VLSI analogs of neuronal visual processing: a synthesis of form and function
Creators: name: Mahowald, Misha
Publisher: name: California Institute of Technology
Year: 1992

description: This thesis describes the development and testing of a simple visual system fabricated using complementary metal-oxide-semiconductor (CMOS) very large scale integration (VLSI) technology. This visual system is composed of three subsystems. A silicon retina, fabricated on a single chip, transduces light and performs signal processing in a manner similar to a simple vertebrate retina. A stereocorrespondence chip uses bilateral retinal input to estimate the location of objects in depth. A silicon optic nerve allows communication between chips by a method that preserves the idiom of action potential transmission in the nervous system. Each of these subsystems illuminates various aspects of the relationship
between VLSI analogs and their neurobiological counterparts. The overall synthetic visual system demonstrates that analog VLSI can capture a significant portion of the function of neural structures at a systems level, and concomitantly, that incorporating neural architectures leads to new engineering approaches to computation in VLSI. The relationship between neural systems and VLSI is rooted in the shared limitations imposed by computing in similar physical media. The systems discussed in this text support the belief that the physical limitations imposed by the computational medium significantly affect the evolving algorithm. Since circuits are essentially physical structures, I advocate the use of analog VLSI as powerful medium of abstraction, suitable for understanding and expressing the function of real neural systems. The working chip elevates the circuit description to a kind of synthetic formalism. The behaving physical circuit provides a formal test of theories of function that can be expressed in the language of circuits.
description: © 1992 California Institute of Technology. 

Defended 12 May 1992. 

my heart has no words to weave the tapestry of time of love and friendship that are mine as gifts. To those people who have known me from the beginning, so that all that i will ever do have a part of them in it: all my family, Mom and Dad, Sheila, Grandpa, and Aunt Tiny; my best friends, to Naomi and to Brian; To Carver Mead who has opened the world for me; To those who shared it: John Lazzaro, Tobi Delbriick, Dave Gillespie, Lloyd Watts, Kwabena Boahen; To those who formed it: Massimo Sivilotti, John Wawrzynek, John Tanner, Steve DeWeerth, MaryAnn Maher, Andy Moore, Jim Campbell, Helen Derevan, William Ceasarotti; To those who showed me to myself: Amro Umrani, John Allman, Bela Julesz, Lounette Dyer, Tom Tucker, David Feinstein; To those who saved me from myself Madelyn Sobel, Holly Campbell, Carlotta Glackin, Liz Smith, Carol Polansky, Thomas White, Pamela Abshire, Andy Dowsett, Todd Murray, Mark 07Dell, Tim Rentsch; To those who welcomed me into the far out future: Christof Koch, Kevan Martin, and Rodney Douglas; I run grateful for the weaving together of our lives, arid for the strength and joy that the weaving has given me.
description: Submitted - CS-TR-92-15.pdf