desertshore
Bluelighter
^ I wrote a lengthy answer but somehow deleted it, so I'll try to be short this time 
Action potentials (neuronal 'firing') last about a millisecond (let's say _at least_ a millisecond). In a day there are 86 millions of milliseconds, but in an human brain there are 86 billions of neurons (ok, they say 85.. but in this case 86 sounds better
). This means that if neurons are completely random and only fire ONCE a day (but the average firing rate is much higher), we can expect about 1000 neurons to be firing at any given time (yes.. some will be just starting, others almost ending, but there will on average be much overlap).
But neurons are not random number generators, and the activity of the neuron that receives the input from the 'W' in the 'What's New?' tag in the Bluelight menu will be probably similar to the one of the neuron that receives the input from the 'W' in the 'Wiki' tag.
Furthermore, in some areas neurons are connected by electrical (not chemical) synapses, which are _very_ fast ( http://en.wikipedia.org/wiki/Electrical_synapse ) and allow neurons to fire virtually syncronously.
On the other side: variation in the magnetic field caused by brain activity do exist and can be recorded... by machines such as this one http://en.wikipedia.org/wiki/MEG . The noise is high, and the signal too low... so low that I seriously doubt that a neuron placed on your scalp could be activated by the fluctuations in electromagnetic fields caused by your brain activity.

Action potentials (neuronal 'firing') last about a millisecond (let's say _at least_ a millisecond). In a day there are 86 millions of milliseconds, but in an human brain there are 86 billions of neurons (ok, they say 85.. but in this case 86 sounds better

But neurons are not random number generators, and the activity of the neuron that receives the input from the 'W' in the 'What's New?' tag in the Bluelight menu will be probably similar to the one of the neuron that receives the input from the 'W' in the 'Wiki' tag.
Furthermore, in some areas neurons are connected by electrical (not chemical) synapses, which are _very_ fast ( http://en.wikipedia.org/wiki/Electrical_synapse ) and allow neurons to fire virtually syncronously.
On the other side: variation in the magnetic field caused by brain activity do exist and can be recorded... by machines such as this one http://en.wikipedia.org/wiki/MEG . The noise is high, and the signal too low... so low that I seriously doubt that a neuron placed on your scalp could be activated by the fluctuations in electromagnetic fields caused by your brain activity.
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