ConceptTiming

Related: ConceptAxonDelay

Neurons can be used to handle timing far more accurately than you might think. Even though a neuron can only fire once every 4 ms and the neural spike is 1 ms long, the neuron (both biological and simulated) can differentiate very small timing differences through a neat trick.

Consider that if a neuron receives a +1 and -1 simultaneously or if the -1 arrives first, it will not spike (as in the previous models). If the -1 comes later (even by a tiny amount once the spike is being emitted), the -1 signal will arrive in the refractory period and will be ignored. How can your brain control the arrival times so precisely? With varying axon lengths. By having multiple neurons connected to both ears with varying axon lengths, your brain can determine the angle with great precision.

// In the same way that the previous rate-detector had different neurons which responded to different spike timings, an array of neurons could fire only for specific sound directions. In order to simulate this in the brain simulator, you’d need to set the refractory period to 40 or even more so you could represent timing with sub-millisecond precision.

• Source: Brain Simulator II: The Guide - Charles Simon
• Chapter 4: Axon Delays