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View submission: Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology
This is a sneaky complex question about a concept termed "Mental Chronometry"^([1]), which is a super rad topic.
Ignoring for a moment the computational nature of the brain and instead choosing to focus on the informational relay capacity of the central, peripheral, and enteric nervous systems, information transmission throughout the body (aka the basis of thought and action) is fundamentally defined by the biomechanics of the cells themselves, notably the neurons and their associated glial counterparts. For long distance forms of communication, many of our neurons have specific minimum time intervals (refractory periods^([2])) that define the minimum rate at which they can transmit data through 'bursts' of electrochemical activity (a process we have term "action potentials"), which ends up being roughly 1 action potential for each 1-2 milliseconds of elapsed time.
At the same time, those electrochemical signal 'bursts' travel significantly slower than electrical signals in electronics. To put it in perspective, information transmission via electromagnetic field propagation (the basis of neuron electrochemical signaling) can move at around 150-250 mph in a ideal setting^([3]). This is in contrast to information transmission sent via electrons flowing down a wire, which can move at 300-600 *million* mph. All that is to say, it can take many milliseconds for a signal to migrate the vast distances down the dendrites and axons of the neurons in our brain and nerves. As a realistic example, a standard neural pathway could easily have 10 to 20 synapses spanning a distance of >0.5 meters, meaning that to connect a part of your brain, like your premotor/motor cortex, to a far off region of your body, like a muscle in your finger, you could end up with latencies of over >100-300 milliseconds for a single small piece of a volitional motor signal to arrive at its destination^([4]).
That said, to cleverly dodge around the question of the speed of "thoughts" or any type of computationally complex neural signal, there are many overlapping, compounding factors at play in higher level cognition, ranging from the miniscule scope of molecular interactions all the way to vast networks of billions of cells and trillions of synapses^([1]). Some of these factors include information density and encoding, internally generated vs externally stimulated thoughts, stimulus intensity, neural rhythmic activity between distant brain regions, how many and which regions of the brain are being recruited to solve the computational task, memory priming, cognitive activity level, attentional volitional control, fatigue states, and the list goes on. This also ignores the huge elephant in the room being that "time" as a neural construct is not a universal truth, and the "time" we perceive is only one of the many complex illusions created by our brains to help us cope with the complexities of our environments^([6]). That being said, I'm going to hold off from diving into how all these elements overlap, as this is already far too long and I'm not sure I'm qualified. However, I *will* list some great articles that delve into these concepts for anyone interested:
There's nothing here!