June 2007
Volume 7, Issue 9
Free
Vision Sciences Society Annual Meeting Abstract  |   June 2007
Object representations in the dorsal pathway: fMRI adaptation effects in topographically organized areas of the human posterior parietal cortex
Author Affiliations
  • Christina Konen
    CSBMB, Princeton University
  • Sabine Kastner
    CSBMB, Princeton University, and Department of Psychology, Princeton University
Journal of Vision June 2007, Vol.7, 332. doi:10.1167/7.9.332
  • Views
  • Share
  • Tools
    • Alerts
      ×
      This feature is available to authenticated users only.
      Sign In or Create an Account ×
    • Get Citation

      Christina Konen, Sabine Kastner; Object representations in the dorsal pathway: fMRI adaptation effects in topographically organized areas of the human posterior parietal cortex. Journal of Vision 2007;7(9):332. doi: 10.1167/7.9.332.

      Download citation file:


      © ARVO (1962-2015); The Authors (2016-present)

      ×
  • Supplements
Abstract
 

The visual system is divided into two separate pathways, which are specialized for functionally distinct tasks (Ungerleider & Mishkin 1982). The dorsal stream is associated with visually guided action, while the ventral pathway is involved in object recognition.

 

Physiology studies in monkeys have shown that activity of area LIP in the posterior parietal cortex (PPC) is related to motor intention and visual attention. Moreover, many LIP neurons exhibit shape-selectivity (Sereno & Maunsell 1998). This result indicates that area LIP integrates information from both pathways. In contrast, less is known about the crosstalk between both pathways in humans. Here, we mapped the human PPC and used fMRI adaptation to assess object selectivity in this region.

 

Six subjects participated in 6 scanning sessions. In session 1 and 2, we applied retinotopic mapping and a delayed saccade task in order to define areas in occipital and parietal cortex, respectively. In the following sessions, we investigated adaptation effects to different categories of objects (2D-, 3D-objects; line drawings). Furthermore, we examined geometric objects under different viewing conditions.

 

The delayed saccade paradigm revealed 4 topographically organized areas along the intraparietal sulcus (IPS): 2 areas in the posterior part (IPS1/2) and 2 in the anterior branch (IPS3/4). Only IPS1/2, but not IPS3/4 showed object adaptation effects. The signal was reduced when identical objects were presented repetitively compared to an equivalent number of non-repeated objects. Furthermore, adaptation remained when object size and viewpoint were changed.

 

The adaptation profiles found in IPS1/2 were similar to those in LOC, an area of the ventral stream thought to be critical for object recognition. Together, the similar response patterns in IPS1/2 and LOC point to object representations in both pathways that might be further used for object recognition in the ventral system and object-related action in the dorsal system.

 
Konen, C. Kastner, S. (2007). Object representations in the dorsal pathway: fMRI adaptation effects in topographically organized areas of the human posterior parietal cortex [Abstract]. Journal of Vision, 7(9):332, 332a, http://journalofvision.org/7/9/332/, doi:10.1167/7.9.332. [CrossRef]
Footnotes
 DAAD, NIMH
×
×

This PDF is available to Subscribers Only

Sign in or purchase a subscription to access this content. ×

You must be signed into an individual account to use this feature.

×