Neuroconstructivism

Neuroconstructivism is a theory that states that gene/gene interaction, gene/environment interaction and, crucially, ontogeny are all considered to play a vital role in how the brain progressively sculpts itself and how it gradually becomes specialized over developmental time.

Neuroplasticity is considered an essential part of development.

Supporters of neuroconstructivism, such as Annette Karmiloff-Smith, argue against innate modularity of the mind. Instead, emphasis is put on innate domain relevant biases. These biases are understood as aiding learning and directing attention. Module-like structures are therefore the product of both experience and these innate biases. Neuroconstructivism can therefore be seen as a bridge between Jerry Fodor's Psychological nativism and Jean Piaget's Theory of cognitive development.

Development vs. Innate Modularity

Neuroconstructivism has arisen as a direct rebuttal against psychologists who argue for an innate modularity of the brain.[1][2] Modularity of the brain would require a prespecified pattern of synaptic connectivity within the cortical microcircuitry of a specific neural system.[3] Instead, Annette Karmiloff-Smith has suggested that the microconnectivity emerges from the gradual process of ontogenetic development.[3][4][5] Proponents of the modular theory might have been misled by test results for individuals who possess a learning disability. While it may appear that cognitive functioning may be impaired in only specified areas, this may be a functional flaw in the test. Many standardized tasks used to assess the extent of damage do not measure underlying causes, instead only showing the static end-state.[6] An alternative explanation to account for these normal test scores would be the ability of the individual to compensate using other brain regions that are not normally used for such a task.[3] Such compensation could only have resulted from developmental plasticity and the interaction between environment and brain functioning.

Differences arise in the brain instead through development. Instead of having prespecified patterns of connectivity, neuroconstructivism suggests that there are "tiny regional differences in type, density, and orientation of neurons, in neurotransmitters, in firing thresholds, in rate of myelination, lamination, ratio of gray matter to white matter," etc. that lead to differing capabilities of neurons to handle specific functions.[7][8] For example, the ventral and dorsal streams only arise because of innate differences in processing speed, not an innate desire to be either ventral or dorsal by the respective neurons.[7] Such a differentiation has been entitled a domain-relevant approach to development.[7][8][9] This contrasts the previous domain-general and domain-specific approaches. In the domain-general framework, differences in cognitive functioning are attributed to overarching differences in the neurons across the entire brain. The domain-specific approach contrasts this framework by arguing instead for inherent, specific differences within the genes, which directly control a person's development.

However, domain-specificity cannot be ruled out by neuroconstructivism.[9] Instead, it offers a developmental approach that focuses on change and emergent outcomes.[9] Such change leads to domain-specificity in adult brains, but the key component to the specificity occurred from the domain-general start state.[3] Every aspect of development is dynamic and interactive.[9] Human intelligence may be more accurately defined by focusing on the plasticity of the brain and its interactions with the environment rather than inherent differences within the DNA structure. In fact, dissociations that arise from disorders like Williams syndrome or autism allow neuroscientists to explore differing developmental trajectories, informing the nature versus nurture debate.[3]

Context Dependence

Neuroconstructivism, by viewing development as an emerging process, uses context to demonstrate the possible changes to the brain's neural connections. Starting with genes and incorporating progressively more context illustrates some of the constraints involved in development. Instead of viewing the brain as independent of its current or previous environment, neuroconstructivism shows how context gradually interacts with the brain to eventually form the specialized, adult brain. In fact, by building on preexisting representations, representations become increasingly context bound (rather than context free).[10] This leads to "restrictions of fate," in which later learning is more restricted than earlier learning.[10]

Genes

Previous theories have supposed that genes are static, unchanging code for specific developmental outcomes. However, new research suggests that genes may be triggered by both environmental and behavioral influences.[11] This probabilistic epigenesis view of development,[12] offers that genes, instead of following a predetermined path to expression, are modified by the behavior and environment of an organism. Furthermore, these modifications can then act on the environment, creating a causal circle in which genes influencing the environment are re-influenced by these changes in the environment.

Encellment

Cells do not develop in isolation. Even from a young age, neurons are influenced by the surrounding environment (e.g., other neurons).[13] Over time, neurons interact either spontaneously or in response to some sensory experience to form neural networks.[11] Competition between neurons plays a key role in establishing the exact pattern of connections.[14] As a result, only certain neural activation patterns may arise due to the underlying morphology and connection patterns within the specified neural structures. These may subsequently be modified by morphological change imposed by the current representations. Progressively more complex patterns may arise through manipulation of current neuronal structures by someone's experience.[11]

Enbrainment[15]

While neurons are embedded within networks, these networks are further embedded within the brain as a whole. Neural networks do not work in isolation, such as in the modularity of mind perspective. Instead, different regions interact through feedback processes and top-down interactions,[16] constraining and specifying the development of each region. For example, the primary visual cortex in blind individuals has been shown to process tactile information.[17] The function of cortical areas emerges as a result of this sensory input and competition for cortical space.[18] "This interactive specialization view implies that cortical regions might initially be non-specific in their response but gradually sharpen their responses as their functional specialization restricts them to a narrower set of circumstances."[11]

Enbodiment

The brain is further limited by its constraint within the body. The brain receives input from receptors on the body (e.g., somatosensory system, visual system, auditory system, etc.). These receptors provide the brain with a source of information. As a result, they manipulate the brain's neural activation patterns, and thus its structure, leading to constraining effects on the construction of representations in the mind. The sensory systems limit the possible information the brain can receive and therefore act as a filter.[11] However, the brain may also interact with the environment through manipulation of the body (e.g., movement, changes in attention, etc.), thus manipulating the environment or information received. Pro-activity while exploring the environment leads to altered experiences, and consequently altered cognitive development.[11]

Ensocialment

While a person may manipulate the environment, the specific environment in which the person develops has highly constraining effects on the possible neural representations by restricting the possible physical and social experiences.[11] For example, if a child is raised without a mother, the child cannot change her responses or actions to generate a mother. She may only work within the specified constraints of the environment in which she is born.

The nature of representations

All of the above constraints interact to form cognitive representations in the brain. The main principle is context dependence, with shaping occurring through competition and cooperation.[11] Through competition, developing components may become specialized, leading to new representations. Cooperation, on the other hand, leads to combinations of existing mental representations that allow existing knowledge to be reused. Construction of representations also depends on a person's exploration. However, the experiences derived from this pro-activity constrain the range of possible adaptations within the mental representations.[11] Such progressive specialization arises from the constraints of the past and current learning environment. In order to alter representations, the environment must demand improvements, through small additions to the current mental state. This leads to partial representations[11] instead of the fixed, static representations that are assumed to occur in adults. Neuroconstructivism argues such end products do not exist. The brain's plasticity leads to constant and ever-changing mental representations through individual pro-activity and environmental interactions. Such a viewpoint would then imply that any current mental representations are the optimal outcome for a specified environment. For example, in developmental disorders like autism, atypical development arises because of adaptations to multiple interacting constraints, as in normal development. However, the constraints differ and thus result in a different end-product. This view directly contrasts previous theories which assumed that disorders arise from isolated failures of particular functional modules.[11]

See also

References

  1. ↑ Fodor, J. (1983). The modularity of mind. Cambridge, MA: MIT Press.
  2. ↑ Pinker, S. (1994). The language instinct. London: Penguin.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 Karmiloff-Smith, A. (1997). "The tortuous route from genes to behavior: A neuroconstructivist approach". Cognitive Affective & Behavioral Neuroscience 6 (1): 9–17. doi:10.3758/cabn.6.1.9. PMID 16869225.
  4. ↑ Karmiloff-Smith, A. (1992). Beyond modularity: A developmental perspective on cognitive science. Cambridge, MA: MIT Press, Bradford Books.
  5. ↑ Karmiloff-Smith, A.; Plunkett, K.; Johnson, M.; Elman, J.L.; Bates, E. (1998). "What does it mean to claim that something is "innate"?". Mind & Language 13: 588–597. doi:10.1111/1468-0017.00095.
  6. ↑ Oliver, A.; Johnson,M.H.; Karmiloff-Smith, A.; Pennington, B. (2000). "Deviations in the emergence of representations: a neuroconstructivist framework for analysing developmental disorders". Developmental Science 3 (1): 1–40. doi:10.1111/1467-7687.00094.
  7. ↑ 7.0 7.1 7.2 Karmiloff-Smith, A. (2009). "Preaching to the converted? from constructivism to neuroconstructivism". Child Development Perspectives 3 (2): 99–102. doi:10.1111/j.1750-8606.2009.00086.x.
  8. ↑ 8.0 8.1 Karmiloff-Smith, A. (2012). "Challenging the use of adult neuropsychological models for explaining neurodevelopmental disorders: Developed versus developing brains". The Quarterly Journal of Experimental Psychology 66 (1): 1–14. doi:10.1080/17470218.2012.744424. PMID 23173948.
  9. ↑ 9.0 9.1 9.2 9.3 Karmiloff-Smith, A. (2009). "Nativism versus neuroconstructivism: Rethinking the study of developmental disorders". Developmental Psychology 45 (1): 56–63. doi:10.1037/a0014506. PMID 19209990.
  10. ↑ 10.0 10.1 Mareschal, D. (2011). "From NEOconstructivism to NEUROconstructivism". Child Development Perspectives 5 (3): 169–170. doi:10.1111/j.1750-8606.2011.00185.x.
  11. ↑ 11.0 11.1 11.2 11.3 11.4 11.5 11.6 11.7 11.8 11.9 11.10 Westermann, G.; Mareschal, D.; Johnson, M. H.; Sirois, S.; Spratling, M. W.; Thomas, M. S. C. (2007). "Neuroconstructivism". Developmental Science 10 (1): 75–83. doi:10.1111/j.1467-7687.2007.00567.x. PMID 17181703.
  12. ↑ Gottlieb, G. (1992). Individual development and evolution. Oxford: Oxford University Press.
  13. ↑ Jessell, T.M., & Sanes, J.R. (2000). The induction and patterning of the nervous system. In E.R. Kandel, J.H. Schwartz, & T.M. Jessell (Eds.), Principles of neural science (4th edn., pp. 1019-1040). New York and London: McGraw-Hill.
  14. ↑ Stryker, M.P.; Strickland, S.L. (1984). "Physiological segregation of ocular dominance columns depends on the pattern of afferent electrical activity". Ophthalmological Visual Science (Suppl). 25 (6): 727–788.
  15. ↑ Johnson, M.H. (2005). Developmental cognitive neuroscience (2nd edn.). Oxford: Blackwell.
  16. ↑ Friston, K.J.; Price, C.J. (2001). "Dynamic representations and generative models of brain function". Brain Research Bulletin 15 (1): 94–100. doi:10.1016/s0361-9230(00)00436-6. PMID 11287132.
  17. ↑ Sadato, N.; Pascual-Leone, A., Grafman, J., Ibanez, V., Deiber, M.-P., Dold, G., & Gallett, M. (1996). "Activation of the primary visual cortex by braille reading in blind subjects". Nature 380 (6574): 526–528. doi:10.1038/380526a0. PMID 8606771.
  18. ↑ Johnson, M.H. (2000). "Functional brain development in infants: elements of an interactive specialization framework". Child Development 71 (1): 75–81. doi:10.1111/1467-8624.00120. PMID 10836560.

Further reading