Varying Timescales of Stimulus Integration Unite Neural Adaptation and Prototype Formation

Human visual perception is both stable and adaptive. Perception of complex objects, such as faces, is shaped by the long-term average of experience as well as immediate, comparative context. Measurements of brain activity have demonstrated corresponding neural mechanisms, including norm-based respon...

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Bibliographic Details
Published in:Current biology 2016-07, Vol.26 (13), p.1669-1676
Main Authors: Mattar, Marcelo G., Kahn, David A., Thompson-Schill, Sharon L., Aguirre, Geoffrey K.
Format: Article
Language:English
Subjects:
Adaptation, Physiological
Adult
Face
Female
Humans
Magnetic Resonance Imaging
Male
Photic Stimulation
Temporal Lobe - physiology
Time Factors
Visual Perception
Young Adult
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Summary:Human visual perception is both stable and adaptive. Perception of complex objects, such as faces, is shaped by the long-term average of experience as well as immediate, comparative context. Measurements of brain activity have demonstrated corresponding neural mechanisms, including norm-based responses reflective of stored prototype representations, and adaptation induced by the immediately preceding stimulus. Here, we consider the possibility that these apparently separate phenomena can arise from a single mechanism of sensory integration operating over varying timescales. We used fMRI to measure neural responses from the fusiform gyrus while subjects observed a rapid stream of face stimuli. Neural activity at this cortical site was best explained by the integration of sensory experience over multiple sequential stimuli, following a decaying-exponential weighting function. Although this neural activity could be mistaken for immediate neural adaptation or long-term, norm-based responses, it in fact reflected a timescale of integration intermediate to both. We then examined the timescale of sensory integration across the cortex. We found a gradient that ranged from rapid sensory integration in early visual areas, to long-term, stable representations in higher-level, ventral-temporal cortex. These findings were replicated with a new set of face stimuli and subjects. Our results suggest that a cascade of visual areas integrate sensory experience, transforming highly adaptable responses at early stages to stable representations at higher levels. [Display omitted] •We used fMRI to measure the temporal integration of face stimuli in neural responses•Within the fusiform gyrus, an intermediate timescale of integration was observed•This single mechanism accounted for both neural adaptation and norm-based responses•Across the visual cortex, a gradient of increasing temporal integration was found Mattar et al. use fMRI to show that face stimuli are integrated continuously into a representation that modulates neural response. This integration can vary in timescale. Variation in timescale can account for neural adaptation and norm-based effects. A smooth gradient of temporal integration is found across the ventral pathway of the visual cortex.
ISSN:0960-9822
1879-0445
DOI:10.1016/j.cub.2016.04.065