Humans can focus on one thing amidst many. “Searchlight of attention” is the metaphor. You recall a childhood friend’s face one moment, then perhaps the dog you loved back then, and then…what you will. Your son’s face on stage rivets your attention; the rest of the cast is unseen.
No “ghost” in the brain aims that searchlight. What does? Neurons do, somehow, but how is a mystery that new research actually deepened.
The experiment used monkeys. They can focus attention like people do. They can zero in on a red square on a screen full of distractions, for instance. When the square moves, a trained monkey will press a button. Electrodes inserted in a monkey neuron will reveal “firing” (minuscule electrical ripples) simultaneous with attention. This may locate brain areas by which the monkey watched that red square.
It’s not only the explosive firing in neurons that instruments detect. They also spot the milder priming to fire, when the monkey expects (from training) that neurons are about to be stimulated. Neurons in a one area of the cortex fire when an object moves (but not, for instance, if it gets brighter but stays still.) If a monkey learns that an onscreen cue (a blip of light) signals that the red square is about to move, the cue alone primes the motion-sensing neurons. They also synchronize more tightly (i.e. reduce random noise among them.) Cues cock neurons, like a gun. It’s like Pavlov’s dogs salivating at the bell that preceded feeding.
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