Developing Intelligence

Parietal cortex is critical for the maintenance of object information over delays. This is true both in tests of working memory (e.g., 1, 2 and 3) as well as simple visual manipulations involving the occlusion of visible objects.

A great example is this study by Olson et al., who demonstrated that neurons in human intraparietal sulcus (IPS) and middle temporal (MT) cortex increased their activity in response to objects which disappeared due to occlusion (i.e., they were hidden behind another object) relative to those which simply disappeared without an occluder. This was particularly robust in the case of IPS, and was observed even in the context of a task in which no responses were required – indicating the IPS result did not merely reflect motoric preparation or response-related intentions.

This has been replicated in subsequent work, with the important caveat that other regions are also more active during occlusion than other visual events (including frontal cortex, which is more traditionally associated with object permanence).

Other work also finds parietal activity in object permanence paradigms among adult humans (here, although it was superior parietal lobe and precuneus, and not the IPS, and it’s reported only in the supplementary information, since parietal was for some reason not an a priori ROI).

One working hypothesis is that the parietal cortex is responsible for maintenance in working memory tasks because that function – active maintenance of object information in pursuit of goals – relies on the same neural regions subserving the maintenance demands imposed by a much older problem (developmentally and evolutionarily): processing visually occluded objects.

Comments

  1. #1 Luci
    August 27, 2008

    Ever play peek-a-boo, or I’ve got your nose with a pre-schooler? Really little kids can give all kinds of explanations for where things go when they go out of sight. Clouds hiding the sun and sunsets are good.
    Cats will follow TV animals around to the side of the set then get bewildered. They seem convinced that the object of attention hasn’t vanished, it’s only in another part of the box.
    Why do human adults still get fooled by the shell game or three card monte?
    Does occlusion, like illusion, stimulate some kind of ‘are you trying to fool me’ reaction?

    (Will the temporal lobe ever make it back to the current posts, or will we have all parietal, all the time? Maybe it’s Mo’s Dr. Penfield profile on Neurophilosophy today that makes me wish all the better neurobloggers would take a temporal trip and walk on the Wilder side) )

    Thanks for keeping all the lobes fired up with articulate wonderings and clues to answers.

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