Language

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Chapter 12 endnote 16, from How Emotions are Made: The Secret Life of the Brain by Lisa Feldman Barrett.
Some context is:

The next question, then, is whether great apes have the capacity to learn words and use them for learning concepts in the way that human infants do. [...] Scientists actively debate the brain mechanisms for human language.

Some believe that the capacity for human language is due to absolute brain size. Larger brains have more neurons and therefore more computational power. Others argue that certain brain regions have grown disproportionately large.[1][2] Still others emphasize more nuanced changes in microcircuitry.

Macaques and chimps both have a language network and a default mode network,[3][4][5][6] as well as some sort of a salience network. (Recall that the salience and default mode networks together form an interoceptive network.) These networks look very similar to the human versions at a macro level, but the wiring differences within and between these networks are substantial across species, with increased connectivity from macaques to chimps to humans. In the language network, Wernicke’s Area is left lateralized in chimps and humans, whereas Broca’s Area is left lateralized only in humans.[7][8][9] Scientists are coming to the conclusion that many differences between humans and our closest primate cousins are due to the large differences in microscopic wiring in these association regions, allowing better multi-sensory summarizing (i.e., better abstraction) from sensory prediction errors.[10][11]

Note: There are also differences in the wrapping around neurons (to speed information transfer between neurons, called myelination), dendritic densities (increasing the strength of connection at synapses, to help transmit the electrical signal to the neuron’s cell body), neurotransmitter concentrations (the chemicals that sit in the synapses between neurons and allow them to transfer information), and the number and type and distribution of glial cells (brain cells that help to regulate how efficiently neurons pass information to one another, along with other things like brain metabolism).[8][12][13]

The human capacity for creating social reality, glued together and communicated with symbols such as words, may be a uniquely human adaptation. The evolution of language may have been a game-changer in terms of how the human brain processes prediction error, learns and generates concepts.


Notes on the Notes

  1. Barton, Robert A., and Chris Venditti. 2013. "Human frontal lobes are not relatively large." Proceedings of the National Academy of Sciences 110 (22): 9001-9006.
  2. Passingham, Richard E., and Jeroen B. Smaers. 2014. "Is the prefrontal cortex especially enlarged in the human brain? Allometric relations and remapping factors." Brain, Behavior and Evolution 84 (2): 156-166.
  3. Summarized in Binder, Jeffrey R., Rutvik H. Desai, William W. Graves, and Lisa L. Conant. 2009. "Where is the semantic system? A critical review and meta-analysis of 120 functional neuroimaging studies." Cerebral Cortex 19 (12): 2767-2796.
  4. VanDuffel [full reference to be provided]
  5. Barks, Sarah K., Lisa A. Parr, and James K. Rilling. 2013. "The default mode network in chimpanzees (Pan troglodytes) is similar to that of humans." Cerebral Cortex 25 (2): 538-544.
  6. Hutchinson refs [full reference to be provided]
  7. Sherwood, Chet C., Amy L. Bauernfeind, Serena Bianchi, Mary Ann Raghanti, and Patrick R. Hof. 2012. "Human brain evolution writ large and small." In Progress in Brain Research, Volume 195: Evolution of the Primate Brain From Neuron to Behavior, edited by Michel A. Hofman and Dean Falk, 237-254. New York: Elsevier.
  8. 8.0 8.1 Preuss, Todd M. 2011. "The human brain: rewired and running hot." Annals of the New York Academy of Sciences 1225 (S1): E182-E191.
  9. Rilling 2013 [full reference to be provided]
  10. Also suggested by Binder, Jeffrey R., Rutvik H. Desai, William W. Graves, and Lisa L. Conant. 2009. "Where is the semantic system? A critical review and meta-analysis of 120 functional neuroimaging studies." Cerebral Cortex 19 (12): 2767-2796.
  11. Also suggested by Goulas et al., 2014
  12. Sherwood, Chet C., Amy L. Bauernfeind, Serena Bianchi, Mary Ann Raghanti, and Patrick R. Hof. 2012. "Human brain evolution writ large and small." In Progress in Brain Research, Volume 195: Evolution of the Primate Brain From Neuron to Behavior, edited by Michel A. Hofman and Dean Falk, 237-254. New York: Elsevier.
  13. Striedter, Georg F. 2005. Principles of Brain Evolution. Sunderland, MA: Sinauer Associates.