The projections of the small ganglion (PC cells) and large ganglion (MC cells) cells to the parvocellular and magnocellular layers of the LGN: Acknowledgement: Image from Webvision by Kolb, Fernandez and Nelson, courtesy of Matthew Schmolesky at Erasmus University, Rotterdam.
A recently recognized, anatomically & functionally distinct third subdivision of the visual pathway, called the koniocellular (KC) pathway.
The properties of koniocellular cells have only recently been studied in anthropoid primates, and their importance for human vision is only now becoming understood, particularly with respect to S-cone operations.
KC cells form thin layers that lie between the M and P layers..formally referred to as “intercalated layers”.
Generally, the spatial and temporal properties of the KC cells in primates fall between the parvocellular and magnocellular spatiotemporal properties..
Spatially, the KC cells are species specific. Generally, however, they are tuned to spatial frequencies that are lower than the PC system but higher than the MC system. Similarly, the temporal modulation (i.e., “timing”) sensitivity of KC cells are higher than PC but lower than MC cells.
The projections of the koniocellular cells to the primary visual cortex (V1) appear to be towards the cytochrome oxidase (CO) cortical blobs (i.e., cortical areas responsive to chromatic changes). KC cells are particularly responsive to “blue-yellow” differences (S-cone ON mediated).
V1 The projections of the koniocellular cells to the primary visual cortex (V1) appear to be towards the cytochrome oxidase (CO) cortical blobs (i.e., cortical areas responsive to chromatic changes). KC cells are particularly responsive to “blue-yellow” differences (S-cone ON mediated).
Margaret Wong-Riley (1979) coined the term blobs. Introduced labeled cytochrome oxidase (an enzyme used in cellular metabolism) and measured its migration to V1. Prominent blobs found in layer III of V1 cortex.
Modular processing Modular processing architecture has a number of virtues. –For example, each module can be optimized for its specific function, operating with maximum speed and efficiency rather than compromised to serve several functions at once. –Errors remain confined to one function, rather the propagated widely. –New functions can be created by adding new modules.