Causal Evidence for the Role of Neuronal Oscillations in Top–Down and Bottom–Up Attention

Beta and gamma frequency neuronal oscillations have been implicated in top–down and bottom–up attention. In this study, we used rhythmic TMS to modulate ongoing beta and gamma frequency neuronal oscillations in frontal and parietal cortex while human participants performed a visual search task that manipulates bottom–up and top–down attention (single feature and conjunction search). Both task conditions will engage bottom–up attention processes, although the conjunction search condition will require more top–down attention. Gamma frequency TMS to superior precentral sulcus (sPCS) slowed saccadic RTs during both task conditions and induced a response bias to the contralateral visual field. In contrary, beta frequency TMS to sPCS and intraparietal sulcus decreased search accuracy only during the conjunction search condition that engaged more top–down attention. Furthermore, beta frequency TMS increased trial errors specifically when the target was in the ipsilateral visual field for the conjunction search condition. These results indicate that beta frequency TMS to sPCS and intraparietal sulcus disrupted top–down attention, whereas gamma frequency TMS to sPCS disrupted bottom–up, stimulus-driven attention processes. These findings provide causal evidence suggesting that beta and gamma oscillations have distinct functional roles for cognition.

Membrane Structures - Aspects of Form-Finding Process

This paper is concerned with the selected aspects, which are discovered during a design stage of cable and membrane structures, known as “form-finding” process. The aim of this paper is the understanding of the basic principles of the form-finding process and their explanation of the very simple examples. The use of the finding a shape of a tension membrane that is in static equilibrium as an analogy with the search condition of minimal surfaces is explained. The basic principles are demonstrated on simple 2D example, in which the finding a stable minimal surface passes in the finding a stable minimal length.

A Modified Spectral Conjugate Gradient Methods with the New Line Search Condition

In this Paper, Combining the Nonmonotone and Monotone Line Search ,a Spectral Conjugate Gradient Methods Are Used in this Paper. by the Concept of Spectral, we Construct a Class of Spectral Conjugate Gradient with Different form . we Also Give the Algorithm for Conjugate Gradient Method. the Numerical Result Show the Efficiency of the Method.

Learning in Consistent Search-Detection Tasks: Type of Search (Memory vs. Visual) Determines Type of Learning

The theoretical and practical importance of search paradigms has been well established. This experiment was designed to extend understanding of learning processes in search tasks. Subjects trained under memory, visual, or hybrid memory/visual search conditions and then either transferred to a different search condition (e.g., train on memory, transfer to visual search) or served as controls (e.g., train on memory, transfer to memory search). Asymmetrical transfer was observed. These results have implications for current theories of attention as well as applicability in training situations.