, number = {24}, pages = {9782-9787}, abstract = {We present an optical scheme to actively suppress statistical noise in Laser Speckle Imaging (LSI). This is achieved by illuminating the object surface through a diffuser. Slow rotation of the diffuser leads to statistically independent surface speckles on time scales that can be selected by the rotation speed. Active suppression of statistical noise is achieved by accumulating data over time. We present experimental data on speckle contrast and noise for a dynamically homogenous and a heterogeneous object made from Teflon. We show experimentally that for our scheme spatial and temporal averaging provide the same statistical weight to reduce the noise in LSI: The standard deviation of the speckle contrast value scales with the effective number N of independent speckle as 1/\(\sqrt{}\)N.}, department = {Department Logothetis}, web_url = {https://www.osapublishing.org/oe/viewmedia.cfm?uri=oe-13-24-9782\&seq=0}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1364/OPEX.13.009782}, author = {Voelker, AC and Zakharov, P and Weber, B and Buck, A and Scheffold, F} } @Article { 2648, title = {Attention and interhemispheric transfer: A behavioral and fMRI study}, journal = {Journal of Cognitive Neuroscience}, year = {2005}, month = {1}, volume = {17}, number = {1}, pages = {113-123}, abstract = {When both detections and responses to visual stimuli are performed within one and the same hemisphere, manual reaction times (RTs) are faster than when the two operations are carried out in different hemispheres. A widely accepted explanation for this difference is that it reflects the time lost in callosal transmission. Interhemispheric transfer time can be estimated by subtracting RTs for uncrossed from RTs for crossed responses (crossed – uncrossed difference, or CUD). In the present study, we wanted to ascertain the role of spatial attention in affecting the CUD and to chart the brain areas whose activity is related to these attentional effects on interhemispheric transfer. To accomplish this, we varied the proportion of crossed and uncrossed trials in different blocks. With this paradigm subjects are likely to focus attention either on the hemifield contralateral to the responding hand (blocks with 80\% crossed trials) or on the ipsilateral hemifield (blocks with 80\% uncrossed trials). We found an inverse correlation between the proportion of crossed trials in a block and the CUD and this effect can be attributed to spatial attention. As to the imaging results, we found that in the crossed minus uncrossed subtraction, an operation that highlights the neural processes underlying interhemispheric transfer, there was an activation of the genu of the corpus callosum as well as of a series of cortical areas. In a further commonality analysis, we assessed those areas which were activated specifically during focusing of attention onto one hemifield either contra- or ipsilateral to the responding hand. We found an activation of a number of cortical and subcortical areas, notably, parietal area BA 7 and the superior colliculi. We believe that the main thrust of the present study is to have teased apart areas important in interhemispheric transmission from those involved in spatial attention.}, web_url = {http://www.mitpressjournals.org/doi/abs/10.1162/0898929052880002}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1162/0898929052880002}, author = {Weber, B and Treyer, V and Oberholzer, N and Jaermann, T and Boesiger, P and Brugger, P and Regard, M and Savazzi, S and Marzi, CA} } @Article { 2649, title = {18F-choline in experimental soft tissue infection assessed with autoradiography and high-resolution PET}, journal = {Eur J Nucl Med Mol Imaging}, year = {2004}, volume = {31}, pages = {312-316}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Wyss, M and Weber, B and Honer, M and Spaeth, N and Ametamey, S and Westera, G and Bode, B and Kaim, AK and Buck, A} } @Article { 2647, title = {Constant infusion H215O PET and acetazolamide challenge in the assessment of the cerebral perfusion status}, journal = {Journal of Nuclear Medicine}, year = {2004}, number = {45}, pages = {1344-1349}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weber, B and Westera, G and Treyer, V and Burger, C and Kahn, N and Buck, A} } @Article { 3059, title = {Influence of ceftriaxone treatment on FDG uptake - An in vivo 18F-fluorodeoxyglucose study in soft tissue infections in rats}, journal = {Nucl Med Biol}, year = {2004}, volume = {31}, pages = {875-882}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Wyss, M and Honer, M and Spath, N and Gottschalk, J and Ametamey, SM and Weber, B and von Schulthess, GK and Buck, A and Kaim, AH} } @Article { 2881, title = {Optical Imaging of the Spatiotemporal Dynamics of Cerebral Blood Flow and Oxidative Metabolism in the Rat Barrel Cortex}, journal = {European Journal of Neuroscience}, year = {2004}, volume = {20}, number = {10}, pages = {2664-2670}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/pdf2881.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weber, B and Burger, C and Wyss, M and von Schulthess, GK and Scheffold, F and Buck, A} } @Article { 2996, title = {Uptake of 18F-Fluorocholine, 18F-Fluoroethyl-L-Tyrosine, and 18F-FDG in Acute Cerebral Radiation Injury in the Rat: Implications for Separation of Radiation Necrosis from Tumor Recurrence}, journal = {Journal of Nuclear Medicine}, year = {2004}, volume = {45}, number = {11}, pages = {1931-1938}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Spaeth, N and Wyss, MT and Weber, B and Scheidegger, S and Lutz, A and Verwey, J and Radovanovic, I and Pahnke, J and Wild, D and Westera, G and Weishaupt, D and Hermann, DM and Kaser-Hotz, B and Aguzzi, A and Buck, A} } @Article { 2997, title = {VEGF overexpression induces post-ischaemic neuroprotection, but facilitates haemodynamic steal phenomena}, journal = {Brain}, year = {2004}, volume = {128}, pages = {52-63}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Wang, Y and Kilic, E and Kilic, U and Weber, B and Bassetti, CL and Marti, HH and Hermann, DM} } @Article { 2650, title = {Quantitative Cerebral Blood Flow Measurements in the Rat Using a Beta-Probe and H215O}, journal = {Journal of Cerebral Blood Flow and Metabolism}, year = {2003}, month = {12}, volume = {23}, number = {12}, pages = {1455-1460}, abstract = {Beta-probes are a relatively new tool for tracer kinetic studies in animals. They are highly suited to evaluate new positron emission tomography tracers or measure physiologic parameters at rest and after some kind of stimulation or intervention. In many of these experiments, the knowledge of CBF is highly important. Thus, the purpose of this study was to evaluate the method of CBF measurements using a beta-probe and H215O. CBF was measured in the barrel cortex of eight rats at baseline and after acetazolamide challenge. Trigeminal nerve stimulation was additionally performed in five animals. In each category, three injections of 250 to 300 MBq H215O were performed at 10-minute intervals. Data were analyzed using a standard one-tissue compartment model (K1 = CBF, k2 = CBF/p, where p is the partition coefficient). Values for K1 were 0.35 plusminus 0.09, 0.58 plusminus 0.16, and 0.49 plusminus 0.03 mL dot min-1 dot mL-1 at rest, after acetazolamide challenge, and during trigeminal nerve stimulation, respectively. The corresponding values for k2 were 0.55 plusminus 0.12, 0.94 plusminus 0.16, and 0.85 plusminus 0.12 min-7, and for p were 0.64 plusminus 0.05, 0.61 plusminus 0.07, and 0.59 plusminus 0.06.The standard deviation of the difference between two successive experiments, a measure for the reproducibility of the method, was 10.1\%, 13.0\%, and 5.7\% for K1, k2, and p, respectively. In summary, beta-probes in conjunction with H215O allow the reproducible quantitative measurement of CBF, although some systematic underestimation seems to occur, probably because of partial volume effects.}, web_url = {http://www.nature.com/jcbfm/journal/v23/n12/pdf/9591495a.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, DOI = {10.1097/01.WCB.0000095799.98378.7D}, author = {Weber, B and Spaeth, N and Wyss, MT and Wild, D and Burger, C and Stanley, R and Buck, A} } @Article { 2651, title = {Functional neuroimaging predicts individual memory outcome after amygdalohippocampectomy}, journal = {Neuroreport}, year = {2003}, volume = {14}, pages = {1197-2002}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Henke, K and Treyer, V and Weber, B and Nitsch, RM and Hock, C and Wieser, HG and Buck, A} } @Article { 2655, title = {(18)F-FDG and (18)F-FET uptake in experimental soft tissue infection}, journal = {J Nucl Med Mol Imaging}, year = {2002}, volume = {29}, pages = {648-654}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Kaim, AK and Weber, B and Kurrer, MO and Westera, G and Schweizer, A and Gottschalk, J and VSG and Buck, A} } @Article { 2652, title = {A femoral arteriovenous shunt facilitates arterial whole blood sampling in animals}, journal = {Eur J Nucl Med Mol Imaging}, year = {2002}, volume = {29}, pages = {319-323}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weber, B and Burger, C and Biro, P and Buck, A} } @Article { 2654, title = {Autoradiographic quantification of 18F-FDG uptake in experimental soft-tissue abscesses in rats}, journal = {Radiology}, year = {2002}, volume = {223}, pages = {446-451}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Kaim, AK and Weber, B and Kurrer, MO and Gottschalk, J and von Schulthess, GK and Buck, A} } @Article { 2653, title = {White matter glucose metabolism during intracortical electrostimulation: a quantitative [(18)F]Fluorodeoxyglucose autoradiography study in the rat}, journal = {Neuroimage}, year = {2002}, volume = {16}, pages = {993-998}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/pdf2653.pdf}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weber, B and Fouad, K and Burger, C and Buck, A} } @Article { 2656, title = {Effects of vigabatrin on brain GABA+/CR signals in patients with epilepsy monitored by 1H-NMR-spectroscopy: responder characteristics}, journal = {Epilepsia}, year = {2001}, volume = {42}, pages = {29-40}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Mueller, SG and Weber, OM and Duc, CO and Weber, B and Meier, D and Russ, W and Boesiger, P and Wieser, HG} } @Article { 2657, title = {Hierarchical visual processing is dependent on the oculomotor system}, journal = {Neuroreport}, year = {2000}, volume = {11}, pages = {241-247}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weber, B and Schwarz, U and Kneifel, S and Treyer, V and Buck, A} } @Article { 2658, title = {Human hippocampus associates information in memory}, journal = {Proceedings of the National Acadamy of Sciences of the United States of America}, year = {1999}, month = {5}, volume = {96}, number = {10}, pages = {5884-5889}, abstract = {The hippocampal formation, one of the most complex and vulnerable brain structures, is recognized as a crucial brain area subserving human long-term memory. Yet, its specific functions in memory are controversial. Recent experimental results suggest that the hippocampal contribution to human memory is limited to episodic memory, novelty detection, semantic (deep) processing of information, and spatial memory. We measured the regional cerebral blood flow by positron-emission tomography while healthy volunteers learned pairs of words with different learning strategies. These led to different forms of learning, allowing us to test the degree to which they challenge hippocampal function. Neither novelty detection nor depth of processing activated the hippocampal formation as much as semantically associating the primarily unrelated words in memory. This is compelling evidence for another function of the human hippocampal formation in memory: establishing semantic associations.}, web_url = {http://www.ncbi.nlm.nih.gov/pmc/articles/PMC21955/}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Henke, K and Weber, B and Kneifel, S and Wieser, HG and Buck, A} } @Article { 2659, title = {Context-dependent force coding in motor and premotor cortical areas}, journal = {Exp Brain Res}, year = {1999}, volume = {128}, pages = {123-133}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Hepp-Reymond, M-C and Kirkpatrick-Tanner, M and Gabernet, L and Qi, HX and Weber, B} } @Article { 2665, title = {Electroencephalograms in epilepsy: analysis and seizure prediction within the framework of Lyapunov theory}, journal = {Physica D}, year = {1999}, volume = {130}, pages = {291-305}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Moser, HR and Weber, B and Wieser, HG and Meier, PF} } @Article { 2663, title = {Changes of cerebral blood flow during short-term exposure to normobaric hypoxia}, journal = {J Cereb Blood Flow Metab}, year = {1998}, volume = {18}, pages = {906-910}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Buck, A and Schirlo, C and Jasinsky, V and Weber, B and Burger, C and von Schulthess, GK and Koller, EA and Pavlicek, V} } @Article { 2662, title = {Monoamine oxidase B single-photon emission tomography with [123I]Ro 43-0463: imaging in volunteers and patients with temporal lobe epilepsy}, journal = {Eur J Nucl Med}, year = {1998}, volume = {25}, pages = {464-470}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Buck, A and Frey, LD and Blaeuenstein, P and Kramer, G and Siegel, A and Weber, B and Schubiger, PA and Wieser, HG} } @Article { 2661, title = {Neuronal complexity loss in interictal EEG recorded with foramen ovale electrodes predicts side of primary epileptogenic area in temporal lobe epilepsy: a replication study}, journal = {Epilepsia}, year = {1998}, volume = {39}, pages = {922-927}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Weber, B and Lehnertz, K and Elger, CE and Wieser, HG} } @Article { 2660, title = {PET with 18fluorodeoxyglucose and hexamethylpropylene amine oxime SPECT in late whiplash syndrome}, journal = {Neurology}, year = {1998}, volume = {51}, pages = {345-350}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Bicik, I and Radanov, BP and Schaefer, N and Dvorak, J and Blum, B and Weber, B and Burger, C and von Schulthess, GK and Buck, A} } @Article { 2664, title = {Human hippocampus establishes associations in memory}, journal = {Hippocampus}, year = {1997}, volume = {7}, pages = {249-256}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, author = {Henke, K and Buck, A and Weber, B and Wieser, HG} } @Poster { 6170, title = {Systematic investigation of vascular corrosion casts of the macaque monkey brain}, year = {2008}, month = {7}, volume = {6}, number = {130.8}, abstract = {Introduction: In the past, the structural properties of the cerebral microvasculature have been analyzed using a wide range of anatomical methods, each revealing differential aspects of this system. Here, we used the corrosion cast technique to characterize the arrangement and organization of the blood vessels and the ratio of arteries and veins in different parts of the macaque’s brain. Methods: Following standard perfusion with saline, two adult monkeys (Macaca nemestrina) were injected with Batson’s \#17 resin. After polymerization the brains were extracted, deep-frozen and serial 5 mm thick slabs were cut coronally or horizontally with a dedicated tissue knife. The cut surface was matched with the monkey brain atlas (Saleem, 2006). The slabs were then macerated using 5\% KOH until all tissue was removed, frozen in distilled water and trimmed with a sliding microtome to obtain an even surface. After complete drying, anatomical areas were identified and cut from the slabs, sputter coated with gold and imaged with the use of a scanning electron microscope. Results: The general vascular organization was found to be very similar to that of the human brain as described by Duvernoy (1981). The same classes of vessels (depending on penetration depth and branching points) could be identified. The mean ratio of cortical arteries and veins was found to be 1: \verb=~=1.6, with arteries being the more numerous vessel type. The average irrigation volume of a large penetrating artery was estimated to be 0.44 mm*, whereas the draining volume of a large cortical vein was found to be 0.70 mm*. Different subcortical regions (e. g. LGN) could be identified solely on the basis of the arrangement of blood vessels that clearly followed the shape of the structure. Discussion: The applied method allows for a qualitative description of the general organization principles of the brain’s vasculature, as well as for the estimation of the ratio between arterial and venous vessels.}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/fens2008_[0].pdf}, department = {Department Logothetis}, web_url = {http://fens2008.neurosciences.asso.fr/}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {Geneva, Switzerland}, event_name = {6th Forum of European Neuroscience (FENS 2008)}, author = {Keller, AL and Weber, B and Logothetis, NK} } @Poster { BeedKGSLw2007, title = {Topological tree-analysis of the microvascular system in macaque visual cortex}, journal = {Neuroforum}, year = {2007}, month = {4}, volume = {13}, number = {Supplement}, pages = {736}, abstract = {For a profound understanding of functional brain imaging in research and in clinical applications, investigations of neurovascular coupling are mandatory. Three-dimensional tree-analysis of cortical vasculature elucidates the structural aspects of neurovascular coupling such as the organization of the cortical vasculature and network topology. Here we report a technique to obtain high resolution tomographic images of the cerebral vasculature, accurate reconstructions of the whole vasculature and extraction of vessel attributes to reliably quantitate large vascular networks. Non-human primate (Macaca mulatta) brains were collected and processed. Samples were punched from the primary visual cortex and scanned at the material science beamline of the Swiss Light Source to yield X-ray tomographic images for 3D reconstruction of the vasculature. Key vessel parameters have been evaluated for different levels of analysis (from single samples to grouped data). The diameter and length distributions of the cortical vessels indicated a high percentage of capillaries. Layer 4c\(\beta\) had the highest density of capillary and noncapillary vessels in comparison to the other cortical layers. Mean volume fraction was 2.5\% for cortical gray matter. Extravascular distance measure yielded an average mesh size of 56 \(\mu\)m. Branching pattern analyses have been performed for single vessels extracted from whole networks for investigation of network geometry. In conclusion, these results indicate the reliability of the technique in studying cortical vasculature. The results were in good agreement with histological data as well as with data from the literature. Quantitative three-dimensional morphometry of vascular networks is critical for future blood flow modeling in the cerebral cortex.}, department = {Department Logothetis}, web_url = {http://nwg.glia.mdc-berlin.de/media/pdf/conference/Proceedings-Goettingen2007.pdf}, event_place = {G{\"o}ttingen, Germany}, event_name = {7th Meeting of the German Neuroscience Society, 31st G{\"o}ttingen Neurobiology Conference}, author = {Beed, P and Keller, AL and Groso, A and Stampanoni, M and Logothetis, NK and Weber, B} } @Poster { 4242, title = {Vascular density in regions of different levels of oxidative metabolism within the macaque primary visual cortex}, year = {2006}, month = {10}, volume = {36}, number = {363.8}, abstract = {Introduction: The primary visual cortex of the primate shows distinct regions of increased cytochrome oxidase activity, the so called “blobs”. When visualized in tangential sections the blobs form a pattern of regularly distributed patches which are most prominent in the third cortical layer. Since cytochrome oxidase is an enzyme of the oxidative chain, increased local enzyme activity indicates an increased metabolic activity of a given region. It has been shown in the squirrel monkey cortex that this metabolic difference is reflected in the density of the cortical vascularization. The aim of this study was to replicate and extend this finding with a quantitative and layer specific assessment of the vascular density in blob and interblob regions. Methods: Formalin-fixed frozen sections of 2 animals (M. mulatta) were first stained with the classical cytochrome oxidase staining method that uses the enzyme activity to precipitate DAB. The sections were then further processed for fluorescence immunohistochemistry. They were incubated with anti-collagen type IV and a Cy3-conjugated secondary antibody to stain for blood vessels. Epifluorescence micrographs were taken and the vessels were manually and automatically delineated. The length density (mm/mm³) and volume fraction (mm³/mm³) of vessels was taken as a measure for the vascular density. The blobs were determined in the corresponding brightfield micrograph of the same section on the basis of the cytochrome oxidase stain. Results: The vascular length density and volume fraction was significantly higher inside the blobs as compared to the interblob regions (paired t-test, p<0.001). The absolute values were 535.2 +/-57.8 mm/mm³ (mean +/- SD of 2 animals) for the blobs and 485.5 +/- 51.2 mm/mm³ for interblob areas, which is 108.7 \% for blobs and 98.1 \% for interblobs of the overall mean vascular length density in V1. The blob-interblob difference was most prominent in cortical layer IV. Conclusion: In summary, the blobs’ vascular density is significantly higher as compared to the surrounding cortex in V1. This reflects an adaptation of blood supply in these metabolically and most likely also functionally different regions of V1. However, the measured difference is considerably smaller when compared to the previously published data. This discrepancy could be due inter-species or methodological differences between the studies.}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/SfN2006_AnnaLenaKeller_4242[0].pdf}, department = {Department Logothetis}, web_url = {http://www.sfn.org/index.aspx?pagename=abstracts_ampublications}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {Atlanta, GA, USA}, event_name = {36th Annual Meeting of the Society for Neuroscience (Neuroscience 2006)}, language = {en}, author = {Keller, AL and Logothetis, NK and Weber, B} } @Poster { 4243, title = {Quantitative aspects of the microvascular system in macaque visual cortex}, year = {2006}, month = {7}, volume = {5}, number = {A179.27}, pages = {179}, abstract = {The basic principle of the most frequently used functional neuroimaging methods is the brain’s local dynamic regulation of blood flow. For a correct interpretation of neuroimaging results the structural and functional neurovascular coupling underlying this regulation must be well understood. Here we report quantitative anatomical data of the microvasculature in the macaque visual cortex. Formalin-fixed frozen sections of 4 animals (M. mulatta) were processed for double fluorescence immunohistochemistry. Sections were incubated with anti-collagen type IV and DAPI to stain for vessels and cell nuclei. In one additional animal, the anti-collagen procedure was combined with cytochrome oxidase staining in V1. The length density (LD), surface density (SD), volume fraction (VF) and diameter (D) of the vessels were stereologically determined. Furthermore, synchrotron-based computed tomographies (SRCT) of formalin-fixed and barium sulfate-perfused brain samples from another 2 animals were used to corroborate the histological results. In V1, the vascular density was highest in layer IVc- (LD 674.7 mm/mm3, SD 15.2 mm2/mm3, VF 2.6 \%, D 7.2 microns) and lowest in layer I (LD 461.5 mm/mm3, SD 10.9 mm2/mm3, VF 1.9 \%, D 7.5 microns). In all extrastriate visual areas analyzed (V2, V3, V4, V5), the vascular density was generally lower, and the difference between layer IV and the remaining layers was less prominent when compared to V1. These density values were similar compared to the ones tomographically obtained from SRCT. The vascular density in cytochrome oxidase rich blobs in V1 was 14 \% higher as compared to the interblob region. In summary, V1 is different from all extrastriate areas analyzed with respect to the laminar vessel distribution and overall vascular density. Differences between extrastriate areas were negligible. The overall vascular volume fraction in visual cortex derived from immunostaining was approximately 2 \%, a value that was well reproduced by the SRCT.}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/FENS2006_BrunoWeber_4243[0].pdf}, department = {Department Logothetis}, web_url = {http://fens2006.neurosciences.asso.fr/}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {Wien, Austria}, event_name = {5th Forum of European Neuroscience (FENS 2006)}, language = {en}, author = {Weber, B and Keller, AL and Groso, A and Stampanoni, M and Logothetis, NK} } @Poster { 3842, title = {Area- and layer-specific vascular density in the macaque striate and extrastriate cortex}, year = {2005}, month = {11}, volume = {35}, number = {456.9}, abstract = {Introduction: Most functional neuroimaging methods, including fMRI, rely on the hemodynamic response following neural activation. Consequently in order to correctly interpret the results of neuroimaging experiments both the functional and the structural neurovascular coupling must be well understood. The former includes the degree and density of cortical vascularization. Here we studied the layer and area specific vascular differences in areas V1, V2, V3, V4 and V5 in the macaque monkey. Methods: Formalin-fixed frozen sections of 4 animals (M. mulatta) were processed for double fluorescence immunohistochemistry. Sections were incubated with anti-collagen type IV and DAPI to stain for vessels and cell nuclei. The length density (mm/mm³) of vessels was taken as a measure for vascular density. Layer and area specific regions of interest were determined on the basis of the DAPI stain and if necesary with the help of consecutive Nissl and myelin stains. Results: The procedure yielded high quality vessel-specific images with excellent reproducibility within and between animals. In V1, the vascular density was highest in layer IVc-\(\beta\) (871.9 +/- 47.1 mm/mm³, mean +/- sd of 4 animals) and lowest in layer I (587.17 +/- 31.7 mm/mm³). In all extrastriate visual areas analyzed, the vascular density was generally lower, and the difference between layer IV and the remaining layers was less prominent when compared to V1. The vascular length density in V2 was 674.0 +/- 31.8 mm/mm³ in layer IV and 585.1 +/- 40.0 mm/mm³ in layer I. As a further example, in V5 672.7 +/- 41.6 mm/mm³ was measured in layer IV and 584.0 +/- 52.0 mm/mm³ in layer I. Conclusion: In summary, V1 was clearly different from all extrastriate areas analyzed with respect to the laminar vessel distribution and the overall vascular density. Differences between extrastriate areas were negligible. The influence of differences in vascularization on the neuroimaging signals remains largely unknown. However, this study suggests that caution is advised particularly when response patterns are compared between V1 and extrastriate areas.}, department = {Department Logothetis}, web_url = {http://www.sfn.org/absarchive/}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, institution = {Society for Neuroscience}, event_place = {Washington, DC, USA}, event_name = {35th Annual Meeting of the Society for Neuroscience (Neuroscience 2005)}, language = {en}, author = {Weber, B and Keller, AL and Logothetis, NK} } @Conference { 4290, title = {Application of two-compartmental model on non-human primate perfusion data: quantification and sensitivity mapping}, journal = {Magnetic Resonance Materials in Physics, Biology and Medicine}, year = {2006}, month = {9}, day = {22}, volume = {19}, number = {Supplement 1}, pages = {121-122}, abstract = {Quantification of cerebral blood flow (CBF) using magnetic resonance imaging still suffers from many unresolved methodological issues. In this study we report the successful modeling of monkey CBF data, using the two-compartmental model introduced by Parkes et al. [1]. Absolute flow and transit times were derived including uncertainties of the assumed parameters as well as the signal noise. The precision of the model's result was investigated and an acquisition paradigm to maximize the information content is proposed.}, url = {http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/ESMRMb2006_Johannes_Reichold_[0].pdf}, department = {Department Logothetis}, talk_type = {Abstract Talk}, web_url = {http://www.esmrmb.org/index.php?id=/en/post_conference_information/2006/esmrmb_2006_congress.htm}, institute = {Biologische Kybernetik}, organization = {Max-Planck-Gesellschaft}, event_place = {Warsaw, Poland}, event_name = {23rd Annual Scientific Meeting of the ESMRMB 2006}, language = {en}, DOI = {10.1007/s10334-006-0041-3}, author = {Reichold, J and Zappe, A-C and Burger, C and Weber, B and Buck, A and Pfeuffer, J and Logothetis, NK} } @Conference { Weber2005, title = {High Resolution Analyses of Cerebral Blood Vessels and Blood Flow}, year = {2005}, month = {9}, pages = {186}, abstract = {Introduction: The hemodynamic response following neural activation is the basis for most functional neuroimaging methods, including functional magnetic resonance imaging (fMRI). Consequently, in order to correctly interpret the results of neuroimaging experiments both the functional and the structural neurovascular coupling must be well understood. The degree and density of cortical vascularization should be compared with high resolution maps of blood flow changes induced by neural activation. In this presentation, methods will be described that try to elucidate this coupling using ex-vivo and in-vivo approaches. Methods: Ex-vivo experiments: Formalin-fixed frozen sections of brain tissue (macaque monkey) were processed for anti-collagen type IV fluorescence immunohistochemistry to stain for vessels. Digital image processing was applied to compute the length density [m/m3], surface density [m2/m3], volume fraction [m3/m3], and mean diameter [m] of the vessels. Scanning electron microscopic analyses of intravascular polymer fillings and synchrotron-based micro-CT (using a voxel size of 1.4 m) have been performed using monkey and rat tissue and the results were compared with the data obtained from the histological methods. In-vivo experiments: Laser speckle contrast imaging was applied in the rat barrel cortex and blood flow changes in response to single vibrissa deflection were recorded with sub-second and sub-millimeter resolution. Results: Ex-vivo experiments: The immunohistochemical staining procedure yielded vessel-specific images of high quality and reproducibility within and between animals. The vascular density is in close relationship with the steady-state metabolic demand of the particular region, as can be seen in the high vascular density of layer IV (the layer with the highest cell density) in all visual cortices of the macaque monkey. The quantification of the synchrotron-based micro-CTs confirms the histologically obtained results and renders a true 3D-analysis possible. In-vivo experiments: Laser speckle contrast imaging provides blood flow maps with a high signal-to-noise ratio, making single trial analysis feasible. The spatial resolution of the method is excellent as neighboring cortical columns could be differentiated. Conclusion: Several high resolution approaches to study structural and functional aspects of the cortical vasculature have been successfully implemented. The influence of differences in vascularization on the neuroimaging signals is of utmost importance but remains largely unknown. Future work will involve modeling approaches on the basis of the three dimensional vascular architecture (obtained from synchrotron-based micro-CT) to understand the basic mechanisms that are used by the brain to locally regulate the blood flow. Precise in-vivo measurements of the flow changes (obtained from laser speckle contrast imaging) will in turn be necessary to validate these modeling results.}, department = {Department Logothetis}, talk_type = {Abstract Talk}, web_url = {http://istina.msu.ru/media/publications/article/7ff/9ff/25323684/AbstractBookScreen.pdf}, event_place = {Davos, Switzerland}, event_name = {Microscopy Conference 2005: 6. Dreil{\"a}ndertagung}, author = {Weber, B} } @Conference { KellerWL2005, title = {Quantification of the Layer Specific Vascular Density using anti-Collagen Fluorescence Immunohistochemistry in the Primate Striate and Extrastriate Cortex}, year = {2005}, month = {9}, pages = {177}, abstract = {Introduction: Non-invasive functional neuroimaging methods such as functional magnetic resonance imaging (fMRI) have become indispensable tools for the neurosciences. The underlying principle of the most frequently used methods is the brain’s local, dynamic regulation of blood flow. The correct interpretation of the neuroimaging results requires an in-depth understanding of the structural and functional neurovascular coupling underlying this regulation. The structural coupling, among others, presumes a close mach between the vascular density and the steady-state metabolic activity of a given region (e.g. a tangential or laminar subdivision). Here we studied the layer and area specificity of vascularization of V1, V2, V3, V4 and V5 in macaques. Methods: Formalin-fixed frozen sections (60}, department = {Department Logothetis}, talk_type = {Abstract Talk}, web_url = {http://istina.msu.ru/media/publications/article/7ff/9ff/25323684/AbstractBookScreen.pdf}, event_place = {Davos, Switzerland}, event_name = {Microscopy Conference 2005: 6. Dreil{\"a}ndertagung}, author = {Keller, AL and Weber, B and Logothetis, NK} }