Max Planck Institute for Dynamics and Self-Organization -- Department for Nonlinear Dynamics and Network Dynamics Group
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BCCN AG-Seminar

Tuesday, 04.07.2006 16 c.t.

Cortical algorithms for perceptual grouping

by Prof. Dr. Pieter Roelfsema
from Department of Vision and Cognition, Netherlands Institute for Neuroscience, Amsterdam

Contact person: Fred Wolf


Seminarraum Haus 2, 4. Stock (Bunsenstr.)


Theories of visual perception subdivide the processes underlying identification of objects in natural scenes in pre-attentive and attentive systems. The pre-attentive system operates automatically and rapidly to segregate visual objects from background, whenever this distinction is possible on the basis of primitive image qualities. Pre-attentive processing takes place in parallel across the visual field, a property that accounts for its speed. Attentive processing, on the other hand, performs figure-ground segregation by selecting visual figures that are provided by the pre-attentive system, presumably one at a time. I will discuss the neuronal correlates of pre-attentive and attentive object-selection in the visual cortex, with a focus on the primary visual cortex. At an early point in time after the presentation of a new image, neurons in the primary visual cortex reflect the pre-attentive segregation of objects from the background. At a later point in time, they also reflect the attentive selection of those objects that are relevant for behaviour. Thus, the neuronal correlates of pre-attentive and attentive selection are expressed in the same area (area V1), and even in the same neuron

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