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Are We Really Just Wired Differently?
by Tedd Roberts

It's a common attitude in modern society that persons with extraordinary talent are simply wired differently than everyone else. The notion is reinforced by findings of differences in brain structure between persons with different talents, abilities, and even neurological disorders. In contrast, if there is one thing that neuroscientists are sure of, it's that the human brain is highly "plastic"—capable of overcoming disease and even rewiring itself after injury. There is new emerging evidence that many of the differences aren't really there, and the human brain is capable of re-wiring at need.

The notion of "wired differently" has its basis in developmental neuroscience and is omnipresent in popular psychology and social behavior, so it is no wonder that it has also influenced popular fiction. Therefore, this essay will not only examine the science behind the functional wiring and structure of the human brain, it will also look into how these ideas (true or not) have made some key appearances in science fiction.

What Makes the Human Brain Different in the First Place?

It is common to conduct medical research in nonhuman primates—rhesus monkeys, for example—in order to have a research model that is close to human, without the myriad difficulties of working in humans. By this I mean that the monkeys tend not to get bored, they can perform memory tasks in the absence of work and school schedules, and they tend not to spend much time on social media! (They do like cat videos, though.) Figure 1, shows the progression in brain size and shape from rodents to humans, so you can see how a monkey brain may be much more suitable to the study of brain function than a rat.

Figure 1: Brain size and complexity comparison. Top, size comparison between rat, monkey and human. Bottom, brains shown the same size to illustrate differences in brain surface complexity. Images courtesy of neuroanatomy departments, National Institute of Basic Biology, Japan, and University of Washington.

The human brain, however, is much more complex than a rhesus monkey's. This is evident in the comparison at the bottom of Figure 1. While gorilla and chimpanzee brains approach the complexity of human brains, they are still one-half (gorilla) and one-quarter (chimpanzee) the size of the human brain. [Note that scientists do not experiment on Great Apes—chimps, gorillas, bonobos and orangutans—in part because of the intelligence concomitant with their complex brain structure.] Despite the similarities, however, there are critical differences between primate and human brain.

The major functional difference between human and primate brain lies in language and communication. Great Apes have been taught limited sign language vocabularies and learn to communicate quite complex concepts with human handlers. For this reason, we will actually exclude Great Apes from the following discussion. Figure 2 shows a map of various functions on an outline of the human brain, with emphasis on Wernicke's and Broca's areas. Starting with evidence from human patients with damage to these regions, and continuing with electrical mapping intended to spare these functions in patients undergoing brain surgery, we actually know quite a bit about the function and wiring of these two regions. Wernicke's area processes the understanding of language, and is located adjacent to brain areas associated with vision and hearing. In other words, the language center is "wired" to the brain areas associated with reading and listening. Broca's area is necessary for spoken language, and is likewise in a region that intersects with the motor output (muscle control) brain areas necessary to form speech.

Figure 2: Localization of sensory and language processing centers on schematic of the human brain. Image copyright 2011, Tedd Roberts, Teddy's Rat Lab (http://teddysratlab.blogspot.com).

The key piece of information to be gained from this comparison is that human brains have unique structure and function in these two brain regions to support hearing, reading and speaking language—most primate brains do not! The exception, of course is the Great Apes, but even there, Broca's and Wernicke's areas are much smaller and less developed than in humans. Here, then, is the clear indication that at least one element of the human brain is clearly wired for a specific function!

The distinction has been used to good measure in SF as well, and is central to the plot of the 1968 movie The Planet of the Apes. In the movie, three human astronauts land on a planet ruled by intelligent, talking apes; humans in this case are the unintelligent, speechless primates. The fact that a human could speak comes as a surprise to the apes, and they vivisect one astronaut's brain to figure out how this can happen. Likewise in Michael Crichton's Next (2006), the plot involves splicing of human genes onto animals to give them various degrees of speech and/or intelligence. While much of the speculation in Next is inconsistent with the current understanding of human and primate neuroscience, it still supports the public understanding that speech equals intelligence, and that the human brain is specifically wired for that ability.

Left Brain vs. Right Brain

Having established that there is definitely an importance to the wiring of the brain that makes humans unique, it is important to note that the speech and language centers in the human brain are "lateralized"—that is, they exist in the left half of the brain. The equivalent locations on the areas on the right side of the brain do not support the same functions. The first research on the left brain/right brain nature comes from Dr. Roger W. Sperry, whose epilepsy research determined that cutting the corpus callosum—the "wiring" between left and right halves—was an effective treatment for reducing epileptic seizures, but caused a separation of functions within the brain. For example, if a patient was shown a picture in a manner that it only appeared in the portion of their vision that projected to the right half of the brain, they could not name what they saw. However, if they had the ability to write with their left hand, they could write the name!

Much of our understanding of laterality comes from studying epilepsy and stroke patients. A person with damage to Broca's area might lose the ability of speech, but could still sing songs. Damage to the right half of the brain might impair the ability to draw or paint, but the ability to write would be spared. Sperry was awarded a Nobel Prize in 1981 for his work on laterality of the brain, and from his work derived a whole pop psychology notion of "left brain dominant" vs. "right brain dominant" individuals—with science, math and logic associated with the left brain and art, intuition, and creativity associated with the right brain.

This dichotomy is nicely illustrated by the writing of James P. Hogan, who enjoyed placing both left and right brain characters in his novels. Most notably, the protagonists of his novel (and sequels) Inherit the Stars, Christian Danchekker and Victor Hunt exhibit left brain and right brain traits, respectively. What is notable about this dichotomy in the two characters is that while both are identified as scientists, Hunt considers himself an engineer and creator, solving problems by intuition and imagination while Danchekker plays the classic logical/rational scientist, who is frequently wrong—precisely because of his limited imagination. This is not terribly surprising, as much of Hogan's later writing would express admiration of engineers and creative individuals and distrust of scientists.

I am certain that many readers will have seen an internet video that shows a spinning ballerina, if you perceive the dancer spinning clockwise, you are right-brain dominant, if counterclockwise, you are left-brain dominant. I find it relatively amusing that I, a scientist, quite good at math and logic puzzles always see the dancer spinning clockwise. However, it is relatively easy to reverse your perception and see the ballerina turning in the opposite direction! Thus, the left vs. right laterality supposedly uncovered by the optical illusion is more a trick of our visual system, and not indicative of our wiring at all.

The problem with the left-right view of brain function is that modern functional imaging of the human brain shows that it just isn't true. Moreover, if logic vs. creativity were a product of the native wiring of the brain, then it most certainly could not be learned or trained! Yet, in the course of researching and checking background assumptions for this article, I came across websites and even training academies that purport to teach you to do exactly that—shift your usage from left to right brain, or vice versa.

Since Dr. Sperry's experiments in the ‘60s, science and medicine have developed much more precise methods for examining the function and even the wiring of the human brain. Functional magnetic resonance imaging—a variation on the MRI that tracks oxygen utilization (and hence neural activity) in the brain shows that while there are some lateralized functions such as speech, both hemispheres are active in the brain for any given function; the aforementioned corpus callosum allows both hemispheres of the brain to communicate and send signals back and forth. Even in the case of muscle control—in which the motor areas of the brain control muscles on the opposite side of the body—movement of one limb still causes some activity on the opposite side of the brain, mainly to control balance and posture.

The communication between hemispheres of the brain is an important contributor to the wiring of the brain, and damage to this wiring is where researchers see most evidence of laterality. At the same time, it is essential to reversing that laterality, especially as seen in stroke recovery, or in the near-miraculous recovery of juveniles who sustain brain injury, but can recover function despite damage to lateralized functions. The most astounding proof comes from the development of children who undergo cerebral hemispherectomy for a number of disorders (epilepsy, stroke, hydrocephalus, etc.). As with stroke rehabilitation, physical therapy can restore near-normal muscle function despite the lack of the appropriate motor cortex; and up to the teen years, even language and speech functions can migrate to the right hemisphere.

With respect to left and right brain function, therefore, the notion that humans are prewired for certain functions has some basis in neurophysiology, but it is not an unchangeable feature of the wiring of the brain. We do know that some defects in wiring lead to neuropsychological disorders. It is thought that the Autism-Asperger's Spectrum Disorders are the result of unbalanced wiring, particularly from sensory areas to the regions which integrate sensory information and with attention, decision and communication centers. On the, whole, though, normal human brain function and wiring are capable of rearrangement when necessary.

The Infamous Political Brain Study

Related to the issue of left vs. right brain is a highly controversial study reporting differences in the brains of college students self-described as having liberal or conservative views. The study from the University College of London in 2011 (doi:10.1016/j.cub.2011.03.017) examined the brain structure of 90 students and correlated size of two structures with their political leanings. The results showed that self-professed liberal students had larger cingulate cortex, while conservative students exhibited a larger amygdala. Many commentators immediately jumped on the findings and proclaimed that since "everyone knows" that the amygdala is responsible for fear, and the cingulate is associated with behavioral flexibility; therefore, liberals had flexible minds, while conservatives were ruled by fear!

The problem here is that interpretation of the results more often exposes the commenter's bias, rather than any real difference in the brain. The issue is the "everyone knows" part of the interpretation. While it is true that the amygdala is involved in fear response, it is also an important component of the human memory system; it is active in many emotional contexts as well as recall of "historical" and autobiographical memory. Likewise, the cingulate cortex is not just involved in behavioral and cognitive flexibility, but is essential to comparing expected and actual outcomes of an anticipated event. Thus, amygdala would be active when comparing a current event to history, while cingulate would be active when determining whether that event was expected or surprising.

One could therefore reinterpret the UCL findings as "liberals have an unrealistic expectation and are surprised when things don't happen the way they expected, while conservatives have a realistic view based on past history." Again, this is a controversial stand, and about as likely to be true as the former interpretation. Reasons why neither conclusion is likely stem from the location and type of study. In the first place, the study was conducted on college students in London—the political spectrum of English college students is unlikely to match those of middle-aged Americans (or any other age or nationality). Second, the study was correlative, the size (volume) of many brain areas were computed, then a regression identified these two areas as correlating to the self-identified political ideology. Correlation can go either way—regional sizes (i.e. wiring) may be involved in political outlook, or the thought patterns associated with the political ideology may affect usage (and hence developmental size) of the brain areas. In either event, it is an essential truth of science that correlation does not equate to causality; sometimes events just occur together and are correlated by chance.

This raises an interesting question as to whether use of a brain area can change its wiring. A former post-doc from my laboratory studied birds that store food for the winter and do not migrate. He found that the memory areas of the brain enlarge during summer and fall, and shrink during winter and spring. The interpretation is that the birds must store and remember information regarding their food locations as they build their caches. Once food is removed from the cache; they no longer need to keep that information. This gets back to ideas of memory formation discussed in the June 2015 article "Remember to Remind Me" (http://www.baen.com/remember). However, it does not apply, since mammalian brains do not work the same as in birds; squirrels and other rodents also store food for the winter, but their memory regions do not expand and contract in the process.

The conclusion from these findings is interesting, but ultimately inconclusive. Human brains differ, but whether that difference correlates with political orientation is uncertain. In addition, given some new findings from male and female brains (discussed below) there is unlikely to be a strict one-to-one relationship between wiring and ideology.

Male vs. Female Brain

Having negated the concepts of left vs. right brains (both physically and politically), at least "we all know" that male and female brains are wired differently, right? After all, Heinlein explored this quite powerfully in I Will Fear No Evil in which billionaire Johann Sebastian Bach Smith's male brain has great difficulty adapting to control of the female body into which it was transplanted. Popular psychology [Confession: I may have become a bit jaded by the term] revels in "gender differences" in the human brain, supposedly identifying not just males and females, but underlying trends toward homosexuality and transgender.

Figure 3: Male vs. Female Brain. More than 100 biochemical and anatomical differences have been identified—but are they really significant to brain function? Image © 2016 by Dean Drobot. Used under license from Shutterstock.com.

To start with, scientific accuracy specifies that these are sex differences, given that "gender" is an etymological (language) term, the correct biological term is "sexual dimorphism." Second, the greatest difference between male and female brains is biochemical, and not wiring. The source of the difference is the estrogen, one of two hormones responsible for female menstrual cycle, and a powerful modulator of brain function. For this reason alone, some brain areas associated with hormones and sexuality will be different between men and women; however, estrogen is present in the brains of both men and women, and at similar quantities.

The acknowledgement of sex differences in the human brain came to the forefront of neuroscience in the 1980s, and are particularly associated with research reports by Drs. D.F. Swaab and M.A. Hofman. A very good review and meta-analysis of many studies is compiled in a 2013 review by Amber Ruigrok at Cambridge University (publically available at doi:10.1016/j.neubiorev.2013.12.004). More than 100 discrete sex differences can be identified—ranging from the genetic, to the biochemical, to the anatomic. These differences are thought to account for the differential distribution of diseases and disorders of the brain, such as the presence of autism-spectrum disorders in males, and a skew toward more bipolar and schizophrenia cases in females.

But are these actually wiring differences, and do they account for different behaviors, skills and even sexual identity in humans? A 2015 study says no. Published in the Proceedings of the National Academy of Sciences (USA) (doi: 10.1073/pnas.1509654112) by scientists from Tel-Aviv University, Max-Planck Institute and University of Zurich. The researchers performed an exhaustive study of over 1000 male and female brains, and used using multiple imaging techniques to construct a scale of "maleness-to-femaleness" for many of the sexually dimorphic brain regions as identified by Swaab and Hofman's reports in 1984, as well as the 2013 meta-analysis. The researchers found that rather than clear sex differences, the majority of adult brains were a mosaic of male and female characteristics, irrespective of sex or sexual identity. Thus the supposed "outliers" of the nurturing male and computationally adept female are less the exception, and much more the rule, given a vast dichotomy of brain morphology and function.

Does this support the idea that behavioral traits are due to the mosaic, and hence the wiring of individual brains? In this case, the scientific results tend to support the notion of different abilities from different wiring, it just does not support the idea that the different wiring conforms to the preconceived biological categories.

Strangely, this is an area in which science fiction is rather silent. Heinlein's fictional brain transplant left Joan Eunice Smith nevertheless acting female. Likewise, the head-hopping "Telepathy Corps" in David Gerrold's War Against the Chtorr series, always manage to manifest their own personality, overriding the biological wiring of the host brain. Similar conditions exist throughout the cyberpunk genre, in which the cyber-linked or virtual-reality humans continue to manifest personalities derived from their biological nature. Perhaps this is an area in which the misnamed effort to "end binary gender bias" in SF can take the lead—examining how gradations in the sexual mosaic in the brain intersect with identity and personality!

Twin Brains

SF and science are both fascinated by the notion of twin or cloned brains. Certainly there are many examples of treating clones as virtual twins in fiction, but the reality of the twin brain is much subtler.

Perhaps the most notable study of twin brains is ongoing right now on Earth and in the International Space Station. Fifty-one year old Scott Kelly currently holds the record for most days in space by an American, and at the end of his (current) one-year stay on the ISS, he will be in fourth-place internationally, with over 450 days in space (cumulative over his career). His identical biological twin, Mark Kelly (husband of former Congresswoman Gabrielle Giffords) is likewise an astronaut, but with only 45 days in space. Scott Kelly's mission to spend one-year in the ISS (along with Cosmonaut Mikhail Korniyenko) provides plenty of opportunity to examine the effects of long-duration space flight on the human body—but more importantly, it provides the opportunity to compare effects between the Kelly twins, with particular emphasis on the differences in genes, proteins, and physiological/neurological function.

This is an important study considering the fact that despite identical genetics (and hence neural wiring) between identical twins, their personalities and abilities are so often widely different. Twins are common in my extended family, and it is fascinating to see how different such twins behave; even more so than ordinary siblings. Neurological studies show that while identical genetics may confer a predisposition to disorders such as alcoholism, depression, schizophrenia, etc., twins quite frequently do not develop the same disorders, and when they do, the disorders arise a very different times in the individuals' life.

If twins, with genetically identical wiring, can be different in personality and talents, how do those differences arise? Here we can return again to science fiction for illustration. Lois McMaster Bujold's protagonist Miles Vorkosigan is a strategic genius, with a distinct tendency to think outside the box. His clone-twin Mark is in many ways Miles's exact opposite. Leaving aside the fact that Mark was cloned as part of a plot to kill Miles; the author delves into important questions that are frequently summed up as nature vs. nurture. A very important review from 2011 by Dr. Joan Stiles (https://www.researchgate.net/publication/51047911_Brain_development_and_the_nature_versus_nurture_debate) makes it quite clear that despite genetic programming, experience plays a vital role in affecting nervous system development. Nature, environment, experience; all play a role in the wiring of the human brain. Thus Miles Vorkosigan, from the toxin which affected his growth, to the family environment with his parents Aral and Cordelia, received a vastly different development than Mark, who was subject to accelerated growth and absence of family.

Aside from clones, however, there are still relatively few fictional treatments of twins that do not consider them as identical in genetics and behavior—from telepathic links to finishing each other's sentences. Interestingly there are twin sisters that write SF: Brianna and Brittany Winner, authors of The Strand series of young adult SF novels. Unlike the examples above, it appears that the Winner Twins share many traits in common: despite diagnoses of dyslexia and dysgraphia at age 9, they also had college-level verbal skills by that age, and were recognized as authorial prodigies by age 12! They report that they share many traits, which fuels their collaborative writing and other endeavors.

Figure 4: The diversity of the human brain. Clockwise from top left: Overlaid elements illustrate logic, biochemistry, electrophysiology, computation and gene expression. Image copyright 2015, Robert E. Hampson, used with permission.

Incredible Plasticity

If there is a takeaway conclusion, it is that individual human brains are wired differently; however, it is not the wiring which accounts for differences, but the experiences and patterns that are laid down upon genes, biochemistry, anatomy and physiology of those brains. As Isaac Asimov proposed in "The Ugly Little Boy" (1958), the capabilities of the brain and intelligence (and personality) are the products of experiences, rather than simply wiring. This is evident in the ability to learn new skills such as languages or musical instruments. Likewise, a stroke patient can undergo rehabilitation therapy to regain muscle abilities, or an amputee/quadriplegic can learn to operate an artificial limb. That plasticity is greatest in the developing brain: learning is easier, and at the youngest ages, brain areas explicitly not wired for certain functions can take them over even in the extreme case where one hemisphere is damaged and/or removed because of disease.

So, where does that leave the myriad Internet memes, brain trainers and personality tests? As with anything, some of them work, some don't. True aptitude, memory and personality tests consist of hundreds of questions and/or assessments administered under controlled conditions. Simply looking at a video of a spinning ballerina cannot detect essential differences in inductive vs. deductive reasoning. A 2014 report from seventy neuroscientists associated with Stanford University and Max-Planck Institute concluded:

"To date, there is little evidence that playing brain games improves underlying broad cognitive abilities, or that it enables one to better navigate a complex realm of everyday life."

(http://longevity3.stanford.edu/blog/2014/10/15/the-consensus-on-the-brain-training-industry-from-the-scientific-community-2/)

On the other hand, it is most definitely possible to engage the plasticity and capability of even older human brains to learn new skills such as languages, martial arts or ballroom dancing!

Yes, we are just wired differently; in fact, each human is wired uniquely. By its very nature, the wiring of our brain cannot alone account for different personality, emotion, political outlook, skill, talent or ability since even individuals with similar traits would necessarily have different neural wiring. Even genetic identity (twins and/or clones) results in different experience, such as Scott Kelly experiencing ten times as many days in orbit as his twin brother. Thankfully, this is good news! It not only means that our experience shapes our traits, it provides considerable hope for restoration and recovery of brain function as our medical science advances in the treatment of neurological diseases.

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