From the third trimester of gestation through 24 months, the neural connections in a baby's brain increase by about threefold. During this time, the infant brain imprints genetic information into brain cells and body cells. To properly develop right-hemisphere functions pertaining to emotion, social interaction and creativity, the infant needs secure bonds of attachment with his caretakers, especially his mother. To develop left-hemisphere functions pertaining to logic, grammar and reason, he needs adequate sensory stimulus. Environmental factors can make the difference between well-adapted and maladapted brain chemistry.
Relationship Attachment
In experimental results published in the September 2001 publication of the "Infant Mental Health Journal," psychiatrist Allan Schore of the University of California School of Medicine documented a causal relationship between mother-child bonding and right-hemisphere development. Skin-to-skin contact between mother and child expands the neural connections responsible for stress adaptation, anxiety regulation and social bonding. Soothing and nurturing interactions between parent and child also increase the efficiency of the limbic system -- a set of neural connections that regulate humans' fight or flight response.
Stimulus
While right-hemisphere functions develop in the context of human relationships, left-hemisphere functions develop through interacting with objects. In a study published in the February 2008 edition of the "Public Library of Science Journal," brain scientist Véronique Izard found that infants who play with tactile toys such as blocks or clay exhibit greater left-hemisphere development than those who don't. Verbal stimulation helps develop the reasoning and linguistic skills localized in the left brain. Even simple conversation increases the strength of neural pathways associated with grammar, vocabulary and rational thinking.
Trauma
Infants who suffer from neglect or dysfunction within their primary relationships are susceptible to maladaptive right-brain development, which can lead to depression, psychosis and hyperaggression later in life. As late as 24 months, new genetic information is still encoding in the infant brain. The infant's environment influences what genetic information will be encoded. In his 2001 brain-image scanning experiments, Dr. Schore found that infants who suffer traumatic events encode less than optimal genetic information that prevents the brain from responding appropriately to social and emotional stimulus.
Relationship Between Hemispheres
The majority of brain functions involve both hemispheres. Higher-level mental functioning requires thousands of neural interactions that occur both within and between the hemispheres. Psychologist Eric Jensen, author of "A Fresh Look at Brain-Based Education," argues that the current right-brain/left-brain paradigm is based on a false notion of brain anatomy and functioning. The degree to which functions are localized within specific centers of the brains is a subject of wide dispute within the scientific community.
References
- "Infant Mental Health Journal"; Effects of a Secure Attachment Relationship on Right Brain Development, Affect Regulation, and Infant Mental Health; Allan Schore; September 2001
- "Public Library of Science Journal"; Distinct Cerebral Pathways for Object Identity and Number in Human Infant; Véronique Izard, et. al.; February 2008
- "Phi Delta Kappan" Magazine; A Fresh Look at Brain-Based Education; Eric Jensen; February 2008
