Infancy

Infancy

Background Brain Anatomy

Two hundred billion neurons comprise the human brain, these specialized nerve cells transmit information through various connections, known as synapses,  with other neurons throughout the body.  As described below, throughout brain development different regions of the brain become functionally specialized for different functions such as receiving sensory information,  planning movements, or language. The diagram below indicates some general regions involved in these different functions.

The prefrontal cortex (not directly labelled above but considered the anterior portion of the brain) controls movement and higher cognitive functions, such as planning, consciousness, inhibition, memory, and problem solving. This region begins functioning more effectively after two months of age and continues to develop throughout the lifespan.

The limbic system controls the emotional components of our cognition as well as the learning of safe vs threatening stimuli in our environment which has promoted the survival of our species throughout time. The limbic structures include the amygdala and the hippocampus.

The reward centres of the brain include...

Some functions are mostly localized to one half, or hemisphere, of the brain. For example, in most individuals, especially those whose dominant hand is their right hand, the language centres are localized to the left hemisphere. Also, in terms of sensation and motor control, the opposite side of the body is controlled by a given hemisphere. Therefore, the right hemisphere receives sensory information from and controls movement of the left side of the body. This specialization of the hemispheres is known as lateralization.

Brain Development

During the first two years of life, neurons proliferate exponentially but also undergo programmed cell death. This is an important concept for learning throughout the lifespan because as we learn from our experiences neurons that are no longer required die (this is known as “synaptic pruning”), and new connections regarding what has stimulated us and what we have learned are created. Through this method various parts of the brain become somewhat specialized for various functions as described above. The process of myelination, by which neurons receive an outer fatty layer that speeds conduction, is responsible for much of the increases in brain size in early life.

There are sensitive periods in human brain development and environment affects brain growth. Children who have been victims of neglect and abuse show impairments in development, such as inattention, social disinterest, stereotyped behaviours, and high levels of  stress reactivity.

Brain Plasticity

Children, especially of younger ages, have an immense capacity for brain plasticity, whereby the brain is responsive to influential experiences. This quality is maintained throughout life but decreases in its intensity with age. According to the lifestyle perspective, “development is lifelong, multidimensional, multidirectional, highly plastic, and affected by multiple, interacting forces.” This means that if a region of the brain becomes damaged, especially early in life, other areas of the brain may be able to take over its function and compensate on its behalf.

Piaget’s Cognitive Development Theory

According to Piaget’s Cognitive Development Theory, children actively learn as they manipulate and experience the environment around them. This theory encompasses intellectual development from infancy to adulthood. Piaget describes the following stages:

1. sensorimotor stage (0-2 years): infants and toddlers “think” with through sensorimotor means, thereby using their eyes, ears, and hands to learn.
2. preoperational stage (2-7 years): children think more symbolically, they show advancements in language, imagination (make believe play), and memory.
3. concrete operational stage (7-12 years): children now display more concrete, logical reasoning, thinking becomes less egocentric.
4. formal operational stage (12 years-adulthood): adolescents and adults may use symbols to relate to abstract concepts, for example when learning algebra.

Development of Attachment

Attachment is the emotional connection formed between an infant and their caregivers. The ethological theory of attachment recognizes an infant’s emotional tie to the caregiver as “an evolved response” promoting survival. Often, between the ages of 6 months to two years separation anxiety increases when a parent leaves the sight of an infant. This is dependent on both the attachment formed with caregivers and the temperament of the child. There are different forms of attachment that are dependent upon cultural variation and other variables, but especially the consistency of early caregivers:

1. secure attachment: separation anxiety occurs and is alleviated when the parent returns, the child prefers the caregiver to strangers
2. avoidant attachment: the infant is unresponsive to a present caregiver and not distressed when that caregiver leaves, they treat strangers and caregivers similarly
3. resistant attachment: these infants are overly attached when their caregivers are present and fail to explore their environment, when the caregiver leaves they are distressed but when the caregiver returns their are angry and are not easily comforted
4. disorganized/disoriented attachment: these infants show confused behaviours when their caregivers return

Attachment patterns are also related to socioeconomic status. Families with low SES are more likely to encounter stressors and lack supports, thus insecure attachment forms and fluctuates between infants and caregivers. In later development, those who experienced secure attachment and sensitive parenting had better social, cognitive, and emotional outcomes.