Scientific Understanding of Consciousness
Bistable Vision and the Prefrontal Cortex
(Joaquín Fuster; The Prefrontal Cortex, 182)
Journal of Cognitive Neuroscience 18:3, pp. 456–471
Role of the Prefrontal Cortex in Attentional Control over Bistable Vision
Sabine Windmann1, Michaela Wehrmann2, Pasquale Calabrese2 and Onur Güntürkün2
1University of Plymouth, UK, 2Ruhr-University, Bochum, Germany
The primary source of top-down attentional control in object perception is the prefrontal cortex. This region is involved in the maintenance of goal-related information as well as in attentional selection and set shifting. Recent approaches have emphasized the role of top-down processes during elementary visual processes as exemplified in bistable vision where perception oscillates automatically between two mutually exclusive states. The prefrontal cortex might influence this process either by maintaining the dominant pattern while protecting it against the competing representation, or by facilitating perceptual switches between the two competing representations. To address this issue, we investigated reported perceptual reversals in patients with circumscribed lesions of the prefrontal cortex and healthy control participants in three experimental conditions: hold (maintaining the dominant view), speed (inducing as many perceptual switches as possible), and neutral (no intervention). Results indicated that although the patients showed normal switching rates in the neutral condition and were able to control perceptual switches in the hold condition as much as control subjects were, they were less able to facilitate reversals specifically in the speed condition. These results suggest that the prefrontal cortex is necessary to bias the selection of visual representations in accord with current goals, but is less essential for maintaining selected information active that is continuously available in the environment. As for attentional selection, the present results suggest that the prefrontal cortex initiates perceptual reversals by withdrawing top-down support from the dominant representation without (or prior to) boosting the suppressed view.
To specify the role of the prefrontal areas in multistable vision, we presented various kinds of bistable figures to patients with circumscribed lesions in the prefrontal cortex. We then investigated these patients’ spontaneous reversal rates (neutral condition), as well as their ability to voluntarily suppress perceptual reversals (hold condition), and to induce as many reversals as possible (speed condition). If the prefrontal cortex is required for stabilizing the dominant pattern, then we would expect differences between patients and controls in the hold condition. By contrast, if the prefrontal cortex selects among competing input patterns, thereby promoting perceptual switches in accord with current goals, then we would expect differences between patients and controls in the speed condition. Finally, both conditions were expected to give rise to differences between patients and controls if the prefrontal cortex was necessary for both, attentional stabilization and selection of the alternative view.
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