Introducing the brain: not understanding how it works (Introduction)

by David Turell @, Sunday, February 02, 2020, 19:29 (161 days ago) @ David Turell

Even if all the connections were known, we still will not fully understand how it works:

http://nautil.us//issue/81/maps/an-existential-crisis-in-neuroscience?utm_source=Nautil...

"Subtitle to article: :We’re mapping the brain in amazing detail—but our brain can’t understand the picture."

"...computer servers were holding on to a precious 48 terabytes of my data. I have recorded the 13 trillion numbers in this dataset as part of my Ph.D. experiments, asking how the visual parts of the rat brain respond to movement.

"Printed on paper, the dataset would fill 116 billion pages, double-spaced

***

"But, as massive as my dataset sounds, it represents just a tiny chunk of a dataset taken from the whole brain. And the questions it asks—Do neurons in the visual cortex do anything when an animal can’t see? What happens when inputs to the visual cortex from other brain regions are shut off?—are small compared to the ultimate question in neuroscience: How does the brain work?

***

"We can identify brain regions that respond to the environment, activate our senses, generate movements and emotions. But we don’t know how different parts of the brain interact with and depend on each other. We don’t understand how their interactions contribute to behavior, perception, or memory. Technology has made it easy for us to gather behemoth datasets, but I’m not sure understanding the brain has kept pace with the size of the datasets.

***

"The mysteries of how brains create memories, thoughts, perceptions, feelings—consciousness itself—must be hidden in this labyrinth of neural connections.

***

"Scientists still need to understand the relationship between those minute anatomical features and dynamical activity profiles of neurons—the patterns of electrical activity they generate—something the connectome data lacks. This is a point on which connectomics has received considerable criticism, mainly by way of example from the worm: Neuroscientists have had the complete wiring diagram of the worm C. elegans for a few decades now, but arguably do not understand the 300-neuron creature in its entirety; how its brain connections relate to its behaviors is still an active area of research.

***

"Lichtman didn’t entertain the far-out ideas in science fiction, but acknowledged that a network that would have the same wiring diagram as a human brain would be scary. “We wouldn’t understand how it was working any more than we understand how deep learning works,” he said. “Now, suddenly, we have machines that don’t need us anymore.”

***

"A strong intuition among many neuroscientists is that individual neurons are exquisitely complicated: They have all of these back-propagating action potentials, they have dendritic compartments that are independent, they have all these different channels there. And so a single neuron might even itself be a network. To caricature that as a rectified linear unit”—the simple mathematical model of a neuron in DNNs [deep neuron networks]—“is clearly missing out on so much.”

***

"It seems likely that Lichtman’s two exabytes of brain slices, and even my 48 terabytes of rat brain data, will not fit through any individual human mind. Or at least no human mind is going to orchestrate all this data into a panoramic picture of how the human brain works...The machines we have built—the ones architected after cortical anatomy—fall short of capturing the nature of the human brain. But they have no trouble finding patterns in large datasets. Maybe one day, as they grow stronger building on more cortical anatomy, they will be able to explain those patterns back to us, solving the puzzle of the brain’s interconnections, creating a picture we understand."

Comment: First of all, this complexity demands a designer. Secondly this applies to our discussion about which came first large brain or from dhw a necessity telling the brain to enlarge and complexify. The dhw approach demands to know how did the brain learn to make itself function better by enlarging and complexifying? Only a designer could have created that mechanism, a mechanism dhw awards to evolving organisms by his suggesting God gave such a mechanism so they could do it themselves. But we know the modern brain shrinks under such circumstances. dhw's theory requires the ancient brains had an enlarging mechanism and now they don't. Evolution in reverse!? Not logical and inconsistent reasoning. In evolution doesn't the present build from the past? We know local brain areas enlarge, when required (London cabbies, illiterate women). Why a limited capacity now?


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