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Consciousness & Neuroscience Francis Crick & Christof Koch


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Consciousness & Neuroscience Francis Crick & Christof Koch

  1. 1. Consciousness & Neuroscience Francis Crick & Christof Koch Consciousness is a scientifically tractable problem and can be approached using the modern tools in neurobiology. Anna Tomas
  2. 2. My Sources: Christof Koch’s website Koch’s video lectures for undergrads at CalTech Francis Crick cis_crick Francis Crick papers available for download: http//
  3. 3. Main Points of the Paper don’t want to make it too long  • Who are these guys and why should we take them seriously? • That consciousness and its different aspects (pain, visual awareness & self-consciousness, etc) employ basic mechanisms that we all have • The neuronal correlate of consciousness or NCC • The idea of visual consciousness and visual representation • How this relates to machine consciousness • Two hard problems: the problem of qualia & the problem of meaning & problems omitted in the paper
  4. 4. Brief Background on Crick & Koch • Christof Koch neuroscientist & prof. of biology & engineering at CalTech. Wrote, „The Quest for Consciousness” „To understand how consciousness is linked to the brain, how the flickering activity of myriad of nerve cells leads to ineffable experiences, of seeing blue, of being warmed by the sun, or of being scared by exposure on a climb” (Koch 2005) • Francis Crick molecular biologist & physicist. Co-discoverer of the DNA molecule in 1953—subsequently jointly won Nobel Prize in 1962. • His later research centered on theoretical neurobiology and attempts to advance the scientific study of human consciousness.
  5. 5. What is this NCC all About? • constitute the minimal set of neuronal events and mechanisms sufficient for a specific conscious percept (Koch 2004) • A scientific study of consciousness must explain the exact relationship between subjective mental states and brain states, the nature of the relationship between the conscious mind and the electro-chemical interactions within your body. • NCC may be viewed as its causes and consciousness thought of as a state-dependent property of an undefined type of complex, adaptive, and highly interconnected biological system (Koch 2006)
  6. 6. What was focused on in the Paper—visual systems: Visual REPRESENTATION Note: in a paper from 2003 by Krick & Koch: „We propose that conscious awareness for vision is a series of static snapshots with motion „painted on them” • They chose visual consciousness for an initial scientific attack into understanding consciousness in a scientific manner. We are extremely visual and our visual precepts are strong & rich in information • Nature of Visual Representation is multifaceted o Psychologically different levels that correspond to for example, lines and faces o Physiologically our brain has to construct a multilevel, explicit, symbolic interpretation of a visual scene o Neurologically-- there are differing levels in the visual hierarchy IMPORTANT! EXPLICIT REPRESENTATION = small group of neurons that employ coarse coding to represent some aspect of the visual scene. o Where is this stuff? its likely this is distrubuted in the cerebral cortex and maybe some areas of the subcortical structures
  7. 7. Visual Systems con’t: Visual CONSCIOUSNESS • Normal vivid experience which encompasses a variety of processes. • Iconic memory is essential for visual consciousness (working memory for expanding the time frame of consciousness & as a mechanism for remembering) • Visual attention is consciously directed and in order for us to interpret the visual input our brain must arrive at a coalition of neorions whose firing best represents the interpretation of the visual scene • There were many studies done, I will summarize the most important (to NCC): BISTABLE PRECEPTS
  8. 8. Bistable Precepts: • Perceptual multistability can be evoked by visual patterns that are too ambiguous for the visual system to recognise with one unique interpretation ex. Necker cube • Study the behavior of single neurons when a monkey is looking at a bistable precept. Why? the visual input (other than eye movement) is constant; but the subjects perception can take one of two alternative forms. • Which neurons are following the precept? The NCC neurons can be elsewhere. BUT! Where are they? In what way do they fire? And WHERE DO THEY PROJECT? • These questions are important to understand neural nature of consciousness.
  9. 9. The Cliffnotes Version of the Problem of Qualia & the Meaning Problem (plus what issues were put aside for purposes of this paper): • Qualia the greeness of green, the sadness of sad. How can you possibly argue explain consciousness by the behavior of the brain? (vivid, rich visual scene=firing of neurons(?!) • Visual consciousness can be a result of the way the brain works. Your preception of blue and my preception of blue may turn out to be the same neural correlate of blue in both our brains—in essence then we see blue the same. • Problem of Meaning  How is meaning generated by the brain? How do other parts of the brain know that the firing of a set of neurons produces the conscious precept of a face? How is meaning expressed in neural terms? And how does this expression of meaning arise? The neurons may be part of a larger network, for example: the firing of neorons to see a face activates the neurons firing to remember the name, to her/his voice/ and memories. A chain reaction.
  10. 10. What was omitted in the Paper: • A semantic discussion and deliberation of what it means to be conscious & a precise definition of consciousness. • That whether simple animals and plants are conscious(octous, fruit flies, plant). • There are different forms of consciousness (we focused on visual) & self-consciousness is special—but we cannot study self-consciousness in a moneky. • Some species, especially higher mammals possess essential features of consciousness and studies on monkeys to finding the mechanism underlying consciousness.
  11. 11. All this Neuroscience & Consciousness...great, what does this have to do with us in this class? • Well, basically if our conscioussness has biological and neurological underpinnings then conscioussness is not a nebulous, ephermeal concept but a definable and transferable idea that can be applied to a computer. • My consciousness is biological fact in functional terms so in extension a computer can be conscious • Implications for people?
  12. 12. A parting thought: From Christof Koch’s personal website: • I'm also interested in a theory of consciousness, a formal framework - formulated using the idiom of information theory - that explains what consciousness is, which system can have subjective experiences and why in functional terms. Such a theory would imply that a computer, properly programmed as to mimic the functional connectivity of the human brain, could be consciousness. Together with Giulio Tononi, a neuroscientist at the University of Madison in Wisconsin working on such a theory of Integrated Information, I recently surveyed what we can learn about biological consciousness and apply to machine sentience (and how we can teach a machine to truly understand the movie Blade Runner). (Koch 2010)