By Paul King, Computational Neuroscientist, Data Scientist, Technology Entrepreneur Updated 23 Apr · Featured in Forbes · Upvoted by Ryan Maloney, PhD Student in Neuroscience, Brown University and Jeffrey Schweitzer, Neurosurgeon The brain is neither analog nor digital, but works using a signal processing paradigm that has some properties in common with both.
Unlike a digital computer, the brain does not use binary logic or binary addressable memory, and it does not perform binary arithmetic. Information in the brain is represented in terms of statistical approximations and estimations rather than exact values. The brain is also non-deterministic and cannot replay instruction sequences with error-free precision. So in all these ways, the brain is definitely not "digital".
At the same time, the signals sent around the brain are "either-or" states that are similar to binary. A neuron fires or it does not. These all-or-nothing pulses are the basic language of the brain. So in this sense, the brain is computing using something like binary signals. Instead of 1s and 0s, or "on" and "off", the brain uses "spike" or "no spike" (referring to the firing of a neuron). Internal to the neuron, everything works via biochemical pathways, which are somewhat similar to analog. Neurons also perform internal electrical signal integration in an analog fashion. Analogously, the digital logic gates used by computers are implemented internally using transistors and resistors, which are also analog. This recording of neural spikes over time shows that the spatiotemporal pulses of the neural code looks a lot like digital signaling: The bottom line is that the brain processes information using a representation strategy that is neither analog nor digital. It is a different type of computation, involving circuits and networks composed of spiking neurons. One of the central tasks of neuroscience is to figure out how this information processing paradigm works.