Introduction. Prenatal Development Stage
The Germinal Period: Last about 14 days in length) lasts from conception to implantation of the fertilized egg in the lining of the Uterus. The organism begins cell division through mitosis.
The Embryonic Period: Starting the third week the blastocyst has implanted in the uterine wall. During this period, cells continue to differentiate. Structures nearest the head develop. Gills and a tail are apparent.
The Fetal Period: From the ninth week until birth, the organism is referred to as a fetus. By the third month, the fetus has all its body parts including external genitalia. At 4th- 6th months, the eyes become more sensitive to light and hearing develops. At around 36 weeks the fetus is almost ready for birth.
Prenatal Brain Development: Starts in the third gestational week. Two ridges appear along the neural plate. At week eight, the neural tube is divided into the forebrain, midbrain, and hindbrain. Neural migration is accomplished in the cerebral cortex by 24 weeks.
The stages of cognitive development from ages 0-2 are integral in shaping a child’s understanding of the world and their ability to interact with it. During this period, the brain and the nervous system are changing rapidly, allowing for a wide range of new abilities to be developed. For example, the use of language and physical development allows infants and toddlers to communicate their needs and wants and make more complex movements (Zullei et al., 2020). In addition to this, the development of the nervous system allows for the recognition of familiar faces, the formation of mental images, and the understanding of abstract concepts.
Infancy and Toddlerhood: Sensory-Motor Period
Physical growth: Infant weighs 7.5 pounds and is 20 inches in length. At 4 months, the weight doubles and the brain grows faster and weights 250mg (Lally & Valentine-French, 2019).
Nervous System: In the first few months of life, an infant’s cognitive development is Sensory-Motor. During this stage, infants use their senses to explore their environment and to learn. During this stage, infants also start to learn the basics of communication, such as babbling and pointing, and they start to develop their gross and fine motor skills. The brain and nervous system are developing rapidly in this period, allowing infants to learn more and more (Zullei et al., 2020). Infants learn to use their senses to make sense of their surroundings.
Infancy and Toddlerhood: Preoperational Stage
Physical development: At one year, the weight of the infant triples.
Brain development: At one year, the size of the brain is about 750mg and they are 33% the size of the adult’s brain (Lally & Valentine-French, 2019).
Nervous system: By the end of the first year, an infant’s cognitive development is Preoperational. This stage is marked by a period of symbolic thinking, as infants begin to think in terms of symbols and images rather than concrete objects to represent real-world objects. This stage is also marked by an increased use of language, as infants start to use words to communicate their needs and wants (Peng & Kievit, 2020). The development of the nervous system also allows for more complex movements, such as walking and running.
Infancy and Toddlerhood: Concrete Operations Stage
Physical growth: the weight of the infant at year 2 is quadrupled the initial size at birth.
Brain: During this time, the brain is approximately 55% of the adult’s brain size (Lally & Valentine-French, 2019).
Nervous system: During the second year, a toddler’s cognitive development is Concrete Operations. During this stage, children begin to use logic and reasoning to solve problems. They are also able to understand the concept of conservation, which means that the amount of an object does not change even when its shape does (Zullei et al., 2020). Additionally, children are able to understand more abstract concepts and are able to think more logically.
Infancy and Toddlerhood: Formal Operations Stage
By age two, toddler’s cognitive development is Formal Operations. During this stage, children are able to think more abstractly and make deductions and inferences from the information they have. Furthermore, they are able to reason logically and understand the cause and effect of their actions and the actions of others (Zullei et al., 2020). The development of the nervous system also allows for more complex movements, such as running and jumping. During this period, infants and toddlers understand simple concepts, and solve simple problems (Peng & Kievit, 2020). Finally, they are able to think abstractly and understand more complex concepts.
Other Physical Development and Nervous Development: At Birth-4 Months
At birth, a baby is largely helpless and dependent on others for survival (Zullei et al., 2020). During this time, the brain and nervous system will undergo dramatic changes in order to support this development (Lally & Valentine-French, 2019). In the first few months of life, a baby’s physical development is mostly reflexive and instinctive. This includes movements such as sucking, grasping, and blinking. This is when they begin to develop head control and can support their body weight when held upright (Lally & Valentine-French, 2019). During this time, they start to explore their environment with their hands and feet (Zullei et al., 2020). They also start to become more vocal and use primitive babbling to express themselves.
Other Physical and Nervous Development: 6 Months to 24 Months
By the age of six months, babies can usually roll over, sit up with support, and can recognize their environment (Lally & Valentine-French, 2019). They are also starting to recognize their own name, respond to simple commands, and imitate sounds and movements (Zullei et al., 2020). At nine months, babies should be able to crawl, get into a sitting position, and pull themselves up to stand. They may also be able to say a few simple words and understand simple instructions. At 18 months, the toddlers can usually walk independently and climb stairs with one hand. By the age of two, toddlers should be able to follow simple instructions and understand simple conversations.
Summary of Development of Brain and Nervous System
The development of the brain and nervous system is an integral part of physical development during this time. At birth, the brain is only 25%-33% of its adult size and will continue to grow rapidly over the first two years (Peng & Kievit, 2020; Lally & Valentine-French, 2019). During this time, the neurons in the brain become increasingly interconnected, allowing for more complex thought processes (Zullei et al., 2020). The nervous system also develops rapidly during this time, allowing for more refined motor control and coordination.
References
Lally, M., & Valentine-French, S. (2019). Lifespan development: A psychological perspective. (2rd ed.). y Martha Lally and Suzanne Valentine-French.
Peng, P., & Kievit, R. A. (2020). The development of academic achievement and cognitive abilities: A bidirectional perspective. Child Development Perspectives, 14(1), 15-20. Web.
Zullei, L., Iglesias, J. E., Ou, Y., Grant, P. E., & Fischl, B. (2020). Infant FreeSurfer: An automated segmentation and surface extraction pipeline for T1-weighted neuroimaging data of infants 0–2 years. Neuroimage, 218(1), 1-52. Web.