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Understanding neurons

Aug 10, 2015

For people interested in understanding how the brain gives rise to vision, memory, pleasure, pain, and other mental phenomena, it's worthwhile to start by understanding what it means for a neuron to become activated and to communicate with other neurons.

When you touch something with your finger, the touch sensation is not occurring in the finger but in your brain.  At the moment of touch, neurons in your fingers send 'signals' to the spinal cord, and neurons in the spinal cord send signals to particular areas of the brain that give rise to the touch sensation. 

You can tell that the sensation arises from the brain and not the finger because if you interrupt the neural signal at some point between the finger and the brain, you will feel no sensation.  Novocain (like other local anesthetics) does exactly this -- it prevents neurons from carrying messages to the brain.  No neural activity, no sensation.

Of course, it's one thing to say that touch arises from neuronal activity in the brain; it's another to explain how that brain activity gives rise to the conscious sensations you experience.  Even after neuroscientists discover every neuron activated during touch, and the patterns of neural activity produced when you touch a wood table versus a coffee cup versus hot wax, the question will remain, 'How does any pattern of neural activity give rise to any conscious sensation?'
In the next several posts, I'm going to describe what it means for neurons to 'fire' and send 'signals' to one another.   Having a clear idea about the activity of neurons makes it easier to understand discoveries about the brain that come up in the news.  So these next posts will be geared toward filling in some of the story about how neurons work; some of the basics, long before "a miracle occurs".