2 upvotes, 3 direct replies (showing 3)
View submission: Ask Anything Wednesday - Biology, Chemistry, Neuroscience, Medicine, Psychology
Which part of the brain is responcible for speed of thought and movement?
Comment by Cadel13 at 15/03/2023 at 15:52 UTC
3 upvotes, 0 direct replies
Speed of thought isn’t really a measurement that can be made. We can measure the time it takes to receive an outside stimulus and the time it takes to react to that stimulus. We can also check how long it takes to solve certain kinds of problems, but you’ll have to be more specific about what problems to identify parts of the brain associated with that specific kind of question.
Movement is complex and requires several parts of the brain. The two that are probably the most noteworthy is the motor cortex in the telencephalon and the cerebellum, but to say it’s only those two structures would be a gross oversimplification.
Comment by bwyazel at 15/03/2023 at 16:14 UTC*
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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:
Comment by Brain_Hawk at 16/03/2023 at 03:33 UTC
2 upvotes, 0 direct replies
All of it. Sort of. These aren't things that have really specific. Structural bases. Movement is controlled by the motor cortex, if by speed of moment you mean things like your reaction time, it's all about pathways and networks and systems and how well they connect.
So the features you're describing are very distributed in the brain, and are based on certain types of basic neurophysiological development. Some of us think faster than others, which can be good and can be bad. Some people have great reaction time, which is probably mostly a plus, but there's not like it's one region that somehow are differently, it's about how everything interacts, how synapses and neurons function, all kinds of things
The most important thing to remember when trying to understand the brain is that it's goddamn complicated