Coding of Shape and Position in Macaque Lateral Intraparietal Area

@article{citeulike:2926445, abstract = {The analysis of object shape is critical for both object recognition and grasping. Areas in the intraparietal sulcus of the rhesus monkey are important for the visuomotor transformations underlying actions directed toward objects. The lateral intraparietal (LIP) area has strong anatomical connections with the anterior intraparietal area, which is known to control the shaping of the hand during grasping, and LIP neurons can respond selectively to simple two-dimensional shapes. Here we investigate the shape representation in area LIP of awake rhesus monkeys. Specifically, we determined to what extent LIP neurons are tuned to shape dimensions known to be relevant for grasping and assessed the invariance of their shape preferences with regard to changes in stimulus size and position in the receptive field. Most LIP neurons proved to be significantly tuned to multiple shape dimensions. The population of LIP neurons that were tested showed barely significant size invariance. Position invariance was present in a minority of the neurons tested. Many LIP neurons displayed spurious shape selectivity arising from accidental interactions between the stimulus and the receptive field. We observed pronounced differences in the receptive field profiles determined by presenting two different shapes. Almost all LIP neurons showed spatially selective saccadic activity, but the receptive field for saccades did not always correspond to the receptive field as determined using shapes. Our results demonstrate that a subpopulation of LIP neurons encodes stimulus shape. Furthermore, the shape representation in the dorsal visual stream appears to differ radically from the known representation of shape in the ventral visual stream. 10.1523/JNEUROSCI.0499-08.2008}, author = {Janssen, Peter and Srivastava, Siddharth and Ombelet, Sien and Orban, Guy A. }, citeulike-article-id = {2926445}, comment = {* Electrophysiological examination of monkey LIP shape selectivity, showing that while many LIP neurons are selective for certain dimensions of shape (along with the well-characterized selectivity for retinotopic position), there is little position or size invariance * Based on previous studies showing shape selectivity in LIP ( 'Sereno and Maunsell 1998':http://www.citeulike.org/user/klouie/article/2926462... ), which argues against a strict dorsal-ventral separation of location and object information as in 'Goodale and Milner':http://www.citeulike.org/user/klouie/article/1298305... * Author presented 56 stimuli varying in five dimensions imposed upon a square: curvature along the vertical boundaries, curvature along the horizontal boundaries, horizontal taper, vertical taper, and aspect ratio * ''A key question is the interaction between shape selectivity and RF characteristics; can some of the apparent selectivity for spatial dimensions be explained by differential activiation of position-dependent RFs''?}, doi = {http://dx.doi.org/10.1523/JNEUROSCI.0499-08.2008}, journal = {J. Neurosci.}, keywords = {electrophysiology, lip, monkey, saccade, shape}, month = {June}, number = {26}, pages = {6679--6690}, posted-at = {2008-06-25 18:32:21}, priority = {2}, title = {Coding of Shape and Position in Macaque Lateral Intraparietal Area}, url = {http://dx.doi.org/10.1523/JNEUROSCI.0499-08.2008}, volume = {28}, year = {2008} }

TY - JOUR ID - citeulike:2926445 L3 - citeulike-article-id:2926445 TI - Coding of Shape and Position in Macaque Lateral Intraparietal Area JF - J. Neurosci. VL - 28 IS - 26 SP - 6679 EP - 6690 N2 - The analysis of object shape is critical for both object recognition and grasping. Areas in the intraparietal sulcus of the rhesus monkey are important for the visuomotor transformations underlying actions directed toward objects. The lateral intraparietal (LIP) area has strong anatomical connections with the anterior intraparietal area, which is known to control the shaping of the hand during grasping, and LIP neurons can respond selectively to simple two-dimensional shapes. Here we investigate the shape representation in area LIP of awake rhesus monkeys. Specifically, we determined to what extent LIP neurons are tuned to shape dimensions known to be relevant for grasping and assessed the invariance of their shape preferences with regard to changes in stimulus size and position in the receptive field. Most LIP neurons proved to be significantly tuned to multiple shape dimensions. The population of LIP neurons that were tested showed barely significant size invariance. Position invariance was present in a minority of the neurons tested. Many LIP neurons displayed spurious shape selectivity arising from accidental interactions between the stimulus and the receptive field. We observed pronounced differences in the receptive field profiles determined by presenting two different shapes. Almost all LIP neurons showed spatially selective saccadic activity, but the receptive field for saccades did not always correspond to the receptive field as determined using shapes. Our results demonstrate that a subpopulation of LIP neurons encodes stimulus shape. Furthermore, the shape representation in the dorsal visual stream appears to differ radically from the known representation of shape in the ventral visual stream. 10.1523/JNEUROSCI.0499-08.2008 KW - electrophysiology KW - lip KW - monkey KW - saccade KW - shape N1 - * Electrophysiological examination of monkey LIP shape selectivity, showing that while many LIP neurons are selective for certain dimensions of shape (along with the well-characterized selectivity for retinotopic position), there is little position or size invariance * Based on previous studies showing shape selectivity in LIP ( 'Sereno and Maunsell 1998':http://www.citeulike.org/user/klouie/article/2926462... ), which argues against a strict dorsal-ventral separation of location and object information as in 'Goodale and Milner':http://www.citeulike.org/user/klouie/article/1298305... * Author presented 56 stimuli varying in five dimensions imposed upon a square: curvature along the vertical boundaries, curvature along the horizontal boundaries, horizontal taper, vertical taper, and aspect ratio * ''A key question is the interaction between shape selectivity and RF characteristics; can some of the apparent selectivity for spatial dimensions be explained by differential activiation of position-dependent RFs''? AU - Janssen, Peter AU - Srivastava, Siddharth AU - Ombelet, Sien AU - Orban, Guy PY - 2008/06/25/ UR - http://dx.doi.org/10.1523/JNEUROSCI.0499-08.2008 ER -