Neuroconstructivism is a theory that states that phylogenetic developmental processes such as gene–gene interaction, gene–environment interaction and, crucially, ontogeny all play a vital role in how the brain progressively sculpts itself and how it gradually becomes specialized over developmental time.
Supporters of neuroconstructivism, such as Annette Karmiloff-Smith, argue against innate modularity of mind, the notion that a brain is composed of innate neural structures or modules which have distinct evolutionarily established functions. 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.Fodor, J. (1983). The modularity of mind. Cambridge, MA: MIT Press.Pinker, S. (1994). The language instinct. London: Penguin. Modularity of the brain would require a pre-specified pattern of synaptic connectivity within the cortical microcircuitry of a specific neural system. Instead, Annette Karmiloff-Smith has suggested that the microconnectivity of the brain emerges from the gradual process of ontogenetic development.Karmiloff-Smith, A. (1992). Beyond modularity: A developmental perspective on cognitive science. Cambridge, MA: MIT Press, Bradford Books. Proponents of the modular theory might have been misled by the seemingly normal performances of individuals who exhibit a learning disability on tests. 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 within the brain do not measure underlying causes, instead only showing the static end-state of complex processes. 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. Such compensation could only have resulted from developmental neuroplasticity and the interaction between environment and brain functioning.
Different functions within the brain arise 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 led to differing capabilities of neurons or brain regions to handle specific functions. For example, the ventral and dorsal streams only arise because of innate differences in processing speed of neurons, not an innate selection to be either ventral or dorsal by the respective neurons. Such a differentiation has been entitled a domain-relevant approach to development.
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 in contrast argues for inherent, specific differences within the genes which directly control a person's development. While it cannot rule out domain-specificity, neuroconstructivism instead offers a developmental approach that focuses on change and emergent outcomes. Such change leads to domain-specificity in adult brains, but neuroconstructivism argues that the key component of the specificity occurred from the domain-general start state.
Every aspect of development is dynamic and interactive. 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. Dissociations seen in Williams syndrome or autism provide neuroscientists with a means of exploring different developmental trajectories.
Context dependence
Neuroconstructivism uses context to demonstrate the possible changes to the brain's neural connections. Starting with genes and incorporating progressively more context indicates some of the constraints involved in development. Instead of viewing the brain as independent of its current or previous environment, neuroconstructivism shows how context interacts with the brain to gradually form the specialized adult brain. In fact, by being built on preexisting representations, representations become increasingly context bound (rather than context free). This leads to "restrictions of fate" in which later learning is more restricted than earlier learning. Neuroconstructivism refers to how we construct our conceptual frameworks throughout our lives. It appeals to early childhood development, culture, and education.
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. This probabilistic epigenesis view of developmentGottlieb, G. (1992). Individual development and evolution. Oxford: Oxford University Press. suggests that instead of following a predetermined path to expression, genes 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).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. Over time, neurons interact either spontaneously or in response to some sensory stimulation to form neural networks. Although the exact number of neurons in the brain is an unknown, there are estimations ranging from 100 billion to an approximate 128 billion. This allows a vast neural network to be formed, and consequently a "storage capacity of the human brain." Competition between neurons plays a key role in establishing the exact pattern of connections. Through neuron-neuron communication made possible by the neuron's synapses, axon, and dendrites, different neurons can influence each other and lead to changes in the neural network. This is important for processing information and learning new material. This is possible because of neuron interactions that occur between neurons. As a result, specific 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 the manipulation of current neuronal structures by an organism's experience.
Enbrainment
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, constraining and specifying the development of each region. For example, the primary visual cortex in blind individuals has been shown to process tactile information. The function of cortical areas emerges as a result of this sensory input and competition for cortical space. "This interactive specialization view implies that cortical regions might initially be non-specific in their responses but gradually narrow their responses as their functional specialization restricts them to a narrower set of circumstances." Circumstances within a person's life can result in head trauma. Instances such as concussions from sports and high-impact accidents can result in the brain colliding into the skull. This causes neurons to be damaged and the brain to be bruised. During this time, brain function is temporarily lost since the neurons are being damaged. Repeated instances of head trauma can lead to the development of lasting brain damage.
Chronic stress causes long-term changes in the structure and function of the brain. This form of stress can cause an increase in myelin-producing cells and a decrease in neurons. Chronic stress reduces the amount of stem cells that grow into neurons, which may explain how it impacts learning and memory. Having said that, the neuronal network of a brain is continually changing due to plasticity. Chronic stress, as well as mindset and behaviour, are never resolved. The power of neuroplasticity allows to modify the shape and function of a brain throughout its lifespan.
Embodiment
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. 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 and the subsequent information received. Pro-activity while exploring the environment leads to altered experiences and consequently altered cognitive development.
Constructing and reconstructing schemas