Unsurprising but interesting

Every negative feedback system needs an error detector.

A new study pins down the neurons responsible for detecting a wrong sound associated with a habitual action.

We know that the phone gives a dial tone when we pick it up. If the dial tone is missing, we know it’s busted. We know how the toilet sounds in an ordinary flush. If part of the sequence is slow, we know it’s clogged.

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In the experiments, the mice heard a particular sound after pressing on a lever. This was done repeatedly, until they associated this sound when pressing. The researchers then altered the sounds the mice heard in making subsequent presses—a method designed to mimic unexpected sounds humans hear when making errors.

Every time the sound was too quiet, one group of prediction-error neurons was activated. However, when the sound was the expected volume but came too late, a completely different group of prediction-error neurons was active.

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In short, nonbark matters more than bark.

Incidentally, my oft-reprinted discussion of aphids deals with a presumed nonbark detector for temperature.