April 1, 2021

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This article was originally published as a chapter in the book “Design and Catastrophe: 51 Scientists Explore Evidence in Nature"

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Bonding or attachment is a basic instinct that binds the helpless newborn and the mother, real or surrogate. This mysterious but automatic binding relationship is symbiotic—favoring survival for the infant and affiliation of intimacy for the mother. Newborn babies sleeping alone on cot beds next to their mothers even for a short time have significantly higher heart rate and more restless sleep than those who co-sleep with their mothers and have skin-to-skin contact.[1] A fascinating animal study by Harry Harlow shows that baby monkeys prefer to cling onto a terry cloth mother than a wire mother with a milk bottle attached to it.[2] Mother’s intimacy is the environment most comfortable and restful during the early years of life.

Forming an unconscious but deep and permanent emotional bond at infancy is called “filial imprinting,” a term coined by a Nobel laureate, Konrad Lorenz, a behavioral ornithologist. Filial imprinting solidifies within a narrow window of time during infancy when the brain is most susceptible and sensitive to environmental stimuli.[3] In humans, the first three years of life determine the lifetime closeness and belongingness between the child and caregiver, primarily the mother. In animals, ewes lick their own lambs within four hours of giving birth in order to recognize their offspring from other young born to the flocks of sheep that graze that same time of year. Infant rats develop a lifetime preference to the smell similar to the nipples of the dam they suck during the first week of life, but not later.

Separation from the mother, the main caregiver, early in life spoils the filial imprinting.[4] It disturbs the immature and sensitive molecular, cellular, neurological, and physiological development of the individual with a long-term impact. Experts believe that psychiatric disorders, depression, anxiety, and addiction in adults originate from a compromising environment of infancy. Poor performance on memory, behavioral response, decision-making, fear or anxiety, and coping strategies later in life is a projection of the emotional damage sustained in the early years of life.

Emotional stress early in life has an undeniable impact on the cellular and molecular components of the brain[5] in adult experimental animals, particularly rats. For example, it reduces both the number of branches and connections of neurons in the medial frontal cortex, the region for emotional control and social behavior. It reduces production of neurotransmitters while increasing the production of neuroinflammatory molecules in the limbic regions, which are associated with mood disorders. It reduces long-term potential signals in the hippocampus, amygdala, and prefrontal cortex, loosening the bond between synapses and resulting in reduced memory and inadequate emotionality. It also delays the production of neurotransmitters for the optimal development and function of the brain.

Initially, I was neither a believer nor a fan of the so-called early separation research. When my professor assigned me to investigate its impact on young astrocytes, I rebelliously but silently agreed. My study was to answer the question, What is the impact of the early separation on astrocytes in the prefrontal cortex of infant trumpet-tailed rats, Octodon degus? My experimental strategy mimicked the separation in human babies from their mother during the pre-weaning stage.

I investigated the astrocytes in the prefrontal cortex of the brains of infant rats. As I watched infant rats scream in panic inside the isolation boxes searching for the dam, it seemed it was all behavioral, an outward reaction without any neurobiological component. But seeing through the microscope the damaged, broken, shrunken, and disfigured growing astrocytes, their reduced cell count, reduced branching complexity as well as reduced protein expression all due to separation,[6] I changed my mind. I realized that bonding is innate in all living things, particularly mammals. It is ingrained in the microscopic cells of the brain; separation is debilitating. Depending on the time and degree of exposure, separation may delay, disable, and/or stagnate the brain development for emotional and social control.

Astrocytes are indispensable partners for neurons in the mammalian brain.[7] They participate extensively in the formation, maturation, maintenance, and function of the brain for the entire period of development. During early development, astrocytes release gliotrophic and neurotrophic factors for neurite growth and extension in sculpting, pruning, and guiding the neurons to their final destinations in the brain. In the mature brain, astrocytes are active partners of neurons in synapses. They release gliotransmitters like glutamate that act on themselves and on neurons in order to propagate and regulate synaptic transmission. They are positioned strategically so that a single astrocyte may contact as many synapses as possible. They also form blood-brain barriers to prevent blood from entering the brain. During brain injury, they patch the affected site, forming a glial scar.

In recent decades, the hyperproliferation of astrocytes has become a prominent biomarker in neurological and psychiatric pathologies including Alzheimer’s Disease, Parkinson’s Disease, Down syndrome, depression, and schizophrenia.8 Yes, astrocytes are emotional. They respond to emotional stress, which I was privileged to observe firsthand.

In summary, bonding is a universal instinct initiated by God for the benefit of humans. We are made to attach, relate, and be emotional, intimate social beings—a reflection of who God is. The God of love plans that He bonds with us from eternity to eternity.

NOTES

[1] BE Morgan, AR Horn, NJ Bergman. Should neonates sleep alone? Biological Psychiatry 2011; 70(9):817–825.

[2] SJ Suomi, FC Van der Horst, R Van der Veer. Rigorous experiments on monkey love: an account of Harry F. Harlow’s role in the history of attachment theory. Integrative Psychological and Behavioral Science 2008; 42(4):354–369.

[3] J Chambers. The neurobiology of attachment: from infancy to clinical outcomes. Psychodynamic Psychiatry 2017; 45(4):542–563.

[4] T Sarkar, N Patro, IK Patro. Cumulative multiple early life hits: a potent threat leading to neurological disorders. Brain Research Bulletin 2019; 147:58–68.

[5] Z Duenas, JC Caicedo-Mera, L Torner. Global effects of early life stress on neurons and glial cells. Current Pharmaceutical Design 2017; 23(39):6042–6049.

[6] K Braun, R Antemano, C Helmeke, M Büchner, G Poeggel. Juvenile separation stress induces rapid region- and layer-specific changes in S100ßand glial fibrillary acidic protein-immunoreactivity in astrocytes of the rodent medial prefrontal cortex. Neuroscience 2009; 160(3):629–638.

[7] Duenas et al., op. cit. 8. CL Bender, GD Calfa, VA Molina. Astrocyte plasticity induced by emotional stress: a new partner in psychiatric physiopathology? Progress in Neuro-Psychopharmacology and Biological Psychiatry 2016; 65:68–77.

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Rowena R. Antemano is an adjunct professor of biology at Mountain View College in the Philippines. She holds a PhD in Developmental Neurobiology from Otto von Guericke University in Magdeburg. She loves teaching natural science courses, looking at cells through a microscope, writing brain-related articles, and conducting health-related seminars. She currently serves as editor in chief for the book project Grand Designs, sponsored by the Southern Asia-Pacific Division of Seventh-day Adventists.