1. Perceptual Development

2. Food for thought How do perceptual systems develop?
How do different senses interact in development?

3. General concepts Sensory receptors/Sense organs
General pattern of transmission
Sense organs Thalamus Cortical areas
Organizational principle
Topographical mapping
Receptors translate stimuli into electrical signals

4. Olfactory System development
Smell is one of the earliest emerging perceptual systems
The olfactory bulb acts as the major brain sensation organ for small
Ventral temporal lobe acts as primary cortical area
Olfactory areas have many connections with brain areas involved in memory

6. 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?

7. 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?

8. 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

9. Taste System 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?

11. Babies seem to prefer flavors that are adaptive for them
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
Example – Infant with imbalance in adrenal hormones that regulate salt had craving for salty foods

12. 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

13. Breast milk vs. formula
Breast – fed babies have been shown in some cases to out-perform bottle fed babies
Why?
Nutrition in breast milk
Difference in social relationship
Unlikely – babies fed breast milk through tubes (so no difference in interaction) still outperformed babies fed formula
Maternal education

14. 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

17. Types of touch
Different types of touch are associated with different types of receptors
Pain
Temperature

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

19. Most aspects of these functions are fairly mature at birth.

20. Whisker barrels in rodents
Whiskers are represented in “barrels”
Patch-like organization
Removal of whiskers increases area represented by each whisker
Significance for development/humans?

21. 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