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A mother picks up her baby and shows her a stuffed giraffe toy. She tells her baby that giraffes have long necks and spots. The child feels her mother’s arms around her, hears her voice, and looks at the giraffe.

The mother has provided tactile, auditory, and visual input, otherwise known as sensory signals. A new study has shown that when infants or young children experience unpredictable sensory signals from their parents, their brains, in particular their executive functioning, doesn’t develop properly and can contribute to mental health problems as they grow.

“It is widely known that a child’s early experiences have long-lasting impacts on brain development,” study author, Elysia Davis told us. “Infancy is a sensitive window when the baby’s brain is shaped by his or her experiences. We tested the novel idea that patterns of sensory signals from the mother influence the maturation of brain circuits that influence cognitive functions.”

It is known that patterned sensory signals to the developing brain are necessary for the maturation of sensory circuits (e.g., those that underlie hearing and vision). Davis and her team hypothesized that sensory signals and their patterns also influence the maturation of circuits underlying cognitive and emotional functions.

“It is our goal to understand how very early experiences in a child’s life impact later mental health,” Davis told us. “This is important in order to identify children who may be vulnerable to later mental illness and to establish early interventions.”
Researchers focused on the unpredictability of sensory signals to test the idea that patterns of maternal signals have a potent influence on the developing brain. Elysia explained that there is emerging evidence from research with animals that exposure to unpredictable maternal sensory signals has long-term consequences on brain circuits that lasts throughout the lifetime.

“Further, we have previously shown that exposure to unpredictability early in life impacts memory in both human children and rats.” Davis told us. “The current study tested the impact of unpredictability on executive function, an aspect of cognition that is plays a central role in emotional wellbeing.”

Researchers evaluating whether patterns of maternal sensory signals (auditory, tactile, visual) impact children’s cognitive development. To do this, they assessed two independent cohorts, one from Turku, Finland and another from Irvine, California. Exposure to sensory signals was assessed in the context of a caregiving interaction during infancy in both cohorts. Executive function was then evaluated longitudinally from infancy to childhood. Children in the Turku cohort were followed until 2.5 years of age and children in the Irvine cohort were followed to nine and a half.

“We found that exposure to unpredictable maternal sensory signals during infancy has negative consequences for infant and child outcomes,” Davis told us. “Importantly, this robust finding was present in two independent cohorts in California and Finland. The effect of unpredictable maternal signals on poor effortful control persisted for as long as the children were studied (through nine and a half years of age) and across different cultural contexts.”

Elysia explained that the result provides important support for the emerging concept that unpredictable patterns of sensory signals are related to executive function, an aspect of cognition that has broad consequences for mental health.

“Our research builds on prior studies showing the critical importance of parental care,” Davis told us. “What is surprising, is that the pattern of maternal sensory information, a relatively subtle signal, has as potent an impact as well-established risk factors such as maternal depression. In fact, unpredictability is related to child outcomes beyond the effects of other risk factors such as maternal depression.”

Patterns of maternal signals to her infant may play a fundamental role in shaping brain development. Unpredictable maternal sensory signals may be a form of early adversity that has enduring consequences and contributes to vulnerability to subsequent psychopathology.

“This study supports the idea that predictable care is crucial for the developing infant,” Davis told us, “and that reducing the impact of modern life intrusions, such as cell phones, that make our behavior more unpredictable could be an important goal.”

The enduring associations between early-life unpredictability and executive function through nine years of age suggests that this early exposure contributes to a developmental trajectory leading to increased vulnerability to subsequent psychopathology.