DJ's Reviews > The Quest for Consciousness: A Neurobiological Approach

The Quest for Consciousness by Christof Koch
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Jul 23, 2009

really liked it
bookshelves: brain, dad
Read in February, 2010

Until recently, those interested in learning about consciousness have had just three options: (1) introspection (informative but deceiving), (2) books by philosophers (interesting but completely speculative), and (3) books by crazies (the majority of the literature on consciousness). Consciousness has long been a naughty word in science, but ho! No longer! While the "hard problem" of exactly why phenomenological states arise from the collective squirts of neurotransmitters washing across your brain at all is still a crapshoot, the relatively "easy problem" of correlating certain neural activity with certain phenomenological experiences is well underway.

Christof Koch of Caltech is one of the leaders in probing visual consciousness (or "awareness" if we are speaking to grant committees - shh!) - a particularly "easy" form of consciousness that is amenable to experiment both in humans. Dr. Koch's "quest" is to identify the minimal set of neurons whose activation leads to consciousness. The book provides a grand tour of all the interesting quirks and subtleties of visual consciousness discovered in the last few decades, painting a picture that is far more fractured and fragile than our daily experience might suggest. If you still cling to the picture of the homunculus dictator riding a meatbag mech warrior around the world, this book will, at the very least, convince you that biological dictators can't do their jobs without an army of unconscious robot agents. The book also includes some more speculative thoughts on the purposes and general nature of consciousness but, perhaps surprisingly for a book with such a lofty title, consists almost entirely of good old-fashioned science.

What Brian Greene's The Fabric of the Cosmos is to modern physics, Quest for Consciousness is to modern neuroscience - the finest popular account available for lawyers, stock brokers, and mailmen with a bad science habit. Koch's book might focus on visual consciousness, but he touches on learning and memory, motor control, and lots more on this quest and does so in his highly readable and concise style. While mucking around in neurobiology can make for dangerous trekking, Koch organized the book very well with small, informatively titled sections, making it easy to remember the salient point of a particular passage if you're a neuro-rookie and easy to skim a particular passage if you're a neuro-master.

For a more philosophical approach, I'd also recommend Daniel Dennett's Consciousness Explained.


WARNING: The rest of this review is a collection of my reading notes. Readability not guaranteed.


The evolutionary development of the brain makes it the ultimate kluge. New functions are continuous adaptations of old ones, making for some pretty wonky and unintuitive design principles. Speculative example: humans evolve disgust to avoid bad food. As humans form larger societies and viral epidemics become a problem, it becomes evolutionarily advantageous to avoid certain people. Rather than reinventing an avoidance mechanism, evolution simply co-opts the old disgust system (for dealing with bad food) to deal with potentially infected fellow humans.
Is the function of emotions to allow detected correlations without known functional relationships to influence decision making? (In other words, I might not know by what mechanism two things are related but have unconsciously noticed a pattern in their coincidence.)
Approach to decoding neural computation: consider that the typical sensory stimuli or brain info that feeds into a circuit will be highly tuned to the absolute scale, relative scales, and symmetries of that which it represents. Considering the nature of the input may constrain neural computation and suggest approaches to understanding it in a particular circuit.
Does our consciousness integration window increase in unfamiliar environments and/or decrease in familiar ones? Does it increase or decrease in rapidly changing environments? How does one test the integration window in a dynamic setting? Traditional artificial masking protocols used in highly controlled environments don't seem appropriate.
As consciousness seems to change continuously, does this mean that the NCCs (neural correlates of consciousness) must be constrained in their activation patterns? How does the continuity of conscious experience arise from the somewhat digital spiking of neurons? Is there perhaps a continuous "read-out" process wedged between NCCs and qualia? Does the distinction between discontinuous and continuous dynamics suggest a useful approach to decoding neural computation?
How does the brain optimize the balance between zombie agents and conscious processing? The zombie system offers speed at the cost of flexibility, operating through previously detected correlations and heuristics. Conscious processing offers flexibility at the cost of speed, offering a rich simulation of a series of events in order to consider and weigh consequences. (Simulation is the best word for this - you don't know where your thoughts will end until you "run the program.")
How might one quantify consciousness? Do more explicit representations lead to more meaning and hence more consciousness? Would this justify deeming babies "less conscious", since they have not yet developed the repertoire of explicit representations available to an adult?
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