Lecture 3: new-borns and reflexes

Question 1

Sensory Capabilities of Newborns (6)

Answer 1

• Touch: Includes sensations of pain, pressure, proprioception (awareness of body position), and temperature.
• Balance: Enabled by the vestibular system.
• Smell: Newborns can differentiate between smells from birth.
• Taste: Sensitivity to basic tastes: salt, bitter, sweet, and sour.
• Hearing: Newborns hear lower frequencies and improve sound localization over the first seven years.
• Farroni et al. (2002) studied sensory perception, including sound localization, in newborns.
• Vision: Visual clarity starts at 20/400 at birth and improves to 20/20 by about six months.

Question 2

Neonatal Behavioral Repertoires: Orienting Responses

Answer 2

• Visual Tracking: Following moving objects with their eyes.
• Auditory Tracking: Turning toward sound sources.

Question 3

Neonatal Behavioral Repertoires: Reflexes

Answer 3

• Clinging Reflexes: Palmar (hand) and plantar (foot) grasp, Moro reflex (startle response).
• Nursing Reflexes: Rooting (turning toward a stimulus on the cheek), sucking reflex.
• Locomotion Reflexes: Crawling and stepping movements.
• Vestigial Reflexes: Reflexes that have partially or fully lost their original purpose (e.g., Moro reflex).

Question 4

Postnatal Brain Growth: Neurons and Glial Cells

Answer 4

• Most neurons are present at birth, but glial cells continue to multiply.
• Glial cells provide structural support, maintain neurons, and insulate axons with myelin.

Question 5

Postnatal Brain Growth: Myelination

Answer 5

Formation of fatty sheaths (myelin) around axons, increasing nerve signal speed.
* Unmyelinated Nerves: Signal speed ~1 meter/second.
* Myelinated Nerves: Signal speed ~10–100 meters/second.

Question 6

Postnatal Brain Growth: Synaptogenesis

Answer 6

Creation of new connections between neurons.

Question 7

Critical periods in brain development and example

Answer 7

Specific times when certain sensory or social experiences are crucial for typical brain development.
* Hubel and Wiesel (1960s): Their monocular and binocular deprivation studies in cats highlight critical periods in visual development. When one eye was deprived of visual input during early development, the corresponding areas of the visual cortex did not develop properly, even if the eye was later restored.
* Congenital Cataracts: Highlighted by studies showing that untreated cataracts at birth severely affect visual development leading to permanent deficit.

Question 8

Sensitive Periods in brain development

Answer 8

Flexible periods when the brain is highly adaptable to certain stimuli.
* Bruce Perry et al. (2000s): Demonstrated the effects of extreme social deprivation and neglect on brain growth and function.

Question 9

Imaging Studies: PET Scans

Answer 9

Comparison by Children’s Hospital of Michigan of typically developing children versus neglected children (e.g., Romanian orphans) showed reduced glucose activity in the prefrontal and temporal regions of neglected children.

Question 10

Imaging Studies: CT Scans

Answer 10

Highlight differences in brain development in cases of sensory deprivation or neglect.