Tag Archives: Consciousness

The Hard Problem of Consciousness

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You’re lying on a sandy beach on a hot sunny afternoon, enjoying a few hours of much needed laziness. As you open your eyes and confront the vastness of the ocean in front of you, light of 600nm wavelength hits your retina, kindling an impossibly long cascade of events in your brain: a molecule called retinal changes shape, neurons fire action potentials down the optic nerve, arrive at the lateral geniculate nucleus deep in the brain causing more action potentials in primary visual cortex in the back of your head, and so on ad infinitum. At some point, the mechanical wonder of 100 billion neurons working together produces something special: your experience of the color blue. What’s special is not that you can discriminate that color from others; nor that you are aware of it and paying attention to it. It is not notable that you can tell us about it, or assign a name to it. It’s that you have a subjective, qualitative experience of the color; there is something it is like to experience the color blue. Some philosophers call these experiences qualia – meaning “what kind” – but it is not important what kind of experience you are having, just that you are having one at all. Modern science hypothesizes that subjective experience is a product of the brain, but has no explanation for it. Continue reading →

Scientific Misinformation

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Stuart Hameroff, MD, is an anesthesiologist and professor at the University of Arizona. In one of many articles and videos about consciousness on the Huffington Post, Hameroff describes how anesthesia can help explain consciousness.

If the brain produces consciousness (all aspects of the term), then it seems to follow that turning off the brain will also turn off consciousness. This is exactly how anesthetics work.

While most anesthetics are nonselective “dirty” drugs, they all produce loss of consciousness, amnesia, and immobility by either opening inhibitory ion channels or closing excitatory ion channels in neurons. The commonly used intravenous drug propofol, for example, acts by activating GABA receptors, the ubiquitous inhibitory channels in CNS interneurons. Brain off = consciousness off.

Hameroff does not subscribe to this. He argues that consciousness is an intrinsic part of the universe and that anesthetics simply disconnect it from the brain. He also thinks that by saying “quantum” a lot, he can scientifically prove the existence of the soul.

What’s scary is that Hameroff has “MD” and “Professor” next to his name. Will Joe the Plumber see through the misinformation?

Don’t take the HuffPost too seriously:

Consciousness and Anesthesia with Stuart Hameroff

Can Science Explain the Soul?

Replacing Neurons

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Imagine: a mad scientist with a ray gun shoots at a neuron somewhere in cortical layer IV of your visual area MT, burning it up in a matter of microseconds (just for fun, imagine also that the ray gun leaves everything else intact).

With one neuron missing, you probably won’t notice any perceptual change. But what if, one by one, all neurons in are MT went AWOL? You’d be stuck with an annoying inability to visually detect motion.

Now imagine that for every cell that our fancy ray gun hits, it replaces it with a magical transistor equivalent. These magical transistors have wires in place of each and every dendrite, a processing core, and some wires in place of axon(s). Naturally, the computational core analyzes the sum of all inputs and instructs the axon to “fire” accordingly. Given any set of inputs to the dendrite wires, the output of the axon wires is indistinguishable from that of the deceased neuron.

We can still imagine that with one neuron replaced with one magical transistor, there wouldn’t be any perceptual change. But what happens when more and more cells are replaced with transistors? Does perception change? Will our subject become blind to motion, as if area MT weren’t there? Or will motion detection be just as good as with the real neurons? I am tempted to vote in favor of “No change [we can believe in],” but have to remain skeptical: there is simply no direct evidence for either stance.

Ray guns aside, it is not hard to see that a computational model of a brain circuit may be a candidate replacement of real brain parts (this is especially true considering the computational success of the Blue Brain Project’s cortical column, which comprises 10,000 neurons and many more connections among them). For example, we can imagine thousands of electrodes in place of inputs to area MT that connect to a computer model (instead of to MT neurons); the model’s outputs are then connected, via other electrodes, to the real MT’s outputs, and ta-da!  Not so fast. This version of the upgrade doesn’t shed any more light on the problem than the first, but it does raise some questions: do the neurons in a circuit have to be connected in one specific way in order for the circuit to support perception? Or is it sufficient simply for the outputs of the substitute to match those of the real circuit, given any set of inputs? And, what if the whole brain were replaced with something that produced the same outputs (i.e. behavior) given a set of sensory inputs – would that “brain” still produce perception?