Authors:

CUSACK, R.

Reference:

Year of publication:

2004

CBU number:

5874

Abstract:

Often, many objects in the visual scene, and many sources of sound, contribute to what arrives at our senses. The early sensory systems extract a number of features, such as color, orientation or sound frequency. The resulting vast array of information must then be structured into a set of perceptual objects or streams. This structuring process is as known as perceptual organization, and it has a profound effect on what we can selectively attend to, and on many other characteristics of what we perceive. We used fMRI to identify the neural structures involved in perceptual organization. Our results show that multiple neural levels in the processing pathways are involved. In both modalities, activity in sensory specific cortices was strongly modulated by the number of objects or streams perceived, even when the peripheral excitation was controlled. We also found that regions in the intraparietal sulcus are affected by the state of perceptual organization, even in the absence of a requirement for selection. A number of previous studies have implicated the intraparietal sulcus in the binding together of features of visual, auditory and tactile sensory information, using investigative methods including neuropsychology, neuroimaging and electrophysiology. We suggest a general role for the intraparietal sulcus in structuring sensory information, and propose that multiple stages of sensory processing work together to determine perceptual organization.