Mind Hacks

Hack #33. Neural Noise Isn’t a Bug; It’s a Feature

Neural signals are innately noisy, which might just be a good thing.

Neural signals are always noisy: the timings of when they fire, or even whether they fire at all, is subject to random variation. We make generalizations at the psychological level, such as saying that the speed of response is related to intensity by a certain formula—Pieron’s Law [[Hack #11]]. And we also say that cells in the visual cortex respond to different specific motions [[Hack #25]]. But both of these are true only on average. For any single cell, or any single test of reaction time, there is variation each time it is measured. Not all the cells in the motion-sensitive parts of the visual cortex will respond to motion, and those that do won’t do it exactly the same each time we experience a particular movement.

In the real world, we take averages to make sense of noisy data, and somehow the brain must be doing this too. We know that the brain is pretty accurate, despite the noisiness of our neural signals. A prime mechanism for compensating for neural noise is the use of lots of neurons so that the average response can be taken, canceling out the noise.

But it may also be the case that noise has some useful functions in the nervous system. Noise could be a feature, rather than just an inconvenient bug.

In Action

To see how noise can be useful, visit Visual Perception of Stochastic Resonance ( http://www.umsl.edu/~neurodyn/projects/vsr.html ; Java) designed ...