Zusammenfassung für den Vortrag am 05.06.2002 (14:15 Uhr)Arbeitsgemeinschaft NEURONALE NETZE UND KOGNITIVE SYSTEME
Udo Ernst (Universität Bremen, Institut für Theoretische Physik)
Transient feature binding and spatio-temporal activation dynamics in a cortical model
Transient feature binding and spatio-temporal activation dynamics in a cortical model In the primary stages of the visual system, different areas are devoted to the processing of different stimulus features like orientation, color, or movement. During perception, these features will be grouped together to form representations of "objects". Psychophysical experiments revealed that the spatial as well as the temporal context of visual stimuli play an important role in this grouping process. By driving the visual system to its spatial and temporal limits, it is even possible to induce erroneous groupings. The dynamics of this complex grouping process involving a whole hierarchy of processing stages in the brain can be captured by a structurally simple cortical model consisting of an excitatory and an inhibitory neuronal layer. Both layers are coupled reciprocally, and receive input from the model retina, where the same stimuli being used in the masking experiments are shown. The visibility and the grouping of specific stimulus features is determined by the duration of a transient activation in the neuronal layer. The dynamics of the network reveals possible mechanisms underlying the experimentally observed phenomena, while its simple structure allows for an analytical treatment and fit of parameters.