3,040 research outputs found

    Partial Information Decomposition as a Unified Approach to the Specification of Neural Goal Functions

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    In many neural systems anatomical motifs are present repeatedly, but despite their structural similarity they can serve very different tasks. A prime example for such a motif is the canonical microcircuit of six-layered neo-cortex, which is repeated across cortical areas, and is involved in a number of different tasks (e.g.sensory, cognitive, or motor tasks). This observation has spawned interest in finding a common underlying principle, a 'goal function', of information processing implemented in this structure. By definition such a goal function, if universal, cannot be cast in processing-domain specific language (e.g. 'edge filtering', 'working memory'). Thus, to formulate such a principle, we have to use a domain-independent framework. Information theory offers such a framework. However, while the classical framework of information theory focuses on the relation between one input and one output (Shannon's mutual information), we argue that neural information processing crucially depends on the combination of \textit{multiple} inputs to create the output of a processor. To account for this, we use a very recent extension of Shannon Information theory, called partial information decomposition (PID). PID allows to quantify the information that several inputs provide individually (unique information), redundantly (shared information) or only jointly (synergistic information) about the output. First, we review the framework of PID. Then we apply it to reevaluate and analyze several earlier proposals of information theoretic neural goal functions (predictive coding, infomax, coherent infomax, efficient coding). We find that PID allows to compare these goal functions in a common framework, and also provides a versatile approach to design new goal functions from first principles. Building on this, we design and analyze a novel goal function, called 'coding with synergy'. [...]Comment: 21 pages, 4 figures, appendi

    Cross-Sectional Analysis of the Association Between Age and Corpus Callosum Size in Chimpanzees (\u3cem\u3ePan troglodytes\u3c/em\u3e)

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    The CC is the major white matter tract connecting the cerebral hemispheres and provides for interhemispheric integration of sensory, motor and higher‐order cognitive information. The midsagittal area of the CC has been frequently used as a marker of brain development in humans. We report the first investigation into the development of the corpus callosum and its regional subdivisions in chimpanzees (Pan troglodytes). Magnetic resonance images were collected from 104 chimpanzees (female n = 63, male n = 41) ranging in age from 6 years (pre‐pubescent period) to 54 years (old age). Sustained linear growth was observed in the area of the CC subdivision of the genu; areas of the posterior midbody and anterior midbody displayed nonlinear growth during development. After adjusting for total brain size, we observed linear growth trajectories of the total CC and CC subdivisions of the genu, posterior midbody, isthmus and splenium, and nonlinear growth trajectories of the rostral body and anterior midbody. These developmental patterns are similar to the development of the CC in humans. As the growth curves of the CC mirrors growth seen in the percentage of white matter in humans, our results suggest chimpanzees show continued white matter development in regions related to cognitive development

    Synthesis and crystal structure of calcium hydrogen phosphite, CaHPO3

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    We thank Kirstie McCombie for collecting the powder pattern, Sarah Ferrandin for collecting the IR spectrum and the EPSRC National Crystallography Service (University of Southampton) for the X-ray data collection. This work was performed, in part, at the Center for Integrated Nanotechnologies, an Office of Science User Facility operated for the US Department of Energy (DOE) Office of Science by Los Alamos National Laboratory (Contract DE-AC52–06 N A25396) and Sandia National Laboratories (Contract DE-NA-0003525).Peer reviewedPublisher PD

    Composite fibrous filters

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    Disclosed are novel composite fibrous structures which have utility as filters. These composite structures have at least two layers. The first layer is a nonwoven fibrous structure made from uniquely grooved fibers. The second layer is of a fibrous material that offers high filter efficiency.. The first layer has significantly lower pressure drop and higher dust holding capacity than the second layer

    The hierarchy of stability and predictability in orthognathic surgery with rigid fixation: an update and extension

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    A hierarchy of stability exists among the types of surgical movements that are possible with orthognathic surgery. This report updates the hierarchy, focusing on comparison of the stability of procedures when rigid fixation is used. Two procedures not previously placed in the hierarchy now are included: correction of asymmetry is stable with rigid fixation and repositioning of the chin also is very stable. During the first post-surgical year, surgical movements in patients treated for Class II/long face problems tend to be more stable than those treated for Class III problems. Clinically relevant changes (more than 2 mm) occur in a surprisingly large percentage of orthognathic surgery patients from one to five years post-treatment, after surgical healing is complete. During the first post-surgical year, patients treated for Class II/long face problems are more stable than those treated for Class III problems; from one to five years post-treatment, some patients in both groups experience skeletal change, but the Class III patients then are more stable than the Class II/long face patients. Fewer patients exhibit long-term changes in the dental occlusion than skeletal changes, because the dentition usually adapts to the skeletal change

    Corpus Callosal Microstructure Influences Intermanual Transfer in Chimpanzees

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    Learning a new motor skill with one hand typically results in performance improvements in the alternate hand. The neural substrates involved with this skill acquisition are poorly understood. We combined behavioral testing and non-invasive brain imaging to study how the organization of the corpus callosum was related to intermanual transfer performance in chimpanzees. Fifty-three chimpanzees were tested for intermanual transfer of learning using a bent-wire task. Magnetic resonance and diffusion tensor images were collected from 39 of these subjects. The dominant hand showed greater performance benefits than the nondominant hand. Further, performance was associated with structural integrity of the motor and sensory regions of the CC. Subjects with better intermanual transfer of learning had lower fractional anisotropy values. The results are consistent with the callosal access model of motor programming

    Record of an alleged Solitary Eagle in Oaxaca is a Great Black Hawk

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    In a recent article in this journal (García-Grajales et al., 2018), an adult Great Black Hawk (Buteogallus urubitinga) was mistakenly identified as an adult of the Solitary Eagle (Buteogallus solitarius). The Solitary Eagle differs from the Greater Black Eagle in having the longest and widest wings, and the shortest tail. These characteristics give it a more triangular shape in flight. These differences are easy to see in Figures 1–3. The same authors also cite a case of the nesting of the Solitary Eagle in Mexico (Smith, 1982). However, after reviewing photos of the young, we consider that this record is probably the Common Black Hawk (B. anthracinus). The illustrations of the Solitary Eagle in field guides of Mexico and Central America (Howell & Webb, 1995; Van Perlo, 2006) demonstrate greater similarity with the Great Black Hawk, contributing to the frequent confusion of the two species if used without consulting the text. The new features published here and in Clark et al. (2006) and Clark and Schmitt (2017) should help with correct identification of Buteogallus species in the future.En un artículo reciente en esta revista (García-Grajales et al., 2018), un adulto del Aguililla Negra Mayor (Buteogallus urubitinga) fue identificado erróneamente como un adulto del Águila Solitaria (Buteogallus solitarius). El Águila Solitaria difiere del Aguililla Negra Mayor en tener las alas más largas y anchas, y la cola más corta. Estas características le confieren una forma más triangular en el vuelo. Estas diferencias son fáciles de apreciar en la Figuras 1–3. Los mismos autores también citan un caso del anidamiento del Águila Solitaria en México (Smith, 1982). Sin embargo, después de revisar fotos de las crías, consideramos que este registro probablemente se trata del Aguililla Negra Menor (B. anthracinus). Las ilustraciones del Águila Solitaria en guías de campo de México y Centroamérica (Howell & Webb, 1995; Van Perlo, 2006) demuestran mayor similitud con el Aguililla Negra Mayor, contribuyendo a la confusión frecuente de las dos especies si se utilizan sin consultar el texto. Las nuevas características publicadas aquí y en Clark et al. (2006) y Clark y Schmitt (2017) deben ayudar a su correcta identificación en el futuro
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