ValverdeSalzmannBLS2012 3 MF Valverde Salzmann A Bartels NK Logothetis A Schüz 2012-06-00 23 32 7881 7894 Journal of Neuroscience Color vision is reserved to only few mammals, such as Old World monkeys and humans. Most Old World monkeys are trichromats. Among them, macaques were shown to exhibit functional domains of color-selectivity, in areas V1 and V2 of the visual cortex. Such color domains have not yet been shown in New World monkeys. In marmosets a sex-linked dichotomy results in dichromatic and trichromatic genotypes, rendering most male marmosets color-blind. Here we used trichromatic female marmosets to examine the intrinsic signal response in V1 and V2 to chromatic and achromatic stimuli, using optical imaging. To activate the subsystems individually, we used spatially homogeneous isoluminant color opponent (red/green, blue/yellow) and hue versus achromatic flicker (red/gray, green/gray, blue/gray, yellow/gray), as well as achromatic luminance flicker. In contrast to previous optical imaging studies in marmosets, we find clearly segregated color domains, similar to those seen in macaques. Red/green and red/gray flicker were found to be the appropriate stimulus for revealing color domains in single-condition maps. Blue/gray and blue/yellow flicker stimuli resulted in faint patch-patterns. A recently described multimodal vessel mapping approach allowed for an accurate alignment of the functional and anatomical datasets. Color domains were tightly colocalized with cytochrome oxidase blobs in V1 and with thin stripes in V2. Thus, our findings are in accord with 2-Deoxy-d-glucose studies performed in V1 of macaques and studies on color representation in V2. Our results suggest a similar organization of early cortical color processing in trichromats of both Old World and New World monkeys. no notspecified http://www.kyb.tuebingen.mpg.de/ published 13 15017 15421 ValverdeSalzmannWLS2011 3 MF Valverde Salzmann DJ Wallace NK Logothetis A Schüz 2011-09-00 1 201 159 172 Journal of Neuroscience Methods Imaging technologies, such as intrinsic optical imaging (IOI), functional magnetic resonance imaging (fMRI) or multiphoton microscopy provide excellent opportunities to study the relationship between functional signals recorded from a cortical area and the underlying anatomical structure. This, in turn, requires accurate alignment of the recorded functional imaging data with histological datasets from the imaged tissue obtained after the functional experiment. This alignment is complicated by distortions of the tissue which naturally occur during histological treatment, and is particularly difficult to achieve over large cortical areas, such as primate visual areas. We present here a method that uses IOI vessel maps revealed in the time course of the intrinsic signal, in combination with vascular casts and vascular lumen labeling techniques together with a pseudo three dimensional (p3D) reconstruction of the tissue architecture in order to facilitate alignment of IOI data with posthoc histological datasets. We demonstrate that by such a multimodal vessel mapping approach, we are able to constitute a hook in anatomical-functional data alignment that enables the accurate assignment of functional signals over large cortical regions. As an example, we present precise alignments of IOI responses showing orientation selectivity of primate V1 with anatomical sections stained for cytochrome-oxidase-reactivity. no notspecified http://www.kyb.tuebingen.mpg.de/ published 13 15017 15421 15017 18825 ValverdeSalzmannBLS2012_2 7 MF Valverde Salzmann A Bartels NK Logothetis A Schüz New Orleans, LA, USA2012-10-00 42nd Annual Meeting of the Society for Neuroscience (Neuroscience 2012) Color vision is reserved to only few mammals, such as Old World monkeys and humans. Most Old World monkeys are trichromats. Among them, macaques were shown to exhibit functional domains of color-selectivity, in areas V1 and V2 of the visual cortex. Such color domains have not yet been shown in New World monkeys. In marmosets a sex-linked dichotomy results in dichromatic and trichromatic genotypes, rendering most male marmosets color-blind. Here we used trichromatic female marmosets to examine the intrinsic signal response in V1 and V2 to chromatic and achromatic stimuli, using optical imaging. In order to activate the visual subsystems individually, we used spatially homogeneous isoluminant color opponent (red/green, blue/yellow) and hue versus achromatic flicker (red/gray, green/gray, blue/gray, yellow/gray), as well as achromatic luminance flicker. In contrast to previous optical imaging studies in marmosets, we find clearly segregated color domains, similar to those seen in macaques. Red/green and red/gray flicker were found to be the appropriate stimulus for revealing color domains in single condition maps (see figure). Blue/gray and blue/yellow flicker stimuli resulted in faint patch-patterns. A recently described multimodal vessel mapping approach allowed for an accurate alignment of the functional and anatomical datasets. Color domains were tightly colocalized with cytochrome oxidase blobs in V1 and with thin stripes in V2. Thus, our findings are in accord with 2-Deoxy-D-glucose studies performed in V1 of macaques and studies on color representation in V2. Our results suggest a similar organization of early cortical color processing in trichromats of both, Old World and New World monkeys. no notspecified http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/2012/Neuroscience-2012-Valverde.pdf published 0 15017 1882115017 15421 ValverdeSalzmannLP2011 7 MF Valverde Salzmann NK Logothetis R Pohmann Montréal, Canada2011-05-00 19th Annual Meeting and Exhibition of the International Society for Magnetic Resonance in Medicine (ISMRM 2011) While several atlases are available depicting the spatial distribution of various parameters either measured with MRI or from histological section, no comparable comprehensive data exists for the distribution of vessels in the rat brain. Angiography is able to use the blood flow in the brain of the living rat to display the largest arteries, while SWI can visualize veins down to medium size. The aim of this study was to obtain a full picture of vessels even down to relatively small size in the isolated rat brain perfused with contrast agents at ultra-high field. no notspecified http://www.kyb.tuebingen.mpg.de/fileadmin/user_upload/files/publications/ISMRM-2011-2382.pdf published 0 15017 1542115017 18821 4912 7 M Valverde V Braitenberg Trieste, Italy2007-09-00 36 39th Annual General Meeting of the European Brain and Behaviour Society “Optical imaging” maps of the visual cortex after systematic application of variously oriented visual stimuli provide an opportunity to test different hypotheses on the distribution of orientation sensitive neurons over the surface of the cortex. Rectilinear “slabs” of uniform orientation, as postulated in some earlier models, are not supported by the evidence. What is compatible with the optical imaging maps is the arrangement of neurons with different orientation around centers, regularly spaced at distances of about 0.5mm in a hexagonal array. According to the model proposed by [3], the orientations to which the neurons are sensitive should be arranged either radially, or, more likely, like the tangents [1] of circles around said centers, whereby in either case twice the same orientation occurs in opposite positions of the “hypercolumn” thus defined. The centers of the hypercolumns very likely coincide with the so-called cytochrome oxidase “blobs” which are spaced at the same distance. The fact that within these “blobs” orientation tuning of cortical neurons becomes undefined [4], makes the array of orientations around these centers less spectacular, and indeed other interpretations of the coloured maps produced by optical recording were put forward. So-called “pinwheels” stole the show, that is centers around which neurons with different orientation sensitivity crowd with the colours representing their orientation clashing without interposed indifferent regions. In these pinwheels each of the different orientations occurs only once as you go full circle around their center. They most likely correspond to the corners between the hypercolumns in their hexagonal array, and the different orientations within one “pinwheel” most likely belong to three different hypercolumns that meet there [2]. The distinction between the two entities, orientation hypercolumns and pinwheels may sound academic but becomes crucial when one endeavours to underpin orientation specificity of cortical neurons with schemes of neuronal interactions at the elementary level. The accompanying illustration should help the reader to partake in this discussion. no notspecified http://www.kyb.tuebingen.mpg.de/ published -36 15017 1542115017 15423 4859 7 M Valverde V Braitenberg Tübingen, Germany2007-07-00 93 10th Tübinger Wahrnehmungskonferenz (TWK 2007) “Optical imaging” of the visual cortex after application of variously oriented visual stimuli provides an opportunity to test different models of the distribution of orientation sensitive neurons over the surface of the cortex. Rectilinear “slabs” of uniform orientation are not supported by the evidence. What is compatible with the optical imaging is the arrangement of neurons with different orientation around centers, regularly spaced at distances of about 0.5 mm in a hexagonal array. According to a model proposed in 1979 [1], the orientations to which the neurons are sensitive should be arranged either radially, or, more likely, like the tangents [2] of circles around said centers, whereby in either case twice the same orientation occurs in opposite positions of the “hypercolumn” thus defined. For this reason each colour, indicating a certain orientation on the optical recording maps, should form a blotch the shape of two sectors meeting at the center of the hypercolumn. We chose the term “bow tie” for this configuration, to match the facetiousness of the competing term “pinwheel”. The centers of the hypercolumns very likely coincide with the so-called cytochrome oxidase “blobs” which are spaced at the same distance. The fact that within these “blobs” orientation tuning of cortical neurons becomes rather undefined [3], makes the array of orientations around these centers less spectacular, and indeed other interpretations of the coloured maps were put forward. “Pinwheels” stole the show, i.e. centers around which neurons with different orientation sensitivity crowd with the colours representing their orientation clashing without interposed indifferent regions. In these pinwheels each of the different orientations occurs only once as you go full circle around their center. They most likely correspond to the corners between the hypercolumns in their hexagonal array, and the different orientations within one “pinwheel” most likely belong to three different hypercolumns that meet there [4]. The distinction between the two entities, orientation hypercolumns and pinwheels may sound academic but becomes crucial when one endeavours to underpin orientation specificity of cortical neurons with schemes of neuronal interactions at the elementary level. This is fairly easy in the case of the hypercolumns under the assumption that in their centers are housed special inhibitory neurons [2], while a similar elementary scheme was never found as an explanation of the pinwheels. On the coloured maps obtained with “optical recording” it is possible to discern both “pinwheels” and “bow ties” as an aid to the localization of the two types of centers. no notspecified http://www.kyb.tuebingen.mpg.de/ published -93 15017 1542115017 15423