The Spike: An Epic Journey Through the Brain in 2.1 Seconds

by Mark Humphries

As theorists, they instantly realized something was amiss. Our best models for how neurons make spikes don’t have randomly different intervals between those spikes. No matter how irregularly spaced the spikes these models receive, the spikes they make are evenly spaced, the intervals between them far more regular than Softky and Koch saw in the cortex. To grasp why, think about the total number of spikes arriving at a neuron. Even though each of the individual inputs has highly irregular spikes, there are thousands of such inputs. So when we sum over them to get the total number of spikes arriving, then we find the sum is pretty constant in time. So if a model neuron needs, say, 175 input spikes to make one new spike, then a total of 175 input spikes turns up regular as clockwork, thus making a new spike regular as clockwork (figure 3.3).