Biological Foundations of Developmental Psychology

Study Notes

Pre-natal and post-natal brain development are distinct phases of neural development
Piaget's theory of cognitive development, with its focus on pre-natal influences, has been challenged
Brain development is not just about the brain getting bigger; it involves changes in synapse density and long-range connectivity

Synapse Density and Long-Range Connectivity:

Brain has approximately 86 billion neurons (Herculano-Houzel, 2012)
Synapses are local connections, but long-range connections are essential for creating brain networks and enabling functions like speech
Connectivity changes during post-natal brain development
Brain development is crucial for understanding psychological development
Mark Johnson's textbook on developmental neuroscience introduced three ways brain development can lead to cognitive development
Inhibitory examples:
- Maturational account suggests brain activity becomes focused in specific areas, with the IFG showing increased activity during development (Smith et al., 2017)
- Interactive specialisation account suggests brain networks develop through coordination, as shown by better IFG-basal ganglia-thalamus coordination during development (Ruby et al., 2007)
- Skill learning requires executive function but decreases in activity once the skill is learnt (Simpson & Carroll, 2019)
Evolution and inheritance:
- Natural Selection relies on differences between individuals within a species (traits), their passing onto offspring, the fitness of certain traits, and the existence of excess individuals
- Unit of inheritance is the "gene," and different versions of a gene are "alleles"
- Monogenic traits were initially believed to be determined by a single gene, but now it is known that psychological traits are polygenic (the product of many genes, each with a small effect)
DNA is the heritable material in most life forms, composed of a four-letter code (A, T, G, and C) in a double-stranded form
DNA makes proteins, and proteins control development before and after birth
Humans have about 20,000 genes, more than half of which are expressed in the brain, and each gene influences every psychological trait
Gene definition changed from a unit of inheritance to a sequence of DNA that codes for a protein
Human genome was sequenced in the 1990s, and the project was completed in 2003
DNA is organized into chromosomes, with humans having 46 chromosomes (22 identical pairs and 23rd pairs, which are different - sex chromosomes)
Heritability is the proportion of variation in a population due to genetic influences, and it is a misunderstood concept.