Representation (systemics)

About: Representation (systemics) is a research topic. Over the lifetime, 33821 publications have been published within this topic receiving 475461 citations.

A Distributed Cortical Representation Underlies Crossmodal Object Recognition in Rats

Abstract: The mechanisms by which the brain integrates the unimodal sensory features of an object into a comprehensive multimodal object representation are poorly understood. We have recently developed a procedure for assessing crossmodal object recognition (CMOR) and object feature binding in rats using a modification of the spontaneous object recognition (SOR) paradigm. Here we show for the first time that rats are capable of spontaneous crossmodal object recognition when they are asked to recognize a visually presented object having previously only explored the tactile features of that object. Moreover, rats with bilateral perirhinal cortex (PRh) lesions were impaired on the CMOR task and a visual-only, but not a tactile-only, version of SOR. Conversely, rats with bilateral posterior parietal cortex (PPC) lesions were impaired on the CMOR and tactile-only tasks but not the visual-only task. Finally, crossmodal object recognition ability was severely and selectively impaired in rats with unilateral lesions made to PRh and PPC in opposite hemispheres. Thus, spontaneous tactile-to-visual crossmodal object recognition in rats relies on an object representation that requires functional interaction between PRh and PPC, which appear to mediate the visual and tactile information-processing demands of the task, respectively. These results imply that, at least under certain conditions, the separate sensory features of an object are represented in a distributed manner in the cortex. The novel paradigm introduced here should be a valuable tool for further study of the neurobiological bases of crossmodal cognition and object feature binding.

Representing and Acquiring Geographic Knowledge

Abstract: : This thesis presents a computational model of memory for spatial relations; how knowledge of geography may be represented, retrieved, and acquired. We focus particularly on the problems of representing incomplete and inexact information in a knowledge base and of learning a large scale area from a sequence of small scale views of the area. Our model, called MERCATOR, includes an original representation scheme for two-dimensional space; routines that retrieve information from the knowledge base in useful form; and a routine (the assimilator) that builds up a knowledge base incrementally from a sequence of scene descriptions. All these have been implemented in a running computer program. The representation approximates object boundaries in terms of sequences of straight edges, and it records object positions in terms of the dimensions of edges. Inexactness information is represented by recording bounds on edge dimensions and on the maximal distance from an edge to a boundary, Incomplete information is represented by recording only part of the boundary and interior of an object. This scheme is capable of representing many kinds of situations and of partial states of knowledge. The assimilator consists of two parts. The matcher finds correspondences between a scene description and the knowledge base. The merger adds the new information from the scene description into the knowledge base. The major result of this thesis is that a representation of space should integrate shape and positional information, but should maintain an abstract level of geometric description separate from object descriptions.

Computer generated representation of the imaging pattern of an imaging device

Abstract: The present invention provides systems for locating an imaging device within or outside of the body and for displaying a graphical representation of the imaging pattern associated with the imaging device within a global representation of the body. The imaging pattern characterizes the "field of vision" of the imaging device, and the graphical imaging pattern within the global representation of the body visually indicates the portion of the body that is being imaged by the imaging device in relation to the global representation of the body.