Children require sensory stimulation of an appropriate nature and duration, at the right time, failing which they are at high risk of developmental and cognitive delays. This is known to have been recorded in young babies who grew up in orphanages, and in preterm babies.

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One such sensory pathway is touch, which facilitates normal growth and development. From worms and rats to human beings, the offspring of each species shows positive responses to supplemental touch.

Research is still ongoing into the best ways to stimulate by touch and other sensations, so as to promote growth normalization and increase the level of response to multisensory stimuli, especially in children who were deprived of such stimulation in early life.

Multisensory integration is now recognized as being extremely important in the scheme of things. It seems to be acquired but to mature with growth, peaking in late childhood but with much variation depending on the level of prior experience.

Children with neurodevelopmental disorders often have impaired integration of multiple sensory modalities and must be trained to perceive and to interpret them correctly.

Lack of Tactile Stimulation

Experiments on rat pups reared in isolation vs under maternal care, and with those reared in isolation but modified by brief sessions of stroking, showed that deprivation of tactile stimulation (licking by the mother rat) caused aberrations of behavior in the deprived pups even after they became adults.

Morever, when these pups became mothers themselves, they failed to show fully maternal behavior towards their own pups. This has been seen in preterm babies kept in incubators for the first few weeks, deprived of touch but exposed to sounds and lights without always being able to correlate them with the source.

This can set them back in responding to social as well as environmental cues as they grow up. On the other hand, “kangaroo care” in which a baby is carried against the caregiver’s chest skin-to-skin in a carrier, wearing a diaper only, for at least an hour every day, for at least two weeks, has been shown to produce consistently improved scores in both mental and physical assessment, which persist for months afterwards.

Father holding a premature baby with an oxygen mask in Kangaroo method. Image Credit: Kristina Bessolova / Shutterstock

Brain Development and Sensory Stimulation

Mechanosensory stimulation is thus very important in the development of a baby, and it is difficult to reverse the negative effects in an individual who was deprived of it in early life.

Research has shown that the newborn’s brain develops 2-3 million synapses each second! These synapses forge the route for sensory messages to reach the brain, and the more they are used, the more quickly they become permanent. If not used they may die out, a phenomenon called pruning, which is really meant to prevent information overload by cutting out non-functional pathways.

Sensory stimulation is vital to develop these pathways, and thus promote normal development. It also helps the child learn about the world, communicate and form attachments to the people around.

Normal Maternal Stimulation

In most cases, daily interactions between a mother and her infant cause stimulation of key senses, mostly touch, but also stimulation of the joints, hearing, vision and balance.

According to research/evidence, the daily activity found to be most stimulating is feeding, while playing with the baby, carrying, bathing and changing the diaper/clothing are other sources of mechanosensory stimulation.

Image Credit: Evgeny Atamanenko / Shutterstock

Sucking on a pacifier or other object is also beneficial in terms of promoting growth and maturation in preterm babies. It is seen that such sucking activity influences gastrointestinal endocrine secretions via the vagus nerve and may thus increase insulin release, stimulate gastrointestinal motility, and functional maturation. The mother also benefits from this by activation of the gut endocrine system and improved energy intake.

When compared on a minute-by-minute basis, research indicates that the most exciting activity is playing with the baby. However, individual differences exist between mothers and infants, which affect the amount of stimulation that occurs with each activity. Thus, individual counseling should be given to ensure that each infant is optimally stimulated at home when planning a remedial program.

Order of Sensory Maturation

Another finding is that all sensory systems do not mature simultaneously, but rather in a specific order which does not vary.

This is tactile > vestibular > chemical > auditory > visual. The baby thus has five senses working at very different levels at the time of birth.

The fetus has already developed much experience of tactile and vestibular system sensations by the time of delivery, including feeling when the mother is walking, laughing, talking, exercising, bathing and so on.

These different feelings are often accompanied by auditory cues and physiological differences such as an increased heartbeat, uterine contractions and stroking feelings when toweling down.

The auditory system develops much later, however, and thus knowing how the baby receives various sensory modalities has much to do with how activities are planned.

Tips on Sensory Stimulation in Babies

Some ways to promote stimulation of multiple senses in babies include:

• Introducing a variety of textured objects
• Playing in water at appropriate temperature
• Holding the baby up to face level, or lying down where the baby can see the caregiver’s face
• Spending time outside the house in quiet listening
• Sucking on clean objects
• Playing music appropriate for the child
• Watching moving objects such as fan blades, leaves, branches or shadows on a wall
• Bouncing balls where the baby can see them bounce and come back up again
• Rattles and other colorful and movable toys or objects (should be light and without sharp edges)
• Foods of different tastes and textures
• Coloring, painting, stamping and other art activities for toddlers
• Smelling various safe substances such as foods, flowers (if not allergic to pollen), grass
• Looking through various transparent colored objects

The infant should be supervised, and all objects should be clean and should not be capable of choking or suffocating the child.

Reviewed by Gillian D’Souza, MSc