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Séminaire impromptu - Nelson Cortés HernándezThe role of the cortico-pulvinar-cortical loop in the integration of visual information

Abstract :

 Classically only cortico-cortical pathways have been considered in the flow of information through visual cortex.
However, several experiments have shown that this mode of transmission has many problems. I have theoretically explored the role of an alternative pathway of the flow of information:
The visual cortical hierarchy is connected to the Pulvinar nucleus (Pul) of the thalamus and this provides a second pathway through which activity of dierent cortical areas are linked.

The Pul has long-range connections which give it a global coupling, leading to an effective shortcut between cortical areas. This property enables an almost linear transmission of visual input throughout the visual cortex.

Two theoretical models have been implemented to analyze how the Pul improves cortical transmission. To investigate the transmission through a visual hierarchy, a network with rate model neurons is considered. A second model with integrate and fire neurons is implemented to explore propagation of spike activity.

The results of these simulations show that while cortico-cortical connections are devoted to the structure and creation of visual receptive elds through hierarchical levels, the Pul controls the gain of propagation. Furthermore, while cortico-cortical connections are responsible for decorrelating the signal transmitted through the cortex, synchronized Pulvinar bursts supply the input-output fi ring-rate relationship of two separated cortical areas without changing the cortical pathway strength.

Selected publications

Cortes, N. and van Vreeswijk, C. (2012). The role of pulvinar in the transmission of information in the visual hierarchy. Front Comput Neurosci, 6(29):1, 21.