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Models of the Posterior Parietal Cortex Which Perform Multimodal Integration and Represent Space in Several Coordinate Frames

Xing, Jing and Andersen, Richard A. (2000) Models of the Posterior Parietal Cortex Which Perform Multimodal Integration and Represent Space in Several Coordinate Frames. Journal of Cognitive Neuroscience, 12 (4). pp. 601-614. ISSN 0898-929X. http://resolver.caltech.edu/CaltechAUTHORS:20111209-141152273

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Abstract

Many neurons in the posterior-parietal cortex (PPC) have saccadic responses to visual and auditory targets. The responses are modulated by eye position and head position. These findings suggest that PPC integrates multisensory inputs and may provide information about saccadic targets represented in different coordinate frames. In addition to an eye-centered output representation, PPC may also project to brain areas which contain head-centered and body-centered representations of the space. In this report, possible coordinate transformations in PPC were examined by comparing several sets of models of PPC, each having different representations in the output layer: (i) an eye-centered map only; (ii) a head-centered map only; (iii) an eye-centered map and a head-centered map; and (iv) an eye-centered map, a head-centered map, and a body-centered map. These output maps correctly encoded saccades to visual and auditory targets through training. The units in the hidden layers of the models exhibited the following properties: (1) The units had gain fields (GFs) for eye position, and also for head position if the model had a body-centered output representation; (2) As the result of the GF and the nonlinear activation function of the units, the hidden layers often employed “intermediate” coding, e.g., the hidden units coded targets partially in eye-centered coordinates and, partially, in head-centered coordinates; (3) Different types of coordinate transformations in these models were carried out by different relationships between the receptive fields (RFs) and the GFs of the hidden units; and (4) The properties of PPC neurons are in better accordance with the hidden units of the models that had multiple-output representations than the models that had only one single-output representation. In conclusion, the results show that the GF is an effective mechanism for performing coordinate transformations. The models also suggest that neurons with intermediate coding are to be expected in the process of coordinate transformations.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1162/089892900562363DOIUNSPECIFIED
http://www.mitpressjournals.org/doi/abs/10.1162/089892900562363PublisherUNSPECIFIED
Additional Information:© 2000 Massachusetts Institute of Technology. Posted Online March 13, 2006. This work was supported by NIH Grant No. EY05522. J. Xing was supported by the Del Webb Foundation fellowship. We thank B. Stricanne and J. Linden for many valuable discussions.
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NIHEY05522
Del Webb Foundation fellowshipUNSPECIFIED
Record Number:CaltechAUTHORS:20111209-141152273
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20111209-141152273
Official Citation:Models of the Posterior Parietal Cortex Which Perform Multimodal Integration and Represent Space in Several Coordinate Frames full access Jing Xing, Richard A. Andersen Journal of Cognitive Neuroscience July 2000, Vol. 12, No. 4: 601–614.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:28403
Collection:CaltechAUTHORS
Deposited By: Ruth Sustaita
Deposited On:09 Dec 2011 22:38
Last Modified:26 Dec 2012 14:36

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