Is intelligence the result of nurture or nature?

Among the neuroscientists who research how the brain works to process and encode information, there's a simple saying that summarizes their understanding of the basic biology involved, which would give the answer to that question to be "nurture":

"Cells that fire together, wire together."

The cells in this case would be groups of neurons, where the phrase describes how many neuroscientists believe these cells within a brain process new information by "firing" to create neural networks whenever a new stimulus is experienced. If that stimulus is experienced over and over again, the brain responds by triggering the same groups of neurons tied to the same sensory inputs again and again, where memory and learning is established through a form of path dependence, where the connections between the neurons are strengthened by their repeated firings in response the same stimulus, thanks in good part to the work of a "master switch" found in the brain's individual neurons: the NMDA receptor.

But the results of new research suggest that the neurons within the brain may be working in a wholly different way to process and learn new information. Instead of the adaptive "fire and wire" experiential learning system described by the older research, the newer research suggests that the brain's neural networks are already prewired together, which when exposed to stimuli, are combined into what the neuroscientists call "functional connectivity motifs" according to a simple mathematical relationship.

So, instead of its neural pathways being generated entirely through experience, the way the brain is wired together is inherently built into its structure, where its "nature" is what causes learning and memory to work the way they do. Here's the abstract from the recently published paper describing the new findings:

There is considerable scientific interest in understanding how cell assemblies—the long-presumed computational motif—are organized so that the brain can generate intelligent cognition and flexible behavior. The Theory of Connectivity proposes that the origin of intelligence is rooted in a power-of-two-based permutation logic (N = 2ⁱ–1), producing specific-to-general cell-assembly architecture capable of generating specific perceptions and memories, as well as generalized knowledge and flexible actions. We show that this power-of-two-based permutation logic is widely used in cortical and subcortical circuits across animal species and is conserved for the processing of a variety of cognitive modalities including appetitive, emotional and social information. However, modulatory neurons, such as dopaminergic (DA) neurons, use a simpler logic despite their distinct subtypes. Interestingly, this specific-to-general permutation logic remained largely intact although NMDA receptors—the synaptic switch for learning and memory—were deleted throughout adulthood, suggesting that the logic is developmentally pre-configured. Moreover, this computational logic is implemented in the cortex via combining a random-connectivity strategy in superficial layers 2/3 with nonrandom organizations in deep layers 5/6. This randomness of layers 2/3 cliques—which preferentially encode specific and low-combinatorial features and project inter-cortically—is ideal for maximizing cross-modality novel pattern-extraction, pattern-discrimination and pattern-categorization using sparse code, consequently explaining why it requires hippocampal offline-consolidation. In contrast, the nonrandomness in layers 5/6—which consists of few specific cliques but a higher portion of more general cliques projecting mostly to subcortical systems—is ideal for feedback-control of motivation, emotion, consciousness and behaviors. These observations suggest that the brain's basic computational algorithm is indeed organized by the power-of-two-based permutation logic. This simple mathematical logic can account for brain computation across the entire evolutionary spectrum, ranging from the simplest neural networks to the most complex.

That's a very interesting finding, so we've built the following tool to do the related math to indicate just how many neural network "cliques" or pre-existing clusters of connected neurons are involved to process a given number of information inputs. If you're reading this article on a site that republishes our RSS news feed, please click here to access a working version of this tool!

That the relationship indicated by the tool above appears to hold is suggested by the neuroscientists' experimental results using mice.

If the brain really operates on N= 2ⁱ-1, the theory should hold for multiple types of cognitive tasks. Putting the idea to the test, the researchers fitted mice with arrays of electrodes to listen in on their neural chatter.

In one experiment, they gave the animals different combinations of four types of food — standard chow, sugar pellets, rice or skim milk droplets. According to the theory, the mice should have 15 (N= 2⁴-1) neuronal cliques to fully represent each food type and their various combinations.

And that’s what they found.

When recording from the amygdala, a brain area that processes emotions, some neurons responded generally to all kinds of food, whereas others were more specific. When clustered for their activity patterns, a total of 15 cliques emerged — just as the theory predicted.

In another experiment aimed at triggering fear, the animals were subjected to four scary scenarios: a sudden puff of air, an earthquake-like shake, an unexpected free-fall or a light electrical zap to the feet. This time, recordings from a region of the cortex important for controlling fear also unveiled 15 cell cliques.

Similar results were found in other areas of the brain — altogether, seven distinct regions.

The most interesting part of the researchers' experiments was that they found the mathematical relationship held even in mice that had been genetically-modified so that their brain's neurons lacked the NMDA receptor, which therefore could not possibly "fire" in response to the experimental stimuli to form neural networks according to the long prevailing theory of how memories are formed.

The other really interesting finding from the new research is that the brain's reward center would appear to operate according to different parameters.

The notable exception was dopamine neurons in the reward circuit, which tend to fire in a more binary manner to encode things like good or bad.

Overall, these new findings indicate new directions for research into the brain's plasticity, which has important applications for developing treatments for traumatic injuries to the brain.

References

Xie, Kun; Fox, Grace E.; Liu, June; Lyu, Cheng; Lee, Jason C.; Kuang, Hui; Jacobs, Stephanie; Li, Meng; Liu, Tianming; Song, Sen; Tsien, Joe Z. Brain Computation Is Organized via Power-of-Two-Based Permutation Logic. Frontiers in Systems Neuroscience, 15 November 2016 | http://dx.doi.org/10.3389/fnsys.2016.00095.

We weren't kidding when we said that Garth Sundem's new book, Brain Candy, would be likely to inspire new tools here at Political Calculations!

Our first venture takes us into the murky depths of your own morality where your task, if you dare, shall be to read the story below, then use our tool to rank the characters from the familiar tales of Sherwood Forest in order from the most to least moral.

When you've finalized your order, click the Calculate button and we'll tell you what you've just communicated about your views of morality and of male-female relationships

We'll also give you a pretty good idea of the percentage of people who have taken the same quiz have answered the same way you have!

Here's the story:

The Sheriff of Nottingham has finally caught Robin Hood and Little John! Instead of killing them immediately, he makes the mistake of all storybook villains in simply stashing them in the dungeon. Despite their track record of heroics, there the two benevolent outlaws rot - until Maid Marian shows up pleading her love for Robin and begging for his release. Sure, says the Sheriff, if Marian will sleep with him.

She does. Robin and Little John are released. But when Maid Marian tells Robin the truth of how she earned their freedom, Robin dumps her faster than a leprous leech. Little John defends her behavior and offers his lifelong devotion if she will ride away from Sherwood with him forever.

She does. The end.

Quite the moral dilemma, eh? It's time for you to rank the players from our tale:

According to Garth, the most common order in which the "lusty quartet" are ranked is: Little John, Maid Marian, Robin Hood and the Sheriff of Nottingham (about 15% of all test-takers). The second most common ranking is: Maid Marian, Little John, Robin Hood and the Sheriff of Nottingham (about 13%).

He offers these insights into what each character represents:

Robin Hood: He's your sense of absolute morality. Putting Robin first implies a degree of chauvinism and putting him last implies a whatever-it-takes view of morality.

Little John: He's a bit underpowered man-wise, but he represents good-hearted pragmatism. Ranking him high implies realism, honesty, and steadfastness.

Sheriff of Nottingham: You value truth above morality - and, if you ranked him high, may have a bit of the sulky child about you.

Maid Marian: You value strong women. Did you put Little John or Robin Hood second? If the latter, you might feel a bit guilty about your contentedness. If you put the Sheriff second, you likely know the location of the nearest leather-and-lace store.

And there you have it - a Rorschach test for determining which moral universe you call home!