Neural Representations for Sensory-Motor Control, III: Learning a Body-Centered Representation of 3-D Target Position

A neural model is described of how the brain may autonomously learn a body-centered representation of 3-D target position by combining information about retinal target position, eye position, and head position in real time. Such a body-centered spatial representation enables accurate movement commands to the limbs to be generated despite changes in the spatial relationships between the eyes, head, body, and limbs through time. The model learns a vector representation--otherwise known as a parcellated distributed representation--of target vergence with respect to the two eyes, and of the horizontal and vertical spherical angles of the target with respect to a cyclopean egocenter. Such a vergence-spherical representation has been reported in the caudal midbrain and medulla of the frog, as well as in psychophysical movement studies in humans. A head-centered vergence-spherical representation of foveated target position can be generated by two stages of opponent processing that combine corollary discharges of outflow movement signals to the two eyes. Sums and differences of opponent signals define angular and vergence coordinates, respectively. The head-centered representation interacts with a binocular visual representation of non-foveated target position to learn a visuomotor representation of both foveated and non-foveated target position that is capable of commanding yoked eye movementes. This head-centered vector representation also interacts with representations of neck movement commands to learn a body-centered estimate of target position that is capable of commanding coordinated arm movements. Learning occurs during head movements made while gaze remains fixed on a foveated target. An initial estimate is stored and a VOR-mediated gating signal prevents the stored estimate from being reset during a gaze-maintaining head movement. As the head moves, new estimates arc compared with the stored estimate to compute difference vectors which act as error signals that drive the learning process, as well as control the on-line merging of multimodal information.

María Antonieta, la última reina: sinopsis fílmica y reseña literaria [Ressenya del llibre María Antonieta: la última reina, d'Antonia Fraser; Ressenya de la pel·lícula María Antonieta, de Sofia Coppola]

Sinopsi fílmica i ressenya literària d’aquestes dues obres sobre la figura de la última reina de França, amb 8 suggeriments didàctics que tenen com a fil conductor ambdues obres

Morphological Notes on the Worker and Queen Larvae of the Thief Ant Solenopsis helena (Hymenoptera, Formicidae, Myrmicinae) from Brazil

Young and mature larvae of queen and workers of the thief ant, Solenopsis helena, are herein described for the first time. Specimens were treated and described by usual methods of light and scanning electron microscopy. Many of the observed characteristics confirmed traits of the thief ant larva, reinforcing the assumption that they are a distinct group from fire ants. The larva of S. helena can be recognized from other close species by details of the mouthparts, but seem extensively similar to Solenopsis molesta. These findings are useful for taxonomic studies and phylogenetic inferences.

Triunfo de la fidelidad murciana ... que dedico a la ... proclamacion por rey de España D. Carlos III ... : exequias por el rey D. Fernando el sexto ... año de 1759

El pie de imp. consta en colofón

Bond between John Leverett and Elisha Cooke to John White, Treasurer of Harvard College, 1716 November 20

Two folio-sized leaves containing a one-and-a-half page copy of the bond between John Leverett and Elisha Cooke to John White, Treasurer of Harvard, for £200. The bond was witnessed by William Austin and Mary Gilbert. An October 3, 1726 receipt of payment from Nathaniel Byfield on the bond, signed by Treasurer Edward Hutchinson, is located on the verso of the first leaf.

La marchande de modes de Marie-Antoinette, Rose Bertin.

Mode of access: Internet.

La dernière dauphine, Madame duchesse d'Angoulême (1778-1851) /

Mode of access: Internet.

Mémoire de Marie Caroline, reine de Naples, intitulé De la révolution de royaume de Sicile ... par un témoin oculaire ...

Includes bibliographical references (pages xxiii-xxv) and index.

Two medieval satires on the University of Paris: La bataille des vii ars of Henri d'Andeli, and the Morale scolarium of John of Garland.

Series note varies: At head of title of v. 1 and on verso of t.-p of v. 2, Memoirs of the University of California. v. 4, no. 1, 2. History, v. 1, no. 1, 2.

Test facility inventory for the U.S. Department of Transportation. Final report. Volume III of VI. D-I.

National Highway Safety Bureau, Washington, D.C.

Henry VIII and his court /

"Shakespearean plays produced under Herbert Beerbohm Tree's management": p. 115-[117]