11.1: Brain Development

Learning Objectives

1. Describe the timeline of brain growth from prenatal development through early childhood.
2. Identify the primary structures of the brain and their functions in early learning and development.
3. Distinguish between the roles of the left and right hemispheres and the function of the corpus callosum.

Introduction

Brain development begins long before birth, with neural structures forming as early as the first trimester. By the third trimester, the brain undergoes significant growth, establishing the foundation for sensory processing, movement, and early learning (Kolb & Gibb, 2011). At birth, the brain is about 25 percent of its adult weight. By age 2, it is at 75 percent of its adult weight, at 95 percent by age 6, and at 100 percent by age 7.

Neural connections, or synapses, form at an extraordinary rate, influenced by both genetic programming and early experiences (Center on the Developing Child at Harvard University, 2020). These connections create the brain’s architecture, which is refined through synaptic pruning—a process that strengthens frequently used pathways while eliminating those that are less active (Nelson, 2019).

The relationship between the body and the brain is deeply interconnected. As infants develop motor control, sensory awareness, and coordination, these physical developments significantly shape their cognitive and emotional growth (Shonkoff & Phillips, 2000). Likewise, the experiences young children have—such as caregiver interactions, sensory stimulation, and environmental exposure—directly influence both brain and body development. Positive experiences, such as responsive caregiving and rich learning environments, support healthy growth, while adverse experiences, such as chronic stress, can disrupt brain-body connections and impact long-term well-being (National Scientific Council on the Developing Child, 2014).

Understanding this dynamic interplay between brain and body is essential for fostering optimal development in early childhood. This section explores the foundational aspects of brain growth, the impact of early experiences, and strategies for promoting healthy cognitive and physical development in infants and toddlers.

Structures of the Brain

The human brain is a complex organ responsible for processing information, controlling movement, and regulating emotions. Understanding the basic structures of infants and toddlers helps explain how they learn, develop, and interact with the world around them.

The brain is divided into two halves, known as the left and right hemispheres. Each hemisphere specializes in different functions, a process known as lateralization (Kolb & Gibb, 2011). While both hemispheres communicate and work together, they tend to have distinct roles:

Left Hemisphere: Generally associated with language processing, logic, and analytical thinking. It becomes especially important as children begin developing speech and comprehension.

Right Hemisphere: Primarily involved in spatial abilities, creativity, and processing emotions. This hemisphere plays a crucial role in recognizing facial expressions and interpreting social cues.

Figure \(\PageIndex{1}\). Brain Lateralization. Image by Chickensaresocute is licensed CC BY-SA 2.5

The corpus callosum, a thick bundle of nerve fibers, connects the two hemispheres, allowing information to pass between them. This structure supports coordination between different types of thinking and movement, helping infants integrate sensory experiences and motor skills (Gazzaniga et al., 2018).

Figure \(\PageIndex{2}\). Emphasizing the Corpus Callosum. Image by Gray's Anatomy. Image is in the public domain.

Beyond the hemispheres and corpus callosum, several other brain regions play important roles in early development.

Table \(\PageIndex{1}\). Brain Structure and Primary Functions.

Brain Structure	Function(s)
Cerebral Cortex	Higher-level thinking, perception, and voluntary movement
Frontal Lobe	Planning, problem solving, and self-regulation
Temporal Lobe	Processing sounds, language, comprehension, and memory
Parietal Lobe	Interpreting sensory input, spatial awareness
Occipital Lobe	Visual processing and recognition
Cerebellum	Coordination of movement, balance, and posture
Hippocampus	Memory formation and learning
Amygdala	Processing emotions, particularly fear and attachment
Hypothalamus	Regulate hunger, sleep, and body temperature

Each of these structures develops rapidly during infancy and toddlerhood, influenced by genetics, experiences, and environmental factors. Early interactions, such as responsive caregiving and rich sensory experiences, help shape these brain areas and support overall development (Shonkoff & Phillips, 2000).

References, Contributors and Attributions

Center on the Developing Child at Harvard University. (2020). The science of early childhood development (InBrief). https://developingchild.harvard.edu/

Kolb, B., & Gibb, R. (2011). Brain plasticity and behavior in the developing brain. Journal of the Canadian Academy of Child and Adolescent Psychiatry, 20(4), 265–276.

National Scientific Council on the Developing Child. (2014). Excessive stress disrupts the architecture of the developing brain: Working paper No. 3. Harvard University.

Nelson, C. A. (2019). Neural plasticity and human development: The role of early experience in sculpting memory systems. Cambridge University Press.

Shonkoff, J. P., & Phillips, D. A. (Eds.). (2000). From neurons to neighborhoods: The science of early childhood development. National Academies Press.