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PERCEPTUAL DEVELOPMENT

PERCEPTUAL DEVELOPMENT. HDP 110. Outline: Perceptual Development. Chemical Senses - SMELL - TASTE Somatosensation. FOOD FOR THOUGHT: How do perceptual systems develop? How do different senses interact in development?. General Concepts. Sensory receptors/Sense organs

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PERCEPTUAL DEVELOPMENT

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  1. PERCEPTUAL DEVELOPMENT HDP 110 HDP110 C.N. Carlo

  2. Outline: Perceptual Development • Chemical Senses - SMELL - TASTE • Somatosensation • FOOD FOR THOUGHT: • How do perceptual systems develop? • How do different senses interact in development? HDP110 C.N. Carlo

  3. General Concepts • Sensory receptors/Sense organs • General pattern of transmission • Sense organs Thalamus Cortical areas • Receptors translate stimuli into electrical signals HDP110 C.N. Carlo

  4. Old Senses • In both “old” senses (taste and smell), input goes first to very primitive structures, then to cortical areas. • The more primitive aspects of this system may underlie differentiation early in development, with cortical control kicking in later HDP110 C.N. Carlo

  5. Olfactory System Development • Smell is one of the earliest emerging perceptual systems • The olfactory bulb acts as the major brain sensation organ for smell • Ventral temporal lobe acts as primary cortical area • Olfactory areas have many connections with brain areas involved in memory HDP110 C.N. Carlo

  6. Olfactory Bulb Olfactory Bulb HDP110 C.N. Carlo

  7. Thalamus OFC Olfactory bulb Olfactory epithelial cell Entorhinal cortex 1° olfactory cortex Air flow Olfactory Pathway HDP110 C.N. Carlo

  8. Olfactory System: Development 5 wks Nasal pit forms Olf. Bulb functions • Olfactory system becomes more acute in the first few days after birth • 6-7 years of age before the development of preference. HDP110 C.N. Carlo

  9. Olfactory System • New olfactory cells (in nostrils & olfactory bulbs) are generated throughout lifetime • Precursor cells are required for this generation • Relatively little plasticity – human olfactory system is largely developed by birth • Babies can smell in utero • Survival mechanism? HDP110 C.N. Carlo

  10. Early Development of Smell • Babies can identify smells (especially their mothers) very soon after birth. • Babies discriminate mother’s milk smell from other women very early • Early developed sense of smell might relate to social and cognitive development • How? HDP110 C.N. Carlo

  11. Taste System: Gustation • Also an early maturing system • Taste buds are receptor cells • Input to medulla, and from there to thalamus and limbic system • Why might it be important for the taste system to interact with the limbic system? HDP110 C.N. Carlo

  12. Taste Medulla HDP110 C.N. Carlo

  13. Smell info OFC = taste perception Cortical taste area Thalamus Taste nucleus in pons To limbic areas Taste nucleus in medulla Tongue Taste Pathway HDP110 C.N. Carlo

  14. Taste Development 35 wks Perceive taste identified by changes in swallowing or sucking 8 wks Taste buds emerge 13 wks communicating • At birth the ability to taste is fully developed • There is an increase in the number of taste buds HDP110 C.N. Carlo

  15. Babies and Taste • Babies discriminate and respond differently to different tastes from early on • Babies seem to prefer flavors that are adaptive for them • E.g., sweet is the “most popular” flavor for newborns, corresponds to milk. • Infants seem to be programmed to crave what’s good for them • E.g., Infant with imbalance in adrenal hormones that regulate salt had craving for salty foods. HDP110 C.N. Carlo

  16. Development of Taste • Role in dietary preference? • Perhaps, but there is very little data from humans • Preferences can also be learned • Conditioned responses and associative learning • Developments in taste perception • Some tastes are delayed • Salt preference increases with age • Wanes after about age 2 • May relate to organ development HDP110 C.N. Carlo

  17. Breast Milk vs.. Formula • Breast-fed babies have been shown in some cases to out-perform bottle bed babies • WHY? • Nutrition in breast milk • Difference in social relationship • UNLIKELY--babies fed breast milk through tubes (so difference in interaction) still outperformed babies fed formula • Maternal education HDP110 C.N. Carlo

  18. Tactile System • Involves synapses from sense organs to spinal chord, ultimately ending up in somatosensory cortex • Some sense of touch develops in utero • Touch involves very long axons – sensation continues to improve until they are myelinated HDP110 C.N. Carlo

  19. Touch Postcentral gyrus HDP110 C.N. Carlo

  20. Homunculus HDP110 C.N. Carlo

  21. Left somatosensory cortex Temperature& pain pathway Touch pathway Thalamus Spinal cord Touch Pathway Right fingers Brainstem HDP110 C.N. Carlo

  22. Pressure • Different type of receptors respond to different types of touch • Differences in how quickly they adapt or habituate • Complex stimuli activate a larger number and many different types of receptors • Spacing of receptors influences how sensitive a particular part of the body is • This sensitivity information is translated on the humunculus HDP110 C.N. Carlo

  23. Touch Development plasticity 6 wks Sense touch to the lips & nose 10 wks Entire body sensitive to touch 20 wks Thalamic neurons complete their connections to cortex Perception of touch • In utero sensation necessary to produce representation in cortex. HDP110 C.N. Carlo

  24. Whisker Barrels in Rodents • Whiskers are represented in “barrels” • Patch-like organization • Removal of whiskers increases area represented by each whisker http://www.neurobio.pitt.edu/barrels/figure1.html HDP110 C.N. Carlo

  25. Newborn Touch Therapy • Eliot suggests that touch and massage can help with later development • What might be a problem with this interpretation? • These data are much more well established for premature infants than for full term infants HDP110 C.N. Carlo

  26. Summary: Perceptional Development • Most aspects of these functions are fairly mature at birth. Taste identified Touch pathway complete Olfactory system functioning HDP110 C.N. Carlo

  27. Next Week:AUDITION& VISION HDP110 C.N. Carlo

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