Recent research conducted at the California National Primate Research Center (CNPRC) has uncovered fascinating insights into the perception of touch in nonhuman primates, shedding light on how our brains process pleasurable sensations. Led by Ph.D. Candidate Joey Charbonneau and CNPRC core scientist Eliza Bliss-Moreau, the study investigates the neural responses to gentle, pleasurable touch. Given that the animals were anesthetized, researchers were surprised to find that the brain activity in monkeys mirrored that of humans experiencing pleasant touch. 

Published in the Proceedings of the National Academy of Sciences, the study unveils age-related differences in touch perception, sparking intriguing questions about consciousness and the brain’s processing of tactile stimuli. Understanding these mechanisms not only illuminates fundamental aspects of neuroscience but also has implications for various human conditions, from autism spectrum disorder to neurodegenerative diseases like Alzheimer’s. 

Using functional magnetic resonance imaging (fMRI), researchers examined the brain activity of monkeys who were anesthetized in response to slow, pleasurable touch (also known as affective touch) and faster, discriminative touch (referred to as discriminative touch). Remarkably, they found that the same brain regions activated from pleasurable touch in awake humans and monkeys who were not awake. This suggests that the rewarding aspects of affective suggests that touch transcend species boundaries and do not necessarily require consciousness. 

Moreover, the study identified age-related changes in how touch is represented in the brain, particularly in regions associated with affective processing. Older monkeys exhibited alterations in brain activity patterns to discriminative but not affective touch, highlighting the importance of considering age-related factors in understanding touch perception. 

Nonhuman primates serve as invaluable models for studying touch perception, offering insights that could inform additional research. By leveraging this model, researchers aim to understand the mechanisms underlying touch perception across the lifespan and develop interventions for age-related diseases impacting affective processing. 

This pioneering work, supported by the National Institute of Health and other funding sources, represents a crucial step toward unraveling the mysteries of touch perception and its implications for human health and well-being.