FUNCTIONAL STREAMS IN THE PRIMATE VISUAL CORTEX

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DESCRIPTION: The Principal Investigator and his team propose to expand our understanding of the functions of the magnocellular and parvocellular streams in primate vision and especially their relationships to the anatomically identified neural populations of the cytochrome oxidase blobs and stripes in areas V1 and V2. This will be achieved by recording neural activity from the visual cortex of macaque monkeys using optical methods and analyzing the images with extensions of the Karhunen-Loeve (KL) principle component methods. This approach will provide information about both the spatial and temporal distributions of coordinated activity. They suggest that this information is contained in a small number of spatially segregated dynamical components and that some of these components correspond to known cortical structures such as ocular dominance columns. The study will 1) investigate the contributions of known neuronal subpopulations (streams) to the optically monitored neuronal activity by using two complimentary methods: a) use of visual stimuli that excite primarily one cell populations such as the M-stream and b) silence selected neuronal populations by pressure injections of Mg++ or lidocaine into portions of the lateral geniculate nucleus, 2) compare optical signals recorded from CO blobs with those recorded from interblob regions, 3) compare the optical activity maps with the distribution of CO blobs, and 4) correlate the optical activity with simultaneously recorded electrical activity of cortical neurons. The PI believes that these combined apparoches will reveal further organizational principles of the visual cortex and will deepen our understanding of the functions of its constituent streams.