Task-Dependent Incremental Binding Explained by Cortico-Thalamo-Cortical Interactions – A Neuro-Dynamical Model of Mental Contour Tracing
Daniel Schmid, Heiko Neumann, Ulm University, Germany
Posters 1 Poster
Pacific Ballroom H-O
Thu, 25 Aug, 19:30 - 21:30 Pacific Time (UTC -8)
The mammalian visual system can link spatially disparate visual items to build object related representations. Initially, parallel processes form base items by grouping along predefined feature dimensions. Complex task demands require more flexible evaluation of features by incremental binding of base items. For instance, mental contour tracing deploys attention to serially evaluate visuospatial relations. Numerous experiments studied the neural correlates of mental contour tracing. However, a mechanistic understanding of these processes is still lacking. Here, we introduce a neuro-dynamical model that suggests incremental binding is accomplished by the interplay of cortico-thalamo-cortical and cortico-cortical loops. The model predicts complementary roles for cortex and thalamus: Cortical areas compute topographic maps factorized by feature preference, while higher-order visual thalamic regions encode behavioral relevance of responses in such maps. Pyramidal cells are segregated into somatic and apical compartments. There, thalamic activity controls apical integration of contextual information upon entering the somatic compartment. Incremental binding then occurs by activity spreading of an attentional label among neighboring cortical columns when matched by a thalamic control signal. We demonstrate the model functionality on panels of different contour densities. Temporal dynamics and effects of lesions provide testable hypotheses of incremental binding.