fMRI Data Reveals How Many Parallel Processes Run In the Brain

New submitter xgeorgio writes: From MIT Technology Review: "The human brain carries out many tasks at the same time, but how many? Now fMRI data has revealed just how parallel gray matter is. ... Although the analysis is complex, the outcome is simple to state. Georgiou says independent component analysis reveals that about 50 independent processes are at work in human brains performing the complex visuo-motor tasks of indicating the presence of green and red boxes. However, the brain uses fewer processes when carrying out simple tasks, like visual recognition.

That's a fascinating result that has important implications for the way computer scientists should design chips intended to mimic human performance. It implies that parallelism in the brain does not occur on the level of individual neurons but on a much higher structural and functional level, and that there are about 50 of these. 'This means that, in theory, an artificial equivalent of a brain-like cognitive structure may not require a massively parallel architecture at the level of single neurons, but rather a properly designed set of limited processes that run in parallel on a much lower scale,' he concludes." Here's a link to the full paper: "Estimating the intrinsic dimension in fMRI space via dataset fractal analysis – Counting the `cpu cores' of the human brain."

Comments

Re:analog computer

[Spazmania]

You misunderstand the difference between a digital computer and an analog computer. Both are based on 1's and 0's, on and off.

The digital computer is driven by a clock strobe. When the clock strobes, the whole set of circuits accepts and processes the next inputs. As a result, the circuit is stable at the end of each clock cycle.

An analog computer has no clock. Inputs are processed as soon as they arrive. As a result, the circuit is never known to be in a stable state. It's continually in flux based on its inputs.

"Parallel processing" describes a digital computer in which multiple programs advance with each cycle of the clock. There is no clock in an analog computer. Every single circuit acts independently as soon as its inputs change. Groups of circuits can be heavily interconnected or lightly interconnected but that interconnectedness is very poorly described by digital computer concepts like "parallel processing."

If we ever build a true AI on a digital computer, it won't work anything like the human brain. The underlying hardware is just too different.

Re:analog computer

[ultranova]

The brain is an analog computer. The notion of parallelism is fundamentally different for an analog computer...

Citation needed. Intuitively the difference between a digital and analog computer is that the former has two discrete signal levels while the latter has a continuous band. This doesn't seem to imply anything about the actual structure of the system.

Also, it isn't certain that the brain is actually analog. Individual neurons have discrete "firing" and "not firing" states. Firing rate is often summarized as neuron activation level, since it correlates with energy usage which is what various imaging techniques actually measure, but that doesn't prove that the timing of individual firing events doesn't matter. And if they do, we have a digital system.

In a sense, every single neuron is operating independently and in parallel with the rest. Describing it in terms of parallel processing with digital CPUs makes no sense.

Every single transistor is also operating independently and in parallel with the rest.