S-cone signal processing

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There are three neural pathways which carry information from the retina to cortex: Two of these: the parvocellular (PC) and magnocellular (MC) pathways have been studied extensively for almost half a century. The function of the third, “koniocellular” (KC) pathway is relatively obscure. Recent work suggests it represents an independent, rapid and developmentally robust input to visual cortex driven by the short-wavelength-sensitive (‘S’) cones.

 

(1) When and where do S-cone signals arrive in cortex?

 

(2) How do S-cone signals interact with signals in other pathways?

 

(3) Does the KC pathway play a privileged role in the feedback from visual cortex to

the thalamus?

 

We address the first and second questions using a novel combination of functional magnetic resonance imaging (fMRI), high-density electrical encephalography (EEG)

and source imaging. This reveals the spatiotemporal dynamics of signals in individual cortical visual areas with millisecond temporal resolution. To answer the third question, high-resolution fMRI is used to measure and compare the way in which KC, PC and MC signals in visual cortex and the lateral geniculate nucleus (LGN) are altered by attention.