Describe how the nervous system and brain develop in the first two years of life and how the environment affects such development.

The brain's development in the first few years of life is both rapid and remarkable. Neurological growth is characterized by an explosion in the number of connections, or synapses, between neurons. From birth to age two, a child's brain is busy forming these neural connections at a pace rarely seen later in life. It's during these formative years that critical skills such as language, motor functions, and problem-solving begin to emerge. As neurons establish more connections, the potential for learning expands, laying the groundwork for future intellectual acuity.

Reflective of the importance of this stage, the brain at two years old has twice as many synapses as the adult brain, which demonstrates the incredible plasticity and growth potential present in early development.

Myelination is a fascinating biological process that enables the efficient transmission of neural signals across the brain's pathways. During early childhood, many neurons are coated with a fatty substance known as myelin. This process enhances the speed and reliability of nerve impulse transmission, a critical factor in the developing nervous system. Aggregate myelination advances the child's ability to process complex information, thus influencing cognition and motor control. This phase is vital for sensory processing as well, as it allows for faster reactions and processing of sensory information, which is essential for babies learning to explore and understand their environment.

The saying 'nurture impacts nature' holds true when considering brain development during early childhood. The stimuli a child is exposed to can significantly shape the brain's architecture, influencing the course of neurological growth. Positive environmental factors, ranging from physical affection and verbal engagement to adequate nutrition and educational toys, can cultivate an optimal setting for a flourishing brain. In contrast, environments marred by neglect, traumatic stress, or sensory deprivation, may lead to neural pathways that are underdeveloped or miswired, adversely affecting the child's development. The brain's adaptability to environmental factors means that quality care and interactive learning experiences are key components in promoting healthy cognitive and emotional development.

Synapse formation, or synaptogenesis, is integral to cognitive development. A synapse is the junction between two neurons where information is transmitted, and as a child grows, countless synapses are formed to enable various brain functions. In these early years, children's brains are especially receptive to learning and experience, which can lead to an increase in synapse density. The 'use it or lose it' principle applies here; synapses that are frequently used strengthen over time, while those that don't may be pruned away in a process that enhances neural network efficiency. This selective pruning ensures that a child's brain remains adaptable and can form strong connections that support higher cognitive functions such as memory, attention, and problem-solving skills.