
Speaking of brain injury, here's Jill's very inspirational personal experience
with additional commentary by Perplexity that highlights brain's left/right hemisphere
specialization and hints of similar specialization in three-brained humans (UB, 49:4.3).
Re:
https://www.ted.com/talks/jill_bolte_ta ... of_insight
"Jill Bolte Taylor: My stroke of insight"

Re:
https://www.perplexity.ai/
Q: Why did evolution create two hemispheres of the brain, each with different but complementing functionality?
The evolution of the human brain into two hemispheres with different but complementary functionalities is a complex process
driven by several factors, including efficiency, specialization, and genetic influences.
Structural and Functional Asymmetry
While the human brain is largely symmetrical anatomically, it exhibits fine-scale structural asymmetries that underpin functional divisions. This phenomenon, known as brain lateralization or hemispheric specialization, allows different cognitive functions to be processed predominantly in one hemisphere. For instance, language is typically processed in the left hemisphere, while spatial attention is more often managed by the right hemisphere.
Evolutionary Advantages
One of the primary evolutionary advantages of having two specialized hemispheres is efficiency. By localizing specific cognitive functions to one hemisphere, the brain can free up neural space for other functions in the opposite hemisphere, reducing the frequency of transmission errors and enhancing overall cognitive performance. This specialization allows for a broader range of tasks to be managed more effectively, expanding the brain's functional capabilities.
Genetic and Environmental Influences
Research indicates that the structural asymmetry of the human brain has been shaped by evolutionarily ancient genes that have assumed new functions over time. These genes, which originated before the emergence of bilaterally symmetrical animals and bony vertebrates, are upregulated in brain tissues, suggesting a significant evolutionary role in brain asymmetry. Additionally, individual variations in brain asymmetry are influenced by both genetic and non-genetic factors, including personal experiences.
Adaptive Significance
Brain asymmetry is not unique to humans and is observed in other animals, suggesting adaptive benefits. For example, the asymmetry in the claws of fiddler crabs and the eyes of flatfish highlights how asymmetry can be advantageous in specific contexts. In humans, asymmetry in brain regions is linked to advanced neural functions such as consciousness, speech, language, memory, and cognitive performance.
Implications for Disorders
Abnormalities in brain asymmetry have been associated with various neuropsychiatric disorders, including dyslexia, schizophrenia, and autism spectrum disorders. Understanding the heritability and functional implications of brain asymmetry can provide insights into the development of these conditions and potential therapeutic interventions. In summary, the evolution of two hemispheres in the human brain, each with different but complementary functionalities, is a result of evolutionary pressures favoring efficiency, specialization, and adaptability. This structural and functional asymmetry enhances the brain's ability to manage a wide range of cognitive tasks, contributing to the complexity and versatility of human intelligence.
Q: Is the right hemisphere of the brain predominantly parallel processing and the left hemisphere serial processing?
"The relationship between hemispheric processing styles (parallel vs. serial) is more nuanced than a simple right-parallel, left-serial dichotomy. Research suggests that both hemispheres can engage in parallel and serial processing, but they may have different tendencies or strengths depending on the task and stimuli.
Left Hemisphere Processing:
Contrary to the assumption that the left hemisphere is strictly serial, studies have shown that it can process information in parallel when the task requires featural analysis of stimulus materials. This parallel processing capability in the left hemisphere was observed in visual search tasks involving both letter and symbol stimuli.
Right Hemisphere Processing:
While the right hemisphere is often associated with parallel processing, it's not exclusively limited to this mode. The right hemisphere
has been found to play important roles in both language and action processing, suggesting a more complex processing style.
Task and Stimuli Dependence:
The processing style (parallel or serial) employed by each hemisphere appears to depend on the nature of the task and the type of stimuli presented.
For instance, linguistic material can be analyzed either verbally or visually, which may influence the processing approach used by each hemisphere.
Specialization and Complementarity:
Rather than a strict parallel vs. serial division, the hemispheres show specialization for different types of information processing. The right hemisphere is generally better at processing global information, while the left hemisphere excels at processing local details. This specialization allows for complementary processing of information.
Flexibility in Processing:
Both hemispheres demonstrate flexibility in their processing strategies. The left hemisphere, traditionally associated with language
and sequential processing, can adapt to parallel processing when required by the task.
In conclusion, while there may be tendencies for the right hemisphere to engage more in parallel processing and the left in serial processing, this is not an absolute rule.
Both hemispheres can employ parallel and serial processing strategies depending on the task demands, stimulus characteristics, and cognitive requirements. The brain's hemispheric specialization is more about
complementary processing styles that work together to efficiently handle various types of information and cognitive tasks."
Q: Can a human influence left- or right-brain dominance?
"T
he concept of left-brain or right-brain dominance in humans is largely a myth. This idea suggests that individuals are either left-brained (analytical and logical) or right-brained (creative and intuitive), and that this dominance influences their personality and cognitive abilities. However, recent research and scientific consensus indicate that this is not accurate.
Brain Function and Hemispheric Specialization
While it is true that the left and right hemispheres of the brain specialize in different tasks, such as language being predominantly processed in the left hemisphere and spatial tasks in the right, the brain operates as a whole. Both hemispheres are interconnected and work together to perform a wide range of functions. For instance, creativity and logical thinking often require the integration of multiple brain regions across both hemispheres.
Research Findings
A 2013 study from the University of Utah examined brain scans of over 1,000 individuals and found no evidence of a dominant side of the brain. The study concluded that activity levels were similar on both sides of the brain, regardless of the individual's personality traits. This finding undermines the notion that people are either left-brained or right-brained.
Misconceptions and Popularity
The myth of left-brain vs. right-brain dominance persists partly because it offers a simplistic way to categorize personality traits and cognitive styles. It aligns with the human tendency to sort individuals into types, similar to personality tests like the Myers-Briggs Type Indicator, which also lack strong scientific support. The myth is further perpetuated by self-help books and educational materials that claim to help individuals optimize the functions of their supposedly dominant brain hemisphere.
Conclusion
In summary, while there are specialized functions within each hemisphere of the brain,
the idea that individuals can influence or are inherently dominated by one side of their brain is not supported by scientific evidence. The brain's hemispheres work together, and cognitive abilities and personality traits are the result of complex interactions across the entire brain."
Rod
